Anti-hemagglutinin antibodies and uses thereof

Abstract

Provided herein are antibodies and fragments thereof that bind to hemagglutinin (HA) of H5 influenza A viruses of clade 2.3.4.4b, host cells for producing such antibodies and antigen-binding fragments, and kits comprising such antibodies and antigen-binding fragments. Also provided herein are compositions comprising antibodies and fragments thereof that bind to HA of an influenza A virus clade 2.3.4.4b and methods of using such antibodies and antigen-binding fragments to diagnose, prevent and / or treat influenza virus disease.

Description

Attorney Docket No. 6923-437-228ANTI-HEMAGGLUTININ ANTIBODIES AND USES THEREOFCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U. S. Provisional Patent Application No. 63 / 760,049, filed February 18, 2025, the disclosure of which is incorporated by reference herein in its entirety.1. GOVERNMENT SUPPORT CLAUSE

[0002] This invention was made with Government support under award 75N93021C00014 and 75N39019C00051 awarded by the National Institutes of Health. The Government has certain rights in this invention.2. SEQUENCE LISTING

[0003] This application contains an electronic Sequence Listing which has been submitted in XML file format with this application, the entire content of which is incorporated by reference herein in its entirety. The Sequence Listing XML file submitted with this application is entitled “06923-437-228_SEQ_LISTING.xml”, was created on February 17, 2026, and is 322,850 bytes in size.3. INTRODUCTION

[0004] Provided herein are antibodies and fragments thereof that bind to hemagglutinin (HA) of H5 influenza A viruses of clade 2.3.4.4b, host cells for producing such antibodies and antigen-binding fragments, and kits comprising such antibodies and antigen-binding fragments. Also provided herein are compositions comprising antibodies and fragments thereof that bind to HA of an influenza A virus clade 2.3.4.4b and methods of using such antibodies and antigen-binding fragments to diagnose, prevent and / or treat influenza virus disease.4. BACKGROUND

[0005] Highly pathogenic H5N1 avian influenza virus emerged as a human disease in 19971. After variable H5N1 virus activity in the years before the coronavirus disease 2019 (COVID-19) pandemic, a subclade of H5N1, clade 2.3.4.4b, started to spread globally in 2022. This spread has resulted in significant losses in the poultry industry and endangered millions of wild birds2,3. This virus clade has also spilled over into mammals, causing severe disease and high fatality rates4. In March 2024, the virus was detected in the United States (U. S.) dairy cattle, spreading among herds with high titers of virus present in the cow’s milk and in October 2024, virus was detected in a pig in a backyard farm in Oregon5. Even more alarming is the reported transmission of the virus to humans, posing a risk to workers who areNAI-5010413635vl 1in contact with infected animals and raising concerns about the potential for a pandemic. So far, more than 70 clade 2.3.4.4b human infections have been reported, with the vast majority in the U. S. While antivirals licensed for seasonal influenza are likely effective for H5N1, there are currently no long-acting treatments available6,7. Thus, there is a need for prophylactic and therapeutic agents for use in potential future H5N1 epidemics or pandemics.5. SUMMARY

[0006] Provided herein are antibodies and fragments thereof that bind to H5 influenza A virus (e.g., H5 influenza A virus of clade 2.3.4.4b) HA and the use of those antibodies and antigen-binding fragments. In some embodiments, provided herein is an antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region (VH) complementarity determining region (CDR)1 comprising the amino acid sequence of SEQ ID NO: 55, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 61; and (ii) a variable heavy chain region (VL) CDR1 comprising the amino acid sequence of SEQ ID NO: 64, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 66; (B)(i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 67, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 71, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 75; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 211, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 79, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 80; or (C)(i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 81, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 82, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 83; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 86, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 87. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 1; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 6; (B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 2; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8; (C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 7; (D) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 4; and NAI-5010413635vl 2(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8; or (E) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 5; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8. In a specific embodiments, the antibody or antigen-binding fragment thereof comprises: (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 7. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to 95% the amino acid sequence of SEQ ID NO: 1; and (ii) a variable light chain region comprising an amino acid sequence at least 95% identical to the amino acid sequence of SEQ ID NO: 6; (B) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 2; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 8; (C) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 7; (D) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 4; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 8; or (E) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 5; and (ii) the variable light chain region comprises the amino acid sequence of SEQ ID NO: 8.. In a specific embodiments, the antibody or antigen-binding fragment thereof comprises: (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 7.

[0007] In some embodiments, provided herein is an antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 88, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 89, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 90; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 94, a VL CDR2 comprising the amino acid sequence LGX, wherein X is S or T, and a VL CDR3 comprising the amino NAI-5010413635vl 3acid sequence of SEQ ID NO: 98; (B) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 99, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 100, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 101; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 104, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 108, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 109; or (C) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 110, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 111, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 112; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 115, a VL CDR2 comprising the amino acid sequence LGX, wherein X is S or T, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 116. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 9; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 12; (B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 10; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 13; or (C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 11; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 14. In a specific embodiments, the antibody or antigen-binding fragment thereof comprises: (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 11; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 14. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 9; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 12; (B) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 10; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 13; or (C) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 11; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 14. In a specific embodiments, the antibody or antigen-binding fragment thereof comprises: (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identicalNAI-5010413635vl 4to the amino acid sequence of SEQ ID NO: 11; and (ii) a variable light chain region an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 14.

[0008] In some embodiments, provided herein is an antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 119, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 122, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 125; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 194, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 127; (B) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 130, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 134, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 137; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 140, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 141, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 142; or (C) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 143, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 146, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 149; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 207, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 151. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 15 and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20; (B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 16; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20; (C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 17; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 21; (D) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 18; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20; or (E) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 19; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 22. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 15 and (ii) a variable light chain region comprises the amino acid sequence of SEQ ID NO: 20; (B) (i) a variable heavy chain region comprising NAI-5010413635vl 5an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 16; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 20; (C) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 17; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 21; (D) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 18; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 20; or (E) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 19; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 22. In a specific embodiments, the antibody or antigen-binding fragment thereof comprises: (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 19; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 22.

[0009] In some embodiments, provided herein is an antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 154, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 155, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 156; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 157, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 158, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 159; (B) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 160, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 161, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 162; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 163, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 164, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 165; or (C) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 168, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 169, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 170; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 171, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 158, and a VL CDR3 comprising the NAI-5010413635vl 6amino acid sequence of SEQ ID NO: 172. In some embodiments, the antibody or antigenbinding fragment thereof comprises: (A) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 23; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 25; or (B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 24; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 25. In some embodiments, the antibody or antigenbinding fragment thereof comprises: (A) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 23; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 25; or (B) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 24; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 25.

[0010] In some embodiments, provided herein is an antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 190, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 191, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 192; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 177, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 195; (B) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 130, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 196, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 197; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 198, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 199, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 200; or (C) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 201, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 208, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 203; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 204, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 205. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 15 and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20; (B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 16; and(ii) a variable NAI-5010413635vl 7light chain region comprising the amino acid sequence of SEQ ID NO: 20; (C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 17; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 21; (D) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 18; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20; (E) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 19; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 22; or (F) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 26; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 27. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 15 and (ii) a variable light chain region comprises the amino acid sequence of SEQ ID NO: 20; (B) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 16; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 20; (C) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 17; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 21; (D) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 18; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 20; (E) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 19; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 22; or (F) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 26; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 27.

[0011] In some embodiments, provided herein is an antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the variable heavy chain region (VH) complementarity determining region (CDR) 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 1; and (ii) the variable light chain region NAI-5010413635vl 8(VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 6; (B) (i) the variable heavy chain region (VH)CDRl, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 2; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 8; (C) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 3; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 7; (D) (i) the variable heavy chain region (VH) CDR1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 4; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 8; (E) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 5; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 8; (F) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 9; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 12; (G) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 10; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 13; (H) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 11; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 14; (I) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 15; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 20; (J) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 16; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 20; (K) (i) the variable heavy chain region (VH) CDR1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 17; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 21; (L) (i) the variable heavy chain region (VH) CDR1, NAI-5010413635vl 9the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 18; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 20; (M) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 19; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 22; (N) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 23; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 25; (O) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 24; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 25; or (P) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 26; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 27.

[0012] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 55, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 56, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 59; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 62, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 66; (B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 67, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 68, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 72; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 76, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 79, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 80; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 81, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 82, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 83; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 84, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 87.NAI-5010413635vl 10

[0013] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 55, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 57, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 59; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 63, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 66; (B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 67, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 69, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 72; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 77, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 79, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 80; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 81, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 82, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 83; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 85, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 87.

[0014] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 55, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 56, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 209; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 210, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 66; (B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 67, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 70, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 73; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 78, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 79, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 80; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 81, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 82, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 83; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 212, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 87.NAI-5010413635vl 11

[0015] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 55, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 56, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 209; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 63, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 66; (B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 67, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 70, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 73; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 77, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 79, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 80; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 81, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 82, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 83; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 85, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 87.

[0016] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 55, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 56, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 60; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 63, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 66; (B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 67, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 70, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 74; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 77, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 79, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 80; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 81, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 82, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 83; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 85, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 87.NAI-5010413635vl 12

[0017] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 88, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 89, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 90; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 91, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 98; (B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 99, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 100, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 101; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 102, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 105, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 109; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 110, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 111, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 112; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 113, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 116.

[0018] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 88, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 89, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 90; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 92, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 98; (B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 99, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 100, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 101; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 103, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 106, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 109; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 110, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 111, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 112; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 114, the VL CDR2 comprises the NAI-5010413635vl 13amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 116.

[0019] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 88, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 89, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 90; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 93, the VL CDR2 comprises the amino acid sequence LGT, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 98; (B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 99, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 100, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 101; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 102, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 107, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 109; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 110, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 111, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 112; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 113, the VL CDR2 comprises the amino acid sequence LGT, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 116.

[0020] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 117, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 120, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 123; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 126, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 127; (B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 128, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 131, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 135; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 138, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 141, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 142; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 143, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 144, NAI-5010413635vl 14and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 147; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 150, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 151.

[0021] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 118, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 121, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 123; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 126, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 127; (B)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 129, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 132, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 135; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 138, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 141, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 142; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 143, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 145, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 147; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 150, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 151.

[0022] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 118, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 121, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 123; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 126, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 127; (B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 129, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 133, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 135; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 138, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 141, and the VL CDR3 comprises the amino acid NAI-5010413635vl 15sequence of SEQ ID NO: 142; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 143, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 145, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 147; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 150, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 151.

[0023] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 117, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 121, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 123; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 126, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 127; (B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 128, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 213, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 135; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 138, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 141, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 142; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 143, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 145, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 147; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 150, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 151.

[0024] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 117, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 120, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 124; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 193, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 127; (B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 128, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 131, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 136; and (ii) the VL NAI-5010413635vl 16CDR1 comprises the amino acid sequence of SEQ ID NO: 139, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 141, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 142; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 143, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 144, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 148; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 206, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 151.

[0025] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 152, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 155, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 156; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 157, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 158, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 159; (B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 160, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 161, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 162; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 163, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 164, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 165; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 166, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 169, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 170; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 171, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 158, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 172.

[0026] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 153, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 155, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 156; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 157, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 158, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 159; (B) (i) the VH CDR1 comprises the amino acid NAI-5010413635vl 17sequence of SEQ ID NO: 160, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 161, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 162; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 163, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 164, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 165; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 167, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 169, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 170; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 171, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 158, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 172.

[0027] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 173, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 174, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 175; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 176, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 178; (B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 128, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 180, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 181; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 182, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 183, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 184; or (C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 185, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 186, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 187; and (ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 188, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 189.

[0028] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 1; and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 6; (B) (i) a variable heavy chain region amino acid NAI-5010413635vl 18sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 2; and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 8; (C) (i) a variable heavy chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 7; (D) (i) a variable heavy chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 4; and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 8; (E) (i) a variable heavy chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 5; and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 8; (F) (i) a variable heavy chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 9; and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 12; (G) (i) a variable heavy chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 10; and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 13; (H) (i) a variable heavy chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 11; and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 14; (I) (i) a variable heavy chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 15 and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 20; (J) (i) a variable heavy chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 16; and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 20; (K) (i) a variable heavy chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 17; and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 21; (L) (i) a variable heavy chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 18; and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 20; (M) (i) a variable heavy chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 19; and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino NAI-5010413635vl 19acid sequence of SEQ ID NO: 22; (N) (i) a variable heavy chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 23; and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 25; (O) (i) a variable heavy chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 24; and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 25; or (P) (i) a variable heavy chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 26; and (ii) a variable light chain region amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 27. In some embodiments, the variable heavy chain region amino acid sequence and variable light chain region amino acid sequence each have at least 96%, at least 97%, at least 98%, or at least 99% identity to the recited amino acid sequence.

[0029] In a specific embodiment, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (i) a variable heavy chain region comprising an amino acid sequence that is at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 7. In a specific embodiment, provided herein is an antibody or antigenbinding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (i) a variable heavy chain region comprising an amino acid sequence that is at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 11; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 14. In a specific embodiment, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (i) a variable heavy chain region comprising an amino acid sequence that is at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 19; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 22. In a specific embodiment, provided herein is an antibody or NAI-5010413635vl 20antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (i) a variable heavy chain region comprising an amino acid sequence that is at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 26; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 27.

[0030] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 1; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 6; (B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 2; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8; (C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 7; (D) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 4; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8; (E) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 5; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8; (F) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 9; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 12; (G) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 10; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 13; (H) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 11; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 14; (I) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 15 and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20; (J) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 16; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20; (K) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 17; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 21; (L) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 18; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20; (M) (i) a variable heavy chain region NAI-5010413635vl 21comprising the amino acid sequence of SEQ ID NO: 19; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 22; (N) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 23; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 25; (O) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 24; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 25; or (P) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 26; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 27.

[0031] In a specific embodiment, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 7. In a specific embodiment, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigenbinding fragment thereof comprises: (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 11; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 14. In a specific embodiment, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 19; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 22. In a specific embodiment, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 26; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 27.

[0032] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO: 15; and (ii) a variable light chain region amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO: 20; (B) (i) a variable heavy chain region amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO: 16; and (ii) NAI-5010413635vl 22a variable light chain region amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO: 20; (C) (i) a variable heavy chain region amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO: 17; and (ii) a variable light chain region amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO: 21; (D) (i) a variable heavy chain region amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO: 18; and (ii) a variable light chain region amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO: 20; (E) (i) a variable heavy chain region amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO: 19; and (ii) a variable light chain region amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO: 22; or (F) (i) a variable heavy chain region amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO: 26; and (ii) a variable light chain region amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO: 27.

[0033] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO: 26; and (ii) a variable light chain region amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO: 27.

[0034] In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof competes for binding with the antibody or antigen-binding fragment thereof provided herein (e.g., a clonotype antibody provided herein), and wherein the antibody or antigen-binding fragment binds to: (a) three or more or all of amino acid residues 125B, 128, 129, 168, 169, 123, 124, 125, 168, 167, 169, 126, 129, 164, 129, 162, 163, 165, 167, 187, 189, 219, 227, 244, and 246 of SEQ ID NO: 179; (b) three or more, or all of amino acid residues 125B, 128, 129, 168, 169, 171, 123, 124, 168, 167, 126, 165, 166, 163, 166, 162, 163, 165, 167, 169, 187, 189, 219, 227, 242, 244, 246 and 323 of SEQ ID NO: 179; (c) three or more, or all of amino acid residues 125B, 128, 171, 168, 169, 171, 166, 168, 167, 126, 129, 163, 165, 167, 169, 219, 222, 227, 242, 244, and 323 of SEQ ID NO: 179; or (d) three or more, or all of amino acid residues 98, 125A, 127, 128, 129, 130, 131, 132, 133, 133A, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 152, 153, 154, 155, 156, 157, 158, 159, 161, 183, 185, 186, 190, 191, 192, 193, 194, NAI-5010413635vl 23195, 222, 224, 225, 226, 227, 228, 229, 230, 251, 252, and 253 of the amino acid sequence of SEQ ID NO: 179. In a specific embodiment, provided herein is an antibody or antigenbinding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof competes for binding with a clonotype antibody provided herein, and wherein the antibody or antigen-binding fragment binds to or engages amino acid residues 125, 167, 169, and 169 of the amino acid sequence of SEQ ID NO: 179. In some embodiments, provided herein is an antibody or antigen-binding fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof competes for binding with a clonotype antibody provided herein, and wherein the antibody or antigen-binding fragment inserts into the hydrophobic groove composed of amino acid residues 123-129 and 164-171 of the amino acid sequence of SEQ ID NO: 179.

[0035] In some embodiments, provided herein is an antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises: (A) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 1; and (ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 6; (B) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 2; and (ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 8; (C) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 3; and (ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 7; (D) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 4; and (ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 8; (E) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 5; and (ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 8; (F) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 9; and (ii) a light chain comprising a variable light NAI-5010413635vl 24chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 12; (G) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 10; and (ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 13; (H) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 11; and (ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 14; (I) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 15 and (ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 20; (J) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 16; and (ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 20; (K) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 17; and (ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 21; (L) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 18; and (ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 20; (M) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 19; and (ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 22; (N) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 23; and (ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 25; (O) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 24; and (ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 25; or (P) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino NAI-5010413635vl 25acid sequence of SEQ ID NO: 26; and (ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 27.

[0036] In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is an avian influenza A virus H5N1. In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is influenza virus A / mallard / New York / 22-008760-007-original / 2022 (H5), A / chicken / New York / NYCVH 168127 / 2023 (H5N1), A / Canada goose / New York / NYCVH 23-453 / 2023 (H5N1), A / Canada goose / New York / NYCVH 22-9190 / 2022 (H5N1), A / peregrine falcon / New York / NYCVH 160820 / 2022 (H5N1), A / red-tailed hawk / New York / NYCVH 22-8477 / 2022 (H5N1), A / bald eagle / FL / W22-134-OP / 2022 (H5N1), A / chicken / Netherlands / 14015531 / 2014 (H5N8), A / northem pintail / WA / 40964 / 2014 (H5N1), A / dairy cattle / Texas / 24-008749-001-original / 2024 or A / Jiangsu / NJ210 / 2023 (H5N1). In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is an H5 influenza A virus of clade 2.3.4.4b in Section 8.

[0037] In some embodiments, the antibody or antigen-binding fragment thereof is any one of a Fab, Fab’, F(ab’)2, Fv, scFv, (scFv)2, single chain antibody molecule, dual variable region antibody, single variable region antibody, linear antibody, V antibody, a monoclonal antibody, a bispecific antibody, or a multi-specific antibody. In some embodiments, the antibody or antigen-binding fragment thereof is a chimeric antibody or a human antibody. In some embodiments, the antibody or antigen-binding fragment thereof comprises human-derived heavy and light chain constant regions. In some embodiments, the heavy chain constant region has an isotype selected from the group consisting of gammal, gamma2, gamma3, and gamma4. In some embodiments, the light chain constant region has an isotype selected from the group consisting of kappa and lambda. In some embodiments, the antibody is an immunoglobulin comprising two identical heavy chains and two identical light chains. In some embodiments, the antibody is an IgGl. In some embodiments, the antibody further comprises an IgGl heavy chain constant region and kappa light chain constant region. In some embodiments, the antibody or antigen-binding fragment thereof is recombinant. In some embodiments, the antibody is conjugated to a detectable agent, a diagnostic agent, or a therapeutic agent.

[0038] In another aspect, provided herein is a polynucleotide or set of polynucleotides encoding the antibody or antigen-binding fragment thereof provided herein. In some embodiments, provided herein is an isolated polynucleotide or set of polynucleotides encoding an antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A NAI-5010413635vl 26virus of clade 2.3.4.4b, wherein the polynucleotide or set of polynucleotides comprises: (A) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 28; and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 33; (B) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 29; and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 35; (C) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 30; and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 34; (D) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 31; and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 35; (E) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 32; and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 35; (F) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 36; and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 39; (G) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 37; and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 40; (H) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 38; and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 41; (I) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 42 and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 47; (J) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence NAI-5010413635vl 27comprises the nucleic acid sequence of SEQ ID NO: 43; and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 47; (K) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 44; and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 48; (L) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 45; and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 47; (M) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 46; and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 49; (N) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 50; and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 52; (O) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 51; and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 52; or (P) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 53; and (ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 54. In some embodiments, the polynucleotide or set of polynucleotides comprises deoxyribonucleic acids, ribonucleic acids, or a combination thereof. In some embodiments, the polynucleotide or set of polynucleotides is / are isolated.

[0039] In another aspect, provided herein is a vector or set of vectors comprising a polynucleotide or a set of polynucleotides provided herein. In some embodiments, the vector or set of vectors is / are an expression vector or set of expression vectors. In some embodiments, the polynucleotide or set of polynucleotides is or are operably linked to one or more regulatory regions. In another aspect, provided herein is a host cell comprising a polynucleotide or a set of polynucleotides provided herein, or a vector or a set of vectors provided herein.NAI-5010413635vl 28

[0040] In another aspect, provided herein are compositions (e.g., pharmaceutical compositions). In some embodiments, provided herein is a composition (e.g., a pharmaceutical composition) comprising a polynucleotide or a set of polynucleotides provided herein or a vector or a set of vectors provided herein. In some embodiments, provided herein is a lipid nanoparticle comprising a polynucleotide or a set of polynucleotides provided herein. In some embodiments, provided herein is a lipid nanoparticle comprising a vector or a set of vectors provided herein. In some embodiments, provided herein is a composition (e.g., a pharmaceutical composition) comprising such a lipid nanoparticle.

[0041] In some embodiments, provided herein is a composition comprising one or more of the antibodies or antigen-binding fragments thereof provided herein. In some embodiments, provided herein is a pharmaceutical composition comprising one or more of the antibodies or antigen-binding fragments thereof provided herein, and one or more pharmaceutically acceptable carriers, excipients, or stabilizers. In some embodiments, provided herein is a pharmaceutical composition comprising one or more of the antibodies or antigen-binding fragments thereof provided herein, and one or more of any one of a buffer and a stabilizer.

[0042] In some embodiments, provided herein is a composition (e.g., a pharmaceutical composition) comprising: (A) a first antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the first antibody or antigen-binding fragment thereof comprises: (a) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 55, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 61; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 64, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 66; (b) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 67, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 71, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 75; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 211, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 79, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 80; or (c) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 81, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 82, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 83; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 86, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 NAI-5010413635vl 29comprising the amino acid sequence of SEQ ID NO: 87; and (B) a second antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the second antibody or antigen-binding fragment thereof comprises: (a) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 88, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 89, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 90; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 94, a VL CDR2 comprising the amino acid sequence LGX, wherein X is S or T, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 98; (b) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 99, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 100, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 101; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 104, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 108, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 109; or (c) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 110, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 111, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 112; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 115, a VL CDR2 comprising the amino acid sequence LGX, wherein X is S or T, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 116. In some embodiments, the second antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 9; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 12; (B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 10; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 13; or (C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 11; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 14. In some embodiments, the first antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 1; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 6; (B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 2; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8; (C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 7; (D) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 4; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8; or (E) (i) a variable heavy NAI-5010413635vl 30chain region comprising the amino acid sequence of SEQ ID NO: 5; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8. In some embodiments, the first antibody or antigen-binding fragment thereof comprises (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 7; and the second antibody or antigen-binding fragment thereof comprises (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 11; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 14. In some embodiments, the composition provided herein further comprises one or more pharmaceutically acceptable carriers, excipients, or stabilizers.

[0043] In some embodiments, provided herein is a composition (e.g., a pharmaceutical composition) comprising: (A) a first antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the first antibody or antigen-binding fragment thereof comprises: (a) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 55, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 61; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 64, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 66; (b) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 67, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 71, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 75; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 211, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 79, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 80; or (c) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 81, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 82, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 83; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 86, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 87; and (B) a second antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the second antibody or antigen-binding fragment thereof comprises: (a) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 119, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 122, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 125; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 194, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 NAI-5010413635vl 31comprising the amino acid sequence of SEQ ID NO: 127; (b) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 130, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 134, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 137; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 140, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 141, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 142; or (c) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 143, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 146, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 149; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 207, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 151. In some embodiments, the second antibody or antigenbinding fragment thereof comprises: (A) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 15; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20; (B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 16; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20; (C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 17; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 21; (D) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 18; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20; or (E) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 19; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 22. In some embodiments, the first antibody or antigen-binding fragment thereof comprises: (A) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 1; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 6; (B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 2; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8; (C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 7; (D) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 4; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8; or (E) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 5; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8. In some embodiments, the first antibody or antigen-binding fragment thereof comprises (i) a variable heavy chain region NAI-5010413635vl 32comprising the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 7; and the second antibody or antigenbinding fragment thereof comprises (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 19; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 22. In some embodiments, the composition provided herein further comprises one or more pharmaceutically acceptable carriers, excipients, or stabilizers.

[0044] In some embodiments, provided herein is a composition (e.g., a pharmaceutical composition) comprising: (A) a first antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the first antibody or antigen-binding fragment thereof comprises: (a) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 55, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 61; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 64, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 66; (b) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 67, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 71, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 75; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 211, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 79, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 80; or (c) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 81, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 82, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 83; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 86, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 87; and (B) a second antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the second antibody or antigen-binding fragment thereof comprises: (a) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 173, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 174, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 175; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 176, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 178; (b) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 128, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 180, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 181; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 182, a VL NAI-5010413635vl 33CDR2 comprising the amino acid sequence of SEQ ID NO: 183, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 184; or (c) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 185, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 186, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 187; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 188, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 189. In some embodiments, the second antibody or antigenbinding fragment thereof comprises: (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 26; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 27 In some embodiments, the first antibody or antigenbinding fragment thereof comprises: (A) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 1; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 6; (B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 2; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8; (C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 7; (D) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 4; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8; or (E) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 5; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8. In some embodiments, the first antibody or antigen-binding fragment thereof comprises (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 7. In some embodiments, the composition provided herein further comprises one or more pharmaceutically acceptable carriers, excipients, or stabilizers.

[0045] In some embodiments, a composition (e.g., a pharmaceutical composition) provided herein further comprises one or more of any one or more of: (a) an antibody or a fragment thereof that binds to the stalk of influenza A virus hemagglutinin; (b) an antibody or a fragment thereof that binds to influenza A virus neuraminidase; (c) a neuraminidase inhibitor; or (d) a cap snatching inhibitor.

[0046] In another aspect, provided herein is a method for expressing the antibody or antigen-binding fragment thereof provided herein, comprising: (A) culturing the host cellNAI-5010413635vl 34provided herein; and (B) isolating the antibody or antigen-binding fragment thereof from the host cell or cell culture.In another aspect, provided herein is a method for detecting an H5 influenza A virus of clade 2.3.4.4b, comprising: (A) contacting cells or a biological sample with the antibody or antigen-binding fragment thereof provided herein; and (B) detecting the binding of the antibody or fragment thereof to hemagglutinin H5 of an influenza A virus of clade 2.3.4.4b, wherein the influenza A virus is detected if the level of binding of the antibody or antigenbinding fragment thereof to the influenza A virus hemagglutinin is greater than the level of binding of the antibody or antigen-binding fragment thereof to non-influenza virus infected cells or a biological sample not infected with an influenza virus. In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is influenza virus A / mallard / New York / 22-008760-007-original / 2022 (H5), A / chicken / New York / NYCVH 168127 / 2023 (H5N1), A / Canada goose / New York / NYCVH 23-453 / 2023 (H5N1), A / Canada goose / New York / NYCVH 22-9190 / 2022 (H5N1), A / peregrine falcon / New York / NYCVH 160820 / 2022 (H5N1), A / red-tailed hawk / New York / NYCVH 22-8477 / 2022 (H5N1), A / bald eagle / FL / W22-134-OP / 2022 (H5N1), A / chicken / Netherlands / 14015531 / 2014 (H5N8), A / northern pintail / WA / 40964 / 2014 (H5N1), A / dairy cattle / Texas / 24-008749-001-original / 2024 or A / Jiangsu / NJ210 / 2023 (H5N1). In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is an H5 influenza A virus of clade 2.3.4.4b in Section 8. In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is influenza virus A / Jiangsu / NJ210 / 2023, A / mallard / New_York / 22-008760-007-original / 2022, A / chicken / New Fork / NYCVH- 168127 / 2023, A / canada_goose / New_York / NYCVH23-453 / 2023, A / bald_eagle / Florida / W22-134-OP / 2022, A / canada_goose / New_York / NYCVH22-9190 / 2022, A / red-tailed_hawk / New_York / NYCVH22-8477 / 2022, A / peregrine_falcon / New_York / NYCVHl 60820 / 2022,A / chicken / N etherlands / 14015531 / 2014, A / northem_pintail / W A / 40964 / 2014, A / dairy_cattle / Texas / 24-008749-001-original / 2024, A / Cambodia / NPH230032_2 / 2023, A / Shenzhen / 1 / 2016, or A / Indonesia / 5 / 2005.

[0047] In another aspect, provided herein is a binding agent that binds to essentially the same epitope as the antibody or antigen-binding fragment thereof provided herein. In some embodiments, the binding agent is an antibody or an antigen-binding fragment thereof. In some embodiments, the binding agent may be used in the same ways as an antibody or an antigen-binding fragment thereof provided herein (e.g., the binding agent may be used to detect, treat, and / or prevent influenza A virus infection or disease).NAI-5010413635vl 35

[0048] In another aspect, provided herein is a method for neutralizing H5 influenza A virus of clade 2.3.4.4b, comprising contacting cells with the antibody or antigen-binding fragment provided herein, or the composition of provided herein, wherein the cells are infected with influenza A virus of clade 2.3.4.4b. In some embodiments, the contacting of cells with the antibody or antigen-binding fragment thereof in vitro, ex vivo, or in vivo. In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is influenza virus A / mallard / New York / 22-008760-007-original / 2022 (H5), A / chicken / New York / NYCVH 168127 / 2023 (H5N1), A / Canada goose / New York / NYCVH 23-453 / 2023 (H5N1), A / Canada goose / New York / NYCVH 22-9190 / 2022 (H5N1), A / peregrine falcon / New York / NYCVH 160820 / 2022 (H5N1), A / red-tailed hawk / New York / NYCVH 22-8477 / 2022 (H5N1), A / bald eagle / FL / W22-134-OP / 2022 (H5N1), A / chicken / Netherlands / 14015531 / 2014 (H5N8), A / northem pintail / WA / 40964 / 2014 (H5N1), A / dairy cattle / Texas / 24-008749-001-original / 2024 or A / Jiangsu / NJ210 / 2023 (H5N1). In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is an H5 influenza A virus of clade 2.3.4.4b in Section 8.

[0049] In another aspect, provided herein is a method for neutralizing influenza A virus (e.g., influenza A virus of clade 2.3.4.4b) in a subject, comprising administering an antibody or antigen-binding fragment provided herein or a composition provided herein to the subject. In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is influenza virus A / mallard / New York / 22-008760-007-original / 2022 (H5), A / chicken / New York / NYCVH 168127 / 2023 (H5N1), A / Canada goose / New York / NYCVH 23-453 / 2023 (H5N1), A / Canada goose / New York / NYCVH 22-9190 / 2022 (H5N1), A / peregrine falcon / New York / NYCVH 160820 / 2022 (H5N1), A / red-tailed hawk / New York / NYCVH 22-8477 / 2022 (H5N1), A / bald eagle / FL / W22-134-OP / 2022 (H5N1), A / chicken / Netherlands / 14015531 / 2014 (H5N8), A / northem pintail / WA / 40964 / 2014 (H5N1), A / dairy cattle / Texas / 24-008749-001-original / 2024 or A / Jiangsu / NJ210 / 2023 (H5N1). In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is an H5 influenza A virus of clade 2.3.4.4b in Section 8. In some embodiments, the H5 influenza A vims of clade 2.3.4.4b is influenza vims A / Jiangsu / NJ210 / 2023, A / mallard / New fork / 22-008760-007-original / 2022, A / chicken / New_York / NYCVH- 168127 / 2023, A / canada_goose / New_York / NYC VH23 -453 / 2023, A / bald_eagle / Florida / W22-134-OP / 2022, A / canada_goose / New_York / NYCVH22-9190 / 2022, A / red-tailed_hawk / New_York / NYCVH22-8477 / 2022, A / peregrine_falcon / New_York / NYCVHl 60820 / 2022, A / chicken / Netherlands / 14015531 / 2014, A / northem_pintail / WA / 40964 / 2014,NAI-5010413635vl 36A / dairy_cattle / Texas / 24-008749-001-original / 2024, A / Cambodia / NPH230032_2 / 2023, A / Shenzhen / 1 / 2016, or A / Indonesia / 5 / 2005.

[0050] In another aspect, provided herein is a method for inhibiting influenza A virus hemagglutinin activity comprising contacting cells or a biological sample comprising cells with an antibody or antigen-binding fragment provided herein in the presence of influenza A virus (e.g., influenza A virus of clade 2.3.4.4b). In some embodiments, the contacting is conducted ex vivo or in vitro. In some embodiments, provided herein is a method for influenza A virus hemagglutinin activity (e.g., H5 influenza A virus of clade 2.3.4.4b) in a subject, comprising administering an antibody or antigen-binding fragment provided herein to the subject. In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is influenza virus A / mallard / New York / 22-008760-007-original / 2022 (H5), A / chicken / New York / NYCVH 168127 / 2023 (H5N1), A / Canada goose / New York / NYCVH 23-453 / 2023 (H5N1), A / Canada goose / New York / NYCVH 22-9190 / 2022 (H5N1), A / peregrine falcon / New York / NYCVH 160820 / 2022 (H5N1), A / red-tailed hawk / New York / NYCVH 22-8477 / 2022 (H5N1), A / bald eagle / FL / W22-134-OP / 2022 (H5N1), A / chicken / Netherlands / 14015531 / 2014 (H5N8), A / northem pintail / WA / 40964 / 2014 (H5N1), A / dairy cattle / Texas / 24-008749-001-original / 2024 or A / Jiangsu / NJ210 / 2023 (H5N1). In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is an H5 influenza A virus of clade 2.3.4.4b in Section 8.

[0051] In another aspect, provided herein are methods for preventing influenza virus disease and / or treating influenza virus infection or disease. In some embodiments, provided herein is a method for preventing influenza virus disease caused by infection with H5 influenza A virus of clade 2.3.4.4b in a subject, the method comprising administering to the subject a antibody or antigen-binding fragment thereof provided herein, or a composition provided herein. In some embodiments, provided herein is a method for treating influenza virus disease caused by infection with H5 influenza A virus of clade 2.3.4.4b in a subject, the method comprising administering to the subject an antibody or antigen-binding fragment thereof provided herein, or a composition provided herein. In some embodiments, the antibody or antigen-binding fragment comprises the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 of the antibody referred to as 1 Al (see, e.g., Tables 11-16). In some embodiments, the antibody or antigen-binding fragment comprises the variable heavy chain region and variable light chain region of the antibody referred to as 1 Al (see, e.g., Table 1). In some embodiments, the antibody or antigen-binding fragment comprises the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 of the antibody NAI-5010413635vl 37referred to as 20D10 (see, e.g., Tables 17-22). In some embodiments, the antibody or antigen-binding fragment comprises the variable heavy chain region and variable light chain region of the antibody referred to as 20D10 (see, e.g., Table 2). In some embodiments, the antibody or antigen-binding fragment comprises the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 of the antibody referred to as 6G1 (see, e.g., Tables 23-28). In some embodiments, the antibody or antigen-binding fragment comprises the variable heavy chain region and variable light chain region of the antibody referred to as 6G1 (see, e.g., Table 3). In some embodiments, the antibody or antigen-binding fragment comprises the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 of the antibody referred to as 12G1 (see, e.g., Tables 35-40). In some embodiments, the antibody or antigenbinding fragment comprises the variable heavy chain region and variable light chain region of the antibody referred to as 12G1 (see, e.g., Table 5). In some embodiments, the method further comprises administering to the subject one or more of any one or more of: (a) an antibody or a fragment thereof that binds to the stalk of influenza A virus hemagglutinin; (b) an antibody or a fragment thereof that binds to influenza A virus neuraminidase; (c) a neuraminidase inhibitor; or (d) a cap-snatcher inhibitor. In some embodiments, the subject is a human or a non-human animal. In some embodiments, the non-human animal is a bird, dog, cat, cow, horse, or goat. In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is influenza virus A / mallard / New York / 22-008760-007-original / 2022 (H5), A / chicken / New York / NYCVH 168127 / 2023 (H5N1), A / Canada goose / New York / NYCVH 23-453 / 2023 (H5N1), A / Canada goose / New York / NYCVH 22-9190 / 2022 (H5N1), A / peregrine falcon / New York / NYCVH 160820 / 2022 (H5N1), A / red-tailed hawk / New York / NYCVH 22-8477 / 2022 (H5N1), A / bald eagle / FL / W22-134-OP / 2022 (H5N1), A / chicken / Netherlands / 14015531 / 2014 (H5N8), A / northem pintail / WA / 40964 / 2014 (H5N1), A / dairy cattle / Texas / 24-008749-001-original / 2024 or A / Jiangsu / NJ210 / 2023 (H5N1).

[0052] In another aspect, provided herein is a kit comprising an antibody or an antigenbinding fragment thereof provided herein, a vector or a set of vectors provided herein, or a composition provided herein. In some embodiments, the kit comprises instructions for use of the antibody or an antigen-binding fragment thereof, the vector or set of vectors provided herein, or the composition in the prevention and / or treatment of an influenza A virus of clade 2.3.4.4b infection or disease, or in the detection of an influenza A virus of clade 2.3.4.4b.

[0053] In another aspect, provided herein is an antibody means for binding to hemagglutinin H5 of an influenza A virus of clade 2.3.4.4b. In another aspect, provided herein is a method for preventing and / or treating influenza virus disease caused by infection NAI-5010413635vl 38with influenza A virus of clade 2.3.4.4b in a subject, comprising administering to the subject an antibody means for binding to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b. In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is influenza virus A / mallard / New York / 22-008760-007-original / 2022 (H5), A / chicken / New York / NYCVH 168127 / 2023 (H5N1), A / Canada goose / New York / NYCVH 23-453 / 2023 (H5N1), A / Canada goose / New York / NYCVH 22-9190 / 2022 (H5N1), A / peregrine falcon / New York / NYCVH 160820 / 2022 (H5N1), A / red-tailed hawk / New York / NYCVH 22-8477 / 2022 (H5N1), A / bald eagle / FL / W22-134-OP / 2022 (H5N1), A / chicken / Netherlands / 14015531 / 2014 (H5N8), A / northem pintail / WA / 40964 / 2014 (H5N1), A / dairy cattle / Texas / 24-008749-001-original / 2024 or A / Jiangsu / NJ210 / 2023 (H5N1). In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is an H5 influenza A virus of clade 2.3.4.4b in Section 8. In some embodiments, the H5 influenza A virus of clade 2.3.4.4b is influenza virus A / Jiangsu / NJ210 / 2023, A / mallard / New fork / 22-008760-007-original / 2022, A / chicken / New_York / NYCVH- 168127 / 2023, A / canada_goose / New_York / NYC VH23 -453 / 2023, A / bald_eagle / Florida / W22-134-OP / 2022, A / canada_goose / New_York / NYCVH22-9190 / 2022, A / red-tailed_hawk / New_York / NYCVH22-8477 / 2022, A / peregrine_falcon / New_York / NYCVHl 60820 / 2022, A / chicken / Netherlands / 14015531 / 2014, A / northem_pintail / WA / 40964 / 2014, A / dairy_cattle / Texas / 24-008749-001-original / 2024, A / Cambodia / NPH230032_2 / 2023, A / Shenzhen / 1 / 2016, or A / Indonesia / 5 / 2005.NAI-5010413635vl 395.1 SEQUENCESTable 1. First Clonotype - Variable Heavy Chain Region and Variable Light Chain Region Amino Acid SequencesDescription Sequence SEQ ID NO: H5N1 12G9 H QVQLQESGPGLVKPSETLSLTCGVSGYSISSGYYWDWIRQPPGKGLEWIGSIYHSGSTFYNPSLKSRVTI 1 (12G9 VH) SLDTSKNQFSVRLRSVT AADTAL YYCAREYDILTGYPYGFDIWGQGTMVTVSQH5N1 13B9 H QVQLQESGPGLVKPSETLSLTCGVSGYSISSGYYWDWIRQPPGKGLEWIGSIYHSGSAFYNPSFKSRVTI 2 (13B9 VH) SLDTSKNQFSVRLKSVT AADTAL YYCAREYDILTGYPYGFDIWGQGTMVTVSQH5N1 1A1 H QVQLQESGPGLVKPSETLSLTCGVSGYSISSGYYWDWIRQPPGKGLEWIGTIYHSGSTFYNPSFKSRVTI 3 (1A1 VH) SLDTSKNQF S VRLRS VT AADTAL YYC ARQ YDILTGYP YGFDIWGQGTMVT VS SH5N1_12C11_ QVQLQESGPGLVKPSETLSLTCGVSGYSISSGYYWDWIRQPPGKGLEWIGTIYHSGSTFYNPSFKSRVTI 4 H (12C11 VH) SLDTSKNQF S VRLRS VT AADTAL YYCARQYDILTGYPYGFDIWGQGTMVTVSQH5N1 13E8 H QVQLQESGPGLVKPSETLSLTCGVSGYSISSGYYWDWIRQPPGKGLEWIGTIYHSGSTFYNPSFKSRVTI 5 (13E8 VH) SLDTSKNQF S VRLRS VT AADTAL YYC ARQ YDILTGYP YGFDFWGQGTMVT VS SH5N1 12G9 K EIVMTQSPATLYVSPGERATLSCRASQSVSSKLAWYQQKPGQAPRLLIYGAFTRATGIPARFSGSGSGT 6 (12G9 VL) EFTLTISSLQSEDFAVYYCQQYNNWPRTFGQGTKVEIKH5N1_1A1_K EIVMTQSPATLSVSPGERATLSCRASQSVNSNLAWYQQKPGQAPRLLIYGAFTRATGIPARFSGSGSGT 7 (1A1 VL) EFTLTISSLQSEDFAVYYCQQYNNWPRTFGQGTKVEIKH5N1_12C11_ EIVMTQSPATLSVSPGERATLSCRASQSVSSNLAWYQQKPGQAPRLLIYGAFTRATGIPARFSGSGSGT 8 13B9 13E8 K EFTLTISSLQSEDFAVYYCQQYNNWPRTFGQGTKVEIK(12C11 VL,13B9 VL, 13E8VL)Table 2. Second Clonotype - Variable Heavy Chain Region and Variable Light Chain Region Amino Acid SequencesDescription Sequence SEQ ID NO: H5N1 1H2 H QVQLQESGPGLVKPSETLSLTCTVSGGSISSYYWSWIRQPPGKGLEWIGSIYYSGSTNYNPSLKSPSIISVD 9 (1H2 VH) TSKNQFSLKLNSVTAADTAVYYCARELASTGPLYYYYGMDVWGQGTTVTVSQH5N1 17E3 H QVQLQESGPGLVKPSETLSLTCTVSGGSISSYYWSWIRQPPGKGLEWIGSIYYSGSTNYNPSLKSRGIISVD 10 (17E3 VH) TSKNQFSLKLNSVTAADTAVYYCARELASTGPLYYYYGMDVWGPGTTVTVSSH5Nl_20D10_ QVQLQESGPGLVKPSETLSLTCTVSGGSISSYYWSWIRQPPGKGLEWIGSIYYSGSTNYNPSLKSLSIISVD 11 H (20D10 VH) TSKNQFSLKLNSVTAADTAVYYCARELASTGPLYYYYGMDVWGQGTTVTVSQH5N1 1H2 K DIVMTQSPLSLPVTPGEPASISCRSSQSLLHSIGYTYLDWYLQKPGQSPKLLIYLGSDRAPGVPDRFSGSGS 12 (1H2 VL) GTDFTLKISRVEAEDVGVYYCMQALQTPYTFGQGTKLEIKH5N1 17E3 K DIVMTQSPLSLPVTPGEPASISCRSSQSLLHSVGYTYLDWYLQKPGQSPKLLIYLGSDRASGVPDRFSGSG 13 (17E3 VL) SGTDFTLKISRVEAEDVGVYYCMQALQTPYTFGQGTKLEIKH5Nl_20D10_ DIVMTQSPLSLPVTPGEPASISCRSSQSLLHSIGYTYLDWYLQKPGQSPKLLIYLGTDRAPGVPDRFSGSGS 14K (20D10 VL) GTDFTLKISRVEAEDVGVYYCMQALQTPYTFGQGTKLEIKTable 3. Third Clonotype - Variable Heavy Chain Region and Variable Light Chain Region Amino Acid SequencesDescription Sequence SEQ ID NO: H5N1 7G4 H QVQLQESGPGLVKPSETLSLTCTVSGGSISSYYWSWIRQPPGKGLEWIGYIYYSGSTNYNPSLKSRVTISV 15 (7G4 VH) DTAKNQF SLKLHS VT AADT AVYYCARDLREWFGALNYYYGMD VWGQGTP VT VS SH5N1 7G11_H QVQLQESGPGLVKPSETLSLTCTVSGGSISSYFWSWIRQPPGKGLEWIGYIYYSGNTSYNPSLKSRVTISV 16 (7G11 VH) DTAKNQF SLNLNSVT AADT AVYYCARDLREWFGALNYYYGMD VWGQGTP VT VS SH5N1 12G8 H QVQLQESGPGLVKPSETLSLTCTVSGGSISSYFWSWIRQPPGKGLEWIGYIYYSGNTTYNPSLKSRVTISV 17 (12G8 VH) DTAKNQF SLNLNSVT AADT AVYYCARDLREWFGALNYYYGMD VWGQGTP VT VS SH5N1_17C12_ QVQLQESGPGLVKPSETLSLTCTVSGGSISSYYWSWIRQPPGKGLEWIGYIYYSGNTNYNPSLKSRVTISV 18 H (17C12 VH) DTAKNQF SLNLKSVT AADT AVYYCARDLREWFGALNYYYGMD VWGQGTP VT VS SH5N1 6G1 H QVQLQESGPGLVKPSETLSLTCTVSGGSISSYYWSWIRQPPGKGLEWIGYIYYSGSTNYNPSLKSRVTISV 19(6G1 VH) DTAKNQF SLNLNSVT AADT AVYYCARDLREWSGALNYYYGMD VWGQGTP VT VS SDescription Sequence SEQ ID NO: H5N1 7G4 7G DIVMTQSPLSLPVTPGEPASMSCRSSQSLLHSYGSDYLDWYLQKPGQSPQLLIYLGSYRASGVSDRFSGS 20 11_17C12_K GSGTNFTLKISRVEAEDVGVYYCMQALQTPFTFGPGTKVDIK(7G4 VL, 7G11VL, 17C12 VL)H5N1 12G8 K DIVMTQSPLSLPVTPGEPASMSCRSSQSLLHSYGSDYLDWYLQKPGQSPQLLIYLGSYRASGVSDRFSGS 21 (12G8 VL) GSGTNFTLKISRVEAEDVGLYYCMQALQTPFTFGPGTKVEIKH5N1 6G1 K DIVMTQSPLSLPVTPGEPASMSCRSSQSLLHSYGSNYLDWYLQKPGQSPQLLIYLGSYRASGVSDRFSGS 22(6G1 VL) GSGTNFTLKISRVEAEDVGVYYCMQALQTPFTFGPGTKVDIKTable 4. Fourth Clonotype - Variable Heavy Chain Region and Variable Light Chain Region Amino Acid SequencesDescription Sequence SEQ ID NO: H5N1 7H10 H QVQLQESGPGLVKPSETLSLTCTVSGGSISSYYWSWIRQPPGKGLEWIGYIYYSGSTNYNPSLKSRVTISV 23 (7H10 VH) DTSKNQFSLKLTSVTVADTAVYYCARAPMVRGPDLYYYYGMDVWGQGTTVTVSSH5N1 14B8 H QVQLQESGPGLVKPSETLSLTCTVSGDSISSYYWSWIRQPPGKGLEWIGYIYYSGSTNYNPSLKSRVTISV 24 (14B8 VH) DTSKNQFSLKLTSVTVADTAVYYCARAPMVRGPDLYYYYGMDVWGQGTTVTVSSH5N1 7H10 1 EIVMTQSPATLSVSPGERATLSCRASQSVSSNLAWYQQKPGQAPRLLIYGASTRATGIPARFSGSGSGTEF 25 4B8_K (710 TLTISSLQSEDFAVYYCQHYNNWPPFGGGTKVEIKVL, 14B8 VL)Table 5. Fifth Clonotype - Variable Heavy Chain Region and Variable Light Chain Region Amino Acid SequencesDescription Sequence SEQ ID NO: H5N1 12G1 H QVQLQESGPGLVKPSETLSLTCTVSGDSISSYYWSWIRQPPGKGLEWIGYVHYSGNTNYNPSLKSRVTIS 26 (12G1 VH) VDTSKNQF SLKLS S VTAADT AVYYC ARTTMSRGPSL YYYYGLD VWGQGTT VTVS SH5N1 12G1 K DIVMTQSPLSLPVTPGEPASISCRSSQSLLHSYGYIYLDWYLQKPGQSPQLLIYLGSDRASGIPDRFSGSGS 27(12G1 VL) GTDFTLKISRVEAEDVGVYYCMQALQTPITFGQGTRLEIKTable 6. First Clonotype - Variable Heavy Chain Region and Variable Light Chain Region Nucleotide Acid Sequences Description Sequence SEQ ID NO: H5N1 12G9 H CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 28 (12G9 VH) GGTGTCTCTGGTTATTCCATCAGCAGTGGTTACTACTGGGACTGGATCCGGCAGCCCCCAGGGAAG GGGCTGGAGTGGATTGGGAGTATCTATCATAGTGGGAGCACCTTCTACAACCCGTCCCTCAAGAGT CGAGTCACCATATCATTAGACACGTCCAAGAACCAGTTCTCCGTGAGGCTGAGGTCTGTGACCGCC GCAGACACGGCCCTGTATTATTGTGCGAGAGAATACGATATTTTGACTGGTTACCCCTATGGTTTTG ATATTTGGGGCCAAGGGACAATGGTCACCGTCTCTCAGH5N1 13B9 H CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 29 (13B9 VH) GGTGTCTCTGGTTATTCCATCAGCAGTGGTTACTACTGGGACTGGATCCGGCAGCCCCCAGGGAAG GGGCTGGAGTGGATTGGGAGTATCTATCATAGTGGGAGCGCCTTCTACAACCCGTCTTTCAAGAGT CGAGTCACCATATCATTAGACACGTCCAAGAACCAGTTCTCCGTGAGGCTGAAGTCTGTGACCGCC GCAGACACGGCCCTGTATTATTGTGCGAGAGAATACGATATTTTGACTGGTTACCCCTATGGTTTTG ATATTTGGGGCCAAGGGACAATGGTCACCGTCTCTCAGH5N1 1A1 H CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 30 (1A1 VH) GGTGTCTCTGGTTATTCCATCAGTAGTGGTTACTACTGGGACTGGATCCGGCAGCCCCCAGGGAAG GGGCTGGAGTGGATTGGGACTATCTATCATAGTGGGAGCACCTTCTACAACCCGTCTTTCAAGAGTC GAGTCACCATATCATTAGACACGTCCAAGAACCAGTTCTCCGTGAGGCTGAGGTCTGTGACCGCCG CAGACACGGCCCTGTATTATTGTGCGAGACAATACGATATTTTGACTGGTTACCCCTATGGTTTTGA TATTTGGGGCCAAGGGACAATGGTCACCGTCTCTTCAH5N1_12C11_ CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 31 H (12C11 VH) GGTGTCTCTGGTTATTCCATCAGTAGTGGTTACTACTGGGACTGGATCCGGCAGCCCCCAGGGAAG GGGCTGGAGTGGATTGGGACTATCTATCATAGTGGGAGCACCTTCTACAACCCGTCTTTCAAGAGTC GAGTCACCATATCATTAGACACGTCCAAGAACCAGTTCTCCGTGAGGCTGAGGTCTGTGACCGCCG CAGACACGGCCCTGTATTATTGTGCGAGACAATACGATATTTTGACTGGTTACCCCTATGGTTTTGA TATTTGGGGCCAAGGGACAATGGTCACCGTCTCTCAGH5N1 13E8 H CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 32 (13E8 VH) GGTGTCTCTGGTTATTCCATCAGTAGTGGTTACTACTGGGACTGGATCCGGCAGCCCCCAGGGAAGGGGCTGGAGTGGATTGGGACTATCTATCATAGTGGGAGCACCTTCTACAACCCGTCTTTCAAGAGTCGAGTCACCATATCGTTAGACACGTCCAAGAACCAGTTCTCCGTGAGGCTGAGGTCTGTGACCGCCGDescription Sequence SEQ ID NO: CAGACACGGCCCTGTATTATTGTGCGAGACAATACGATATTTTGACTGGTTACCCCTATGGTTTTGA TTTTTGGGGCCAAGGGACAATGGTCACCGTCTCTTCAH5N1 12G9 K GAAATAGTGATGACGCAGTCTCCAGCCACCCTGTATGTGTCTCCAGGGGAAAGAGCCACCCTCTCC 33 (12G9 VL) TGTAGGGCCAGTCAGAGTGTTAGCAGCAAATTAGCCTGGTACCAGCAGAAACCTGGCCAGGCTCCC AGGCTCCTCATCTATGGTGCATTCACCAGGGCCACTGGTATCCCAGCCAGGTTCAGTGGCAGTGGGT CTGGGACAGAGTTCACTCTCACCATCAGCAGCCTGCAGTCTGAAGATTTTGCAGTTTATTACTGTCA GCAGTATAATAACTGGCCTCGGACGTTCGGCCAAGGGACCAAGGTGGAAATCAAAH5N1_1A1_K GAAATAGTGATGACGCAGTCTCCAGCCACCCTGTCTGTGTCTCCAGGGGAAAGAGCCACCCTCTCC 34 (1A1 VL) TGTAGGGCCAGTCAGAGTGTTAACAGCAACTTAGCCTGGTACCAGCAGAAACCTGGCCAGGCTCCC AGGCTCCTCATCTATGGTGCATTCACCAGGGCCACTGGTATCCCAGCCAGGTTCAGTGGCAGTGGGT CTGGGACAGAGTTCACTCTCACCATCAGCAGCCTGCAGTCTGAAGATTTTGCAGTTTATTACTGTCA GCAGTATAATAACTGGCCTCGGACGTTCGGCCAAGGGACCAAGGTGGAAATCAAAH5N1_12C11_ GAAATAGTGATGACGCAGTCTCCAGCCACCCTGTCTGTGTCTCCAGGGGAAAGAGCCACCCTCTCC 35 13B9 13E8 K TGTAGGGCCAGTCAGAGTGTTAGCAGCAACTTAGCCTGGTACCAGCAGAAACCTGGCCAGGCTCCC (12C11 VL, AGGCTCCTCATCTATGGTGCATTCACCAGGGCCACTGGTATCCCAGCCAGGTTCAGTGGCAGTGGGT 13B9 VL, 13E8 CTGGGACAGAGTTCACTCTCACCATCAGCAGCCTGCAGTCTGAAGATTTTGCAGTTTATTACTGTCAVL) GCAGTATAATAACTGGCCTCGGACGTTCGGCCAAGGGACCAAGGTGGAAATCAAATable 7. Second Clonotype - Variable Heavy Chain Region and Variable Light Chain Region Nucleotide Acid Sequences Description Sequence SEQ ID NO: H5N1 1H2 H CAGGTGCAGCTACAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 36 (1H2 VH) ACTGTCTCTGGTGGCTCCATCAGTAGTTACTACTGGAGCTGGATCCGACAGCCCCCAGGGAAGGGA CTGGAGTGGATTGGGTCTATCTATTACAGTGGGAGCACCAACTACAACCCCTCCCTCAAGAGTCCA AGTATCATATCAGTAGACACGTCCAAGAACCAGTTCTCCCTGAAGCTGAATTCTGTGACCGCTGCG GACACGGCCGTTTATTACTGTGCGAGGGAATTAGCATCGACTGGGCCTCTCTACTACTACTACGGGA TGGACGTCTGGGGCCAAGGGACCACGGTCACCGTCTCTCAGH5N1 17E3 H CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 37(17E3 VH) ACTGTCTCTGGTGGCTCCATCAGTAGTTACTACTGGAGCTGGATCCGGCAGCCCCCAGGGAAGGGADescription Sequence SEQ ID NO: CTGGAGTGGATTGGGTCTATCTATTACAGTGGGAGCACCAACTACAACCCCTCCCTCAAGAGTCGA GGCATCATATCAGTAGACACGTCCAAGAACCAGTTCTCCCTGAAGCTGAACTCTGTGACCGCTGCG GACACGGCCGTTTATTACTGTGCGAGAGAGTTAGCATCGACTGGGCCTCTCTACTACTACTACGGTA TGGACGTCTGGGGCCCAGGGACCACGGTCACCGTCTCCTCAH5Nl_20D10_ CAGGTGCAGCTACAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 38 H (20D10 VH) ACTGTCTCTGGTGGCTCCATCAGTAGTTACTACTGGAGCTGGATCCGACAGCCCCCAGGGAAGGGA CTGGAGTGGATTGGGTCTATCTATTACAGTGGGAGCACCAACTACAACCCCTCCCTCAAGAGTCTA AGTATCATATCAGTAGACACGTCCAAGAACCAGTTCTCCCTGAAGCTGAACTCTGTGACCGCTGCG GACACGGCCGTTTATTACTGTGCGAGAGAATTAGCATCGACTGGGCCTCTCTACTACTACTACGGTA TGGACGTCTGGGGCCAAGGGACCACGGTCACCGTCTCTCAGH5N1 1H2 K GATATTGTGATGACTCAGTCTCCACTCTCCCTGCCCGTCACCCCTGGAGAGCCGGCCTCCATCTCCT 39 (1H2 VL) GCAGGTCTAGTCAGAGCCTCCTGCATAGTATTGGATACACCTATTTGGATTGGTACCTGCAGAAGCC AGGGCAGTCTCCAAAGCTCCTGATCTATTTGGGTTCTGATCGGGCCCCCGGGGTCCCTGACAGGTTC AGTGGCAGTGGATCAGGCACAGATTTTACACTGAAAATCAGCAGAGTGGAGGCTGAGGATGTTGG GGTTTATTACTGCATGCAAGCTCTACAGACTCCGTACACTTTTGGCCAGGGGACCAAGCTGGAGATC AAAH5N1 17E3 K GATATTGTGATGACTCAGTCTCCACTCTCCCTGCCCGTCACCCCTGGAGAGCCGGCCTCCATCTCCT 40 (17E3 VL) GCAGGTCTAGTCAGAGCCTCCTGCATAGTGTTGGATACACCTATTTGGATTGGTACCTGCAGAAGCC AGGGCAGTCTCCAAAGCTCCTGATCTATTTGGGTTCTGATCGGGCCTCCGGGGTCCCTGACAGGTTC AGTGGCAGTGGATCAGGCACAGATTTTACACTGAAAATCAGCAGAGTGGAGGCTGAGGATGTTGG GGTTTATTACTGCATGCAAGCTCTACAGACTCCGTACACTTTTGGCCAGGGGACCAAGCTGGAGATC AAAH5Nl_20D10_ GATATTGTGATGACTCAGTCTCCACTCTCCCTGCCCGTCACCCCTGGAGAGCCGGCCTCCATCTCCT 41 K (20D10 VL) GCAGGTCTAGTCAGAGCCTCCTGCATAGTATTGGATACACCTATTTGGATTGGTACCTGCAGAAGCC AGGGCAGTCTCCAAAGCTCCTGATCTATTTGGGTACTGATCGGGCCCCCGGGGTCCCTGACAGGTTC AGTGGCAGTGGATCAGGCACAGATTTTACACTGAAAATCAGCAGAGTGGAGGCTGAGGATGTTGG GGTTTATTACTGCATGCAAGCTCTACAGACTCCGTACACTTTTGGCCAGGGGACCAAGCTGGAGATCAAATable 8. Third Clonotype - Variable Heavy Chain Region and Variable Light Chain Region Nucleotide Acid Sequences Description Sequence SEQ ID NO: H5N1 7G4 H CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 42 (7G4 VH) ACTGTCTCTGGTGGCTCCATCAGTAGTTACTACTGGAGCTGGATCCGGCAGCCCCCAGGGAAGGGA CTGGAGTGGATTGGTTATATCTATTACAGTGGGAGTACCAACTACAACCCCTCCCTCAAGAGTCGA GTCACCATATCAGTAGACACGGCCAAGAACCAGTTCTCCCTGAAACTTCACTCTGTGACCGCTGCG GACACGGCCGTGTATTACTGTGCGAGAGATCTGAGGGAATGGTTCGGGGCGTTAAACTACTACTAC GGTATGGACGTCTGGGGCCAAGGGACCCCGGTCACCGTCTCCTCAH5N1 7G11_H CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 43 (7G11 VH) ACTGTCTCTGGTGGCTCCATCAGTAGTTACTTCTGGAGCTGGATCCGGCAGCCCCCAGGGAAGGGA CTGGAGTGGATTGGGTATATCTATTACAGTGGGAATACCAGCTACAACCCCTCCCTCAAGAGTCGA GTCACCATATCAGTAGACACGGCCAAGAACCAGTTCTCCCTGAACCTGAACTCTGTGACCGCTGCG GACACGGCCGTGTATTACTGTGCGCGAGATCTGAGGGAATGGTTCGGGGCGTTAAACTACTACTAC GGTATGGACGTCTGGGGCCAAGGGACCCCGGTCACCGTCTCCTCAH5N1 12G8 H CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 44 (12G8 VH) ACTGTCTCTGGTGGCTCCATCAGTAGTTACTTCTGGAGCTGGATCCGGCAGCCCCCAGGGAAGGGA CTGGAGTGGATTGGGTATATCTATTACAGTGGGAATACCACCTACAACCCCTCCCTCAAGAGTCGA GTCACCATATCAGTAGACACGGCCAAGAACCAGTTCTCCCTGAACCTGAACTCTGTGACCGCTGCG GACACGGCCGTGTATTACTGTGCGCGAGATCTGAGGGAATGGTTCGGGGCGTTAAACTACTACTAC GGTATGGACGTCTGGGGCCAAGGGACCCCGGTCACCGTCTCCTCAH5N1_17C12_ CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 45 H (17C12 VH) ACTGTCTCTGGTGGCTCCATCAGTAGTTACTACTGGAGTTGGATCCGGCAGCCCCCAGGGAAGGGA CTGGAGTGGATTGGGTATATCTATTACAGTGGGAATACCAACTACAATCCCTCCCTCAAGAGTCGA GTCACCATATCAGTAGACACGGCCAAGAACCAGTTCTCCCTGAACCTGAAGTCTGTGACCGCTGCG GACACGGCCGTGTATTACTGTGCGCGAGATCTGAGGGAATGGTTCGGGGCGTTAAACTACTACTAC GGTATGGACGTCTGGGGCCAAGGGACCCCGGTCACCGTCTCCTCAH5N1 6G1 H CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 46 (6G1 VH) ACTGTCTCTGGTGGCTCCATCAGTAGTTACTACTGGAGCTGGATCCGGCAGCCCCCAGGGAAGGGACTGGAGTGGATTGGATATATCTATTACAGTGGGAGTACCAACTACAACCCCTCCCTCAAGAGTCGAGTCACCATATCAGTAGACACGGCCAAGAACCAGTTCTCCCTGAACCTGAACTCTGTGACCGCTGCGDescription Sequence SEQ ID NO: GACACGGCCGTGTATTACTGTGCGAGAGATCTGAGGGAATGGTCCGGGGCATTAAACTACTACTAC GGTATGGACGTCTGGGGCCAAGGGACCCCGGTCACCGTCTCCTCAH5N1 7G4 7G GATATTGTGATGACTCAGTCTCCACTCTCCCTGCCCGTCACCCCTGGAGAGCCGGCCTCCATGTCCT 47 11_17C12_K GCAGGTCTAGTCAGAGCCTCCTGCATAGTTATGGATCCGACTATTTGGATTGGTACCTGCAGAAGCC (7G4 VL, 7G11 AGGGCAGTCTCCACAGCTCCTGATCTATTTGGGTTCTTATCGGGCCTCCGGGGTCTCTGACAGGTTC VL, 17C12 VL) AGTGGCAGTGGATCAGGCACAAATTTTACACTGAAAATCAGCAGAGTGGAGGCTGAGGATGTTGG GGTTTATTACTGCATGCAAGCTCTACAAACTCCATTCACTTTCGGCCCTGGGACCAAAGTGGATATC AAAH5N1 12G8 K GATATTGTGATGACTCAGTCTCCACTCTCCCTGCCCGTCACCCCTGGAGAGCCGGCCTCCATGTCCT 48 (12G8 VL) GCAGGTCTAGTCAGAGCCTCCTCCATAGTTATGGATCCGACTATTTGGATTGGTACCTGCAGAAGCC AGGGCAGTCTCCACAGCTCCTGATCTATTTGGGTTCTTATCGGGCCTCCGGGGTCTCTGACAGGTTC AGTGGCAGTGGATCAGGCACAAATTTTACACTGAAAATCAGCAGAGTGGAGGCTGAGGATGTTGG GCTTTATTACTGCATGCAAGCTCTACAAACTCCATTCACTTTCGGCCCTGGGACCAAAGTGGAAATC AAAH5N1 6G1 K GATATTGTGATGACTCAGTCTCCACTCTCCCTGCCCGTCACCCCTGGAGAGCCGGCCTCCATGTCCT 49 (6G1 VL) GCAGGTCTAGTCAGAGCCTCCTGCATAGTTATGGATCCAACTATTTGGATTGGTACCTGCAGAAGCC AGGGCAGTCTCCACAGCTCCTGATCTATTTGGGTTCTTATCGGGCCTCCGGGGTCTCTGACAGGTTC AGTGGCAGTGGATCAGGCACAAATTTTACACTGAAAATCAGCAGAGTGGAGGCTGAGGATGTTGG GGTTTATTACTGCATGCAAGCTCTACAAACTCCATTCACTTTCGGCCCTGGGACCAAAGTGGATATCAAATable 9. Fourth Clonotype - Variable Heavy Chain Region and Variable Light Chain Region Nucleotide Acid Sequences Description Sequence SEQ ID NO: H5N1 7H10 H CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 50 (7H10 VH) ACTGTCTCTGGTGGCTCCATCAGTAGCTACTACTGGAGCTGGATCCGGCAGCCCCCAGGGAAGGGGCTGGAGTGGATTGGGTATATCTATTATAGTGGGAGCACCAACTACAACCCCTCCCTCAAGAGTCGAGTCACCATATCAGTAGACACGTCCAAGAACCAGTTCTCCCTGAAGCTGACCTCTGTGACCGTTGCGGDescription Sequence SEQ ID NO: ACACGGCCGTGTATTACTGTGCGAGAGCCCCTATGGTTCGGGGACCTGACCTCTACTACTACTACGG TATGGACGTCTGGGGCCAAGGGACCACGGTCACCGTCTCCTCAH5N1 14B8 H CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 51 (14B9 VH) ACTGTCTCTGGTGACTCCATCAGTAGTTACTACTGGAGCTGGATCCGGCAGCCCCCAGGGAAGGGG CTGGAGTGGATTGGGTATATCTATTATAGTGGGAGCACCAACTACAACCCCTCCCTCAAGAGTCGA GTCACCATTTCAGTAGACACGTCCAAGAACCAGTTCTCCCTGAAGCTGACCTCTGTGACCGTTGCGG ACACGGCCGTTTATTACTGTGCGAGAGCCCCTATGGTTCGGGGACCTGACCTCTACTACTACTACGG TATGGACGTCTGGGGCCAAGGGACCACGGTCACCGTCTCCTCAH5N1_7H1O_1 GAAATAGTGATGACGCAGTCTCCAGCCACCCTGTCTGTGTCTCCAGGGGAAAGAGCCACCCTCTCC 52 4B8_K (7H10 TGCAGGGCCAGTCAGAGTGTTAGCAGCAACTTAGCCTGGTACCAGCAGAAACCTGGCCAGGCTCCC VL, 14B8 VL) AGGCTCCTCATCTATGGTGCATCCACCAGGGCCACTGGTATCCCAGCCAGGTTCAGTGGTAGTGGGTCTGGGACAGAGTTCACTCTCACCATCAGCAGCCTGCAGTCTGAAGATTTTGCAGTTTATTACTGTCAGCACTATAATAACTGGCCTCCTTTCGGCGGAGGGACCAAGGTGGAGATCAAATable 10. Fifth Clonotype - Variable Heavy Chain Region and Variable Light Chain Region Nucleotide Acid Sequences Description Sequence SEQ ID NO: H5N1 12G1 H CAGGTGCAACTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTCACCTGC 53 (12G1 VH) ACTGTCTCTGGTGACTCCATCAGTAGTTACTACTGGAGCTGGATCCGGCAGCCCCCCGGGAAGGGA CTGGAATGGATTGGATATGTCCATTACAGTGGGAACACCAACTACAACCCCTCCCTCAAGAGTCGA GTCACCATATCAGTAGACACGTCCAAGAACCAGTTCTCCCTGAAGCTGAGTTCTGTGACCGCTGCG GACACGGCCGTGTATTACTGTGCGAGAACTACTATGAGTCGGGGACCTTCCCTCTACTACTACTACG GTTTGGACGTCTGGGGCCAAGGGACCACGGTCACCGTCTCCTCAH5N1 12G1 K GATATTGTGATGACTCAGTCTCCACTCTCCCTGCCCGTCACCCCTGGAGAGCCGGCCTCCATCTCCT 54 (12G1 VL) GCAGGTCTAGTCAGAGCCTCCTGCATAGTTATGGATACATCTATTTGGATTGGTACCTGCAGAAGCC AGGGCAGTCTCCACAGCTCCTGATCTATTTGGGTTCTGATCGGGCCTCCGGGATCCCTGACAGGTTC AGTGGCAGTGGGTCAGGCACAGACTTTACACTGAAAATCAGCAGAGTGGAGGCTGAGGATGTTGG GGTTTATTACTGCATGCAAGCTCTACAAACTCCTATCACCTTCGGCCAAGGGACACGACTGGAGATTAAATable 11: First Clonotype - VH CDRs Determined Using IMGTName VH CDR1 VHCDR2 VH CDR3H5N1 12G9 H (12G9 VH) GYSISSGYY (SEQ ID NO: 55) IYHSGST (SEQ ID NO: 56) AREYDILTGYPYGFDI (SEQ ID NO: 59)H5N1 13B9 H (13B9 VH) GYSISSGYY (SEQ ID NO: 55) IYHSGSA (SEQ ID NO: 57) AREYDILTGYPYGFDI (SEQ ID NO: 59)H5N1 1A1 H (1A1 VH) GYSISSGYY (SEQ ID NO: 55) IYHSGST (SEQ ID NO: 56) ARQYDILTGYPYGFDI (SEQ ID NO: 209)H5N1_12C11_H (12C11 VH) GYSISSGYY (SEQ ID NO: 55) IYHSGST (SEQ ID NO: 56) ARQYDILTGYPYGFDI (SEQ ID NO: 209)H5N1 13E8 H (13E8 VH) GYSISSGYY(SEQ ID NO: 55) IYHSGST (SEQ ID NO: 56) ARQYDILTGYPYGFDF (SEQ ID NO: 60)Consensus sequence GYSISSGYY (SEQ ID NO: 55) IYHSGSX (X = T or A) (SEQ ARX1YDILTGYPYGFDX2 (Xi =ID NO: 58) E or Q; X2 = I or F) (SEQ IDNO: 61)Table 12: First Clonotype - VL CDRs Determined Using IMGTName VL CDR1 VL CDR2 VL CDR3H5N1 12G9 K (12G9 VL) QSVSSK (SEQ ID NO: 62) GAF QQYNNWPRT (SEQ ID NO: 66) H5N1 13B9 K (13B9 VL) QSVSSN (SEQ ID NO: 63) GAF QQYNNWPRT (SEQ ID NO: 66) H5N1 1A1 K (1A1 VL) QSVNSN (SEQ ID NO: 210) GAF QQYNNWPRT (SEQ ID NO: 66) H5N1 12C11 K (12C11 VL) QSVSSN (SEQ ID NO: 63) GAF QQYNNWPRT (SEQ ID NO: 66) H5N1 13E8 K (13E8 VL) QSVSSN (SEQ ID NO: 63) GAF QQYNNWPRT (SEQ ID NO: 66) Consensus sequence QSVX1SX2 (Xi = N or S; X2 = GAF QQYNNWPRT (SEQ ID NO: 66)K orN) (SEQ ID NO: 64)Table 13: First Clonotype - VH CDRs Determined Using KabatName VH CDR1 VH CDR2 VH CDR3H5N1 12G9 H (12G9 VH) SGYYWD (SEQ ID NO: 67) SIYHSGSTFYNPSLKS EYDILTGYPYGFDI (SEQ ID NO: 72)(SEQ ID NO: 68)H5N1 13B9 H (13B9 VH) SGYYWD (SEQ ID NO: 67) SIYHSGSAFYNPSFKS EYDILTGYPYGFDI (SEQ ID NO: 72)(SEQ ID NO: 69)H5N1 1 A1_H (1 Al VH) SGYYWD (SEQ ID NO: 67) TIYHSGSTFYNPSFKS QYDILTGYPYGFDI (SEQ ID NO: 73)(SEQ ID NO: 70)H5N1_12C11_H (12C11 VH) SGYYWD (SEQ ID NO: 67) TIYHSGSTFYNPSFKS QYDILTGYPYGFDI (SEQ ID NO:(SEQ ID NO: 70) 73)H5N1 13E8 H (13E8 VH) SGYYWD (SEQ ID NO: 67) TIYHSGSTFYNPSFKS QYDILTGYPYGFDF (SEQ ID NO: 74)(SEQ ID NO: 70)Consensus sequence SGYYWD (SEQ ID NO: 67) XiIYHSGS X2FYNPS X3KS X1YDILTGYPYGFDX2 (Xi = E or Q; X2(XI = S or T; X2= A or T; X3= = I or F) (SEQ ID NO: 75)L or F) (SEQ ID NO: 71)Table 14: First Clonotype - VL CDRs Determined Using KabatName VL CDR1 VL CDR2 VL CDR3H5N1 12G9 K (12G9 VL) RASQSVSSKLA (SEQ ID NO: 76) GAFTRAT (SEQ ID NO: 79) QQYNNWPRT (SEQ ID NO: 80) H5N1 13B9 K (13B9 VL) RASQSVSSNLA (SEQ ID NO: 77) GAFTRAT (SEQ ID NO: 79) QQYNNWPRT (SEQ ID NO: 80) H5N1 1A1 K(1A1 VL) RASQSVNSNLA (SEQ ID NO: 78) GAFTRAT (SEQ ID NO: 79) QQYNNWPRT (SEQ ID NO: 80) H5N1 12C11 K (12C11 VL) RASQSVSSNLA (SEQ ID NO: 77) GAFTRAT (SEQ ID NO: 79) QQYNNWPRT (SEQ ID NO: 80) H5N1 13E8 K (13E8 VL) RASQSVSSNLA (SEQ ID NO: 77) GAFTRAT (SEQ ID NO: 79) QQYNNWPRT (SEQ ID NO: 80) Consensus sequence RASQSVX1SX2LA (Xi = N or S; X2 GAFTRAT (SEQ ID NO: 79) QQYNNWPRT (SEQ ID NO: 80)= K orN) (SEQ ID NO: 211)Table 15: First Clonotype - VH CDRs Determined Using ChothiaName VH CDR1 VH CDR2 VH CDR3H5N1 12G9 H(12G9 VH) GYSISSGY (SEQ ID NO: 81) YHSGS (SEQ ID NO: 82) YDILTGYPYGFD (SEQ ID NO: 83) H5N1 13B9 H (13B9 VH) GYSISSGY (SEQ ID NO: 81) YHSGS (SEQ ID NO: 82) YDILTGYPYGFD (SEQ ID NO: 83) H5N1 1A1 H(1A1 VH) GYSISSGY (SEQ ID NO: 81) YHSGS (SEQ ID NO: 82) YDILTGYPYGFD (SEQ ID NO: 83) H5N1 12C11 H (12C11 VH) GYSISSGY (SEQ ID NO: 81) YHSGS (SEQ ID NO: 82) YDILTGYPYGFD (SEQ ID NO: 83) H5N1 13E8 H (13E8 VH) GYSISSGY (SEQ ID NO: 81) YHSGS (SEQ ID NO: 82) YDILTGYPYGFD (SEQ ID NO: 83)Consensus sequence GYSISSGY (SEQ ID NO: 81) YHSGS (SEQ ID NO: 82) YDILTGYPYGFD (SEQ ID NO: 83) Table 16: First Clonotype - VL CDRs Determined Using ChothiaName VL CDR1 VL CDR2 VL CDR3H5N1 12G9 K (12G9 VL) SQSVSSK (SEQ ID NO: 84) GAF YNNWPR (SEQ ID NO: 87) H5N1 13B9 K (13B9 VL) SQSVSSN (SEQ ID NO: 85) GAF YNNWPR (SEQ ID NO: 87) H5N1_1A1_K (1A1 VL) SQSVNSN (SEQ ID NO: GAF YNNWPR (SEQ ID NO: 87)212)H5N1 12C11 K (12C11 VL) SQSVSSN (SEQ ID NO: 85) GAF YNNWPR (SEQ ID NO: 87) H5N1 13E8 K (13E8 VL) SQSVSSN (SEQ ID NO: 85) GAF YNNWPR (SEQ ID NO: 87) Consensus sequence SQSVX1SX2 (X1 = S or N; X2GAF YNNWPR (SEQ ID NO: 87)= K or N) (SEQ ID NO: 86)Table 17: Second Clonotype -VH CDRs Determined Using IMGTName VH CDR1 VH CDR2 VH CDR3H5N1 1H2 H (1H2 VH) GGSISSYY (SEQ ID NO: 88) IYYSGST (SEQ ID NO: 89) ARELASTGPLYYYYGMDV (SEQ ID NO: 90)H5N1 17E3 H (17E3 VH) GGSISSYY (SEQ ID NO: 88) IYYSGST (SEQ ID NO: 89) ARELASTGPLYYYYGMDV (SEQ ID NO: 90)H5N1 20D10 H (20D10 VH) GGSISSYY (SEQ ID NO: 88) IYYSGST (SEQ ID NO: 89) ARELASTGPLYYYYGMDV (SEQ ID NO: 90)Consensus sequence GGSISSYY (SEQ ID NO: 88) IYYSGST (SEQ ID NO: 89) ARELASTGPLYYYYGMDV (SEQ IDNO: 90)Table 18: Second Clonotype -VL CDRs Determined Using IMGTName VL CDR1 VL CDR2 VL CDR3H5N1 1H2 K (1H2 VL) QSLLHSIGYTY (SEQ ID NO: 91) LGS MQALQTPYT (SEQ ID NO: 98) H5N1 17E3 K (17E3 VL) QSLLHSVGYTY (SEQ ID NO: 92) LGS MQALQTPYT (SEQ ID NO: 98) H5N1 20D10 K (20D10 VL) QSLLHSIGYTY (SEQ ID NO: 93) LGT MQALQTPYT (SEQ ID NO: 98) Consensus sequence QSLLHSXGYTY (X = I or V) (SEQ LGX (X = S or T) MQALQTPYT (SEQ ID NO: 98)ID NO: 94)Table 19: Second Clonotype -VH CDRs Determined Using KabatName VH CDR1 VH CDR2 VH CDR3 H5N1 1H2 H (1H2 VH) SYYWS (SEQ ID NO: 99) SIYYSGSTNYNPSLKS (SEQ ID NO: 100) ELASTGPLYYYYGMDV (SEQ ID NO: 101) H5N1 17E3 H (17E3 VH) SYYWS (SEQ ID NO: 99) SIYYSGSTNYNPSLKS (SEQ ID NO: 100) ELASTGPLYYYYGMDV (SEQ ID NO: 101) H5N1 20D10 H (20D10 VH) SYYWS (SEQ ID NO: 99) SIYYSGSTNYNPSLKS (SEQ ID NO: 100) ELASTGPLYYYYGMDV (SEQ ID NO: 101) Consensus sequence SYYWS (SEQ ID NO: 99) SIYYSGSTNYNPSLKS (SEQ ID NO: 100) ELASTGPLYYYYGMDV(SEQ ID NO: 101) Table 20: Second Clonotype -VL CDRs Determined Using KabatName VL CDR1 VL CDR2 VL CDR3H5N1 1H2 K (1H2 VL) RSSQSLLHSIGYTYLD LGSDRAP (SEQ ID NO: 105) MQALQTPYT (SEQ ID NO: 109)(SEQ ID NO: 102)H5N1 17E3 K (17E3 VL) RSSQSLLHSVGYTYLD LGSDRAS (SEQ ID NO: 106) MQALQTPYT (SEQ ID NO: 109)(SEQ ID NO: 103)H5Nl_20D10_K (20D10 VL) RSSQSLLHSIGYTYLD LGTDRAP (SEQ ID NO: 107) MQALQTPYT (SEQ ID NO: 109)(SEQ ID NO: 102)Consensus sequence RSSQSLLHSXGYTYLD (X = LGX1DRAX2 (Xi = S or T; X2 = P MQALQTPYT (SEQ ID NO: 109)I or V) (SEQ ID NO: 104) or S) (SEQ ID NO: 108)Table 21: Second Clonotype -VH CDRs Determined Using ChothiaName VH CDR1 VH CDR2 VH CDR3H5N1 1H2 H (1H2 VH) GGSISSY (SEQ ID NO: 110) YYSGS (SEQ ID NO: 111) LASTGPLYYYYGMD (SEQ ID NO:112)H5N1 17E3 H (17E VH) GGSISSY (SEQ ID NO: 110) YYSGS (SEQ ID NO: 111) LASTGPLYYYYGMD (SEQ ID NO:112)H5N1 20D10 H (20D10 VH) GGSISSY (SEQ ID NO: 110) YYSGS (SEQ ID NO: 111) LASTGPLYYYYGMD (SEQ ID NO:112)Consensus sequence GGSISSY(SEQ ID NO: 110) YYSGS (SEQ ID NO: 111) LASTGPLYYYYGMD (SEQ ID NO:112)Table 22: Second Clonotype -VL CDRs Determined Using ChothiaName VL CDR1 VL CDR2 VL CDR3H5N1 1H2 K (1H2 VL) SQSLLHSIGYTY (SEQ ID NO: 113) LGS ALQTPY (SEQ ID NO: 116) H5N1 17E3 K (17E3 VL) SQSLLHSVGYTY (SEQ ID NO: 114) LGS ALQTPY (SEQ ID NO: 116) H5N1 20D10 K (20D10 VL) SQSLLHSIGYTY (SEQ ID NO: 113) LGT ALQTPY (SEQ ID NO: 116) Consensus sequence SQSLLHSXGYTY (X = I or V) (SEQ LGX (X = S or T) ALQTPY (SEQ ID NO: 116)ID NO: 115)Table 23: Third Clonotype -VH CDRs Determined Using IMGTName VH CDR1 VHCDR2 VH CDR3H5N1 7G4 H (7G4 VH) GGSISSYY (SEQ ID NO: 117) IYYSGST (SEQ ID NO: 120) ARDLREWFGALNYYYGMDV (SEQ ID NO: 123) H5N1 7G11_H (7G4 VH) GGSISSYF (SEQ ID NO: 118) IYYSGNT (SEQ ID NO: 121) ARDLREWFGALNYYYGMDV (SEQ ID NO: 123) H5N1 12G8 H (12G8 VH) GGSISSYF (SEQ ID NO: 118) IYYSGNT (SEQ ID NO: 121) ARDLREWFGALNYYYGMDV (SEQ ID NO: 123) H5N1_17C12_H (17C12 VH) GGSISSYY (SEQ ID NO: 117) IYYSGNT (SEQ ID NO: 121) ARDLREWFGALNYYYGMDV (SEQ ID NO: 123) H5N1 6G1 H (6G1 VH) GGSISSYY (SEQ ID NO: 117) IYYSGST (SEQ ID NO: 120) ARDLREWSGALNYYYGMDV (SEQ ID NO: 124) Consensus sequence GGSISSYX (X = YorF) (SEQ IYYSGXT (X = S or N) (SEQ ARDLREWXGALNYYYGMDVID NO: 119) ID NO: 122) (X = F or S) (SEQ ID NO: 125) Table 24: Third Clonotype -VL CDRs Determined Using IMGTName VL CDR1 VL CDR2 VL CDR3H5N1 7G4 K (7G4 VL) QSLLHSYGSDY (SEQ ID NO: 126) LGS MQALQTPFT (SEQ ID NO: 127) H5N1 7G11 K (7G11 VL) QSLLHSYGSDY (SEQ ID NO: 126) LGS MQALQTPFT (SEQ ID NO: 127) H5N1 12G8 K (12G8 VL) QSLLHSYGSDY (SEQ ID NO: 126) LGS MQALQTPFT (SEQ ID NO: 127) H5N1 17C12 K (17C12 VL) QSLLHSYGSDY (SEQ ID NO: 126) LGS MQALQTPFT (SEQ ID NO: 127) H5N1 6G1 K (6G1 VL) QSLLHSYGSNY (SEQ ID NO: 193) LGS MQALQTPFT (SEQ ID NO: 127) Consensus sequence QSLLHSYGSXY (X = D or N) (SEQ LGS MQALQTPFT (SEQ ID NO: 127)ID NO: 194)Table 25: Third Clonotype -VH CDRs Determined Using KabatName VH CDR1 VH CDR2 VH CDR3H5N1 7G4 H (7G4 VH) SYYWS (SEQ ID NO: 128) YIYYSGSTNYNPSLKS DLREWFGALNYYYGMDV (SEQ ID (SEQ ID NO: 131) NO: 135)H5N1 7G11_H (7G11 VH) SYFWS (SEQ ID NO: 129) YIYYSGNTSYNPSLKS DLREWFGALNYYYGMDV (SEQ ID (SEQ ID NO: 132) NO: 135)H5N1 12G8 H (12G8 VH) SYFWS (SEQ ID NO: 129) YIYYSGNTTYNPSLKS DLREWFGALNYYYGMDV (SEQ ID (SEQ ID NO: 133) NO: 135)H5N1_17C12_H (17C12 VH) SYYWS (SEQ ID NO: 128) YIYYSGNTNYNPSLKS DLREWFGALNYYYGMDV (SEQ ID (SEQ ID NO: 213) NO: 135)H5N1 6G1 H (6G1 VH) SYYWS (SEQ ID NO: 128) YIYYSGSTNYNPSLKS DLREWSGALNYYYGMDV (SEQ ID (SEQ ID NO: 131) NO: 136)Consensus sequence SYXWS (X = Y or F) (SEQ YIYYSGX1TX2YNPSLKS DLREWXGALNYYYGMDVID NO: 130) (Xi = S or N; X2= N, S or T) (X = F or S) (SEQ ID NO: 137)(SEQ ID NO: 134)Table 26: Third Clonotype -VL CDRs Determined Using KabatName VL CDR1 VL CDR2 VL CDR3H5N1 7G4 K (7G4 VL) RSSQSLLHSYGSDYLD LGSYRAS (SEQ ID NO: 141) MQALQTPFT (SEQ ID NO: 142)(SEQ ID NO: 138)H5N1 7G11_K (7G11 VL) RSSQSLLHSYGSDYLD LGSYRAS (SEQ ID NO: 141) MQALQTPFT (SEQ ID NO: 142)(SEQ ID NO: 138)H5N1 12G8 K (12G8 VL) RSSQSLLHSYGSDYLD LGSYRAS (SEQ ID NO: 141) MQALQTPFT (SEQ ID NO: 142)(SEQ ID NO: 138)H5N1_17C12_K (17C12 VL) RSSQSLLHSYGSDYLD LGSYRAS (SEQ ID NO: 141) MQALQTPFT (SEQ ID NO: 142)(SEQ ID NO: 138)H5N1 6G1 K (6G1 VL) RSSQSLLHSYGSNYLD LGSYRAS (SEQ ID NO: 141) MQALQTPFT (SEQ ID NO: 142)(SEQ ID NO: 139)Name VL CDR1 VL CDR2 VL CDR3Consensus sequence RSSQSLLHSYGSXYLD LGSYRAS (SEQ ID NO: 141) MQALQTPFT (SEQ ID NO: 142)(X = D orN) (SEQ ID NO:140)Table 27: Third Clonotype -VH CDRs Determined Using ChothiaName VH CDR1 VH CDR2 VH CDR3H5N1 7G4 H (7G4 VH) GGSISSY (SEQ ID NO: 143) YYSGS (SEQ ID NO: 144) LREWFGALNYYYGMD (SEQ ID NO: 147)H5N1 7G11_H (7G11 VH) GGSISSY (SEQ ID NO: 143) YYSGN (SEQ ID NO: 145) LREWFGALNYYYGMD (SEQ ID NO: 147)H5N1 12G8 H (12G8 VH) GGSISSY (SEQ ID NO: 143) YYSGN (SEQ ID NO: 145) LREWFGALNYYYGMD (SEQ ID NO: 147)H5N1_17C12_H (17C12 VH) GGSISSY (SEQ ID NO: 143) YYSGN (SEQ ID NO: 145) LREWFGALNYYYGMD (SEQ ID NO: 147)H5N1 6G1 H (6G11 VH) GGSISSY (SEQ ID NO: 143) YYSGS (SEQ ID NO: 144) LREWSGALNYYYGMD (SEQ ID NO:148)Consensus sequence GGSISSY (SEQ ID NO: 143) YYSGX (X = S or N) (SEQ LREWXGALNYYYGMDID NO: 146) (X = F or S) (SEQ ID NO: 149) Table 28: Third Clonotype -VL CDRs Determined Using ChothiaName VL CDR1 VL CDR2 VL CDR3H5N1 7G4 K (7G4 VL) SQSLLHSYGSDY (SEQ ID NO: 150) LGS ALQTPF (SEQ ID NO: 151) H5N1 7G11 K (7G11 VL) SQSLLHSYGSDY (SEQ ID NO: 150) LGS ALQTPF (SEQ ID NO: 151) H5N1 12G8 K (12G8 VL) SQSLLHSYGSDY (SEQ ID NO: 150) LGS ALQTPF (SEQ ID NO: 151) H5N1 17C12 K (17C12 VL) SQSLLHSYGSDY (SEQ ID NO: 150) LGS ALQTPF (SEQ ID NO: 151) H5N1 6G1 K (6G1 VL) SQSLLHSYGSNY (SEQ ID NO: 206) LGS ALQTPF (SEQ ID NO: 151)Name VL CDR1 VL CDR2 VL CDR3Consensus sequence SQSLLHSYGSXY (X = D or N) (SEQ LGS ALQTPF (SEQ ID NO: 151)ID NO: 207)Table 29: Fourth Clonotype -VH CDRs Determined Using IMGTName VH CDR1 VHCDR2 VH CDR3H5N1 7H10 H (7H10 VH) GGSISSYY (SEQ ID NO: 152) IYYSGST (SEQ ID NO: 155) ARAPMVRGPDLYYYYGMDV (SEQ ID NO: 156) H5N1 14B8 H (14B8 VH) GDSISSYY (SEQ ID NO: 153) IYYSGST (SEQ ID NO: 155) ARAPMVRGPDLYYYYGMDV (SEQ ID NO: 156) Consensus sequence GXSISSYY (X = D or G) (SEQ IYYSGST (SEQ ID NO: 155) ARAPMVRGPDLYYYYGMDVID NO: 154) (SEQ ID NO: 156)Table 30: Fourth Clonotype -VL CDRs Determined Using IMGTName VL CDR1 VL CDR2 VL CDR3H5N1 7H10 K (7H10 VL) QSVSSN (SEQ ID NO: 157) GAS QHYNNWPP (SEQ ID NO: 159) H5N1 14B8 K (14B8 VL) QSVSSN (SEQ ID NO: 157) GAS QHYNNWPP (SEQ ID NO: 159)Consensus sequence QSVSSN (SEQ ID NO: 157) GAS QHYNNWPP (SEQ ID NO: 159)Table 31: Fourth Clonotype -VH CDRs Determined Using KabatName VH CDR1 VH CDR2 VH CDR3H5N1 7H10 H (7H10 VH) SYYWS (SEQ ID NO: 160) YIYYSGSTNYNPSLKS APMVRGPDLYYYYGMDV (SEQ ID (SEQ ID NO: 161) NO: 162)H5N1 14B8 H (14B8 VH) SYYWS (SEQ ID NO: 160) YIYYSGSTNYNPSLKS APMVRGPDLYYYYGMDV (SEQ ID (SEQ ID NO: 161) NO: 162)Consensus sequence SYYWS (SEQ ID NO: 160) YIYYSGSTNYNPSLKS APMVRGPDLYYYYGMDV (SEQ ID(SEQ ID NO: 161) NO: 162)Table 32: Fourth Clonotype -VL CDRs Determined Using KabatName VL CDR1 VL CDR2 VL CDR3H5N1 7H10 K (7H10 VL) RASQSVSSNLA (SEQ ID NO: 163) GASTRAT (SEQ ID NO: 164) QHYNNWPP (SEQ ID NO: 165) H5N1 14B8 K (14B8 VL) RASQSVSSNLA (SEQ ID NO: 163) GASTRAT (SEQ ID NO: 164) QHYNNWPP (SEQ ID NO: 165)Consensus sequence RASQSVSSNLA (SEQ ID NO: 163) GASTRAT (SEQ ID NO: 164) QHYNNWPP (SEQ ID NO: 165) Table 33: Fourth Clonotype -VH CDRs Determined Using ChothiaName VH CDR1 VH CDR2 VH CDR3H5N1 7H10 H (7H10 VH) GGSISSY (SEQ ID NO: 166) YYSGS (SEQ ID NO: 169) PMVRGPDLYYYYGMD (SEQ ID NO:170)H5N1 14B8 H (14B8 VH) GDSISSY (SEQ ID NO: 167) YYSGS (SEQ ID NO: 169) PMVRGPDLYYYYGMD (SEQ ID NO:170)Consensus sequence GXSISSY (X = G or D) (SEQ YYSGS (SEQ ID NO: 169) PMVRGPDLYYYYGMD (SEQ ID NO:ID NO: 168) 170)Table 34: Fourth Clonotype -VL CDRs Determined Using ChothiaName VL CDR1 VL CDR2 VL CDR3H5N1 7H10 K (7H10 VL) SQSVSSN (SEQ ID NO: 171) GAS YNNWP (SEQ ID NO: 172) H5N1 14B8 K (14B8 VL) SQSVSSN (SEQ ID NO: 171) GAS YNNWP (SEQ ID NO: 172)Consensus sequence SQSVSSN (SEQ ID NO: 171) GAS YNNWP (SEQ ID NO: 172)Table 35: Fifth Clonotype -VH CDRs Determined Using IMGTName VH CDR1 VH CDR2 VH CDR3H5N1 12G1 H (12G1 VH) GDSISSYY (SEQ ID NO: VHYSGNT (SEQ ID NO: ARTTMSRGPSLYYYYGLDV (SEQ ID173) 174) NO: 175)Table 36: Fifth Clonotype -VL CDRs Determined Using IMGTName VL CDR1 VL CDR2 VL CDR3H5N1 12G1 K (12G1 VL) QSLLHSYGYIY (SEQ ID LGS MQALQTPIT (SEQ ID NO: 178)NO: 176)Table 37: Fifth Clonotype -VH CDRs Determined Using KabatName VH CDR1 Heavy CDR2 Heavy CDR3H5N1 12G1 H (12G1 VH) SYYWS (SEQ ID NO: 128) YVHYSGNTNYNPSLKS TTMSRGPSLYYYYGLDV (SEQ ID(SEQ ID NO: 180) NO: 181)Table 38: Fifth Clonotype -VL CDRs Determined Using KabatName VL CDR1 VL CDR2 VL CDR3H5N1 12G1 K (12G1 VL) RSSQSLLHSYGYIYLD LGSDRAS (SEQ ID NO: MQALQTPIT (SEQ ID NO: 184)(SEQ ID NO: 182) 183)Table 39: Fifth Clonotype -VH CDRs Determined Using ChothiaName VH CDR1 VH CDR2 VH CDR3H5N1 12G1 H (12G1 VH) GDSISSY (SEQ ID NO: 185) HYSGN (SEQ ID NO: 186) TMSRGPSLYYYYGLD (SEQ ID NO:187)Table 40: Fifth Clonotype -VL CDRs Determined Using ChothiaName VL CDR1 VL CDR2 VL CDR3H5N1 12G1 K (12G1 VL) SQSLLHSYGYIY (SEQ ID LGS ALQTPI (SEQ ID NO: 189)NO: 188)Table 41: Third and Fifth Clonotypes - VH CDRs Determined by IMGTName VH CDR1 VH CDR2 VH CDR3H5N1 7G4 H (7G4 VH) GGSISSYY (SEQ ID NO: 117) IYYSGST (SEQ ID NO: 120) ARDLREWFGALNYYYGMDV (SEQ ID NO: 123)H5N1 7G11_H (7G11 GGSISSYF (SEQ ID NO: 118) IYYSGNT (SEQ ID NO: 121) ARDLREWFGALNYYYGMDV (SEQ VH) ID NO: 123)H5N1 12G8 H (12G8 GGSISSYF (SEQ ID NO: 118) IYYSGNT (SEQ ID NO: 121) ARDLREWFGALNYYYGMDV (SEQ VH) ID NO: 123)H5N1_17C12_H (17C12 GGSISSYY (SEQ ID NO: 117) IYYSGNT (SEQ ID NO: 121) ARDLREWFGALNYYYGMDV (SEQ VH) ID NO: 123)H5N1 6G1 H (6G1 VH) GGSISSYY (SEQ ID NO: 117) IYYSGST (SEQ ID NO: 120) ARDLREWSGALNYYYGMDV (SEQ ID NO: 124)H5N1 12G1 H (12G1 GDSISSYY (SEQ ID NO: 173) VHYSGNT (SEQ ID NO: 174) ARTTMSRGPSLYYYYGLDV (SEQ ID VH) NO: 175)Consensus sequence GX1SISSYX2 X1X2YSGX3T ARXiX2X3X4X5X6X7X8LX9YYYGXioDV Xi = G or S Xi = I or V XI=D or TX2 = Y or F (SEQ ID NO: 190) X2=Y or H X2=L or TX3=N or S (SEQ ID NO: 191) X3=R or MName VH CDR1 VH CDR2 VH CDR3X4=E or SX5=W or RX6=F, S or GX7=G or PXs=A or SX9=N or YXio=M or L(SEQ ID NO: 192)Table 42: Third and Fifth Clonotypes - VL CDRs Determined by IMGTName VL CDR1 VL CDR2 VL CDR3H5N1 7G4 K (7G4 VL) QSLLHSYGSDY (SEQ ID LGS MQALQTPFT (SEQ ID NO: 127)NO: 126)H5N1 7G11_K (7G11 VL) QSLLHSYGSDY (SEQ ID LGS MQALQTPFT (SEQ ID NO: 127)NO: 126)H5N1 12G8 K (12G8 VL) QSLLHSYGSDY (SEQ ID LGS MQALQTPFT (SEQ ID NO: 127)NO: 126)H5N1_17C12_K (17C12 VL) QSLLHSYGSDY (SEQ ID LGS MQALQTPFT (SEQ ID NO: 127)NO: 126)H5N1 6G1 K (6G1 VL) QSLLHSYGSNY (SEQ ID LGS MQALQTPFT (SEQ ID NO: 127)NO: 193)H5N1 12G1 K (12G1 VL) QSLLHSYGYIY (SEQ ID LGS MQALQTPIT (SEQ ID NO: 178)NO: 176)Consensus sequence QSLLHSYGX1X2Y LGS MQALQTPXT (X=F or I) (SEQ ID NO:(Xi=S or Y; X2=D, N or I) 195)(SEQ ID NO: 177)Table 43: Third and Fifth Clonotypes - VH CDRs Determined by KabatName VH CDR1 VHCDR2 VH CDR3H5N1 7G4 H (7G4 VH) SYYWS (SEQ ID NO: 128) YIYYSGSTNYNPSLKS DLREWFGALNYYYGMDV (SEQ ID NO:(SEQ ID NO: 131) 135)H5N1 7G11_H (7G11 VH) SYFWS (SEQ ID NO: 129) YIYYSGNTSYNPSLKS DLREWFGALNYYYGMDV (SEQ ID NO:(SEQ ID NO: 132) 135)H5N1 12G8 H (12G8 VH) SYFWS (SEQ ID NO: 129) YIYYSGNTTYNPSLKS DLREWFGALNYYYGMDV (SEQ ID NO:(SEQ ID NO: 133) 135)H5N1_17C12_H (17C12 SYYWS (SEQ ID NO: 128) YIYYSGNTNYNPSLKS DLREWFGALNYYYGMDV (SEQ ID NO:VH) (SEQ ID NO: 213) 135)H5N1 6G1 H (6G1 VH) SYYWS (SEQ ID NO: 128) YIYYSGSTNYNPSLKS DLREWSGALNYYYGMDV (SEQ ID NO:(SEQ ID NO: 131) 136)H5N1 12G1 H (12G1 VH) SYYWS (SEQ ID NO: 128) YVHYSGNTNYNPSLKS TTMSRGPSLYYYYGLDV (SEQ ID NO:(SEQ ID NO: 180) 181)Consensus sequence SYXWS (X = Y or F) (SEQ YX1X2YSGX3TX4YNPSLKS X1X2X3X4X5X6X7X8LX9YYYGX10DV ID NO: 130) (Xi = I or V; X2 = Y or H; Xi=D or TX3=N or S; X4=S, T orN) X2=L or T(SEQ ID NO: 196) X3=R or MX4=E or SX5=W or RX6=F, S or GX7=G or PXs=A or SX9=N or YXio=M or L(SEQ ID NO: 197)Table 44: Third and Fifth Clonotypes - VL CDRs Determined by KabatName VL CDR1 VL CDR2 VL CDR3H5N1 7G4 K (7G4 VL) RSSQSLLHSYGSDYLD LGSYRAS (SEQ ID NO: MQALQTPFT (SEQ ID NO: 142)(SEQ ID NO: 138) 141)H5N1 7G11_K (7G11 VL) RSSQSLLHSYGSDYLD LGSYRAS (SEQ ID NO: MQALQTPFT (SEQ ID NO: 142)(SEQ ID NO: 138) 141)H5N1 12G8 K (12G8 VL) RSSQSLLHSYGSDYLD LGSYRAS (SEQ ID NO: MQALQTPFT (SEQ ID NO: 142)(SEQ ID NO: 138) 141)H5N1_17C12_K (17C12 VL) RSSQSLLHSYGSDYLD LGSYRAS (SEQ ID NO: MQALQTPFT (SEQ ID NO: 142)(SEQ ID NO: 138) 141)H5N1 6G1 K (6G1 VL) RSSQSLLHSYGSNYLD LGSYRAS (SEQ ID NO: MQALQTPFT (SEQ ID NO: 142)(SEQ ID NO: 139) 141)H5N1 12G1 K (12G1 VL) RSSQSLLHSYGYIYLD LGSDRAS (SEQ ID NO: MQALQTPIT (SEQ ID NO: 184)(SEQ ID NO: 182) 183)Consensus sequence RSSQSLLHSYGX1X2YLD LGSXRAS (X=Y or D) (SEQ MQALQTPXT (X=F or I) (SEQ ID NO:Xi =Y or S; X2=D, N or I) ID NO: 199) 200)(SEQ ID NO: 198)Table 45: Third and Fifth Clonotypes - VL CDRs Determined by ChothiaName Heavy CDR1 Heavy CDR2 Heavy CDR3H5N1 7G4 H (7G4 VH) GGSISSY (SEQ ID NO: 143) YYSGS (SEQ ID NO: 144) LREWFGALNYYYGMD (SEQ ID NO: 147)H5N1 7G11_H (7G11 VH) GGSISSY (SEQ ID NO: 143) YYSGN (SEQ ID NO: 145) LREWFGALNYYYGMD (SEQ ID NO: 147)H5N1 12G8 H (12G8 VH) GGSISSY (SEQ ID NO: 143) YYSGN (SEQ ID NO: 145) LREWFGALNYYYGMD (SEQ ID NO: 147)H5N1_17C12_H (17C12 VH) GGSISSY (SEQ ID NO: 143) YYSGN (SEQ ID NO: 145) LREWFGALNYYYGMD (SEQ IDNO: 147)Name Heavy CDR1 Heavy CDR2 Heavy CDR3H5N1 6G1 H (6G1 VH) GGSISSY (SEQ ID NO: 143) YYSGS (SEQ ID NO: 144) LREWSGALNYYYGMD (SEQ ID NO: 148)H5N1 12G1 H (12G1 VH) GDSISSY (SEQ ID NO: 185) HYSGN (SEQ ID NO: 186) TMSRGPSLYYYYGLD (SEQ ID NO:187)Consensus sequence GXSISSY (X=G or D) (SEQ ID X1YSGX2 (Xi = Y or H; X1X2X3X4X5X6X7LX8YYYGX9D NO: 201) X2=N or S) (SEQ ID NO: XI=L or T208) X2=R or MX3=E or SX4=W or RX5=F, S or GX6=G or PX?=A or SXs=N or YX9=M or L(SEQ ID NO: 203)Table 46: Third and Fifth Clonotypes - VL CDRs Determined by ChothiaName VL CDR1 VL CDR2 VL CDR3H5N1 7G4 K (7G4 VL) SQSLLHSYGSDY (SEQ ID LGS ALQTPF (SEQ ID NO: 151)NO: 150)H5N1 7G11_K (7G11 VL) SQSLLHSYGSDY (SEQ ID LGS ALQTPF (SEQ ID NO: 151)NO: 150)H5N1 12G8 K (12G8 VL) SQSLLHSYGSDY (SEQ ID LGS ALQTPF (SEQ ID NO: 151)NO: 150)H5N1_17C12_K (17C12 VL) SQSLLHSYGSDY (SEQ ID LGS ALQTPF (SEQ ID NO: 151)NO: 150)Name VL CDR1 VL CDR2 VL CDR3H5N1 6G1 K (6G1 VL) SQSLLHSYGSNY (SEQ ID LGS ALQTPF (SEQ ID NO: 151)NO: 206)H5N1 12G1 K (12G1 VL) SQSLLHSYGYIY (SEQ ID LGS ALQTPI (SEQ ID NO: 189)NO: 188)Consensus sequence SQSLLHSYGX1X2Y (Xi=S or LGS ALQTPX (X=F or I) (SEQ ID NO: 205)Y; X2=D, N, or I) (SEQ IDNO: 204)Amino acid sequence of influenza virus A / Jiangsu / NJ210 / 2023 hemagglutinin MENIVLLLAIVNLVKSDQICIGYHANNSTEQVDTIMEKNVTVTHAQDILEKTHNGKLCDLNGVKPLILKDCSVAGWLLGNPMCDEFIR VPEWSYIVERDNPANDLCYPGSLNDYEELKHLLSRINHFEKILIIPKSSWPNHETSLGVSAACPYQGAPSFFRNVVWLIKKDDAYPTIKIS YNNTNREDLLILWGIHHSNNAEEQTNLYKNPTTYISVGTSTLNQRLVPKIATRSQVNGQRGRMDFFWTILKPDDAIHFESNGNFIAPEY AYKIVKKGDSTIMKSGVEYGHCNTKCQTPVGAINSSMPFHNIHPLTIGECPKYVKSNKLVLATGLRNSPPREKRRKRGLFGAIAGFIEGG WQGMVDGWYGYHHSNEQGSGYAADKESTQKAIDGVTNKVNSIIDKMNTQFEAVGREFNNLERRIENLNKKMEDGFLDVWTYNAEL LVLMENERTLDFHDSNVKNLYDKVRLQLRDNAKELGNGCFEFYHKCDNECMESVRNGTYYYPQYSEEARLKREEISGVKLESIGTYQ ILSIYSTAASSLALAIMMAGLSLWMCSNGSLQCRICI (SEQ ID NO: 179)6. BRIEF DESCRIPTION OF THE FIGURES

[0054] FIGs. 1A-1D. Immunization in H2L2 Harbor Mice® with HA and NA protein of H5N1 clade 2.3.4.4b virus. (FIG. 1 A) The timeline for vaccination is shown in the upper panel. Five female H2L2 Harbor Mice® mice were immunized by intraperitoneal injection with the protein amounts shown in the figure, adjuvanted with poly IC. Sera was collected at the indicated time points, and the final immunization was performed two and four days before the spleen was harvested for hybridoma fusion (created with BioRender.com). (FIG. IB) Collected sera were tested against the H5 (left) and N1 (right) proteins by enzyme-linked immunosorbent assay (ELISA). Based on the results, a single mouse was selected and sacrificed for spleen harvest and hybridoma fusion. In this graph, the x-axis represents the individual mice, and the y-axis represents the area under the curve (AUC) for the response with the sera. The area under the curve (AUC) was calculated using GraphPad Prism 10, with the average plus three standard deviations of the blank wells serving as the baseline. (FIG. 1 C) A total of 1,977 hybridoma clones were generated from the top responding mouse. Supernatants from the clones were first screened by ELISA coated with a combination of H5 and N1 proteins. Hemagglutinin inhibition (HI) assays were also performed at a fixed supernatant dilution of 1:10. ELISA binders were compared to a 1: 100 dilution of unimmunized sera (normal mouse sera, NMS) and were classified as high (Hi) (>3x NMS), medium (Med) (1.5-3x NMS), and low (<1.5x NMS), with and without HI activity (right pie graph). AH medium and high binding clones with and without HI activity were down-selected for secondary screening (401 clones) by H5-specific ELIS As and HI assays.Seventy-seven total clones (39%) rescreened positive by either ELISA or HI (left pie graph). The top thirty clones that were both ELISA and HI positive were down-selected for isotyping, variable segment sequencing and recombinant production as human Gl / kappa. (FIG. ID) Clonotype analysis based on shared CDR3s (shared length and >90% amino acid identity) and shared VDJ / VJ gene usage on the sequences of the top performing sixteen clones revealed five closely related clonotypes.

[0055] FIGs. 2A-2D. Anti-H5 mAbs bind broadly to HA proteins of virus variants and inhibit virus replication in vitro. (FIG. 2A) Binding breadth of anti-H5 mAbs to H5 protein from infected birds (top panel), cattle (middle panel), and individuals (bottom panel), was evaluated by ELISA in duplicates. Positive control an anti -HA antibody, CR911427. Data shown is minimal binding concentration (ug / ml), defined as the lowest concentration with a signal greater than 3 standard deviations (SD) above blanks. (FIG. 2B) mAbs ability to block the virus-host receptor interaction was assessed by hemagglutination inhibition (HI) assay in NAI-5010413635vl 67duplicates. Positive control, serum (1:10) from a mouse infected with A / bald eagle / FL / W22-134-OP / 2022 (H5N1-A / PR / 8 / 34 reassortant). Data shows minimal HI concentration (pg / ml), defined as the last concentration that neutralizes the virus. (FIG. 2C) Efficacy of the anti-H5 mAbs to inhibit viral replication was evaluated using an in vitro neutralization assay against A / bald eagle / FL / W22-134-OP / 2022 (H5N1-A / PR / 8 / 34 reassortant), in duplicates, with controls identical to FIG. 2A. Data shows minimal neutralizing titer (pg / ml), defined as the lowest concentration where neutralization is observed. (FIG. 2D) mAbs capacity to inhibit neuraminidase (NA) activity of clade 2.3.4.4b virus was tested in duplicates, with positive control an anti -NA antibody, IGO I12. Data shows half inhibitory concentration (ICso) (pg / ml). Negative control for all the assays was an anti-SARS-CoV-2 spike antibody13.

[0056] FIG. 3. Phylogenetic analysis of the HA sequence of the viruses used throughout the study. The phylogenetic tree here was constructed using the HA amino acid (aa) sequence of H5N1 viruses isolated from infected birds and mammals, including humans. The different virus variants are; H5N1 virus used as the antigen, A / mallard / New York / 22-008760-007-original / 2022; the H5N1 virus strains obtained from the New York City Virus Hunters (NYCVH): A / chicken / New York / NYCVH 168127 / 2023, A / Canada goose / New York / NYCVH 23-453 / 2023, A / Canada goose / New York / NYCVH 22-9190 / 2022, A / peregrine falcon / New York / NYCVH 160820 / 2022, and A / red-tailed hawk / New York / NYCVH 22-8477 / 2022, the H5N1 virus strain used for cell culture assays, A / bald eagle / FL / W22-134-OP / 2022; finally, H5N8 and H5N2 virus strains isolated in 2014 from two different geographic locations: A / chicken / Netherlands / 14015531 / 2014 and A / Northern Pintail / Washington / 40964 / 2014, respectively. Recently detected H5N1 bovine virus: A / dairy cattle / Texas / 24-008749-001-original / 2024. Finally, virus strains isolated from humans infected with H5N1 virus strains from 2005 to 2023: A / Vietnam / 1203 / 2004 (H5N1), A / Indonesia / 5 / 2005 (H5N1), A / Shenzhen / 1 / 2016 (H5N6), A / Cambodia / NPH230032_2 / 2023 (H5N1), A / Jiangsu / NJ210 / 2023 (H5N1) and virus strains isolated from humans infected with H1N1 virus A / Wisconsin / 67 / 2022. The scale represents a 0.02% difference in amino acid sequence.

[0057] FIGs. 4A-4D. Anti-H5 mAbs are protective in a prophylactic setting in vivo and promote viral clearance in infected mice lungs. (FIG. 4A) Six-week-old female BALB / c mice (n=5 / group) were injected intraperitoneally with different amounts of anti-H5 mAb, as a negative control anti-SARS-CoV-2 spike mAb was used, and the data of negative control is plotted alongside the experimental groups. After 4 h, mice were infected with 5 x 50% lethal doses (LDso) of A / bald eagle / FL / W22-134-OP / 2022 (H5N1-A / PR / 8 / 34 reassortant)NAI-5010413635vl 68virus. Body weight percentage (FIG. 4B) and survival (FIG. 4C) were plotted over 14 days post-infection. The percentage of the body weight is relative to the starting body weight, data is represented as group means with standard deviation. (FIG. 4D) Six-week-old female BALB / c mice (n=3 / group) received 5 mg / kg of anti-H5 mAbs, and anti-SARS-CoV-2 mAb was used as a control, 4 h before infection done as in FIG. 4A. Lungs were harvested on day 3 and day 5 post-infection.

[0058] FIGs. 5A-5C. Anti-H5 mAbs are protective in a therapeutic setting in vivo. (FIG.5 A) Six-week-old female BALB / c mice (n=5 / group) were injected intraperitoneally with 5 mg / kg of anti-H5 mAb and as a negative control anti-SARS-CoV-2 spike mAb was used. The data of the negative control group is plotted alongside the experimental groups. The antibodies were administered on day 2, 3, and 4 after infecting the mice with 5 LDso of A / bald eagle / FL / W22-134-OP / 2022 (H5N1-A / PR / 8 / 34 reassortant) virus (created with BioRender.com). The percentage of initial body weight (FIG. 5B) and survival (FIG. 5C) were plotted over 14 days post-infection. The percentage of the body weight is relative to the starting weight, and the data is represented as group means with standard deviation. Arrows indicate the time point at which mAbs were administered.

[0059] FIGs. 6A-6B. Negative stain EM reconstructions of representative mAbs for clonotypes 1-3 and 5. Maps demonstrate binding to either recombinantA / Jiangsu / NJ210 / 2023 H5 (FIG. 6 A) or A / red-tailed hawk / New York / NYCVH 22-8477 / 2022 H5 (FIG. 6B) depicted on a map of A / Vietnam / 1203 / 2004 H5 (PDB:6E7G) generated using ChimeraX.

[0060] FIG. 7. Negative stain EM representative 2D classes and 3D reconstructions of monoclonal antibodies bound to A / Jiangsu / NJ210 / 2023 H5. 2D class averages (left panels) representing particles used for negative stain 3D reconstructions (right panels) of mAbs in complex with recombinant A / Jiangsu / NJ210 / 2023 H5. Reconstructions were generated using Relion 3.0. mAbs selected as representative of their respective clonotypes and used for cryoEM analysis are boxed.

[0061] FIG. 8. Negative stain EM representative 2D classes and 3D reconstructions of monoclonal antibodies bound to A / red-tailed hawk / New York / NYCVH 22-8477 / 2022 H5.2D class averages (left panels) representing particles incorporated in negative stain 3D reconstructions (right panels) of mAbs in complex with recombinant A / Jiangsu / NJ210 / 2023 H5. Reconstructions were generated using Relion 3.0.

[0062] FIG. 9A-9E. CryoEM workflow. (FIG. 9A) Representative micrographs with lOOnm white scale bars. (FIG. 9B) Top 20 classes of final 2D class average selection after NAI-5010413635vl 692D clean up steps. (FIG. 9C) Fourier shell correlation (FSC) plots, (FIG. 9D) viewing distribution plots, (FIG. 9E) local resolution maps, and particle count for final 3D reconstructions.

[0063] FIGs. 10A-10G. Structural characterization reveals shared approach to antigen engagement. (FIG. 10A) Footprints for clonotype 1 and clonotypes 2, 3, and 5 on a surface rendering of A / Jiangsu / NJ210 / 2023 H5. (FIG. 10B) Overall architecture of antigen engagement for mAbs 20D10, 6G1, and 12G1 by clonotype. Heavy chains are presented in a darker shade than light chains. (FIG. 10C) Zoomed in overlay of heavy and light chain models of 20D10, 6G1, and 12G1 engaging with the antigen binding pocket. (FIG. 10D) Analysis of residues in mAb CDRH3 loops and the antigen binding pocket highlights conserved motifs across distinct clonotypes. Residue labels are presented in Kabat numbering. (FIG. 10E) Hydrophobic surface renderings of the binding pocket and CDRH3 residues involved in direct engagement. Residue labels are provided using 6G1 numbering. (FIG. 10F) Amino acid sequence conservation of strains presented in FIG. 2 A mapped onto a surface rendering of A / Jiangsu / NJ210 / 2023 H5. (FIG. 10G) Antigen interactions mediated by CDRL1 and CDRL2 for mAbs 20D10, 6G1, and 12G1.

[0064] FIGs. 11A-11B. (FIG. 11 A) Alignment of the variable heavy chain regions of the monoclonal antibodies 1A1, 12C11, 12G9, 13B9, 13E8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, and 12G1. (FIG. 11B) Alignment of variable light chain regions of the monoclonal antibodies 1A1, 12C11, 12G9, 13B9, 13E8), 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, and 12G1. (FIG. 11C) Alignment of the variable heavy chain regions of the monoclonal antibodies of clonotype 1 (1 Al, 12C11, 12G9, 13B9, 13E8). (FIG. 1 ID) Alignment of the variable light chain regions of the monoclonal antibodies of clonotype 1 (1A1, 12C11, 12G9, 13B9, 13E8). (FIG. HE) Alignment of the variable heavy chain regions of the monoclonal antibodies of clonotype 2 (1H2, 17E3, 20D10). (FIG. 1 IF) Alignment of the variable light chain regions of the monoclonal antibodies of clonotype 2 (1H2, 17E3, 20D10). (FIG. 11G) Alignment of the variable heavy chain regions of the monoclonal antibodies of clonotype 3 (6G1, 7G4, 7G11, 12G8, 17C12). (FIG. 11H) Alignment of the variable light chain regions of the monoclonal antibodies of clonotype 3 (6G1, 7G4, 7G11, 12G8, 17C12). (FIG. Ill) Alignment of the variable heavy chain regions of the monoclonal antibodies of clonotype 4 (7H10, 14B8). The variable light chain regions of the monoclonal antibodies of clonotype 4 (7H10, 14B8) are 100% identical (not shown). All antibody sequence alignments were performed usingNAI-5010413635vl 70Geneious Prime software (GraphPad Software LLC) with the built in Geneious Alignment Operation, using a Blosum62 cost matrix. The CDRs are underlined in FIGs. 11A-11B.

[0065] FIG. 12. Neuraminidase inhibition of mAbs via direct binding to the enzyme's active site. MAbs capacity to inhibit enzymatic activity of NA protein of clade 2.3.4.4b virus was tested in duplicates, with a positive control an anti -NA antibody, IGO I12. Data shown as half inhibitory concentration (IC50) (ug / ml). Negative control for all the assays was an anti-SARS-CoV2 spike antibody.

[0066] FIGs. 13A-13B. Binding properties of clonotype 1 and 2-5 anti-H5 mAbs. (FIG.13 A) The obtained curves with the use of the detection antibodies are plotted against the capture antibody, names, which are shown at the top of each graph. (FIG. 13B) Competition matrix of four anti-H5 mAbs. Each box displays the wavelength shift at 405nm for a specific mAb pair; values from anti-SARS control antibody were subtracted, representing negative binding of the detection mAb.

[0067] FIGs. 14A-14F. Structural characterization of cl onotypes 2, 3, and 5. (FIGs. 14A-14B) Map and model for clonotype 2 mAb 20D10 complexed withA / Jiangsu / NJ210 / 2023 H5 protein. The primary protomer is depicted in light gray with adjoining protomers depicted in gray. (FIGs. 14D-14D) Map, model, and antigen contacts identified in the FI5 complex formed with clonotype 3 m Ab 6G1. (FIGs. 14E-14F) Map, model, and antigen contacts identified in the H5 complex formed with clonotype 5 mAb 12G1. (FIGs. 14A-14F) All non-van der Waals 20D10 heavy and light chain contacts with antigen are depicted as dashed lines. Most indicate hydrogen bonds, except for hydrophobic i nteractions at positi on L100 of the heavy chain with the antigen present in all antibody interactions. All antibody residues are presented in Kabat numbering and all H5 residues in H3 numbering

[0068] FIGs. 15A-15E. Clonotypes 2, 3, and 5 have a shared mode of antigen engagement. (FIG. 15 A) Footprints for clonotype 1 (in a lighter shade to the right) and clonotypes 2, 3, and 5 (in a darker shade to the left) on a surface rendering of A / Jiangsu / NJ210 / 2023 H5. (FIG. 15B) Shared architecture of antigen engagement by the variable fragments of mAbs 20D10, 6G1, and 12G1 by clonotype. Heavy chains are presented in a darker shade than light chains. (FIG. 15C) Heavy and light chain complementarity determining regions making direct contact with antigen. Residue labels in 20D10 numbering. (FIG. 15D) Hydrophobic surface renderings of the binding pocket and CDRH3 residues involved in direct engagement. Residue labels are provided using 20D10 numbering. (FIG. 15E) Sequence conservation of clade 2.3.4.4b H5 sequences from strains NAI-5010413635vl 71used for functional characterization as determined by sequence alignment using ClustalW mapped onto a surface rendering of A / Jiangsu / NJ210 / 2023 H5. Residue variability increases from AL2CO score 0.306 to AL2CO score -4.895.

[0069] FIGs. 16A-16F. CryoEM model-to-map fit. Final PDB models docked into their corresponding EM maps. Both global fits and epitope-paratope fits are presented. (FIGs. 16A-16B) Global and local fits for clonotype 1. (FIGs. 16C-16D) Analogous model-to-map fits for clonotype 3. (FIGs. 16E-16F) Analogous model-to-map fits for clonotype 5.

[0070] FIGs. 17A-17D. (FIG. 17A) Binding breadth of anti-H5 mAbs to H5 protein from avian isolates, a cattle isolate, and human isolates, was evaluated by ELISA in duplicates. As positive control, an anti -HA antibody, CR911427was used. Data shown is minimal binding concentration (pg / ml), defined as the lowest concentration with a signal greater than 3 standard deviations (SD) above blanks. (FIG. 17B) MAbs ability to block the virus-host receptor interaction was assessed by hemagglutination inhibition (HI) assay in duplicates. As positive control, serum (1: 10) from a mouse infected with A / bald eagle / FL / W22-134-OP / 2022 (H5N1-A / PR / 8 / 34 reassortant) was used. Data shows minimal HI concentration (pg / ml), defined as the lowest concentration that shows HI activity. (FIG. 17C) Efficacy of the anti-H5 mAbs to inhibit viral replication was evaluated using an in vitro neutralization assay against A / bald eagle / FL / W22-134-OP / 2022 (H5N1-A / PR / 8 / 34 reassortant), in duplicates, with controls identical to FIG. 17A. Data shows minimal neutralizing titer (pg / ml), defined as the lowest concentration where neutralization is observed. (FIG. 17D) MAbs capacity to inhibit neuraminidase (NA) activity of clade 2.3.4.4b virus was tested in duplicates, with an anti -NA antibody, 1G0112, as positive control. Data shown is the 50% inhibitory concentration (ICso) (pg / ml). Negative control for all the assays was an anti-SARS-CoV-2 spike antibody (Clark, J. J. et al. Protective effect and molecular mechanisms of human non -neutralizing cross-reactive spike antibodies elicited by SARS-CoV-2 mRNA vaccination. Cell Rep. 43, 114922 (2024)).

[0071] FIGs. I8A-18E. (FIG. 18A) Six-week-old female BALB / c mice (n::::5 / group) were injected intraperitoneally with different amounts of anti-H5 mAb. As a negative control, an anti-SARS-CoV-2 spike mAb was used and the data of the shared negative control group is plotted alongside the experimental groups. After 4 hours, mice were infected with 5 x 50% lethal doses (LD50) of A / bald eagle / FLAV22-134-OP / 2022 (H5N1-A / PR / 8 / 34 reassortant) virus. Body weight percentage (FIG. 18B) and survival (FIG. 18C) were plotted over 14 days post-infection. Data are presented as the mean (n = 5), with error bars showing the SD of the mean. The dotted line in FIG. 18B indicates the maximum body weight loss NAI-5010413635vl 72(25%) allowed in the experiment, defined as the humane endpoint. FIG. 18D) Six-week-old female BALB / c mice (n:::3 / group) received 5 mg / kg of anti-H5 mAbs 4 h before infection, and anti-SARS-CoV-2 mAb was used as a control, as in FIG. 18 A. Lungs were harvested on day 3 and day 5 post-infection. (FIG. 18E) Viral titers in lungs from individual mice were determined as log 10 plaque forming units (PFU) / ml and samples were analyzed in duplicate. Dots represent values from individual mice while bars show geometric means (n = 3) with geometric SD. The dashed line at the y-axis indicates the limit of detection (LOD), defined by half of the lowest dilution at which a positive assay response is observed. For FIG. 18E, statistical analyses were performed using a two-way ANOVA test ((*) p < 0.05, (ns) no significant). (FIGs. 18 A, 18D) illustration created with BioRender.com.

[0072] FIGs, 19A-19C. (FIG, 19 A) Six-week-old female BALB / c mice (n::::5 / group) were injected intraperitoneally with 5 mg / kg of anti-H5 mAb and as a negative control anti- SARS-CoV-2 spike mAb was used. The data of the shared negative control group is plotted alongside the experimental groups. The antibodies were administered on day 2, 3, and 4 after infecting the mice with 5 LD50 of A / bald eagle / FL / W22-134-OP / 2022 (H5N1-A / PR / 8 / 34 reassortant) virus (created with BioRender.com). The percentage of initial body weight (FIG.19 A) and survival (FIG. 19C) were plotted over 14 days post-infection. Data are presented as the mean (n:::5), with error bars showing the SD of the mean. The dotted line in FIG. 19B indicates the maximum body weight loss (25%) allowed in the experiment, defined as the humane endpoint. Arrows indicate the time points at which m Abs were administered.7. DETAILED DESCRIPTION

[0073] In one aspect, provided herein are antibodies or fragments thereof (see, e.g., Sections 7.1 and 8, infra) that bind to HA of H5 influenza A virus clade 2.3.4.4b and compositions comprising such antibodies or antigen-binding fragments (see, e.g., Section 7.4, infra). In specific embodiments, the antibodies or antigen-binding fragments thereof provided herein comprises the variable regions or complementarity determining regions (CDRs) of the 1A1, 12C11, 12G9, 13B9, 13E8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, or 12G1 antibody.

[0074] It is understood that whenever embodiments are described herein with the term “comprising” otherwise analogous embodiments described in terms of “consisting of’ and / or “consisting essentially of’ are also provided.

[0075] In another aspect, provided herein are polynucleotides encoding antibodies or antigen-binding fragments thereof provided herein (see, e.g., Section 7.2, infra). In another aspect, provided herein are vectors (e.g., expression vectors) comprising a polynucleotide NAI-5010413635vl 73encoding an antibody or an antigen-binding fragment thereof provided herein (see, e.g., Section 7.2, infra). Vectors include expression vectors, plasmids, phage vectors, viral vectors, and artificial chromosomes. In another aspect, provided herein are host cells comprising a polynucleotide encoding an antibody or an antigen-binding fragment thereof provided herein (see, e.g., Section 7.3, infra). In a specific embodiment, provided herein are host cells engineered to express an antibody or an antigen-binding fragment thereof provided herein (e.g., Section 7.3, infra). The host cells may be used to produce the antibody or an antigen-binding fragment thereof using techniques known to one of skill in the art or described herein (see, e.g., Section 7.3, infra).

[0076] In another aspect, provided herein are compositions (e.g., pharmaceutical compositions) comprising an antibody or an antigen-binding fragment provided herein (see, e.g., Sections 7.1 and 8), a polynucleotide coding for an antibody or an antigen-binding fragment provided herein (see, e.g., Section 7.2), or a vector (e.g., an expression vector) (see, e.g., Section 7.3).

[0077] In another aspect, provided herein are methods for preventing influenza virus disease (e.g., disease caused by or resulting from infection with H5 influenza A virus, such as, e.g., an H5 influenza A virus of clade 2.3.4.4b) comprising administering to a subject an antibody or antigen-binding fragment thereof provided herein, or a composition comprising such an antibody or an antigen-binding fragment thereof. See, e.g., Section 7.5, infra, for methods of preventing influenza virus disease (e.g., disease caused by or resulting from infection with H5 influenza A virus, such as, e.g., an H5 influenza A virus of clade 2.3.4.4b). In another aspect, provided herein are methods for treating an influenza virus (e.g., H5 influenza A virus, such as, e.g., H5 influenza A virus of clade 2.3.4.4b) infection or an influenza virus disease (e.g., disease caused by or resulting from infection with H5 influenza A virus, such as, e.g., an H5 influenza A virus of clade 2.3.4.4b) comprising administering to a subject in need thereof an antibody or an antigen-binding fragment thereof, or composition comprising such an antibody or an antigen-binding fragment thereof. In some embodiments, provided herein are methods for preventing influenza virus disease (e.g., disease caused by or resulting from infection with H5 influenza A virus, such as, e.g., an H5 influenza A virus of clade 2.3.4.4b), or treating an influenza virus (e.g., H5 influenza A virus, such as, e.g., H5 influenza A virus of clade 2.3.4.4b) infection or an influenza virus disease (e.g., disease caused by or resulting from infection with H5 influenza A virus, such as, e.g., an H5 influenza A virus of clade 2.3.4.4b) comprising administering to a subject a polynucleotide (e.g., mRNA) coding for an antibody or antigen-binding fragment thereof provided herein, or NAI-5010413635vl 74a composition comprising such a polynucleotide. See, e.g., Section 7.5, infra, for methods of treating an influenza virus (e.g., H5 influenza A virus, such as, e.g., H5 influenza A virus of clade 2.3.4.4b) infection or an influenza virus disease (e.g., disease caused by or resulting from infection with H5 influenza A virus, such as, e.g., an H5 influenza A virus of clade 2.3.4.4b).

[0078] In another aspect, provided herein are methods for detecting an influenza A virus (e.g., H5 influenza A virus, such as, e.g., H5 influenza A virus of clade 2.3.4.4b), or diagnosing an influenza A virus (e.g., H5 influenza A virus, such as, e.g., H5 influenza A virus of clade 2.3.4.4b) infection. See, e.g., Section 7.6, infra, for more regarding such methods. In some embodiments, provided herein is a method for detecting an influenza A virus (e.g., H5 influenza A virus, such as, e.g., H5 influenza A virus of clade 2.3.4.4b), comprising: contacting cells or a biological sample with an antibody or an antigen-binding fragment thereof provided herein, detecting the binding of the antibody or antigen-binding fragment to an influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of H5 influenza A virus of clade 2.3.4.4b), wherein influenza A virus e.g., H5 influenza A virus, such as, e.g., H5 influenza A virus of clade 2.3.4.4b) is detected if the level of binding of the antibody or antigen-binding fragment to an influenza A virus HA (e.g., H5 influenza A virus HA, such as, e.g., HA of H5 influenza A virus of clade 2.3.4.4b) is greater than the level of binding of the antibody or antigen-binding fragment to non-influenza virus infected cells or a biological sample not infected with an influenza virus.

[0079] In another aspect, provided herein are kits comprising an antibody or an antigenbinding fragment provided herein (see, e.g., Sections 6.1 and 7), a polynucleotide coding for an antibody or an antigen-binding fragment provided herein (see, e.g., Section 7.2), a vector (e.g., an expression vector) (see, e.g., Section 7.3), or a composition comprising antibody or an antigen-binding fragment provided herein, a polynucleotide, or a vector (see, e.g., Section 7.4). See, e.g., Section 7.8, infra, regarding kits.7.1 Antibodies

[0080] In one aspect, provided herein are antibodies (e.g., monoclonal antibodies) or fragments thereof that bind to an influenza A virus hemagglutinin (HA). In some embodiments, provided herein are antibodies (e.g., monoclonal antibodies) or fragments thereof that bind to HA of an influenza A virus Group 1 subtype. In specific embodiments, provided herein are antibodies (e.g., monoclonal antibodies) or fragments that bind to HA of an influenza A virus H5 subtype (e.g., an influenza A virus H5N1). In a specific embodiment, provided herein are antibodies (e.g., monoclonal antibodies) or fragments NAI-5010413635vl 75thereof that bind to HA of an H5 influenza A virus of clade 2.3.4.4b. In a specific embodiment, provided herein are antibodies (e.g., monoclonal antibodies) or fragments thereof that bind to HA of an avian H5N1 influenza A virus of clade 2.3.4.4b. In some embodiments, provided herein is an antibody that binds to HA of one, two, three or more of the influenza A virus strains described herein (e.g., the influenza A virus strains described in Section 7, infra, such as, e.g., those shown in FIG. 2A). In specific embodiments, provided herein is an antibody or a fragment thereof that binds to an HA of one or more (e.g., 2, 3, 4, or more) H5 influenza A viruses of clade 2.3.4.4b disclosed herein (e.g., the influenza A virus strains described in Section 8, infra, such as, e.g., those shown in FIG. 2 A). In some embodiments, provided herein are antibodies (e.g, monoclonal antibodies) or fragments thereof that bind to HA of one or more (e.g, 2, 3, 4, or more) of the avian H5N1 influenza A virus of clade 2.3.4.4b (e.g., the influenza A virus strains described in Section 8, infra, such as, e.g., those shown in FIG. 2A). In some embodiments, provided herein is an antibody or a fragment thereof that binds to an HA of one or more (e.g., 2, 3, 4 or more) of the following influenza A viruses: A / mallard / New York / 22-008760-007-original / 2022 (H5) (GISAID number EPI2017135), A / chicken / New York / NYCVH 168127 / 2023 (H5N1) (GenBank number WPF52968.1), A / Canada goose / New York / NYCVH 23-453 / 2023 (H5N1) (GenBank number WPL83443.1), A / Canada goose / New York / NYCVH 22-9190 / 2022 (H5N1) (GenBank number WPF48542.1), A / peregrine falcon / New York / NYCVH 160820 / 2022 (H5N1) (GenBank number WPF49852.1), A / red-tailed hawk / New York / NYCVH 22-8477 / 2022 (H5N1) (GenBank number WPF47596.1), A / bald eagle / FL / W22-134-OP / 2022 (H5N1) (GISAID number EPI3661109), A / chicken / Netherlands / 14015531 / 2014 (H5N8) (GISAID number EPI2817295), A / northem pintail / WA / 40964 / 2014 (H5N1) (GenBank number AJE30344.1), A / dairy cattle / Texas / 24-008749-001-original / 2024 (GISAID number EPI3158678), A / Shenzhen / 1 / 2016 (H5N1) (GISAID number EPI687704), and / or A / Jiangsu / NJ210 / 2023 (H5N1). In some embodiments, provided herein is an antibody or a fragment thereof that binds to an HA of one or more (e.g., 2, 3, 4 or more) of the following influenza A viruses: A / mallard / New York / 22-008760-007-original / 2022 (H5) (GISAID number EPI2017135), A / chicken / New York / NYCVH 168127 / 2023 (H5N1) (GenBank number WPF52968.1), A / Canada goose / New York / NYCVH 23-453 / 2023 (H5N1) (GenBank number WPL83443.1), A / Canada goose / New York / NYCVH 22-9190 / 2022 (H5N1) (GenBank number WPF48542.1), A / peregrine falcon / New York / NYCVH 160820 / 2022 (H5N1) (GenBank number WPF49852.1), A / red-tailed hawk / New York / NYCVH 22-8477 / 2022 (H5N1) (GenBank number WPF47596.1), A / bald eagle / FL / W22-134-OP / 2022 NAI-5010413635vl 76(H5N1) (GISAID number EPI3661109), A / chicken / Netherlands / 14015531 / 2014 (H5N8) (GISAID number EPI2817295), A / northem pintail / WA / 40964 / 2014 (H5N1) (GenBank number AJE30344.1), A / dairy cattle / Texas / 24-008749-001-original / 2024 (GISAID number EPI3158678) and / or A / Jiangsu / NJ210 / 2023 (H5N1). In some embodiments, provided herein is an antibody or a fragment thereof that binds to an HA of one or more (e.g., 2, 3, or more) of the following: influenza A viruses A / bald eagle / FL / W22-134-OP / 2022 (H5N1), A / bovine / Ohio / B24OSU-467 / 2024 (H5N1), A / bovine / Ohio / B24OSU-323 / 2024 (H5N1), and / or A / Jiangsu / NJ210 / 2023 (H5N1). In some embodiments, provided herein is an antibody or a fragment thereof that binds to an HA of influenza A virus A / Jiangsu / NJ210 / 2023 and / or A / Red-tailed Hawk / New York / NYCVH 22-8477 / 2022. In some embodiments, the HA of influenza A virus A / Jiangsu / NJ210 / 2023 comprises the amino acid sequence of SEQ ID NO: 179. In some embodiments, provided herein is an antibody or a fragment thereof that binds to an HA of one or more (e.g., 2, 3, 4 or more), or all of the H5 influenza A viruses of clade 2.3.4.4b disclosed herein. In a specific embodiment, an antibody or an antigen-binding fragment provided herein is isolated or purified.

[0081] The term “and / or” as used in a phrase such as “A and / or B” herein is intended to include both A and B; A or B; A (alone); and B (alone). Likewise, the term “and / or” as used in a phrase such as “A, B, and / or C” is intended to encompass each of the following embodiments: A, B, and C; A, B, or C; A or C; A or B; B or C; A and C; A and B; B and C; A (alone); B (alone); and C (alone).

[0082] Antibodies can include, for example, monoclonal antibodies, recombinantly produced antibodies, monospecific antibodies, multispecific antibodies, bispecific antibodies, human antibodies, humanized antibodies, chimeric antibodies, synthetic antibodies, tetrameric antibodies comprising two heavy chain and two light chain molecule, an antibody light chain monomer, an antibody heavy chain monomer, an antibody light chain dimer, an antibody heavy chain dimer, an antibody light chain-antibody heavy chain pair, intrabodies, heteroconjugate antibodies, dual variable region antibodies, single variable region antibodies, linear antibodies, V antibodies, single domain antibodies, monovalent antibodies, Fv fragments, single chain antibodies or single-chain Fvs (scFv), (scFv)2, camelized antibodies, affibodies, Fab fragments, F(ab’) fragments, F(ab’)2 fragments, disulfide-linked Fvs (sdFv), anti -idiotypic (anti -Id) antibodies (including, e.g., anti-anti -Id antibodies), and antigenbinding fragments of any of the above. In some embodiments, antibodies described herein refer to polyclonal antibody populations. Antibodies can be of any type (e.g., IgG, IgE, IgM, IgD, IgA or IgY), any class, (e.g., IgGl, IgG2, IgG3, IgG4, IgAl or IgA2), or any subclass NAI-5010413635vl 77(e.g., IgG2a or IgG2b) of immunoglobulin molecule. In some embodiments, antibodies described herein are IgG antibodies, or a class (e.g., human IgGl or IgG4) or subclass thereof. In some embodiments, the antibody or fragment thereof comprises human-derived heavy and light chain constant regions. In some embodiments, the heavy chain constant region has an isotype selected from the group consisting of gammal, gamma2, gamma3, and gamma4. In some embodiments, antibodies described herein are an immunoglobulin comprising two identical heavy chains and two identical light chain. In a specific embodiment, an antibody includes any molecule with an antigen-binding site that binds an antigen.

[0083] In context of an antibody fragment, the term “antigen-binding fragment” and similar terms refer a portion of an antibody, which comprises the amino acid residues that interact with an antigen and confer on the fragment its binding to the antigen. An antigenbinding fragment may comprise a variable region or CDR of an antibody.

[0084] In a specific embodiment, an antibody provided herein is a monoclonal antibody. As used herein, the term “monoclonal antibody” refers to an antibody obtained from a population of homogenous or substantially homogeneous antibodies. The term “monoclonal” is not limited to any particular method for making the antibody. Generally, a population of monoclonal antibodies can be generated by cells, a population of cells, or a cell line. In specific embodiments, a “monoclonal antibody,” as used herein, is an antibody produced by a single cell (e.g., hybridoma or host cell producing a recombinant antibody), wherein the antibody binds to an influenza A virus HA (e.g., HA of H5 influenza A virus, such as, e.g., HA of H5 influenza A virus of clade 2.3.4.4b) as determined, e.g., by ELISA or another antigen-binding or competitive binding assay known in the art or in the Examples provided herein. In particular embodiments, a monoclonal antibody can be a chimeric antibody or a human antibody.

[0085] In some embodiments, a monoclonal antibody is a monovalent antibody or multivalent (e.g., bivalent) antibody. In particular embodiments, a monoclonal antibody is a monospecific or multi-specific antibody (e.g., bispecific antibody). Monoclonal antibodies described herein can, for example, be made by the hybridoma method as described in Kohler et al., ' Nature, 256:495 (1975) or can, e.g., be isolated from phage libraries using the techniques as described herein, for example. Other methods for the preparation of clonal cell lines and of monoclonal antibodies expressed thereby are well known in the art (see, for example, Chapter 11 in: Short Protocols in Molecular Biology, (2002) 5th Ed., Ausubel et al., eds., John Wiley and Sons, New York).NAI-5010413635vl 78

[0086] In a specific embodiment, an antibody provided herein is an immunoglobulin, such as an IgG, IgE, IgM, IgD, IgA or IgY. In some embodiments, an antibody provided herein is an IgGl or IgG4. In some embodiments, an antibody provided herein is an antigenbinding fragment, such as, e.g., an Fab fragment or F(ab’)2 fragment. In some embodiments, an antibody provided herein is an scFv.

[0087] As used herein, the terms “HA" and "hemagglutinin" are used interchangeably refer to any influenza virus hemagglutinin known to those of skill in the art or a derivative thereof. A typical hemagglutinin comprises domains known to those of skill in the art including a signal peptide, a globular head domain, a stem or stalk domain, a transmembrane domain, and a cytoplasmic domain. In some embodiments, a hemagglutinin consists of a single polypeptide chain, such as HAO. In some embodiments, a hemagglutinin consists of more than one polypeptide chain in quaternary association, e.g. HA1 and HA2. Those of skill in the art will recognize that an immature HAO might be cleaved to release a signal peptide (generally approximately 15-20 amino acids) yielding a mature hemagglutinin HAO ( / .<?., HAO without a signal peptide). Influenza virus hemagglutinins are found on the viral surface as trimers. Influenza virus hemagglutinins are typically glycosylated.

[0088] HA plays an important role in the attachment to and penetration of the influenza virus into a cell. HA mediates virus binding to the specific terminal sialic acid on sialosides on the surface of a cell.

[0089] In specific embodiments, the hemagglutinin is an influenza A virus hemagglutinin. The HA may be from any influenza A virus known to one of skill in the art (e.g., in GenBank, UniProt, or the scientific literature). In some embodiments, the hemagglutinin is a Group 1 influenza A virus HA (e.g., Hl, H2, H5, H6, H8, H9, Hl 1, H12, H13, H16, H17, or H18). In specific embodiments, the hemagglutinin is the HA of an influenza A virus H5 subtype. In specific embodiments, the hemagglutinin is the HA of H5 influenza A virus of clade 2.3.4.4b (e.g., avian H5N1 influenza A viruses). In some embodiments, the hemagglutinin is an influenza A virus HA of influenza virus A / mallard / New York / 22-008760-007-original / 2022 (H5) (GISAID number EPI2017135), A / chicken / New York / NYCVH 168127 / 2023 (H5N1) (GenBank number WPF52968.1), A / Canada goose / New York / NYCVH 23-453 / 2023 (H5N1) (GenBank number WPL83443.1), A / Canada goose / New York / NYCVH 22-9190 / 2022 (H5N1) (GenBank number WPF48542.1), A / peregrine falcon / New York / NYCVH 160820 / 2022 (H5N1) (GenBank number WPF49852.1), A / red-tailed hawk / New York / NYCVH 22-8477 / 2022 (H5N1) (GenBank number WPF47596.1), A / bald eagle / FL / W22-134-OP / 2022 (H5N1) (GISAID NAI-5010413635vl 79number EPI3661109), A / chicken / Netherlands / 14015531 / 2014 (H5N8) (GISAID number EPI2817295), A / northern pintail / WA / 40964 / 2014 (H5N1) (GenBank number AJE30344.1), A / dairy cattle / Texas / 24-008749-001-original / 2024 (GISAID number EPI3158678), A / bald eagle / FL / W22-134-OP / 2022 (H5N1), A / bovine / Ohio / B24OSU-467 / 2024 (H5N1), A / bovine / Ohio / B24OSU-323 / 2024 (H5N1), or A / Jiangsu / NJ210 / 2023 (H5N1). In some embodiments, the hemagglutinin is the HA of influenza A virus A / Jiangsu / NJ210 / 2023 (H5N1). In some embodiments, the hemagglutinin comprises the amino acid sequence of SEQ IDNO: 179.

[0090] In another aspect, the antibodies provided herein bind to an influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b) with a certain affinity. “Binding affinity” generally refers to the strength of the sum total of non-covalent interactions between a single binding site of a molecule (e.g., an antibody) and its binding partner (e.g., an antigen). Unless indicated otherwise, as used herein, “binding affinity” refers to intrinsic binding affinity which reflects a 1: 1 interaction between members of a binding pair (e.g., antibody and antigen). The affinity of a molecule X for its partner Y can generally be represented by the dissociation constant (KD). Affinity can be measured and / or expressed in a number of ways known in the art, including, but not limited to, equilibrium dissociation constant (KD), equilibrium association constant (KA), and ICso. The KD is calculated from the quotient of k0ff / k0n, whereas KA is calculated from the quotient of k0n / k0ff. konrefers to the association rate constant of, e.g., an antibody to an antigen, and koir refers to the dissociation of, e.g., an antibody to an antigen. The konand koir can be determined by techniques known to one of ordinary skill in the art, such as BIAcore™, Kinexa, or biolayer interferometry. Affinity can be measured by common methods known in the art, including those described herein. For example, individual association (kon) and dissociation (koir) rate constants can be calculated from the resulting binding curves using the BIAevaluation software available through the vendor. Data can then be fit to a 1:1 binding model, which includes a term to correct for mass transport limited binding, should it be detected. From these rate constants, the apparent dissociation binding constant (KD) for the interaction of the antibody (e.g., IgG) with the antigen (e.g., influenza A virus HA) can be calculated from the quotient of koir / kon. Low-affinity antibodies generally bind antigen slowly and tend to dissociate readily, whereas high-affinity antibodies generally bind antigen faster and tend to remain bound longer. A variety of methods of measuring binding affinity are known in the art, any of which can be used for purposes of the describedNAI-5010413635vl 80herein. In some embodiments, the koff is determined using a monovalent antibody, such as a Fab fragment, as measured by, e.g., BIAcore™ surface plasmon resonance technology, Kinexa, or biolayer interferometry. In some embodiments, the ko is calculated as the quotient of koff / kon, and the konand koff are determined using a monovalent antibody, such as a Fab fragment, as measured by, e.g., BIAcore™ surface plasmon resonance technology, Kinexa, or biolayer interferometry.

[0091] In some embodiments, provided herein are antibodies or fragments thereof that bind to the HA of different strains of influenza A virus e.g., 2, 3, 4, 5, 6 or more influenza A virus strains) as assessed by a technique known to one of skill in the art, such as an immunoassay, surface plasmon resonance, or kinetic exclusion assay, or described herein. In some embodiments, provided herein are antibodies or fragments thereof that bind to HA of Group 1 influenza A virus strains as assessed by a technique known to one of skill in the art, such as an immunoassay, surface plasmon resonance, kinetic exclusion assay, biolayer interferometry, or described herein. In some embodiments, provided herein are antibodies or fragments thereof that bind to the HA of an influenza A virus H5 (e.g., influenza A virus H5N1) as assessed by a technique known to one of skill in the art, such as an immunoassay, surface plasmon resonance, kinetic exclusion assay, biolayer interferometry, or described herein. In some embodiments, provided herein are antibodies or fragments thereof that bind to the HA of two or more (e.g, 3, 4, 5, 6 or more) H5 influenza A viruses (e.g, H5N1 influenza A viruses) as assessed by a technique known to one of skill in the art, such as an immunoassay, surface plasmon resonance, kinetic exclusion assay, biolayer interferometry, or described herein. In a specific embodiment, provided herein are antibodies (e.g., monoclonal antibodies) or fragments thereof that bind to HA of an H5 influenza A virus of clade 2.3.4.4b (e.g., avian influenza A virus (H5N1) HA) as assessed by a technique known to one of skill in the art, such as an immunoassay, surface plasmon resonance, kinetic exclusion assay, biolayer interferometry, or described herein. In some embodiments, provided herein are antibodies (e.g., monoclonal antibodies) or fragments thereof that bind to HA of two or more (e.g., 3, 4, 5, 6 or more) H5 influenza A viruses of clade 2.3.4.4b (e.g., H5N1 influenza A viruses) as assessed by a technique known to one of skill in the art, such as an immunoassay, surface plasmon resonance, kinetic exclusion assay, biolayer interferometry, or described herein. For example, the antibodies (e.g., monoclonal antibodies) or fragments thereof that bind to HA of one or more (e.g., 2, 3, 4, 5, 6 or more) H5 influenza A viruses of clade 2.3.4.4b (e.g., H5N1 influenza A viruses) disclosed herein (e.g., in Section 8, infra) as assessed by a technique known to one of skill in the art, such as NAI-5010413635vl 81an immunoassay, surface plasmon resonance, kinetic exclusion assay, biolayer interferometry, or described herein.

[0092] In some embodiments, provided herein are antibodies or fragments that (i) bind to the HA of an influenza A virus as assessed by a technique known to one of skill in the art, such as an immunoassay, surface plasmon resonance, or kinetic exclusion assay, or described herein; and (ii) neutralize the influenza A virus as assessed by a technique known to one of skill in the art, such as a microneutralization assay, such as described infra. In some embodiments, provided herein are antibodies or fragments thereof that (i) bind to the HA of an influenza A virus of Group 1 as assessed by a technique known to one of skill in the art, such as an immunoassay, surface plasmon resonance, or kinetic exclusion assay, or described herein; and (ii) neutralize the influenza A virus of Group 1 as assessed by a technique known to one of skill in the art, such as a microneutralization assay, such as described infra. In some embodiments, provided herein are antibodies or fragments that (i) bind to the HA of an H5 influenza A virus (e.g., H5N1 influenza virus) as assessed by a technique known to one of skill in the art, such as an immunoassay, surface plasmon resonance, or kinetic exclusion assay, or described herein; and (ii) neutralize the H5 influenza A virus (e.g., H5N1 influenza virus) as assessed by a technique known to one of skill in the art, such as a microneutralization assay, such as described infra. In some embodiments, provided herein are antibodies or fragments that (i) bind to the HA of an influenza A virus of clade 2.3.4.4b as assessed by a technique known to one of skill in the art, such as an immunoassay, surface plasmon resonance, or kinetic exclusion assay, or described herein; and (ii) neutralize the influenza A virus as assessed by a technique known to one of skill in the art, such as a microneutralization assay, such as described infra.

[0093] In some embodiments, provided herein are antibodies or fragments that (i) bind to the HA of different strains of influenza A virus (e.g., 2, 3, 4, 5, 6 or more strains) as assessed by a technique known to one of skill in the art, such as an immunoassay, surface plasmon resonance, or kinetic exclusion assay, or described herein; and (ii) neutralize strains of influenza A viruses as assessed by a technique known to one of skill in the art, such as a microneutralization assay, such as described infra. In some embodiments, provided herein are antibodies or fragments thereof that (i) bind to HA of influenza A virus strains of Group 1 as assessed by a technique known to one of skill in the art, such as an immunoassay, surface plasmon resonance, or kinetic exclusion assay, or described herein; and (ii) neutralize influenza A virus strains of Group 1, as assessed by a technique known to one of skill in the art, such as a microneutralization assay, such as described infra. In some embodiments, NAI-5010413635vl 82provided herein are antibodies or fragments that (i) bind to the HA of different strains (e.g., 2, 3, 4, 5, 6 or more strains) of H5 influenza A virus (e.g., H5N1 influenza A virus) as assessed by a technique known to one of skill in the art, such as an immunoassay, surface plasmon resonance, or kinetic exclusion assay, or described herein; and (ii) neutralize strains (e.g., 2, 3, 4, 5, 6 or more strains) of H5 influenza A virus as assessed by a technique known to one of skill in the art, such as a microneutralization assay, such as described infra. In some embodiments, provided herein are antibodies or fragments that (i) bind to the HA of different strains (e.g., 2, 3, 4, 5, 6 or more strains) of H5 influenza A viruses of clade 2.3.4.4b as assessed by a technique known to one of skill in the art, such as an immunoassay, surface plasmon resonance, or kinetic exclusion assay, or described herein; and (ii) neutralize strains (e.g., 2, 3, 4, 5, 6 or more strains) of H5 influenza A virus of clade 2.3.4.4b as assessed by a technique known to one of skill in the art, such as a microneutralization assay, such as described infra.

[0094] In some embodiments, provided herein is an antibody or a fragment thereof that selectively binds to HA of one, two, three or more strains of influenza A virus of Group 1 relative to an HA of an influenza A virus strain of Group 2 as assessed by techniques known in the art, e.g., ELISA, Western blot, biolayer interferometry, FACS or BIACore, or described herein. Those of skilled in the art will know the subtypes of influenza A viruses that belong in Group 1 and those subtypes that belong in Group 2. Typically, Group 1 influenza A viruses include subtypes Hl, H2, H5, H6, H8, H9, Hl 1, H12, H13, H16, H17, and H18, and Group 2 influenza A viruses include subtypes H3, H4, H7, H10, H14, and H15. In some embodiments, the antibody or a fragment thereof binds to an HA from one, two, three or more strains of influenza A virus of Group 1 with a higher affinity than the antibody or fragment thereof binds to an HA of an influenza A virus strain of Group 2, as assessed by techniques known in the art, e.g., ELISA, Western blot, biolayer interferometry, FACS or BIACore, or described herein. In some embodiments, provided herein is an antibody or a fragment thereof that selectively binds to HA of one, two, three or more strains of influenza A virus of Group 1 relative to an HA of an influenza A virus strain of Group 2 as assessed by techniques known in the art, e.g., ELISA, Western blot, biolayer interferometry, FACS or BIACore, or described herein. In specific embodiments, the antibody or a fragment thereof binds to an HA from one, two, three or more strains of H5 influenza A virus (e.g., an avian influenza A virus H5N1) with a higher affinity than the antibody or fragment thereof binds to an HA of an influenza A virus strain of other subtypes of Group 1, as assessed by techniques known in the art, e.g., ELISA, Western blot, biolayer interferometry, FACS or BIACore, or NAI-5010413635vl 83described herein. In some embodiments, the antibody or a fragment thereof binds to an HA from one, two, three or more strains of H5 influenza A virus of clade 2.3.4.4b (e.g., an avian influenza A virus H5N1) with a higher affinity than the antibody or fragment thereof binds to an HA of an H5 influenza A virus strain of other clades (e.g., clade 1 or 2.1.3.2), as assessed by techniques known in the art, e.g., ELISA, Western blot, biolayer interferometry, FACS or BIACore, or described herein.

[0095] In some embodiments, an antibody or fragment thereof provided herein binds to an HA of one, two, three or more strains of influenza A virus of Group 1 with a 1-fold, 1.5-fold, 2-fold, 3-fold, 4-fold, 5-fold, 6-fold, 7-fold, 8-fold, 9-fold, 10-fold, greater than 10-fold, 1- to 2-fold, 1- to 5-fold, 1- to 10-fold, 2- to 5-fold, 2- to 10-fold, 5- to 10-fold, 10- to 15-fold, or 10- to 20-fold greater affinity than that which the antibody or fragment thereof binds to an HA of an influenza A virus strain of Group 2, as assessed by techniques known in the art, e.g., ELISA, Western blot, biolayer interferometry, FACS or BIACore, or described herein. In some embodiments, an antibody or a fragment thereof provided herein binds to an HA of one, two, three or more strains of influenza A virus of Group 1 with a 0.5 log, 1 log, 1.5 log, 2 log, 2.5 log, 3 log, 3.5 log, or 4 log greater affinity than that which the antibody or fragment thereof binds to an HA of an influenza A virus strain of Group 2, as assessed by techniques known in the art, e.g., ELISA, Western blot, biolayer interferometry, FACS or BIACore, or described herein. In some embodiments, an antibody or a fragment thereof provided herein binds to an HA of one, two, three or more strains of influenza A virus of Group 1, with a 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or higher affinity than that which the antibody binds to an HA of an influenza A virus strain of Group 2, as measured by, e.g., a radioimmunoassay, surface plasmon resonance, biolayer interferometry, or kinetic exclusion assay.

[0096] In specific embodiments, an antibody or fragment thereof provided herein binds to an HA of one, two, three or more strains of H5 influenza A virus (e.g., avian influenza A virus H5N1) with a 1-fold, 1.5-fold, 2-fold, 3-fold, 4-fold, 5-fold, 6-fold, 7-fold, 8-fold, 9-fold, 10-fold, greater than 10-fold, 1- to 2-fold, 1- to 5-fold, 1- to 10-fold, 2- to 5-fold, 2- to 10-fold, 5- to 10-fold, 10- to 15-fold, or 10- to 20-fold greater affinity than that which the antibody or fragment thereof binds to an HA of an influenza A virus strain of another Group 1 subtype (e.g., Hl, H2, H6, H8, H9, Hll, H12, H13, H16, H17, or H18) or a Group 2 subtype (e.g., H3, H4, H7, H10, H14, or H15), as assessed by techniques known in the art, e.g., ELISA, Western blot, biolayer interferometry, FACS or BIACore, or described herein. In specific embodiments, an antibody or a fragment thereof provided herein binds to an HA NAI-5010413635vl 84of one, two, three or more strains of H5 influenza A virus (e.g., avian influenza A virus H5N1) with a 0.5 log, 1 log, 1.5 log, 2 log, 2.5 log, 3 log, 3.5 log, or 4 log greater affinity than that which the antibody or fragment thereof binds to an HA of an influenza A virus strain of another Group 1 subtype (e.g, Hl, H2, H6, H8, H9, Hll, H12, H13, H16, H17, or H18) or a Group 2 subtype (e.g., H3, H4, H7, H10, H14, or H15), as assessed by techniques known in the art, e.g, ELISA, Western blot, biolayer interferometry, FACS or BIACore, or described herein. In specific embodiments, an antibody or a fragment thereof provided herein binds to an HA of one, two, three or more strains of H5 influenza A virus (e.g., avian influenza A virus H5N1), with a 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or higher affinity than that which the antibody binds to an HA of an influenza A virus strain of another Group 1 subtype (e.g., Hl, H2, H6, H8, H9, Hll, H12, H13, H16, H17, or H18) or a Group 2 subtype (e.g., H3, H4, H7, H10, H14, or H15), as measured by, e.g., a radioimmunoassay, surface plasmon resonance, biolayer interferometry, or kinetic exclusion assay.

[0097] In some embodiments, an antibody or fragment thereof provided herein binds to an HA of one, two, three or more strains of H5 influenza A virus of clade 2.3.4.4b with a 1-fold, 1.5-fold, 2-fold, 3-fold, 4-fold, 5-fold, 6-fold, 7-fold, 8-fold, 9-fold, 10-fold, greater than 10-fold, 1- to 2-fold, 1- to 5-fold, 1- to 10-fold, 2- to 5-fold, 2- to 10-fold, 5- to 10-fold, 10-to 15-fold, or 10- to 20-fold greater affinity than that which the antibody or fragment thereof binds to an HA of an influenza A virus strain of another clade (e.g., clade 1 or 2.3.2.1c), as assessed by techniques known in the art, e.g., ELISA, Western blot, biolayer interferometry, FACS or BIACore, or described herein. In some embodiments, an antibody or a fragment thereof provided herein binds to an HA of one, two, three or more strains of H5 influenza A virus of clade 2.3.4.4b with a 0.5 log, 1 log, 1.5 log, 2 log, 2.5 log, 3 log, 3.5 log, or 4 log greater affinity than that which the antibody or fragment thereof binds to an HA of an influenza A virus strain of another clade (e.g., clade 1 or 2.3.2.1c), as assessed by techniques known in the art, e.g., ELISA, Western blot, biolayer interferometry, FACS or BIACore, or described herein. In some embodiments, an antibody or a fragment thereof provided herein binds to an HA of one, two, three or more strains of H5 influenza A virus of clade 2.3.4.4b, with a 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or higher affinity than that which the antibody binds to an HA of an influenza A virus strain of another clade (e.g., clade 1 or 2.3.2.1c), as measured by, e.g., a radioimmunoassay, surface plasmon resonance, biolayer interferometry, or kinetic exclusion assay.NAI-5010413635vl 85

[0098] In some embodiments, an antibody or an antigen-binding fragment provided herein binds to HA of an influenza A virus at the same similar minimal binding concentration or a similar (within 25%, 15%, or 10%) minimal binding concentration as exhibited by the 1A1, 12C11, 12G9, 13B9, 13B8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, or 12G1 antibody in using the assay described in Section 8 (see, e.g., FIG. 2A). In some embodiments, an antibody or an antigen-binding fragment provided herein binds to HA of an H5 influenza A virus at the same similar minimal binding concentration or a similar (within 25%, 15%, or 10%) minimal binding concentration as exhibited by the 1 Al, 12C11, 12G9, 13B9, 13B8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, or 12G1 antibody in using the assay described in Section 8 (see, e.g., FIG. 2A). In some embodiments, an antibody or an antigen-binding fragment provided herein binds to HA of an H5 influenza A virus of clade 2.3.4.4b (e.g, avian influenza A virus H5N1) at the same similar minimal binding concentration or a similar (within 25%, 15%, or 10%) minimal binding concentration as exhibited by the 1A1, 12C11, 12G9, 13B9, 13B8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, or 12G1 antibody in using the assay described in Section 8 (see, e.g, FIG. IB). In some embodiments, the antibody or antigenbinding fragment provided herein binds to HA of an H5 influenza A virus (e.g., HA of an H5 influenza A virus of clade 2.3.4.4b) at the same similar minimal binding concentration or a similar (within 25%, 15%, or 10%) minimal binding concentration as exhibited by the 1A1, 12C11, 12G9, 13B9, 13B8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, or 12G1 antibody in using the assay described in Section 8 (see, e.g., FIG. 2 A). In some embodiments, the antibody or antigen-binding fragment provided herein binds to HA of an H5 influenza A virus (e.g., HA of an H5 influenza A virus of clade 2.3.4.4b) at the same similar minimal binding concentration or a similar (within 25%, 15%, or 10%) minimal binding concentration as exhibited by the 1A1, 20D10, 6G1, or 12G1 antibody in using the assay described in Section 8 (see, e.g., FIG. 2 A). In some embodiments, the antibody or antigen-binding fragment provided herein binds to HA of an H5 influenza A virus (e.g., HA of an H5 influenza A virus of clade 2.3.4.4b) at the same similar minimal binding concentration or a similar (within 25%, 15%, or 10%) minimal binding concentration as exhibited by the 20D10, 6G1, or 12G1 antibody in using the assay described in Section 8 (see, e.g., FIG. 2A).

[0099] In some embodiments, an antibody or a fragment thereof provided herein binds to a recombinant HA protein (e.g., a recombinant form of an influenza A virus HA, or a solubleNAI-5010413635vl 86form thereof). In a specific embodiment, an antibody or fragment provided herein binds to a recombinant HA protein in Section 8, infra.

[0100] In some embodiments, an antibody or a fragment thereof provided herein binds to an influenza A virus HA present in the virion particle. In specific embodiments, an antibody or a fragment thereof provided herein binds to an H5 influenza A virus HA present in the virion particle. In some embodiments, an antibody or a fragment thereof provided herein binds to an H5 influenza A virus of clade 2.3.4.4b (e.g., avian influenza A virus H5N1) HA present in the virion particle. In some embodiments, an antibody or a fragment thereof provided herein binds to a protein (e.g., influenza A virus HA) on the surface of a cell infected with an influenza A virus. In specific embodiments, the influenza A virus is an H5 influenza A virus (e.g. an H5N1 influenza A virus). In specific embodiments, the influenza A virus is an H5 influenza A virus of clade 2.3.4.4b (e.g, an avian influenza A virus H5N1). In some embodiments, an antibody or a fragment thereof provided herein binds to an influenza A virus HA present in the virion particle and a protein (e.g, influenza A virus HA) on the surface of a cell infected with an influenza A virus. In specific embodiments, the influenza A virus is an H5 influenza A virus (e.g. an H5N 1 influenza A virus). In specific embodiments, the influenza A virus is an H5 influenza A virus of clade 2.3.4.4b (e.g., an avian influenza A virus H5N1).

[0101] In some embodiments, an antibody or an antigen-binding fragment thereof provided herein inhibits the HA activity of an influenza A virus (e.g., a Group 1 influenza A virus) by 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or more relative to a negative control, such as a control IgG, as measured by a technique known to one of skill in the art or described herein. In some embodiments, an antibody or an antigen-binding fragment thereof provided herein inhibits the HA activity of an influenza A virus (e.g., a Group 1 influenza A virus) by at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% relative to a negative control, such as a control IgG, as measured by a technique known to one of skill in the art or described herein. In some embodiments, an antibody or an antigenbinding fragment thereof provided herein inhibits the activity of an influenza A virus (e.g., a Group 1 influenza A virus) by 20% to 40%, 25% to 50%, 25% to 75%, 50% to 75%, 25% to 50%, 75% to 90%, 50% to 90%, or 85% to 95% relative to a negative control, such as a control IgG, as measured by a technique known to one of skill in the art or described herein.NAI-5010413635vl 87

[0102] In some embodiments, an antibody or an antigen-binding fragment thereof provided herein inhibits the HA activity of an H5 influenza A virus (e.g., influenza A virus H5N1) by 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or more relative to a negative control, such as a control IgG, as measured by a technique known to one of skill in the art or described herein. In some embodiments, an antibody or an antigen-binding fragment thereof provided herein inhibits the HA activity of an H5 influenza A virus (e.g., influenza A virus H5N1) by at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% relative to a negative control, such as a control IgG, as measured by a technique known to one of skill in the art or described herein. In some embodiments, an antibody or an antigenbinding fragment thereof provided herein inhibits the HA activity of an H5 influenza A virus (e.g., influenza A virus H5N1) by 20% to 40%, 25% to 50%, 25% to 75%, 50% to 75%, 25% to 50%, 75% to 90%, 50% to 90%, or 85% to 95% relative to a negative control, such as a control IgG, as measured by a technique known to one of skill in the art or described herein.

[0103] In some embodiments, an antibody or an antigen-binding fragment thereof provided herein inhibits the HA activity of an H5 influenza A virus of clade 2.3.4.4b (e.g., an avian influenza A virus H5N1) by 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or more relative to a negative control, such as a control IgG, as measured by a technique known to one of skill in the art or described herein. In some embodiments, an antibody or an antigen-binding fragment thereof provided herein inhibits the HA activity of an H5 influenza A virus of clade 2.3.4.4b (e.g., an avian influenza A virus H5N1) by 20% to 40%, 25% to 50%, 25% to 75%, 50% to 75%, 25% to 50%, 75% to 90%, 50% to 90%, or 85% to 95% relative to a negative control, such as a control IgG, as measured by a technique known to one of skill in the art or described herein.

[0104] In some embodiments, an antibody or an antigen-binding fragment thereof provided herein inhibits the interaction of an influenza A virus with the host receptor, as assessed using a hemagglutinin inhibition (HI) assay, such as described herein (e.g., in Section 8), or another method known to one of skill in the art. In some embodiments, an antibody or an antigen-binding fragment thereof provided herein inhibits the interaction of an H5 influenza A virus with the host receptor, as assessed using a hemagglutinin inhibition (HI) assay, such as described herein (e.g., in Section 8), or another method known to one of skill in the art. In specific embodiments, an antibody or an antigen-binding fragment thereof provided herein inhibits the interaction of an H5 influenza A virus of clade 2.3.4.4b (e.g., an NAI-5010413635vl 88avian influenza A virus H5N1) with the host receptor, as assessed using a hemagglutinin inhibition (HI) assay, such as described herein (e.g., in Section 8), or another method known to one of skill in the art. In some embodiments, the antibody or antigen-binding fragment exhibits HI activity against A / bald / FL / W22-134-OP / 2022(H5Nl-A / PR / 8 / 34 reassortant), A / bovine / Ohio / B24OSU-467 / 2024 (H5N1), and / or A / bovine / Ohio / B24OSU-323 / 2024 (H5N1) in an HI assay, such as described herein (e.g., in Section 8). In some embodiments, the HI activity exhibited is the same or similar (within 25%, 15%, or 10%) of the HI activity exhibited by the 1A1, 12C11, 12G9, 13B9, 13B8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, or 12G1 antibody in using the HI assay in Section 8 (see, e.g., FIG. 2B). In some embodiments, the HI activity exhibited is the same or similar (within 25%, 15%, or 10%) of the HI activity exhibited by the 1 Al, 20D10, 6G1, or 12G1 antibody in using the HI assay in Section 8 (see, e.g., FIG. 2B). In some embodiments, the HI activity exhibited is the same or similar to (within 25%, 15%, or 10%) the HI activity exhibited by the 20D10, 6G1, or 12G1 antibody in using the HI assay in Section 8 (see, e.g., FIG. 2B).

[0105] In another aspect, an antibody or an antigen-binding fragment thereof provided herein neutralizes an influenza A virus, as assessed using an in vitro microneutralization, such as described herein (e.g., in Section 8), or another method known to one of skill in the art. In some embodiments, an antibody or an antigen-binding fragment thereof provided herein neutralizes an H5 influenza A virus, as assessed using an in vitro microneutralization, such as described herein (e.g., in Section 8), or another method known to one of skill in the art. In specific embodiments, an antibody or an antigen-binding fragment thereof provided herein neutralizes an H5 influenza A virus of clade 2.3.4.4b, as assessed using an in vitro microneutralization, such as described herein (e.g., in Section 8), or another method known to one of skill in the art. In some embodiments, an antibody or antigen-binding fragment provided herein neutralizes A / bald / FL / W22-134-OP / 2022(H5Nl-A / PR / 8 / 34 reassortant) in an in vitro microneutralization assay, such as described herein (e.g., in Section 8). In some embodiments, the neutralization in the in vitro microneutralization assay is the same or similar (within 25%, 15%, or 10%) of the neutralization exhibited by the 1 Al, 12C11, 12G9, 13B9, 13B8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, or 12G1 antibody in the in vitro microneutralization described in Section 8 (see, e.g., FIG. 2C). In some embodiments, the neutralization in the in vitro microneutralization assay is the same or similar (within 25%, 15%, or 10%) of the neutralization exhibited by the 1A1, 20D10, 6G1, or 12G1 antibody in the in vitro microneutralization described in Section 8 (see, e.g., FIG. 2C). In some embodiments, the neutralization in the in vitro microneutralization assay is the same or NAI-5010413635vl 89similar to (within 25%, 15%, or 10%) the neutralization exhibited by the 20D10, 6G1, or 12G1 antibody in the in vitro microneutralization described in Section 8 (see, e.g., FIG. 2C).

[0106] In another aspect, an antibody or an antigen-binding fragment thereof provided herein inhibits neuraminidase (NA) enzymatic activity of an influenza A virus, assessed using an NA inhibition (NI) assay and / or NA-Star assay, such as described herein (e.g., in Section 8), or another method known to one of skill in the art. In some embodiments, an antibody or an antigen-binding fragment thereof provided herein inhibits NA enzymatic activity of an H5 influenza A virus, assessed using an NI assay, such as described herein (e.g., in Section 8), or another method known to one of skill in the art. In specific embodiments, an antibody or an antigen-binding fragment thereof provided herein inhibits NA enzymatic activity of an H5 influenza A virus of clade 2.3.4.4b, assessed using an NI assay and / or NA-Star assay, such as described herein (e.g, in Section 8), or another method known to one of skill in the art. In some embodiments, the antibody or antigen-binding fragment exhibits NI activity against A / bald / FL / W22-134-OP / 2022(H5Nl-A / PR / 8 / 34 reassortant) in anNI assay, such as described herein (e.g., in Section 8). In some embodiments, the NI activity exhibited is the same or similar (within 25%, 15%, or 10%) to the NI activity exhibited by the 1A1, 12C11, 12G9, 13B9, 13B8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, or 12G1 antibody in using the NI assay described in Section 8 (see, e.g., FIG. 2D). In some embodiments, the NI activity exhibited is the same or similar (within 25%, 15%, or 10%) of the HI activity exhibited by the 1 Al, 20D10, 6G1, or 12G1 antibody in using the NI assay in Section 8 (see, e.g., FIG. 2D). In some embodiments, the NI activity exhibited is the same or similar to (within 25%, 15%, or 10%) the NI activity exhibited by the 20D10, 6G1, or 12G1 antibody in using the NI assay and / or NA-Star assay described in Section 8 (see, e.g., FIG. 2D).

[0107] In another aspect, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of one of the antibodies described in Section 8, infra. In some embodiments, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of an antibody of clonotype 1 described herein (e.g., in Section 8, infra). In some embodiments, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of an antibody of clonotype 2 described herein (e.g., in Section 8, infra). In some embodiments, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of an antibody of clonotype 3 described herein (e.g., in Section 8, infra). In some embodiments, an antibody or an antigen-binding fragment thereof provided herein has one, NAI-5010413635vl 90two or more, or all of the characteristics / properties of an antibody of clonotype 4 described herein (e.g., in Section 8, infra). In some embodiments, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of an antibody of clonotype 5 described herein (e.g., in Section 8, infra).

[0108] In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of the 1 Al monoclonal antibody described herein (e.g, in Section 8, infra). In a specific embodiment, an antibody described herein has one, two or more, or all of the characteristics / properties of the 12C11 monoclonal antibody described herein (e.g, in Section 8, infra). In a specific embodiment, an antibody provided herein has one, two or more, or all of the characteristics / properties of the 12G9 monoclonal antibody described herein (e.g., in Section 8, infra). In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of the 13B9 monoclonal antibody described herein (e.g., in Section 8, infra). In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of the 13E8 monoclonal antibody described herein (e.g., in Section 8, infra).

[0109] In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of the 1H2 monoclonal antibody described herein (e.g., in Section 8, infra). In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of the 17E3 monoclonal antibody described herein (e.g., in Section 8, infra). In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of the 20D10 monoclonal antibody described herein (e.g., in Section 8, infra).

[0110] In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of the 6G1 monoclonal antibody described herein (e.g., in Section 8, infra). In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of the 7G4 monoclonal antibody described herein (e.g., in Section 8, infra). In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of the 7G11 monoclonal antibody described herein (e.g., in Section 8, infra). In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein has one, NAI-5010413635vl 91two or more, or all of the characteristics / properties of the 12G8 monoclonal antibody described herein (e.g., in Section 8, infra). In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of the 17C12 monoclonal antibody described herein (e.g., in Section 8, infra).

[0111] In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of the 7H10 monoclonal antibody described herein (e.g., in Section 8, infra). In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of the 14B8 monoclonal antibody described herein (e.g., in Section 8, infra).

[0112] In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein has one, two or more, or all of the characteristics / properties of the 12G1 monoclonal antibody described herein (e.g., in Section 8, infra).

[0113] In some embodiments, provided herein is an antibody described in Section 8 or an antigen-binding fragment thereof that binds to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of a clade 2.3.4.4b influenza A virus).

[0114] In another aspect, an antibody provided herein is the 1 Al, 12C11, 12G9, 13B9, 13E8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, or 12G1 antibody provided herein or an antigen-binding fragment thereof. In another aspect, an antibody provided herein comprises the variable heavy chain region (“VH”; in some instances herein the VH is referred to as the VH region or VH domain) or variable light chain region (“VL”; in some instances herein the VL is referred to as the VL region or VL domain) of the 1 Al, 12C11, 12G9, 13B9, 13E8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, or 12G1 antibody. In another aspect, an antibody provided herein comprises the VH and VL of the 1A1, 12C11, 12G9, 13B9, 13E8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, or 12G1 antibody. The VH of the 12G9 antibody comprises the amino acid sequence of SEQ ID NO: 1, and the VL of the 12G9 antibody comprises the amino acid sequence of SEQ ID NO: 6. The VH of the 13B9 antibody comprises the amino acid sequence of SEQ ID NO: 2, the VL of the 13B9 antibody comprises the amino acid sequence of SEQ ID NO: 8. The VH of the 1 Al antibody comprises the amino acid sequence of SEQ ID NO: 3, and the VL of the 1 Al antibody comprises the amino acid sequence of SEQ ID NO: 7. The VH of the 12C11 antibody comprises the amino acid sequence of SEQ ID NO: 4, and the VL of the 12C11 antibody comprises the amino acid sequence of SEQ ID NO: 8. NAI-5010413635vl 92The VH of the 13B8 antibody comprises the amino acid sequence of SEQ ID NO: 5, and the VL of the 13B8 antibody comprises the amino acid sequence of SEQ ID NO: 8. The VH of the 1H2 antibody comprises the amino acid sequence of SEQ ID NO: 9, the VL of the 1H2 antibody comprises the amino acid sequence of SEQ ID NO: 12. The VH of the 17E3 antibody comprises the amino acid sequence of SEQ ID NO: 10, and the VL of the 17E3 antibody comprises the amino acid sequence of SEQ ID NO: 13. The VH of the 20D10 antibody comprises the amino acid sequence of SEQ ID NO: 11, and the VL of the 20D10 antibody comprises the amino acid sequence of SEQ ID NO: 14. The VH of the 7G4 antibody comprises the amino acid sequence of SEQ ID NO: 15, and the VL of the 7G4 antibody comprises the amino acid sequence of SEQ ID NO: 20. The VH of the 7G11 antibody comprises the amino acid sequence of SEQ ID NO: 16, and the VL of the 7G11 antibody comprises the amino acid sequence of SEQ ID NO: 20. The VH of the 12G8 antibody comprises the amino acid sequence of SEQ ID NO: 17, and the VL of the 12G8 antibody comprises the amino acid sequence of SEQ ID NO: 21. The VH of the 17C12 antibody comprises the amino acid sequence of SEQ ID NO: 18, and the VL of the 17C12 antibody comprises the amino acid sequence of SEQ ID NO: 20. The VH of the 6G1 antibody comprises the amino acid sequence of SEQ ID NO: 19, and the VL of the 6G1 antibody comprises the amino acid sequence of SEQ ID NO: 22. The VH of the 7H10 antibody comprises the amino acid sequence of SEQ ID NO: 23, and the VL of the 7H10 antibody comprises the amino acid sequence of SEQ ID NO: 25. The VH of the 14B8 antibody comprises the amino acid sequence of SEQ ID NO: 24, and the VL of the 14B8 antibody comprises the amino acid sequence of SEQ ID NO: 25. The VH of the 12G1 antibody comprises the amino acid sequence of SEQ ID NO: 26, and the VL of the 12G1 antibody comprises the amino acid sequence of SEQ ID NO: 27. Antibodies 1 Al, 12C11, 12G9, 13B9, and 13E8 belong to clonotype 1. Antibodies 1H2, 17E3, and 20D10 belong to clonotype 2. Antibodies 6G1, 7G4, 7G11, 12G8, and 17C12 belong to clonotype 3.Antibodies 7H10 and 14B8 belong to clonotype 4. Antibody 12G1 belongs to clonotype 5.

[0115] As used herein, the terms “variable region” or “variable domain” are used interchangeably and are common in the art. The variable region typically refers to a portion of an antibody, generally, a portion of a light or heavy chain, typically about the aminoterminal 110 to 130 amino acids in a mature heavy chain and about the amino-terminal 90 to 110 amino acids in a mature light chain, which differs extensively in sequence among antibodies and is used in the binding and specificity of a particular antibody for its particular antigen. The variability in sequence is concentrated in those regions called complementarity NAI-5010413635vl 93determining regions (CDRs) while the more highly conserved regions in the variable domain are called framework regions (FR). CDRs are flanked by FRs. Generally, the spatial orientation of CDRs and FRs are as follows, in an N-terminal to C-terminal direction: FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4. Without wishing to be bound by any particular mechanism or theory, it is believed that the CDRs of the light and heavy chains are generally responsible for the interaction and specificity of the antibody with antigen, and the framework regions generally provide much of the antibody structure as well as interactions with the CDRs that can affect their structure and binding to antigen. In specific embodiments, the variable region is a human variable region. In some embodiments, the variable region comprises human CDRs and non-human animal framework regions (FRs). In some embodiments, the variable region comprises human CDRs and non-human primate framework regions (FRs).

[0116] In another aspect, an antibody or an antigen-binding fragment thereof provided herein comprises one, two or three of the CDRs of the VH a clonotype 1, 2, 3, 4, or 5 antibody, or one, two or three of the CDRs of the VL of a clonotype 1, 2, 3, 4, or 5 antibody. In some embodiments, an antibody or an antigen-binding fragment thereof provided herein comprises one, two or three of the CDRs of the VH of the 1 Al, 12C11, 12G9, 13B9, 13B8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, or 12G1 antibody, or one, two or three of the CDRs of the VL of the 1A1, 12C11, 12G9, 13B9, 13B8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, or 12G1 antibody. In some embodiments, an antibody or an antigenbinding fragment thereof provided herein comprises one, two or three of the CDRs of the VH or one, two or three of the CDRs of the VL of the 1 Al, 20D10, 6G1, or 12G1 antibody.

[0117] In another aspect, an antibody or an antigen-binding fragment thereof provided herein comprises one, two or three of the CDRs of the VH and one, two or three of a clonotype 1, 2, 3, 4, or 5 antibody. In some embodiments, an antibody or an antigen-binding fragment thereof provided herein comprises one, two or three of the CDRs of the VH and one, two or three of the CDRs of the VL of the 1A1, 12C11, 12G9, 13B9, 13E8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, or 12G1 antibody. In some embodiments, an antibody or an antigen-binding fragment thereof provided herein comprises one, two or three of the CDRs of the VH and one, two or three of the CDRs of the VL of the 1A1, 12C11, 12G9, 13B9, 13B8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, or 12G1 antibody. In some embodiments, an antibody or an antigen-binding fragment thereof provided herein comprises one, two or three of the CDRs of the VH and one, two or three of the CDRs of the VL of the 1A1, 20D10, 6G1, or 12G1 antibody.NAI-5010413635vl 94

[0118] In another aspect, an antibody or an antigen-binding fragment thereof provided herein comprises the CDRs of the VH and the CDRs of the VL of a clonotype 1, 2, 3, 4, or 5 antibody. In some embodiments, an antibody or an antigen-binding fragment thereof provided herein comprises the CDRs of the VH and the CDRs of the VL of the 1 Al, 12C11, 12G9, 13B9, 13E8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, or 12G1 antibody. In some embodiments, an antibody or an antigen-binding fragment thereof provided herein comprises the CDRs of the VH and the VL of the 1 Al, 12C11, 12G9, 13B9, 13B8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, or 12G1 antibody. In some embodiments, an antibody or an antigen-binding fragment thereof provided herein comprises the CDRs of the VH and the VL of the 1A1, 20D10, 6G1, or 12G1 antibody. In some embodiments, the antibody or an antigen-binding fragment thereof further comprises framework regions from a human antibody).

[0119] The CDRs of antibodies of the variable heavy chain regions of the monoclonal antibodies 1A1, 12C11, 12G9, 13B9, 13E8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, and 12G1, as determined by the IMGT numbering system, are underlined in FIG. 11 A. The CDRs of antibodies of the variable light chain regions of the monoclonal antibodies 1A1, 12C11, 12G9, 13B9, 13E8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, and 12G1, as determined by the IMGT numbering system, are underlined in FIG. 11B. The framework regions are those regions not underlined in FIGs.11A-11B. Tables 11 and 12 provide the CDRs for clonotype 1 antibodies as determined by IMGT numbering. Tables 17 and 18 provide the CDRs for clonotype 2 antibodies as determined by IMGT numbering. Tables 23 and 24 provide the CDRs for clonotype 3 antibodies as determined by IMGT numbering. Tables 29 and 30 provide the CDRs for clonotype 4 antibodies as determined by IMGT numbering. Tables 35 and 36 provide the CDRs for the clonotype 5 antibody as determined by IMGT numbering.

[0120] The CDRs of an antibody can be determined according to the Kabat numbering system. The terms “Kabat numbering,” and like terms are recognized in the art and refer to a system of numbering amino acid residues in the heavy and light chain variable regions of an antibody, or an antigen-binding portion thereof. In some embodiments, the CDRs of an antibody can be determined according to the Kabat numbering system (see, e.g., Kabat et al. (1971) Ann. NY Acad. Sci. 190:382-391 and, Kabat et al. (1991) Sequences of Proteins of Immunological Interest, Fifth Edition, U. S. Department of Health and Human Services, NIH Publication No. 91-3242). Bethesda: National Institutes of Health, 1983). As is well known to those of skill in the art, using the Kabat numbering system, the actual linear amino acid NAI-5010413635vl 95sequence of the antibody variable domain can contain fewer or additional amino acids due to a shortening or lengthening of a FR and / or CDR and, as such, an amino acid’s Kabat number is not necessarily the same as its linear amino acid number. In some embodiments, the CDRs of a clonotype 1 antibody (i.e., 1A1, 12C11, 12G9, 13B9, 13E8), a clonotype 2 antibody (1H2, 17E3, 20D10), a clonotype 3 antibody (6G1, 7G4, 7G11, 12G8, 17C12), a clonotype 4 antibody (7H10, 14B8), and / or a clonotype 5 antibody (12G1) are determined using the Kabat numbering system. Tables 13 and 14 provide the CDRs for clonotype 1 antibodies as determined by Kabat numbering. Tables 19 and 20 provide the CDRs for clonotype 2 antibodies as determined by Kabat numbering. Tables 25 and 26 provide the CDRs for clonotype 3 antibodies as determined by Kabat numbering. Tables 31 and 32 provide the CDRs for clonotype 4 antibodies as determined by Kabat numbering. Tables 37 and 38 provide the CDRs for the clonotype 5 antibody as determined by Kabat numbering.

[0121] The CDRs of an antibody can be determined according to the Chothia numbering scheme, which refers to the location of immunoglobulin structural loops (see, e.g., Chothia and Lesk, 1987, J. Mol. Biol., 196:901-917; Al-Lazikani et al., 1997, J. Mol. Biol., 273:927-948; Chothia et al., 1992, J. Mol. Biol., 227:799-817; Tramontane A et al., 1990, J. Mol. Biol. 215(1): 175-82; and U. S. Patent No. 7,709,226). The Chothia definition is based on the location of the structural loop regions (Chothia et al., (1987) J Mol Biol 196: 901-917; and U. S. Patent No. 7,709,226). The term “Chothia CDRs,” and like terms are recognized in the art and refer to antibody CDR sequences as determined according to the method of Chothia and Lesk, 1987, J. Mol. Biol., 196:901-917, which will be referred to herein as the “Chothia CDRs” (see also, e.g., U. S. Patent No. 7,709,226 and Martin, A., “Protein Sequence and Structure Analysis of Antibody Variable Domains,” in Antibody Engineering, Kontermann and Diibel, eds., Chapter 31, pp. 422-439, Springer-Verlag, Berlin (2001)). In some embodiments, the CDRs of a clonotype 1 antibody (i.e., 1A1, 12C11, 12G9, 13B9, 13E8), a clonotype 2 antibody (1H2, 17E3, 20D10), a clonotype 3 antibody (6G1, 7G4, 7G11, 12G8, 17C12), a clonotype 4 antibody (7H10, 14B8), and / or a clonotype 5 antibody (12G1) are determined using the Chothia numbering system. Tables 15 and 16 provide the CDRs for clonotype 1 antibodies as determined by Chothia numbering. Tables 21 and 22 provide the CDRs for clonotype 2 antibodies as determined by Chothia numbering. Tables 27 and 28 provide the CDRs for clonotype 3 antibodies as determined by Chothia numbering. Tables 33 and 34 provide the CDRs for clonotype 4 antibodies as determined by Chothia numbering. Tables 39 and 40 provide the CDRs for the clonotype 5 antibody as determined by Chothia numbering.NAI-5010413635vl 96

[0122] The CDRs of an antibody can be determined according to the IMGT numbering system as described in Lefranc, M.-P., 1999, The Immunologist, 7:132-136 and Lefranc, M -P. et al., 1999, Nucleic Acids Res., 27:209-212. The IMGT definition is from the IMGT (“IMGT®, the International ImMunoGeneTics information system® website imgt.org, founder and director: Marie-Paule Lefranc, Montpellier, France; see, e.g., Lefranc, M.-P., 1999, The Immunologist, 7:132-136 and Lefranc, M.-P. et al., 1999, Nucleic Acids Res., 27:209-212, both of which are incorporated herein by reference in their entirety). With respect to the IMGT numbering system, (i) the VH CDR1 is typically present at amino acid positions 25 to 35 of the heavy chain; (ii) the VH CDR2 is typically present at amino acid positions 51 to 57 of the heavy chain; and (iii) the VH CDR3 is typically present at amino acid positions 93 to 102 of the heavy chain. With respect to the IMGT numbering system, (i) the VL CDR1 is typically present at amino acid positions 27 to 32 of the light chain; (ii) the VL CDR2 is typically present at amino acid positions 50 to 52 of the light chain; and (iii) the VL CDR3 is typically present at amino acid positions 89 to 97 of the light chain. In some embodiments, the CDRs of a clonotype 1 antibody (i.e., 1A1, 12C11, 12G9, 13B9, 13E8), a clonotype 2 antibody (1H2, 17E3, 20D10), a clonotype 3 antibody (6G1, 7G4, 7G11, 12G8, 17C12), a clonotype 4 antibody (7H10, 14B8), and / or a clonotype 5 antibody (12G1) are determined using the IMGT numbering system.

[0123] The CDRs of an antibody can be determined according to MacCallum et al., 1996, J. Mol. Biol., 262:732-745. See also, e.g., Martin, A., “Protein Sequence and Structure Analysis of Antibody Variable Domains,” in Antibody Engineering, Kontermann and Diibel, eds., Chapter 31, pp. 422-439, Springer-Verlag, Berlin (2001).

[0124] The CDRs of an antibody can be determined according to the AbM numbering scheme, which refers AbM hypervariable regions which represent a compromise between the Kabat CDRs and Chothia structural loops, and are used by Oxford Molecular’s AbM antibody modeling software.

[0125] The antigen-binding regions (ABRs) of an antibody can be determined using Paratome (see, e.g., Kunik et al., 2012, Nucleic Acids Res. 40(Web Server issue): W521-4).

[0126] In a specific aspect, provided herein are antibodies of clonotype 1 (i.e., antibodies designated 1A1, 12C11, 12G9, 13B9, and 13E8) and antigen-binding fragments thereof. In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 1 Al or an antigen-binding fragment thereof. In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 12C11 or an antigen-binding fragment thereof. In a specificNAI-5010413635vl 97embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 12G9 or an antigen-binding fragment thereof. In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 13B9 or an antigen-binding fragment thereof. In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 13E8 or an antigen-binding fragment thereof. The deduced nucleotide sequences of the variable heavy chain region and variable light chain region of the antibodies of clonotype 1 are shown in Table 6. The deduced amino acid sequences of the variable heavy chain region and variable light chain region of the antibodies of clonotype 1 are shown in Table 1. The CDRs of the variable heavy chain regions of the antibodies of clonotype 1, as determined using IMGT numbering system, are shown in Table 11. The CDRs of the variable heavy chain regions (or VH CDRs) of the antibodies of clonotype 1, as determined using the Kabat numbering system are shown in Table 13. The CDRs of the variable heavy chain regions of the antibodies of clonotype 1, as determined using the Chothia numbering system are shown in Table 15. In some embodiments, an antibody or a fragment thereof that binds to HA of an influenza A virus (e.g., HA of an H5 influenza A virus of clade 2.3.4.4b) comprises the VH CDR1, VH CDR2, and VH CDR3 of the antibody designated 1A1, 12C11, 12G9, 13B9, or 13E8. Table 11, 13, and 15 each provide consensus sequences for the CDRs of the variable heavy chain region of a clonotype 1 antibody. In some embodiments, an antibody or antigenbinding fragment comprises the VH CDRs of the consensus sequences provided in Table 11, 13, or 15. The CDRs of the variable light chain regions of the antibodies of clonotype 1, as determined using the IMGT numbering system are shown in Table 12. The CDRs of the variable light chain regions of the antibodies of clonotype 1, as determined using the Kabat numbering system are shown in Table 14. The CDRs of the variable light chain regions (or VL CDRs) of the antibodies of clonotype 1, as determined using the Chothia numbering system are shown in Table 16. In some embodiments, an antibody or a fragment thereof that binds to HA of an influenza A virus (e.g., HA of an H5 influenza A virus of clade 2.3.4.4b) comprises the VL CDR1, VL CDR2, and VL CDR3 of the antibody designated 1 Al, 12C11, 12G9, 13B9, or 13E8. Table 12, 14, and 16 each provide consensus sequences for the CDRs of the variable light chain region of a clonotype 1 antibody. In some embodiments, an antibody or antigen-binding fragment comprises the VL CDRs of the consensus sequences provided in Table 12, 14, or 16. In some embodiments, an antibody or antigen-binding fragment comprises the VH CDRs of the consensus sequences provided in Table 11, 13, orNAI-5010413635vl 9815, and the VL CDRs of the consensus sequences provided in Table 12, 14, or 16, respectively.

[0127] In a specific aspect, provided herein are antibodies of clonotype 2 ( / .<?., antibodies designated 1H2, 17E3, and 20D10) and antigen-binding fragments thereof. In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 1H2 or an antigen-binding fragment thereof. In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 17E3 or an antigen-binding fragment thereof. In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 20D10 or an antigen-binding fragment thereof. The deduced nucleotide sequences of the variable heavy chain region and variable light chain region of the antibodies of clonotype 2 are shown in Table 7. The deduced amino acid sequences of the variable heavy chain region and variable light chain region of the antibodies of clonotype 2 are shown in Table 2. The CDRs of the variable heavy chain regions of the antibodies of clonotype 2, as determined using IMGT numbering system, are shown in Table 17. The CDRs of the variable heavy chain regions of the antibodies of clonotype 2, as determined using the Kabat numbering system are shown in Table 19. The CDRs of the variable heavy chain regions of the antibodies of clonotype 2, as determined using the Chothia numbering system are shown in Table 21. In some embodiments, an antibody or a fragment thereof that binds to HA of an influenza A virus (e.g., HA of an H5 influenza A virus of clade 2.3.4.4b) comprises the VH CDR1, VH CDR2, and VH CDR3 of the antibody designated 1H2, 17E3, or 20D10. Tables 17, 19, and 21 each provide consensus sequences for the CDRs of the variable heavy chain region of a clonotype 2 antibody. In some embodiments, an antibody or antigen-binding fragment comprises the VH CDRs of the consensus sequences provided in Table 17, 19, or 21. The CDRs of the variable light chain regions of the antibodies of clonotype 2, as determined using the IMGT numbering system are shown in Table 18. The CDRs of the variable light chain regions of the antibodies of clonotype 2, as determined using the Kabat numbering system are shown in Table 20. The CDRs of the variable light chain regions of the antibodies of clonotype 2, as determined using the Chothia numbering system are shown in Table 22. In some embodiments, an antibody or a fragment thereof that binds to HA of an influenza A virus (e.g., HA of an H5 influenza A virus of clade 2.3.4.4b) comprises the VL CDR1, VL CDR2, and VL CDR3 of the antibody designated 1H2, 17E3, or 20D10. Tables 18, 20, and 22 each provide consensus sequences for the CDRs of the variable light chain region of a clonotype 2 antibody. In some embodiments, an antibody or antigen-binding NAI-5010413635vl 99fragment comprises the VL CDRs of the consensus sequences provided in Table 18, 20, or 22. In some embodiments, an antibody or antigen-binding fragment comprises the VH CDRs of the consensus sequences provided in Table 17, 19, or 21, and the VL CDRs of the consensus sequences provided in Table 18, 20, or 22, respectively.

[0128] In a specific aspect, provided herein are antibodies of clonotype 3 ( / .<?., antibodies designated 6G1, 7G4, 7G11, 12G8, and 17C12) and antigen-binding fragments thereof. In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 6G1 or an antigen-binding fragment thereof. In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 7G4 or an antigen-binding fragment thereof. In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 7G11 or an antigen-binding fragment thereof. In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 12G8 or an antigen-binding fragment thereof. In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 17C12 or an antigen-binding fragment thereof. The deduced nucleotide sequences of the variable heavy chain region and variable light chain region of the antibodies of clonotype 3 are shown in Table 8. The deduced amino acid sequences of the variable heavy chain region and variable light chain region of the antibodies of clonotype 3 are shown in Table 3. The CDRs of the variable heavy chain regions of the antibodies of clonotype 3, as determined using IMGT numbering system, are shown in Table 23. The CDRs of the variable heavy chain regions of the antibodies of clonotype 3, as determined using the Kabat numbering system are shown in Table 25. The CDRs of the variable heavy chain regions of the antibodies of clonotype 3, as determined using the Chothia numbering system are shown in Table 27. In some embodiments, an antibody or a fragment thereof that binds to HA of an influenza A virus (e.g., HA of an H5 influenza A virus of clade 2.3.4.4b) comprises the VH CDR1, VH CDR2, and VH CDR3 of the antibody designated 6G1, 7G4, 7G11, 12G8, or 17C12. Tables 23, 25, and 27 each provide consensus sequences for the CDRs of the variable heavy chain region of a clonotype 3 antibody. In some embodiments, an antibody or antigen-binding fragment comprises the VH CDRs of the consensus sequences provided in Table 23, 25, or 27. The CDRs of the variable light chain regions of the antibodies of clonotype 3, as determined using the IMGT numbering system are shown in Table 24. The CDRs of the variable light chain regions of the antibodies of clonotype 3, as determined using the Kabat numbering system are shown in Table 26. The CDRs of the variable light chain regions of the antibodies of NAI-5010413635vl 100clonotype 3, as determined using the Chothia numbering system are shown in Table 28. In some embodiments, an antibody or a fragment thereof that binds to HA of an influenza A virus (e.g., HA of an H5 influenza A virus of clade 2.3.4.4b) comprises the VL CDR1, VL CDR2, and VL CDR3 of the antibody designated 6G1, 7G4, 7G11, 12G8, or 17C12. Tables 24, 26, and 28 each provide consensus sequences for the CDRs of the variable light chain region of a clonotype 3 antibody. In some embodiments, an antibody or antigen-binding fragment comprises the VL CDRs of the consensus sequences provided in Table 24, 26, or 28. In some embodiments, an antibody or antigen-binding fragment comprises the VH CDRs of the consensus sequences provided in Table 23, 25, or 27, and the VL CDRs of the consensus sequences provided in Table 24, 26, or 28, respectively.

[0129] In a specific aspect, provided herein are antibodies of clonotype 4 (i.e., antibodies designated 7H10 and 14B8) and antigen-binding fragments thereof. In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 7H10 or an antigen-binding fragment thereof. In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 14B8 or an antigen -binding fragment thereof. The deduced nucleotide sequences of the variable heavy chain region and variable light chain region of the antibodies of clonotype 4 are shown in Table 9. The deduced amino acid sequences of the variable heavy chain region and variable light chain region of the antibodies of clonotype 4 are shown in Table 4. The CDRs of the variable heavy chain regions of the antibodies of clonotype 4, as determined using IMGT numbering system, are shown in Table 29. The CDRs of the variable heavy chain regions of the antibodies of clonotype 4, as determined using the Kabat numbering system are shown in Table 31. The CDRs of the variable heavy chain regions of the antibodies of clonotype 4, as determined using the Chothia numbering system are shown in Table 33. In some embodiments, an antibody or a fragment thereof that binds to HA of an influenza A virus (e.g., HA of an H5 influenza A virus of clade 2.3.4.4b) comprises the VH CDR1, VH CDR2, and VH CDR3 of the antibody 7H10 or 14B8. Tables 29, 31, and 33 each provide consensus sequences for the CDRs of the variable heavy chain region of a clonotype 4 antibody. In some embodiments, an antibody or antigen-binding fragment comprises the VH CDRs of the consensus sequences provided in Table 29, 31, or 33. The CDRs of the variable light chain regions of the antibodies of clonotype 4, as determined using the IMGT numbering system are shown in Table 30. The CDRs of the variable light chain regions of the antibodies of clonotype 4, as determined using the Kabat numbering system are shown in Table 32. The CDRs of the variable light chain regions of the antibodies of clonotype 4, as NAI-5010413635vl 101determined using the Chothia numbering system are shown in Table 34. In some embodiments, an antibody or a fragment thereof that binds to HA of an influenza A virus (e.g., HA of an H5 influenza A virus of clade 2.3.4.4b) comprises the VL CDR1, VL CDR2, and VL CDR3 of the antibody 7H10 or 14B8. Tables 30, 32, and 34 each provide consensus sequences for the CDRs of a variable light chain region of a clonotype 4 antibody. In some embodiments, an antibody or antigen-binding fragment comprises the VL CDRs of the consensus sequences provided in Table 30, 32, or 34. In some embodiments, an antibody or antigen-binding fragment comprises the VH CDRs of the consensus sequences provided in Table 29, 32, or 34, and the VL CDRs of the consensus sequences provided in Table 30, 32, or 34, respectively.

[0130] In a specific aspect, provided herein is the antibody of clonotype 5 (i.e., the antibody designated 12G1) and antigen-binding fragments thereof. In a specific embodiment, an antibody or an antigen-binding fragment thereof provided herein is the antibody designated 12G1 or an antigen-binding fragment thereof. The deduced nucleotide sequences of the variable heavy chain region and variable light chain region of the antibodies of clonotype 5 are shown in Table 10. The deduced amino acid sequences of the variable heavy chain region and variable light chain region of the antibodies of clonotype 5 are shown in Table 5. The CDRs of the variable heavy chain regions of the antibodies of clonotype 5, as determined using IMGT numbering system, are shown in Table 35. The CDRs of the variable heavy chain regions of the antibodies of clonotype 5, as determined using the Kabat numbering system are shown in Table 37. The CDRs of the variable heavy chain regions of the antibodies of clonotype 5, as determined using the Chothia numbering system are shown in Table 39. In some embodiments, an antibody or a fragment thereof that binds to HA of an influenza A virus (e.g., HA of an H5 influenza A virus of clade 2.3.4.4b) comprises the VH CDR1, VH CDR2, and VH CDR3 of the antibody 12G1. The CDRs of the variable light chain regions of the antibodies of clonotype 5, as determined using the IMGT numbering system are shown in Table 36. The CDRs of the variable light chain regions of the antibodies of clonotype 5, as determined using the Kabat numbering system are shown in Table 38. The CDRs of the variable light chain regions of the antibodies of clonotype 5, as determined using the Chothia numbering system are shown in Table 40. In some embodiments, an antibody or a fragment thereof that binds to HA of an influenza A virus (e.g., HA of an H5 influenza A virus of clade 2.3.4.4b) comprises the VL CDR1, VL CDR2, and VL CDR3 of the antibody 12G1.NAI-5010413635vl 102

[0131] Table 41 provides consensus sequences for the CDRs of the variable heavy chain region of clonotypes 3 and 5 antibodies, as determined using the IMGT numbering system. Table 43 provides consensus sequences for the CDRs of the variable heavy chain region of clonotypes 3 and 5 antibodies, as determined using the Kabat numbering system. Table 45 provides consensus sequences for the CDRs of the variable heavy chain region of clonotypes 3 and 5 antibodies, as determined using the Chothia numbering system. In some embodiments, an antibody or antigen-binding fragment comprises the VH CDRs of the consensus sequences provided in Table 41, 43, or 45. Table 42 provides consensus sequences for the CDRs of the variable light chain region of clonotypes 3 and 5 antibodies, as determined using the IMGT numbering system. Table 44 provides consensus sequences for the CDRs of the variable light chain region of clonotypes 3 and 5 antibodies, as determined using the Kabat numbering system. Table 46 provides consensus sequences for the CDRs of the variable light chain region of clonotypes 3 and 5 antibodies, as determined using the Chothia numbering system. In some embodiments, an antibody or antigen-binding fragment comprises the VL CDRs of the consensus sequences provided in Table 42, 44, or 46. In some embodiments, an antibody or antigen-binding fragment comprises the VH CDRs of the consensus sequences provided in Table 41, 43, or 45, and the VL CDRs of the consensus sequences provided in Table 42, 44, or 46, respectively.

[0132] In a specific embodiment, the position of a CDR along the variable heavy chain region and / or variable light chain region of an antibody provided herein may vary by one, two, three or four amino acid positions so long as binding to influenza A virus HA (e.g,. HA of an H5 influenza A virus, such as clade 2.3.4.4b) is maintained or substantially maintained (for example, by at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% in an assay known in the art or described herein, such as an ELISA). For example, in some embodiments, the position defining a CDR of antibody 1A1, 12C11, 12G9, 13B9, 13E8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, or 12G1 may vary by shifting the N-terminus and / or C-terminus boundary of the CDR by one, two, three, or four amino acids, relative to the CDRs in any one of Tables 11 to 40, so long as binding to influenza A virus HA (e.g, HA of an influenza A virus of subtype H5, such as HA of an H5 influenza A virus of clade 2.3.4.4b) is maintained or substantially maintained (for example, by at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% in an assay known in the art or described herein, such as an ELISA).

[0133] In another aspect, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 NAI-5010413635vl 103influenza A virus of clade 2.3.4.4b) comprising one, two or three CDRs of the variable heavy chain region of the antibody 1A1, 12C11, 12G9, 13B9, 13E8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, or 12G1 and one, two or three CDRs of the variable light chain region of the antibody 1A1, 12C11, 12G9, 13B9, 13E8, 1H2, 17E3, 20D10, 6G1, 7G4, 7G11, 12G8, 17C12, 7H10, 14B8, or 12G1. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b ) comprising one, two or three CDRs of the variable heavy chain region of a clonotype 1 antibody and one, two or three CDRs of the variable light chain region of the same antibody of the clonotype 1. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g, an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b ) comprising the VH CDR1, the VH CDR2, and the VH CDR3 of a clonotype 1 antibody and VL CDR1, VL CDR2, and VL CDR3 of the same antibody of the clonotype 1 antibody. For example, if the clonotype 1 antibody is 1A1, then the reference to “a clonotype 1 antibody” and "the same antibody of clonotype 1” means that the VH CDRs and VL CDRs are from the 1 Al antibody. See Tables 11-16 for the CDRs of the variable heavy chain region and variable light chain region of clonotype 1 antibodies. The clonotype 1 antibody may be the antibody designated 1A1, 12C11, 12G9, 13B9, or 13E8. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g, an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDR consensus sequences of the variable heavy chain region of a clonotype 1 antibody, as determined using IMGT numbering, and one, two or three CDR consensus sequences of the variable light chain region of a clonotype 1 antibody, as determined using IMGT numbering. See Tables 11 and 12 for the consensus sequences of the CDRs of the variable heavy chain region and variable light chain region of a clonotype 1 antibody, as determined by IMGT numbering. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDR consensus sequences of the variable heavy chain region of a clonotype 1 antibody, as determined using Kabat numbering, and one, two or three CDR consensus sequences of the variable light chain region of a clonotype 1 antibody, as determined using Kabat numbering. See Tables 13 and 14 for the consensus sequences of the CDRs of the variable heavy chain region and variable light chain region of a clonotype 1 antibody, as determined by Kabat numbering. In some embodiments, provided herein are NAI-5010413635vl 104antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDR consensus sequences of the variable heavy chain region of a clonotype 1 antibody, as determined using Chothia numbering, and one, two or three CDR consensus sequences of the variable light chain region of a clonotype 1 antibody, as determined using Chothia numbering. See Tables 15 and 16 for the consensus sequences of the CDRs of the variable heavy chain region and variable light chain region of a clonotype 1 antibody, as determined by Chothia numbering. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising the consensus sequences of the VH CDR1, the VH CDR2, and the VH CDR3 of a clonotype 1 antibody, as determined by a numbering system provided herein, and the consensus sequences of the VL CDR1, the VL CDR2, and the VL CDR3 of the clonotype 1 antibody, as determined using the same numbering system.

[0134] In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDRs of the variable heavy chain region of a clonotype 2 antibody and one, two or three CDRs of the variable light chain region of the same antibody of the clonotype 2 antibody. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising the VH CDR1, the VH CDR2, and the VH CDR3 of a clonotype 2 antibody and the VL CDR1, the VL CDR2, and the VL CDR3 of the same antibody of the clonotype 2 antibody. See Tables 17-22 for the CDRs of the variable heavy chain region and variable light chain region of clonotype 2 antibodies. The clonotype 2 antibody may be the antibody designated 1H2, 17E3, or 20D10. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDR consensus sequences of the variable heavy chain region of a clonotype 2 antibody, as determined using IMGT numbering, and one, two or three CDR consensus sequences of the variable light chain region of a clonotype 2 antibody, as determined using IMGT numbering. See Tables 17 and 18 for the consensus sequences of the CDRs of the variable heavy chain region and variable light chain region of a clonotype 2 antibody, as determined by IMGT numbering. In some embodiments, provided herein are antibodies or NAI-5010413635vl 105fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDR consensus sequences of the variable heavy chain region of a clonotype 2 antibody, as determined using Kabat numbering, and one, two or three CDR consensus sequences of the variable light chain region of a clonotype 2 antibody, as determined using Kabat numbering. See Tables 19 and 20 for the consensus sequences of the CDRs of the variable heavy chain region and variable light chain region of a clonotype 2 antibody, as determined by Kabat numbering. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDR consensus sequences of the variable heavy chain region of a clonotype 2 antibody, as determined using Chothia numbering, and one, two or three CDR consensus sequences of the variable light chain region of a clonotype 2 antibody, as determined using Chothia numbering. See Tables 21 and 22 for the consensus sequences of the CDRs of the variable heavy chain region and variable light chain region of a clonotype 2 antibody, as determined by Chothia numbering. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising the consensus sequences of the VH CDR1, the VH CDR2, and the VH CDR3 of a clonotype 2 antibody, as determined by a numbering system provided herein, and the consensus sequences of the VL CDR1, the VL CDR2, and the VL CDR3 of a clonotype 2 antibody, as determined using the same numbering system.

[0135] In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three complementarity determining regions (CDRs) of the variable heavy chain region of a clonotype 3 antibody and one, two or three CDRs of the variable light chain region of the same antibody of the clonotype 3 antibody. See Tables 23-28 for the CDRs of the variable heavy chain region and variable light chain region of clonotype 3 antibodies. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising the VH CDR1, the VH CDR2, and the VH CDR3 of a clonotype 3 antibody and the VL CDR1, the VL CDR2, and the VL CDR3 of the same antibody of the clonotype 3 antibody. The clonotype 3 antibody may be the antibody designated 6G1, 7G4, 7G11, 12G8, or 17C12. In some embodiments, provided herein are antibodies or fragments thereof that bind to an NAI-5010413635vl 106influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDR consensus sequences of the variable heavy chain region of a clonotype 3 antibody, as determined using IMGT numbering, and one, two or three CDR consensus sequences of the variable light chain region of a clonotype 3 antibody, as determined using IMGT numbering. See Tables 23 and 24 for the consensus sequences of the CDRs of the variable heavy chain region and variable light chain region of a clonotype 3 antibody, as determined by IMGT numbering. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDR consensus sequences of the variable heavy chain region of a clonotype 3 antibody, as determined using Kabat numbering, and one, two or three CDR consensus sequences of the variable light chain region of a clonotype 3 antibody, as determined using Kabat numbering. See Tables 25 and 26 for the consensus sequences of the CDRs of the variable heavy chain region and variable light chain region of a clonotype 3 antibody, as determined by Kabat numbering. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising the VH CDR1, the VH CDR2, and the VH CDR3 of a clonotype 3 antibody and the VL CDR1, the VH CDR2, and the VL CDR3 of the same antibody of the clonotype 3 antibody. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDR consensus sequences of the variable heavy chain region of a clonotype 3 antibody, as determined using Chothia numbering, and one, two or three CDR consensus sequences of the variable light chain region of a clonotype 3 antibody, as determined using Chothia numbering. See Tables 27 and 28 for the consensus sequences of the CDRs of the variable heavy chain region and variable light chain region of a clonotype 3 antibody, as determined by Chothia numbering. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising the consensus sequences of the VH CDR1, the VH CDR2, and the VH CDR3 of a clonotype 3 antibody, as determined by a numbering system provided herein, and the consensus sequences of the VL CDR1, the VL CDR2, and the VL CDR3 of a clonotype 3 antibody, as determined using the same numbering system.NAI-5010413635vl 107

[0136] In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDRs of the variable heavy chain region of a clonotype 4 antibody and one, two or three CDRs of the variable light chain region of the same antibody of the clonotype 4 antibody. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising the VH CDR1, the VH CDR2, and the VH CDR3 of a clonotype 4 antibody and the VL CDR1, the VL CDR2, and the VL CDR3 of the same antibody of the clonotype 4 antibody. See Tables 29-24 for the CDRs of the variable heavy chain region and variable light chain region of clonotype 4 antibodies. The clonotype 4 antibody may be the antibody designated 7H10 or 14B8. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDR consensus sequences of the variable heavy chain region of a clonotype 4 antibody, as determined using IMGT numbering, and one, two or three CDR consensus sequences of the variable light chain region of a clonotype 4 antibody, as determined using IMGT numbering. See Tables 29 and 30 for the consensus sequences of the CDRs of the variable heavy chain region and variable light chain region of a clonotype 4 antibody, as determined by IMGT numbering. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g, an HA of an H5 influenza A virus, such as an HA of a clade 2.3.4.4b influenza A virus) comprising one, two or three CDR consensus sequences of the variable heavy chain region of a clonotype 4 antibody, as determined using Kabat numbering, and one, two or three CDR consensus sequences of the variable light chain region of a clonotype 4 antibody, as determined using Kabat numbering. See Tables 31 and 32 for the consensus sequences of the CDRs of the variable heavy chain region and variable light chain region of a clonotype 4 antibody, as determined by Kabat numbering. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g, an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDR consensus sequences of the variable heavy chain region of a clonotype 4 antibody, as determined using Chothia numbering, and one, two or three CDR consensus sequences of the variable light chain region of a clonotype 4 antibody, as determined using Chothia numbering. See Tables 33 and 34 for the consensus sequences of the CDRs of the variable heavy chain region and variable light chain region of a NAI-5010413635vl 108clonotype 4 antibody, as determined by Chothia numbering. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising the consensus sequences of the VH CDR1, the VH CDR2, and the VH CDR3 of a clonotype 4 antibody, as determined by a numbering system provided herein, and the consensus sequences of the VL CDR1, the VL CDR2, and the VL CDR3 of a clonotype 4 antibody, as determined using the same numbering system.

[0137] In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA(e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDRs of the variable heavy chain region of a clonotype 5 antibody and one, two or three CDRs of the variable light chain region of the same antibody of the clonotype 5 antibody. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising the VH CDR1, the VH CDR2, and the VH CDR3 of a clonotype 5 antibody and the VL CDR1, the VL CDR2, and the VL CDR3 of the same antibody of the clonotype 5 antibody. See Tables 35-40 for the CDRs of the variable heavy chain region and variable light chain region of clonotype 5 antibodies. The clonotype 5 antibody may be the antibody designated 12G1. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDRs of the variable heavy chain region of the 12G1 antibody, as determined using Kabat numbering, and one, two or three CDR consensus sequences of the variable light chain region of the 12G1 antibody, as determined using Kabat numbering. See Tables 37 and 38 for the CDRs of the variable heavy chain region and variable light chain region of the 12G1 antibody, as determined by Kabat numbering. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDRs of the variable heavy chain region of the 12G1 antibody, as determined using Chothia numbering, and one, two or three CDRs of the variable light chain region of the 12G1 antibody, as determined using Chothia numbering. See Tables 39 and 40 for the CDRs of the variable heavy chain region and variable light chain region of the 12G1 antibody, as determined by Chothia numbering.NAI-5010413635vl 109

[0138] In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDR consensus sequences of the variable heavy chain region in Table 41, and one, two or three CDR consensus sequences of the variable light chain region in Table 42. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising the VH CDR1, the VH CDR2, and the VH CDR3 consensus sequences in Table 41, and the VL CDR1, the VL CDR2, and the VL CDR3 consensus sequences in Table 42. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDR consensus sequences of the variable heavy chain region in Table 43, and one, two or three CDR consensus sequences of the variable light chain region in Table 44. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising the VH CDR1, the VH CDR2, and the VH CDR3 consensus sequences in Table 43, and the VL CDR1, the VL CDR2, and the VL CDR3 consensus sequences in Table 44. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising one, two or three CDR consensus sequences of the variable heavy chain region in Table 45, and one, two or three CDR consensus sequences of the variable light chain region in Table 46. In some embodiments, provided herein are antibodies or fragments thereof that bind to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b) comprising the VH CDR1, the VH CDR2, and the VH CDR3 consensus sequences in Table 45, and the VL CDR1, the VL CDR2, and the VL CDR3 consensus sequences in Table 46.

[0139] In some embodiments, an antibody or a fragment thereof that binds to an influenza A virus HA (e.g., an HA of an H5 influenza A virus, such as an HA of H5 influenza A virus of clade 2.3.4.4b), comprises (or alternatively, consists of) a VH CDR1 and a VL CDR1; a VH CDR1 and a VL CDR2; a VH CDR1 and a VL CDR3; a VH CDR2 and a VL CDR1; VH CDR2 and a VL CDR2; a VH CDR2 and a VL CDR3; a VH CDR3 and a VL CDR1; a VH CDR3 and a VL CDR2; a VH CDR3 and a VL CDR3; a VH1 CDR1, a VH CDR2 and a VL NAI-5010413635vl 110CDR1; a VH CDR1, a VH CDR2 and a VL CDR2; a VH CDR1, a VH CDR2 and a VL CDR3; a VH CDR2, a VH CDR3 and a VL CDR1; a VH CDR2, a VH CDR3 and a VL CDR2; a VH CDR2, a VH CDR3 and a VL CDR3; a VH CDR1, a VL CDR1 and a VL CDR2; a VH CDR1, a VL CDR1 and a VL CDR3; a VH CDR2, a VL CDR1 and a VL CDR2; a VH CDR2, a VL CDR1 and a VL CDR3; a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR1, a VH CDR2, a VH CDR3 and a VL CDR1; a VH CDR1, a VH CDR2, a VH CDR3 and a VL CDR2; a VH CDR1, a VH CDR2, a VH CDR3 and a VL CDR3; a VH CDR1, a VH CDR2, a VL CDR1 and a VL CDR2; a VH CDR1, a VH CDR2, a VL CDR1 and a VL CDR3; a VH CDR1, a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR1, a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR2, a VH CDR3, a VL CDR2 and a VL CDR3; a VH CDR1, a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR1, a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR1, a VH CDR2, a VL CDR1, a VL CDR2, and a VL CDR3; a VH CDR1, a VH CDR3, a VL CDR1, a VL CDR2, and a VL CDR3; a VH CDR2, a VH CDR3, a VL CDR1, a VL CDR2, and a VL CDR3; a VH CDR1, VH CDR2, a VH CDR3, a VL CDR1, a VL CDR2, and a VL CDR3; or any combination thereof of the VH CDRs and VL CDRs of a clonotype 1, 2, 3, 4, or 5 antibody (and in some embodiments, a clonotype 1, 2, 3, or 5 antibody). The clonotype 1 antibody may be the 1A1, 12C11, 12G9, 13B9, or 13E8 antibody. In some embodiments, the clonotype 1 antibody is the 1A1 antibody. The clonotype 2 antibody may be the 1H2, 17E3, or 20D10 antibody. In some embodiments, the clonotype 2 antibody is the 20D10 antibody. The clonotype 3 antibody may be the 6G1, 7G4, 7G11, 12G8, or 17C12 antibody. In some embodiments, the clonotype 3 antibody is 6G1. The clonotype 4 antibody may be the 7H10 or 14B8 antibody. The clonotype 5 antibody may be 12G1 antibody.

[0140] In some embodiments, an antibody or a fragment thereof, which binds to an influenza A virus HA (e.g., H5 influenza A virus, such as, e.g., H5 influenza A virus of clade 2.3.4.4b), comprises one, two, three, four, five or all six CDRs of a clonotype 1 antibody. The clonotype 1 antibody may be the 1A1, 12C11, 12G9, 13B9, or 13E8 antibody. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., H5 influenza A virus, such as, e.g., H5 influenza A virus of clade 2.3.4.4b), comprises one, two, three, four, five or all six CDRs of a clonotype 1 antibody, as determined by IMGT numbering system, Kabat numbering system, Chothia numbering system or ABM numbering system. In some embodiments, an antibody or a fragment thereof, which binds to influenza A NAI-5010413635vl 111virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising the VH CDR1, the VH CDR2 and the VH CDR3 of a clonotype 1 antibody, as determined by a known numbering system known in the art, such as, e.g, set forth in Table 11, 13, or 15. In some embodiments, the heavy chain or VH comprises human framework regions or framework regions derived from a human antibody. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising the VL CDR1, the VL CDR2 and the VL CDR3 of a clonotype 1 antibody, as determined by a known numbering system known in the art, such as, e.g., set forth in Table 12, 14, or 16. In some embodiments, the light chain or VL comprises human framework regions or framework regions derived from a human antibody. In some embodiments, the light chain or VL comprises human framework regions or framework regions derived from IGKV1-8.

[0141] In some embodiments, an antibody or a fragment thereof, which binds to an influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4bb), comprises a VH or heavy chain comprising amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 of a clonotype 1 antibody, as determined by a numbering system known in the art, such as set forth in Table 11, 13, or 15. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 1A1 antibody the set forth in Table 11. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 1 Al antibody the set forth in Table 13. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 1A1 antibody the set forth in Table 15. In some embodiments, the heavy chain or VH comprises human framework regions or framework regions derived from a human antibody.NAI-5010413635vl 112

[0142] In some embodiments, an antibody or a fragment thereof, which binds to an influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4bb), comprises a VL or light chain comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 of the 1A1 antibody, as determined by a numbering system known in the art, such as set forth in Table 12, 14, or 16. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 1 Al antibody the set forth in Table 12. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 1 Al antibody the set forth in Table 14. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 1 Al antibody the set forth in Table 16. In some embodiments, the light chain or VL comprises human framework regions or framework regions derived from a human antibody.

[0143] In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 12C11 antibody the set forth in Table 11. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 12C11 antibody the set forth in Table 13. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino NAI-5010413635vl 113acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 12C11 antibody the set forth in Table 15. In some embodiments, the heavy chain or VH comprises human framework regions or framework regions derived from a human antibody.

[0144] In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 12C11 antibody the set forth in Table 12. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g, HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 12C11 antibody the set forth in Table 14. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 12C11 antibody the set forth in Table 16. In some embodiments, the light chain or VL comprises human framework regions or framework regions derived from a human antibody.

[0145] In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 12G9 antibody the set forth in Table 11. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4ba), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of VH CDR1, VH CDR2, and the VH CDR3 for 12G9 antibody the set forth in Table 13. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 12G9 antibody the setNAI-5010413635vl 114forth in Table 15. In some embodiments, the heavy chain or VH comprises human framework regions or framework regions derived from a human antibody.

[0146] In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of VL CDR1, the VL CDR2, and the VL CDR3 for 12G9 antibody the set forth in Table 12. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g, HA of an H5 influenza A virus of clade 2.3.4.4bra), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 12G9 antibody the set forth in Table 14. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 12G9 antibody the set forth in Table 16. In some embodiments, the light chain or VL comprises human framework regions or framework regions derived from a human antibody.

[0147] In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 13B9 antibody the set forth in Table 11. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 13B9 antibody the set forth in Table 13. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 13B9 antibody the set forth in Table 15. In some embodiments, the heavy chain or VH comprises human framework regions or framework regions derived from a human antibody.NAI-5010413635vl 115

[0148] In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 13B9 antibody the set forth in Table 12. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g, HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 13B9 antibody the set forth in Table 14. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 13B9 antibody the set forth in Table 16. In some embodiments, the light chain or VL comprises human framework regions or framework regions derived from a human antibody.

[0149] In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 13B8 antibody the set forth in Table 11. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 13B8 antibody the set forth in Table 13. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 13B8 antibody the set forth in Table 15. In some embodiments, the heavy chain or VH comprises human framework regions or framework regions derived from a human antibody.

[0150] In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A NAI-5010413635vl 116virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 13B8 antibody the set forth in Table 12. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 13B8 antibody the set forth in Table 14. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 13B8 antibody the set forth in Table 16. In some embodiments, the light chain or VL comprises human framework regions or framework regions derived from a human antibody.

[0151] In some embodiments, an antibody or a fragment thereof, which binds to an influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises one, two, three, four, five or all six CDRs of a clonotype 2 antibody. The clonotype 2 antibody may be the 1H2, 17E3, or 20D10 antibody. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises one, two, three, four, five or all six CDRs of a clonotype 2 antibody, as determined by IMGT numbering system, Kabat numbering system, Chothia numbering system or ABM numbering system. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising the VH CDR1, the VH CDR2 and the VH CDR3 of a clonotype 2 antibody, as determined by a known numbering system known in the art, such as, e.g., set forth in Table 17, 19, or 21. In some embodiments, the heavy chain or VH comprises human framework regions or framework regions derived from a human antibody. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising the VL CDR1, the VL CDR2 and the VL CDR3 of a clonotype 2 antibody, as determined by a known numbering system known in the art, such as, e.g., set forth in Table 18, 20, or 22. In some embodiments, the light chain or VL comprises NAI-5010413635vl 117human framework regions or framework regions derived from a human antibody. In some embodiments, the light chain or VL comprises human framework regions or framework regions derived from IGKV1-8.

[0152] In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 1H2 antibody the set forth in Table 17. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 1H2 antibody the set forth in Table 19. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 1H2 antibody the set forth in Table 21. In some embodiments, the heavy chain or VH comprises human framework regions or framework regions derived from a human antibody.

[0153] In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 1H2 antibody the set forth in Table 18. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 1H2 antibody the set forth in Table 20. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VL or light chain comprising a VL CDR1, a VL CDR2, and a VL CDR3 comprising the amino acid sequences of the VL CDR1, the VL CDR2, and the VL CDR3 for 1H2 antibody the set forth in Table 22. In some embodiments,NAI-5010413635vl 118the light chain or VL comprises human framework regions or framework regions derived from a human antibody.

[0154] In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 17E3 antibody the set forth in Table 17. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g, HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprising a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of the VH CDR1, the VH CDR2, and the VH CDR3 for 17E3 antibody the set forth in Table 19. In some embodiments, an antibody or a fragment thereof, which binds to influenza A virus HA (e.g., HA of an H5 influenza A virus, such as, e.g., HA of an H5 influenza A virus of clade 2.3.4.4b), comprises a VH or heavy chain comprisin...

Claims

1. WHAT IS CLAIMED:

1. An antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a variable heavy chain region (VH) complementarity determining region (CDR)1 comprising the amino acid sequence of SEQ ID NO: 55, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 61; and(ii) a variable light chain region (VL) CDR1 comprising the amino acid sequence of SEQ ID NO: 64, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 66;(B) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 67, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 71, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 75; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 211, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 79, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 80; or(C) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 81, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 82, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 83; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 86, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 87.

2. An antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 88, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 89, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 90; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 94, a VL CDR2 comprising the amino acid sequence LGX, wherein X is S or T, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 98;NAI-5010413635vl 287(B) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 99, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 100, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 101; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 104, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 108, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 109; or(C) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 110, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 111, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 112; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 115, a VL CDR2 comprising the amino acid sequence LGX, wherein X is S or T, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 116.

3. An antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 119, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 122, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 125; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 194, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 127;(B) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 130, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 134, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 137; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 140, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 141, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 142; or(C) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 143, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 146, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 149; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 207, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 151.NAI-5010413635vl 2884. An antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 154, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 155, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 156; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 157, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 158, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 159;(B) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 160, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 161, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 162; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 163, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 164, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 165; or(C) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 168, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 169, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 170; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 171, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 158, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 172.

5. An antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 190, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 191, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 192; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 177, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 195;(B) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 130, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 196, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 197; andNAI-5010413635vl 289(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 198, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 199, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 200; or(C) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 201, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 208, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 203; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 204, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 205.

6. The antibody or antigen-binding fragment thereof of claim 1, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 1; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 6;(B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 2; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8;(C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 3; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 7;(D)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 4; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8; or(E) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 5; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8.NAI-5010413635vl 2907. The antibody or antigen-binding fragment thereof of claim 2, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 9; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 12;(B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 10; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 13; or(C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 11; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 14.

8. The antibody or antigen-binding fragment thereof of claim 3 or 5, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 15 and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20;(B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 16; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20;(C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 17; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 21;(D)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 18; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20; orNAI-5010413635vl 291(E) (i) a variable heavy chain region comprising the amino acid sequence of SEQ IDNO: 19; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO:

229. The antibody or antigen-binding fragment thereof of claim 4, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a variable heavy chain region comprising the amino acid sequence of SEQ IDNO: 23; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 25; or(B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 24; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 25.

10. The antibody or antigen-binding fragment thereof of claim 1, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to 95% the amino acid sequence of SEQ ID NO: 1; and(ii) a variable light chain region comprising an amino acid sequence at least 95% identical to the amino acid sequence of SEQ ID NO: 6;(B) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 2; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 8;(C) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 7;(D)(i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 4; andNAI-5010413635vl 292(ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 8; or (E) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 5; and (ii) the variable light chain region comprises the amino acid sequence of SEQ ID NO: 8.

11. The antibody or antigen-binding fragment thereof of claim 2, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 9; and (ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 12; (B) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 10; and(ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 13; or (C) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 11; and(ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 14.

12. The antibody or antigen-binding fragment thereof of claim 3 or 5, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 15 and (ii) a variable light chain region comprises the amino acid sequence of SEQ ID NO: 20;(B) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 16; andNAI-5010413635vl 293(ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 20; (C) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 17; and(ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 21; (D)(i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 18; and(ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 20; or (E) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 19; and(ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 22.

13. The antibody or antigen-binding fragment thereof of claim 4, wherein:(A)(i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 23; and(ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 25; or (B) (i) a variable heavy chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 24; and(ii) a variable light chain region comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 25.

14. An antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises:NAI-5010413635vl 294(A) (i) the variable heavy chain region (VH) complementarity determining region (CDR) 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 1; and(ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 6;(B) (i) the variable heavy chain region (VH)CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 2; and(ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 8;(C) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 3; and(ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 7;(D) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 4; and(ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 8;(E) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 5; and(ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 8;(F) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 9; and(ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 12;(G) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 10; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 13;(H) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 11; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 14;NAI-5010413635vl 295(I) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 15; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 20;(J) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 16; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 20;(K) (i) the variable heavy chain region (VH) CDR1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 17; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 21;(L) (i) the variable heavy chain region (VH) CDR1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 18; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 20;(M) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 19; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 22;(N) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 23; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 25;(O) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 24; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 25; or(P) (i) the variable heavy chain region (VH) CDR 1, the VH CDR2, and the VH CDR3 of the variable heavy chain region set forth in SEQ ID NO: 26; and (ii) the variable light chain region (VL) CDR1, the VL CDR2, and the VL CDR3 of the variable light chain region set forth in SEQ ID NO: 27.

15. The antibody or antigen-binding fragment thereof of claim 1 or 14A, wherein:NAI-5010413635vl 296(A) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 55, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 56, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 59; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 62, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 66;(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 67, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 68, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 72; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 76, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 79, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 80; or(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 81, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 82, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 83; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 84, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 87.

16. The antibody or antigen-binding fragment thereof of claim 1 or 14B, wherein: (A)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 55, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 57, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 59; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 63, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 66;(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 67, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 69, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 72; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 77, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 79, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 80; orNAI-5010413635vl 297(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 81, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 82, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 83; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 85, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 87.

17. The antibody or antigen-binding fragment thereof of claim 1 or 14C, wherein: (A)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 55, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 56, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 209; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 210, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 66;(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 67, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 70, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 73; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 78, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 79, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 80; or(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 81, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 82, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 83; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 212, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 87.

18. The antibody or antigen-binding fragment thereof of claim 1 or 14D, wherein: (A)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 55, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 56, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 209; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 63, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 66;NAI-5010413635vl 298(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 67, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 70, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 73; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 77, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 79, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 80; or(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 81, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 82, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 83; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 85, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 87.

19. The antibody or antigen-binding fragment thereof of claim 1 or 14E, wherein: (A)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 55, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 56, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 60; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 63, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 66;(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 67, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 70, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 74; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 77, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 79, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 80; or(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 81, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 82, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 83; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 85, the VL CDR2 comprises the amino acid sequence GAF, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 87.

20. The antibody or antigen-binding fragment thereof of claim 2 or 14F, wherein:NAI-5010413635vl 299(A)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 88, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 89, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 90; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 91, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 98;(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 99, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 100, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 101; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 102, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 105, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 109; or(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 110, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 111, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 112; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 113, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 116.

21. The antibody or antigen-binding fragment thereof of claim 2 or 14G, wherein: (A)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 88, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 89, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 90; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 92, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 98;(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 99, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 100, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 101; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 103, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 106, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 109; orNAI-5010413635vl 300(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 110, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 111, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 112; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 114, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 116.

22. The antibody or antigen-binding fragment thereof of claim 2 or 14H, wherein: (A)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 88, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 89, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 90; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 93, the VL CDR2 comprises the amino acid sequence LGT, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 98;(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 99, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 100, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 101; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 102, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 107, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 109; or(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 110, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 111, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 112; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 113, the VL CDR2 comprises the amino acid sequence LGT, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 116.

23. The antibody or antigen-binding fragment thereof of claim 3, 5, or 141, wherein:(A)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 117, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 120, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 123; andNAI-5010413635vl 301(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 126, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 127;(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 128, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 131, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 135; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 138, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 141, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 142; or(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 143, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 144, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 147; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 150, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 151.

24. The antibody or antigen-binding fragment thereof of claim 3, 5, or 14J, wherein:(A)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 118, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 121, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 123; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 126, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 127;(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 129, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 132, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 135; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 138, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 141, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 142; or(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 143, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 145, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 147; andNAI-5010413635vl 302(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 150, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 151.

25. The antibody or antigen-binding fragment thereof of claim 3, 5, or 14K, wherein:(A)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 118, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 121, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 123; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 126, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 127;(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 129, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 133, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 135; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 138, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 141, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 142; or(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 143, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 145, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 147; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 150, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 151.

26. The antibody or antigen-binding fragment thereof of claim 3, 5, or 14L, wherein:(A)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 117, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 121, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 123; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 126, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 127;NAI-5010413635vl 303(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 128, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 213, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 135; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 138, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 141, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 142; or(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 143, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 145, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 147; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 150, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 151.

27. The antibody or antigen-binding fragment thereof of claim 3, 5, or 14M, wherein:(A)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 117, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 120, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 124; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 193, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 127;(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 128, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 131, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 136; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 139, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 141, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 142; or(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 143, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 144, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 148; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 206, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 151.NAI-5010413635vl 30428. The antibody or antigen-binding fragment thereof of claim 4 or 14N, wherein: (A)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 152, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 155, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 156; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 157, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 158, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 159;(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 160, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 161, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 162; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 163, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 164, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 165; or(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 166, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 169, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 170; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 171, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 158, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 172.

29. The antibody or antigen-binding fragment thereof of claim 4 or 140, wherein: (A)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 153, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 155, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 156; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 157, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 158, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 159;(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 160, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 161, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 162; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 163, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 164, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 165; orNAI-5010413635vl 305(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 167, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 169, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 170; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 171, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 158, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 172.

30. The antibody or antigen-binding fragment thereof of claim 5 or 14P, wherein: (A)(i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 173, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 174, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 175; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 176, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 178;(B) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 128, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 180, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 181; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 182, the VL CDR2 comprises the amino acid sequence of SEQ ID NO: 183, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 184; or(C) (i) the VH CDR1 comprises the amino acid sequence of SEQ ID NO: 185, the VH CDR2 comprises the amino acid sequence of SEQ ID NO: 186, and the VH CDR3 comprises the amino acid sequence of SEQ ID NO: 187; and(ii) the VL CDR1 comprises the amino acid sequence of SEQ ID NO: 188, the VL CDR2 comprises the amino acid sequence LGS, and the VL CDR3 comprises the amino acid sequence of SEQ ID NO: 189.

31. The antibody or antigen-binding fragment thereof of claim 14, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 1; and(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 6;NAI-5010413635vl 306(B) (i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 2; and(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 8;(C) (i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 3; and(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 7;(D)(i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 4; and(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 8;(E) (i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 5; and(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 8;(F) (i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 9; and(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 12;(G)(i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 10; and(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 13;(H)(i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 11; and(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 14;(I) (i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 15 and(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 20;(J) (i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 16; andNAI-5010413635vl 307(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 20;(K)(i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 17; and(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 21;(L) (i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 18; and(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 20;(M) (i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 19; and(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 22;(N)(i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 23; and(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 25;(O)(i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 24; and(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 25; or(P)(i) a variable heavy chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 26; and(ii) a variable light chain region that is at least 95% identical to the amino acid sequence of SEQ ID NO: 27.

32. The antibody or antigen-binding fragment thereof of claim 14, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 1; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 6;NAI-5010413635vl 308(B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 2; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8;(C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 3; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 7;(D)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 4; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8;(E) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 5; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8;(F) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 9; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 12;(G)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 10; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 13;(H)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 11; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 14;(I) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 15 and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20;(J) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 16; andNAI-5010413635vl 309(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 20;(K)(i) a variable heavy chain region comprising the amino acid sequence of SEQ IDNO: 17; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 21;(L) (i) a variable heavy chain region comprising the amino acid sequence of SEQ IDNO: 18; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 20;(M) (i) a variable heavy chain region comprising the amino acid sequence of SEQ IDNO: 19; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 22;(N)(i) a variable heavy chain region comprising the amino acid sequence of SEQ IDNO: 23; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 25;(O)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 24; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 25; or(P)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 26; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 27.

33. An antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a variable heavy chain region comprising the amino acid sequence of SEQ IDNO: 1; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 6;NAI-5010413635vl 310(B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 2; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8;(C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 3; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 7;(D)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 4; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8;(E) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 5; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8;(F) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 9; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 12;(G)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 10; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 13;(H)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 11; and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 14;(I) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 15 and(ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20;(J) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 16; andNAI-5010413635vl 311(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 20;(K)(i) a variable heavy chain region comprising the amino acid sequence of SEQ IDNO: 17; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 21;(L) (i) a variable heavy chain region comprising the amino acid sequence of SEQ IDNO: 18; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 20;(M) (i) a variable heavy chain region comprising the amino acid sequence of SEQ IDNO: 19; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 22;(N)(i) a variable heavy chain region comprising the amino acid sequence of SEQ IDNO: 23; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 25;(O)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 24; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 25; or(P)(i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 26; and(ii) a variable light chain region comprising the amino acid sequence of SEQ IDNO: 27.

34. The antibody or antigen-binding fragment thereof of claim 5, wherein the antibody or antigen-binding fragment thereof comprises:(A) (i) a variable heavy chain region that is at least 70% identical to the amino acid sequence of SEQ ID NO: 15; and(ii) a variable light chain region that is at least 70% identical to the amino acid sequence of SEQ ID NO: 20;NAI-5010413635vl 312(B) (i) a variable heavy chain region that is at least 70% identical to the amino acid sequence of SEQ ID NO: 16; and(ii) a variable light chain region that is at least 70% identical to the amino acid sequence of SEQ ID NO: 20;(C) (i) a variable heavy chain region that is at least 70% identical to the amino acid sequence of SEQ ID NO: 17; and(ii) a variable light chain region that is at least 70% identical to the amino acid sequence of SEQ ID NO: 21;(D)(i) a variable heavy chain region that is at least 70% identical to the amino acid sequence of SEQ ID NO: 18; and(ii) a variable light chain region that is at least 70% identical to the amino acid sequence of SEQ ID NO: 20;(E) (i) a variable heavy chain region that is at least 70% identical to the amino acid sequence of SEQ ID NO: 19; and(ii) a variable light chain region that is at least 70% identical to the amino acid sequence of SEQ ID NO: 22; or(F) (i) a variable heavy chain region that is at least 70% identical to the amino acid sequence of SEQ ID NO: 26; and (ii) a variable light chain region that is at least 70% identical to the amino acid sequence of SEQ ID NO: 27.

35. The antibody or antigen-binding fragment thereof of claim 30, wherein the antibody or antigen-binding fragment thereof comprises: (i) a variable heavy chain region that is at least 70% identical to the amino acid sequence of SEQ ID NO: 26; and (ii) a variable light chain region that is at least 70% identical to the amino acid sequence of SEQ ID NO: 27.

36. An antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof competes for binding with the antibody or antigen-binding fragment thereof of any one of claims 1 to 31, and wherein the antibody or antigen-binding fragment binds to: (a) three or more or all of amino acid residues 125B, 128, 129, 168, 169, 123, 124, 125, 168, 167, 169, 126, 129, 164, 129, 162, 163, 165, 167, 187, 189, 219, 227, 244, and 246 of SEQ ID NO: 179; (b) three or more, or all of amino acid residues 125B, 128, 129, 168, 169, 171, 123, 124, 168, 167, 126, 165, 166, 163, 166, 162, 163, 165, 167, 169, 187, 189, 219, 227, 242, 244, 246 and 323 ofNAI-5010413635vl 313SEQ ID NO: 179; (c) three or more, or all of amino acid residues 125B, 128, 171, 168, 169, 171, 166, 168, 167, 126, 129, 163, 165, 167, 169, 219, 222, 227, 242, 244, and 323 of SEQ ID NO: 179; or (d) three or more, or all of amino acid residues 98, 125A, 127, 128, 129, 130, 131, 132, 133, 133A, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 152, 153, 154, 155, 156, 157, 158, 159, 161, 183, 185, 186, 190, 191, 192, 193, 194, 195, 222, 224, 225, 226, 227, 228, 229, 230, 251, 252, and 253 of SEQ ID NO: 179.

37. The antibody or antigen-binding fragment thereof of any one claim of claims 1 to 36, wherein the antibody or antigen-binding fragment thereof is any one of a Fab, Fab’, F(ab’)2, Fv, scFv, (scFv)2, single chain antibody molecule, dual variable region antibody, single variable region antibody, linear antibody, V antibody, a monoclonal antibody, a bispecific antibody, or a multi-specific antibody.

38. An antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the antibody or antigen-binding fragment thereof comprises:(A)(i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 1; and(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 6;(B) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 2; and(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 8;(C) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 3; and(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 7;NAI-5010413635vl 314(D)(i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 4; and(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 8;(E) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 5; and(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 8;(F) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 9; and(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 12;(G)(i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 10; and(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 13;(H)(i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 11; and(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 14;(I) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 15 andNAI-5010413635vl 315(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 20;(J) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 16; and(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 20;(K)(i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 17; and(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 21;(L) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 18; and(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 20;(M) (i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 19; and(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 22;(N)(i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 23; and(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 25;NAI-5010413635vl 316(O)(i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 24; and(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 25; or(P)(i) a heavy chain comprising a variable heavy chain region, wherein the variable heavy chain region comprises the amino acid sequence of SEQ ID NO: 26; and(ii) a light chain comprising a variable light chain region, wherein the variable light chain region comprises the amino acid sequence of SEQ ID NO: 27.

39. The antibody or antigen-binding fragment thereof of any one of claims 1 to 38, wherein the antibody or antigen-binding fragment thereof is a chimeric antibody or a human antibody.

40. The antibody or antigen-binding fragment thereof of any one of claims 1 to 39, wherein the antibody comprises human-derived heavy and light chain constant regions.

41. The antibody or antigen-binding fragment thereof of claim 40, wherein the heavy chain constant region has an isotype selected from the group consisting of gammal, gamma2, gamma3, and gamma4.

42. The antibody or antigen-binding fragment thereof of claim 40 or 41, wherein the light chain constant region has an isotype selected from the group consisting of kappa and lambda.

43. The antibody or antigen-binding fragment thereof of any one of claims 1 to 42, wherein the antibody is an immunoglobulin comprising two identical heavy chains and two identical light chains.

44. The antibody or antigen-binding fragment thereof of any one of claims 1 to 43, wherein the antibody is an IgGl.NAI-5010413635vl 31745. The antibody or antigen-binding fragment thereof of any one of claims 1 to 44, wherein the antibody further comprises an IgGl heavy chain constant region and kappa light chain constant region.

46. The antibody or antigen-binding fragment thereof of any one of claims 1 to 45, which is recombinant.

47. The antibody or antigen-binding fragment thereof of any one of claims 1 to 46, wherein the antibody or antigen-binding fragment thereof is conjugated to a detectable agent, a diagnostic agent, or a therapeutic agent.

48. An isolated polynucleotide or set of polynucleotides encoding the antibody or antigen-binding fragment thereof of any one of claims 1 to 47.

49. An isolated polynucleotide or set of polynucleotides encoding an antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the polynucleotide or set of polynucleotides comprises:(A) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 28; and(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 33;(B) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 29; and(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 35;(C) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 30; andNAI-5010413635vl 318(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 34;(D)(i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 31; and(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 35;(E) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 32; and(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 35;(F) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 36; and(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 39;(G)(i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 37; and(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 40;(H)(i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 38; and(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 41;NAI-5010413635vl 319(I) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 42 and(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 47;(J) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 43; and(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 47;(K)(i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 44; and(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 48;(L) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 45; and(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 47;(M) (i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 46; and(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 49;(N)(i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 50; andNAI-5010413635vl 320(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 52;(O)(i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 51; and(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 52; or(P)(i) a nucleotide sequence encoding a variable heavy chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 53; and(ii) a nucleotide sequence encoding a variable light chain region, wherein the nucleotide sequence comprises the nucleic acid sequence of SEQ ID NO: 54.

50. The polynucleotide or set of polynucleotides of claim 48 or 49, wherein the polynucleotide or set of polynucleotides comprises deoxyribonucleic acids, ribonucleic acids, or a combination thereof.

51. A vector or set of vectors comprising the polynucleotide or set of polynucleotides of any one of claims 48 to 50.

52. An expression vector or set of expression vectors comprising the polynucleotide or set of polynucleotides of any one of claims 48 to 50.

53. The vector or set of vectors of claim 51 or 52, wherein the polynucleotide or set of polynucleotides is or are operably linked to one or more regulatory regions.

54. A host cell comprising the polynucleotide or set of polynucleotides of any one of claim 48 to 50, the vector of any one of claims 51 to 53.

55. A lipid nanoparticle comprising the polynucleotide or set of polynucleotides of any one of claims 48 to 50, or the vector or set of vectors of any one of claims 51 to 53.NAI-5010413635vl 32156. A composition comprising the polynucleotide or set of polynucleotides of any one of claims 48 to 50, or the vector or set of vectors of any one of claims 51 to 53, or the lipid nanoparticle of claim 55.

57. A composition comprising one or more of the antibodies or antigen-binding fragments thereof of any one of claims 1 to 47.

58. A pharmaceutical composition comprising one or more of the antibodies or antigen-binding fragments thereof of any one of claims 1 to 47, and one or more pharmaceutically acceptable carriers, excipients, or stabilizers.

59. A composition comprising:(A) a first antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the first antibody or antigenbinding fragment thereof comprises:(a) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 55, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 61; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 64, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 66;(b) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 67, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 71, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 75; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 211, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 79, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 80; or (c) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 81, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 82, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 83; andNAI-5010413635vl 322(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 86, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 87; and(B) a second antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the second antibody or antigenbinding fragment thereof comprises:(a) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 88, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 89, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 90; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 94, a VL CDR2 comprising the amino acid sequence LGX, wherein X is S or T, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 98; (b) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 99, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 100, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 101; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 104, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 108, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 109; or (c) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 110, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 111, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 112; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 115, a VL CDR2 comprising the amino acid sequence LGX, wherein X is S or T, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 116.

60. A composition comprising:(A) a first antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the first antibody or antigenbinding fragment thereof comprises:NAI-5010413635vl 323(a) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 55, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 61; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 64, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 66;(b) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 67, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 71, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 75; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 211, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 79, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 80; or (c) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 81, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 82, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 83; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 86, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 87; and(B) a second antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the second antibody or antigenbinding fragment thereof comprises:(a) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 119, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 122, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 125; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 194, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 127;(b) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 130, a VH CDR2 comprising the amino acid sequence of SEQ ID NO:NAI-5010413635vl 324134, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 137; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 140, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 141, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 142; or (c) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 143, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 146, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 149; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 207, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 151.

61. A composition comprising:(A) a first antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the first antibody or antigenbinding fragment thereof comprises:(a) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 55, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 61; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 64, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 66;(b) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 67, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 71, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 75; and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 211, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 79, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 80; or (c) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 81, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 82,NAI-5010413635vl 325and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 83;and(ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 86, a VL CDR2 comprising the amino acid sequence GAF, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 87; and(B) a second antibody or a fragment thereof that binds to hemagglutinin H5 of influenza A virus of clade 2.3.4.4b, wherein the second antibody or antigenbinding fragment thereof comprises:(a) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 173, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 174, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 175; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 176, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 178;(b) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 128, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 180, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 181; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 182, a VL CDR2 comprising the amino acid sequence of SEQ ID NO: 183, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 184; or(c) (i) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 185, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 186, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 187; and (ii) a VL CDR1 comprising the amino acid sequence of SEQ ID NO: 188, a VL CDR2 comprising the amino acid sequence LGS, and a VL CDR3 comprising the amino acid sequence of SEQ ID NO: 189.

62. The composition of claim 59, wherein the second antibody or antigen-binding fragment thereof comprises:(A) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 9; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 12;NAI-5010413635vl 326(B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 10; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 13; or(C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 11; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 14.

63. The composition of claim 60, wherein the second antibody or antigen-binding fragment thereof comprises:(A) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 15; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20;(B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 16; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20;(C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 17; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 21;(D) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 18; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 20; or(E) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 19; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 22.

64. The composition of claim 61, wherein the second antibody or antigen-binding fragment thereof comprises: (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 26; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 2765. The composition of any one of claims 59 to 64, wherein the first antibody or antigen-binding fragment thereof comprises:NAI-5010413635vl 327(A) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 1; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 6;(B) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 2; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8;(C) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 3; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 7;(D) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 4; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8; or(E) (i) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO: 5; and (ii) a variable light chain region comprising the amino acid sequence of SEQ ID NO: 8.

66. The composition of any one of claims 59 to 65, further comprises one or more pharmaceutically acceptable carriers, excipients, or stabilizers.

67. The composition of any one of claims 56 to 66, wherein the composition further comprises one or more of any one or more of: (a) an antibody or a fragment thereof that binds to the stalk of influenza A virus hemagglutinin; (b) an antibody or a fragment thereof that binds to influenza A virus neuraminidase; (c) a neuraminidase inhibitor; or (d) a cap snatching inhibitor.

68. A method for expressing the antibody or antigen-binding fragment thereof of any one of claims 1 to 47, comprising:A. culturing the host cell of claim 54; andB. isolating the antibody or antigen-binding fragment thereof from the host cell or cell culture.

69. A method for detecting an influenza A virus of clade 2.3.4.4b, comprising:A. contacting cells or a biological sample with the antibody or antigenbinding fragment thereof of any one of claims 1 to 47; andNAI-5010413635vl 328B. detecting the binding of the antibody or fragment thereof to hemagglutinin H5 of an influenza A virus of clade 2.3.4.4b, wherein the influenza A virus is detected if the level of binding of the antibody or antigen-binding fragment thereof to the influenza A virus hemagglutinin is greater than the level of binding of the antibody or antigen-binding fragment thereof to non-influenza virus infected cells or a biological sample not infected with an influenza virus.

70. A binding agent that binds to essentially the same epitope as the antibody or antigen-binding fragment thereof of any one of claims 1 to 47.

71. The binding agent of claim 70, which is an antibody or an antigen-binding fragment thereof.

72. A method for neutralizing H5 influenza A virus of clade 2.3.4.4b, comprising contacting cells with the antibody or antigen-binding fragment of any one of claims 1 to 47, or the composition of any one of claims 56 to 67, wherein the cells are infected with influenza A virus clade 2.3.4.4b.

73. The method of claim 72, wherein the contacting of cells with the antibody or antigen-binding fragment thereof in vitro, ex vivo, or in vivo.

74. A method for preventing influenza virus disease caused by infection with H5 influenza A virus of clade 2.3.4.4b in a subject, the method comprising administering to the subject the antibody or antigen-binding fragment thereof of any one of claims 1 to 3, 5 to 8, 10 to 12, 14 to 27, 30 to 35, or 38 to 47, or the composition of any one of claims 56 to 67.

75. A method for treating influenza virus disease caused by infection with H5 influenza A virus of clade 2.3.4.4b in a subject, the method comprising administering to the subject the antibody or antigen-binding fragment thereof of any one of claims 1 to 3, 5 to 8, 10 to 12, 14 to 27, 3o to 35, or 38 to 47, or the composition of any one of claims 56 to 67.

76. The method of claim 74 or 75, wherein the method further comprises administering to the subject one or more of any one or more of: (a) an antibody or a fragment thereof that binds to the stalk of influenza A virus hemagglutinin; (b) an antibody or aNAI-5010413635vl 329fragment thereof that binds to influenza A virus neuraminidase; (c) a neuraminidase inhibitor; or (d) a cap-snatcher inhibitor.

77. The method of any one of claims 74 to 76, wherein the subject is a human or a non-human animal.

78. The method of claim 77, wherein the non-human animal is a bird, dog, cat, cow, horse, or goat.

79. A kit comprising the antibody or antigen-binding fragment thereof of any one of claims 1 to 47, and optionally instructions for use of the antibody or antigen-binding fragment thereof in the prevention or treatment of an influenza A virus of clade 2.3.4.4b infection or an influenza A virus of clade 2.3.4.4b disease, or in the detection of an influenza A virus of clade 2.3.4.4b.

80. A kit comprising the polynucleotide of any one of claims 48 to 50, or the vector or set of vectors of any one of claims 51 to 53, and optionally instructions for use of the polynucleotide or expression vector in the prevention or treatment of an H5 influenza A virus of clade 2.3.4.4b infection or disease, or in the detection of an H5 influenza A virus of clade 2.3.4.4b.

81. A kit comprising the composition of any one of claims 56 to 67, and optionally instructions for use of the pharmaceutical composition in the prevention or treatment of an H5 influenza A virus of clade 2.3.4.4b infection or disease, or in the detection of an H5 influenza A virus of clade 2.3.4.4b.

82. An antibody means for binding to hemagglutinin H5 of an influenza A virus clade 2.3.4.4b.

83. A method for preventing or treating influenza virus disease caused by infection with H5 influenza A virus of clade 2.3.4.4b, comprising administering an antibody means for binding to hemagglutinin H5 of influenza A virus clade 2.3.4.4b.

84. The method of any one of claims 74 to 78 or 83, wherein the H5 influenza A virus of clade 2.3.4.4b is influenza virus A / mallard / New York / 22-008760-007-original / 2022 NAI-5010413635vl 330(H5), A / chicken / New York / NYCVH 168127 / 2023 (H5N1), A / Canada goose / New York / NYCVH 23-453 / 2023 (H5N1), A / Canada goose / New York / NYCVH 22-9190 / 2022 (H5N1), A / peregrine falcon / New York / NYCVH 160820 / 2022 (H5N1), A / red-tailed hawk / New York / NYCVH 22-8477 / 2022 (H5N1), A / bald eagle / FL / W22-134-OP / 2022 (H5N1), A / chicken / Netherlands / 14015531 / 2014 (H5N8), A / northern pintail / WA / 40964 / 2014 (H5N1), A / dairy cattle / Texas / 24-008749-001-original / 2024 or A / Jiangsu / NJ210 / 2023 (H5N1).NAI-5010413635vl 331

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