Conjugate, preparation method therefor, and use thereof

Abstract

The present invention relates to a conjugate for inhibiting viral replication, a preparation method therefor, and use thereof. The conjugate comprises a dimer or trimer of a portion that inhibits influenza virus neuraminidase (e.g. zanamivir, peramivir, oseltamivir, or an analog thereof), the dimer or trimer being conjugated to an Fc domain monomer, an Fc domain, an Fc-binding peptide, an albumin, or an albumin-binding peptide. The conjugate can be used to treat viral infections (e.g., influenza virus infections).

Description

Conjugate and its preparation method and use

[0001] Cross-references

[0002] This application is based on the application with CN application number 202410111150.3 and application date January 26, 2024, and claims its priority. The disclosed content of the CN application is hereby introduced as a whole into this application. Technical Field

[0003] The present application relates to a conjugate for inhibiting viral replication, a preparation method thereof, and uses thereof. Background Art

[0004] In the medical field, new and highly effective anti-influenza virus therapeutic drugs and strategies are being sought. Influenza viruses (the pathogens of influenza) cause three to five million cases of serious illness each year and approximately 500,000 deaths worldwide. Although most people can fully recover on their own within one to two weeks, some people develop life-threatening complications such as pneumonia. Therefore, influenza can be fatal to some susceptible populations, especially children, the elderly or patients with chronic diseases, people with weak or incomplete immune systems. For example, patients with advanced HIV or organ transplant patients (whose immune systems are medically suppressed to prevent transplant organ rejection) are at greater risk of complications related to influenza. Pregnant women and young children are also at high risk of complications.

[0005] The development of antiviral drugs for influenza virus treatment remains an ongoing challenge. Several influenza antiviral agents have been approved for clinical use. However, with long-term use, resistance to the most commonly used influenza inhibitors has emerged.

[0006] Anti-influenza virus drugs mainly target proteins on the surface of influenza virus particles. The envelope of the influenza virus contains two key glycoproteins, hemagglutinin (HA) and neuraminidase (NA), which play a key role in viral infection and spread. Neuraminidase is an exoglycosidase that cleaves sialic acid from glycan structures on the surface of infected host cells, thereby releasing progeny viruses and spreading to uninfected surrounding cells. Therefore, neuraminidase becomes the pharmacological target of antiviral drugs. A variety of small molecule drugs have been listed as neuraminidase inhibitors for reducing viral spread, including oseltamivir (Tamiflu TM ), zanamivir (Relenza TM ) and peramivir (Rapivab TM ).

[0007] Targeted delivery of conjugated drugs is an emerging treatment method. Its basic principle is to connect drugs to targeting molecules so that the drugs can selectively bind to disease-related cells or tissues. In cancer treatment, targeted delivery of conjugated drugs has achieved some encouraging results. For example, some antibody drugs have been successfully used to treat diseases such as breast cancer, colon cancer, and lymphoma. At present, macromolecule conjugation technology has also been used to develop new antiviral drugs. For example, Chidara Therapeutics of the United States has developed a human IgG Fc protein-coupled dimer NA inhibitor (CN 113194983 A, WO 2021 / 046549A1), which has initially demonstrated therapeutic potential in anti-influenza.

[0008] However, since influenza viruses have strong antigenic drift and antigenic shift, new subtypes are constantly generated, which increases the possibility of developing drug-resistant strains. Therefore, new and more effective therapies need to be developed for the treatment of influenza. Summary of the Invention

[0009] The present application relates to a conjugate for inhibiting viral replication, its preparation method, and use. In particular, this conjugate couples an influenza virus neuraminidase inhibitor (e.g., zanamivir, peramivir, oseltamivir, or their analogs) to a biomacromolecule such as an antibody, antibody fragment, or albumin. The neuraminidase inhibitor in the conjugate targets the neuraminidase on the surface of viral particles. The antibody Fc end or Fc protein in the conjugate binds to FcγRs (e.g., FcRn, FcγRI, FcγrIa, FcγRIIc, FcγRIIIa, and FcγRIIIb) on immune cells (e.g., neutrophils), activating the phagocytic function of immune cells, such as antibody-dependent cell-mediated cytotoxicity (ADCC), thereby causing immune cells to engulf and destroy viral particles, further enhancing the antiviral activity of the conjugate. Albumin can extend the half-life of the conjugate. For example, albumin binding to FcRn delays metabolic loss of the conjugate.

[0010] Specifically, the conjugate contains a dimer or trimer of a portion (e.g., zanamivir, peramivir, oseltamivir, or its analogue) that inhibits influenza virus neuraminidase, which is coupled to an Fc domain monomer, an Fc domain, an Fc binding peptide, albumin, or an albumin binding peptide. The neuraminidase inhibitor in the conjugate targets the neuraminidase on the surface of the virion. The Fc monomer or Fc domain in the conjugate binds to FcγR (e.g., FcRn, FcγRI, FcγRIIa, FcγRIIc, FcγRIIIa, and FcγRIIIb) on immune cells (e.g., neutrophils) to activate phagocytosis and effector functions, such as antibody-dependent cell-mediated cytotoxicity (ADCC), thereby engulfing and destroying virions by immune cells and further enhancing the antiviral activity of the conjugate. The albumin or albumin binding peptide can extend the half-life of the conjugate by binding to recycled neonatal Fc receptors (FcRn). The conjugates are useful for inhibiting viral growth and for treating viral infections such as those caused by influenza A, influenza B, and influenza C viruses.

[0011] In one aspect, the present application provides a conjugate represented by formula (I) or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof,

[0012] wherein A1, A2 and A3 are each independently selected from formula (AI) to formula (A-XIV),

[0013] wherein L can be attached to any possible position of the compound of formula (A-XIV);

[0014] wherein R1 is selected from -OH, -NH2, -NHC(=NH)NH2 and -NHC(=NH)NHR6;

[0015] R2 and R3 are each independently selected from -H, -OH, -F, -Cl and -Br;

[0016] R4 is selected from -C(=O)OH, -P(=O)(OH)2, -SO3H, -C(=O)OCH3 and -C(=O)OCF3;

[0017] R5 is selected from -C(=O)CH3, -C(=O)CF3, -SO2CH3;

[0018] X is selected from -O- and -S-;

[0019] Y is selected from -O-, -S-, -NR7-, -OC(=O)NR7-, -OC(=S)NR7-, -OC(=O)O-, -OC(=O)-, -NHC(=O)O-, -NHC(=O)-, -NHC(=NH)-, -NHC(=O)NR7-, -NHC(=NH)NR7-, -NHC(=S)NR7-, -NHC(=S)-, -OCH2C(=O)NR7-, -NH(SO2)- and -NH(SO2)NR7-;

[0020] R' is H or C1-C6 alkyl;

[0021] R6 is selected from

[0022] R7 is selected from H, C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C3-C 20 Heterocycloalkyl; C5-C 15 Aryl and C5-C 15 Heteroaryl; preferably, R7 is H; preferably, C1-C6 alkyl;

[0023] Each E is a biological macromolecule; n is 1 or 2; T is a number between 1 and 20;

[0024] The wavy line connected to each E represents each covalently linked (e.g., by means of a covalent bond or a linker) to each N atom in E (e.g., an N atom on the side chain amino group of a lysine, arginine, asparagine, or glutamine residue), and L is a linker covalently linked to each of E, A1, A2, and A3.

[0025] In some embodiments, in the conjugate represented by formula (I), A1, A2, and A3 are each independently selected from formula (AI) to formula (A-XIII),

[0026] wherein R1, R2, R3, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0027] In some embodiments, in the conjugate represented by formula (I), A1, A2, and A3 are each independently selected from formula (AI) to formula (A-IV) and formula (A-VII),

[0028] wherein R1, R2, R3, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0029] In some embodiments, each E in the conjugate of formula (I) comprises an Fc domain monomer (e.g., an Fc domain monomer having the sequence of any one of SEQ ID NOs: 1-68), an albumin (e.g., an albumin having the sequence of any one of SEQ ID NOs: 69-71), an albumin-binding peptide, or an Fc-binding peptide; and n is 1 or 2, wherein when n is 2 and E is an Fc domain monomer, two E dimerize to form an Fc domain.

[0030] In some embodiments, in the conjugate represented by formula (I), A1, A2 and A3 are each independently selected from formula (AI) to formula (A-III) and formula (A-VII),

[0031] wherein R1, R2, R3, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0032] In some embodiments, in the conjugate represented by formula (I), A1, A2 and A3 are each independently selected from formula (AI), formula (A-III) and formula (A-VII),

[0033] wherein R1, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0034] In some embodiments, in the conjugate of formula (I), E comprises an Fc domain monomer (e.g., an Fc domain monomer having the sequence of any one of SEQ ID NOs: 1-68); n is 1 or 2, wherein when n is 2, two E dimerize to form an Fc domain.

[0035] In some embodiments, in the conjugate represented by formula (I), E is an Fc domain monomer, and the Fc domain monomer has an amino acid sequence selected from the group consisting of:

[0036] i) any one of the sequences shown in SEQ ID NO: 1-68;

[0037] ii) a sequence having one or more amino acid substitutions, deletions or additions (e.g., 1, 2, 3, 4 or 5 amino acid substitutions, deletions or additions) compared to any one of the sequences shown in SEQ ID NOs: 1-68; and

[0038] iii) a sequence that is at least 70% identical (e.g., 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identical) to any one of the sequences shown in SEQ ID NOs: 1-68.

[0039] In some embodiments, the substitutions described in ii) are conservative substitutions.

[0040] In some embodiments, in the conjugate of formula (I), E is an Fc domain monomer having a sequence that is at least 70% identical (e.g., 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identical) to SEQ ID NO: 64.

[0041] In some embodiments, in the conjugate represented by formula (I), E is an Fc domain monomer having the sequence of SEQ ID NO: 64.

[0042] In some embodiments, in the conjugate represented by formula (I), E is an Fc domain monomer having a sequence of SEQ ID NO: 64, n is 2, and two E's dimerize to form an Fc domain.

[0043] In some embodiments, R1 in the conjugate of formula (I) is selected from -OH, -NH2, -NHC(=NH)NH2. In some embodiments, R1 in the conjugate of formula (I) is -NHC(=NH)NH2.

[0044] In some embodiments, R4 in the conjugate of formula (I) is selected from -C(=O)OH, -C(=O)OCH3 and -C(=O)OCF3. In some embodiments, R4 in the conjugate of formula (I) is selected from -C(=O)OH and -C(=O)OCH3.

[0045] In some embodiments, in the conjugate of formula (I), R5 is selected from -C(=O)CH3 and -C(=O)CF3. In some embodiments, in the conjugate of formula (I), R5 is -C(=O)CH3.

[0046] In some embodiments, R' in the conjugate of formula (I) is H or C1-C4 alkyl. In some embodiments, R' in the conjugate of formula (I) is H, methyl or ethyl. In some embodiments, R' in the conjugate of formula (I) is H or ethyl.

[0047] In some embodiments, in the conjugate represented by formula (I), X is -O-.

[0048] In some embodiments, Y in the conjugate of formula (I) is selected from -O-, -S-, and -NH-. In some embodiments, Y in the conjugate of formula (I) is selected from -O- and -NH-.

[0049] In some embodiments, the conjugate of formula (I) has the structure of formula (I-II-A), formula (I-II-B) or formula (I-II-C),

[0050] wherein R1, R4, R5, R', X, Y, E, n, L, and T are as defined in any embodiment of the present application.

[0051] In some embodiments, the conjugate of formula (I) has a structure of formula (I-II-A'), formula (I-II-B') or formula (I-II-C'),

[0052] wherein R1, R4, R5, R', X, Y, E, n, and T are as defined in any embodiment of the present application,

[0053] L1 is selected from:

[0054] wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)- or -CH2-; Z1 and Z2 are each independently selected from -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)- or -CH2-; m and p are each independently an integer from 1 to 20.

[0055] In some embodiments, in the conjugate represented by formula (I), L1 is selected from:

[0056] wherein V, p, m, and Z are defined as described in any embodiment of the present application.

[0057] In some embodiments, in the conjugate represented by formula (I), L1 is wherein V, p, m, and Z are defined as described in any embodiment of the present application.

[0058] In some embodiments, in the conjugate of formula (I), V is -CH2- or -O-. In some embodiments, in the conjugate of formula (I), V is -O-.

[0059] In some embodiments, in the conjugate represented by formula (I), Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, or -C(=O)-. In some embodiments, in the conjugate represented by formula (I), Z is -NH-C(=O)- or -C(=O)-.

[0060] In some embodiments, in the conjugate of formula (I), p is an integer between 1 and 10. In some embodiments, in the conjugate of formula (I), p is an integer between 1 and 6 (e.g., 1, 2, 3, 4, 5, 6).

[0061] In some embodiments, in the conjugate of formula (I), m is an integer between 1 and 12. In some embodiments, in the conjugate of formula (I), m is an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9).

[0062] In some embodiments, the conjugate of formula (I) has the structure of formula (I-II-A'-1), formula (I-II-B'-1), formula (I-II-B'-2), or formula (I-II-C'-1);

[0063] wherein E, n, T, and L1 are defined as described in any embodiment of the present application.

[0064] In some embodiments, the conjugate of formula (I) has a structure represented by formula (I-II-A-2), formula (I-II-B-3), formula (I-II-B-4), or formula (I-II-C-2).

[0065] Wherein, E, n, T, and L1 are as defined in any embodiment of the present application;

[0066] L2 is selected from:

[0067] wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)- or -CH2-; Z1 and Z2 are independently selected from -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)- or -CH2-; m and p are each independently an integer from 1 to 20;

[0068] L3 is Wherein U is -C(=O)-NH-, -NH-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)-, -CH2-; W is -CH2-, -O- or -S-; i and q are each independently an integer of 1-20, one end of L3 is covalently connected to E, and the other end is covalently connected to L2.

[0069] In some embodiments, in the conjugate represented by formula (I), L3 is covalently linked to E through an N atom, wherein the N atom is an N atom from E (e.g., an N atom on the side chain amino group of a lysine, arginine, asparagine, or glutamine residue).

[0070] In some embodiments, in the conjugate represented by formula (I), L2 is selected from:

[0071] wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)- or -CH2-; m and p are each independently an integer from 1 to 20.

[0072] In some embodiments, in the conjugate represented by formula (I), L1 is Wherein V, p, m, and Z are defined as described in any embodiment of the present application. In some embodiments, V is -CH2- or -O-. In some embodiments, V is -O-. In some embodiments, Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)- or -C(=O)-. In some embodiments, Z is -NH-C(=O)- or -C(=O)-. In some embodiments, p is an integer between 1 and 10. In some embodiments, p is an integer between 1 and 6 (e.g., 1, 2, 3, 4, 5, 6). In some embodiments, m is an integer between 1 and 12. In some embodiments, m is an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9).

[0073] In some embodiments, in the conjugate represented by formula (I), L2 is Wherein V, p, m, and Z are defined as described in any embodiment of the present application. In some embodiments, V is -CH2- or -O-. In some embodiments, V is -O-. In some embodiments, Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-. In some embodiments, Z is -C(=O)-NH-. In some embodiments, p is an integer between 1 and 10. In some embodiments, p is an integer between 1 and 6 (e.g., 1, 2, 3, 4, 5, 6). In some embodiments, m is an integer between 1 and 12. In some embodiments, m is an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9).

[0074] In some embodiments, in the conjugate represented by formula (I), L3 is Wherein U, i, q are defined as described in any embodiment of the present application. In some embodiments, U is -NH-C(=O)-, -N(CH3)-C(=O)- or -N(CH2CH3)-C(=O)-. In some embodiments, U is -NH-C(=O)-. In some embodiments, the N atom in U is a N atom from E (e.g., a N atom on the side chain amino group of a lysine, arginine, asparagine, or glutamine residue). In some embodiments, i is an integer between 1-12. In some embodiments, i is an integer between 1-10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9). In some embodiments, q is an integer between 1-10. In some embodiments, q is an integer between 1-6 (e.g., 1, 2, 3, 4, 5, 6).

[0075] In some embodiments, in the conjugate of formula (I), T is a number between 1 and 10. In some embodiments, in the conjugate of formula (I), T is a number between 1 and 9. In some embodiments, in the conjugate of formula (I), T is a number between 1 and 7. In some embodiments, in the conjugate of formula (I), T is a number between 1 and 5. In some embodiments, in the conjugate of formula (I), T is a number between 3 and 7. In some embodiments, in the conjugate of formula (I), T is a number between 3 and 5.5.

[0076] In some embodiments, the conjugate of formula (I) has a structure represented by formula (I-II-A-3), formula (I-II-B-5), formula (I-II-B-6), or formula (I-II-C-3).

[0077] wherein E, n, and T are as defined in any embodiment of the present application; n1, n2, and n3 are each independently an integer between 1 and 20. In some embodiments, n1, n2, and n3 are each independently an integer between 1 and 12. In some embodiments, n1, n2, and n3 are each independently an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9).

[0078] In some embodiments, the conjugate represented by formula (I) is selected from:

[0079] wherein E, n, and T are defined as described in any embodiment of the present application.

[0080] On the other hand, the present application also provides a conjugate represented by formula (II) or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof,

[0081] wherein A1 and A2 are each independently selected from formula (AI) to formula (A-XIV),

[0082] wherein L can be attached to any possible position of the compound of formula (A-XIV);

[0083] wherein R1 is selected from -OH, -NH2, -NHC(=NH)NH2 and -NHC(=NH)NHR6;

[0084] R2 and R3 are each independently selected from -H, -OH, -F, -Cl and -Br;

[0085] R4 is selected from -C(=O)OH, -P(=O)(OH)2, -SO3H, -C(=O)OCH3 and -C(=O)OCF3;

[0086] R5 is selected from -C(=O)CH3, -C(=O)CF3, -SO2CH3;

[0087] X is selected from -O- and -S-;

[0088] Y is selected from -O-, -S-, -NR7-, -OC(=O)NR7-, -OC(=S)NR7-, -OC(=O)O-, -OC(=O)-, -NHC(=O)O-, -NHC(=O)-, -NHC(=NH)-, -NHC(=O)NR7-, -NHC(=NH)NR7-, -NHC(=S)NR7-, -NHC(=S)-, -OCH2C(=O)NR7-, -NH(SO2)- and -NH(SO2)NR7-;

[0089] R' is H or C1-C6 alkyl;

[0090] R6 is selected from

[0091] R7 is selected from H, C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C3-C 20 Heterocycloalkyl; C5-C 15 Aryl and C5-C 15 Heteroaryl; preferably, R7 is H; preferably, C1-C6 alkyl;

[0092] Each E is a biological macromolecule; n is 1 or 2; T is a number between 1 and 20;

[0093] The wavy line connected to each E indicates that each A1-L-A2 is covalently linked (e.g., by means of a covalent bond or a linker) to an N atom in each E (e.g., an N atom on the side chain amino group of a lysine, arginine, asparagine, or glutamine residue), and L is a linker covalently linked to each group in E, A1, and A2.

[0094] In some embodiments, in the conjugate represented by formula (II), A1 and A2 are each independently selected from formula (AI) to formula (A-XIII),

[0095] wherein R1, R2, R3, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0096] In some embodiments, in the conjugate represented by formula (II), A1 and A2 are each independently selected from formula (AI) to formula (A-IV) and formula (A-VII),

[0097] wherein R1, R2, R3, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0098] In some embodiments, each E in the conjugate of formula (II) comprises an Fc domain monomer (e.g., an Fc domain monomer having the sequence of any one of SEQ ID NOs: 1-68), an albumin (e.g., an albumin having the sequence of any one of SEQ ID NOs: 69-71), an albumin-binding peptide, or an Fc-binding peptide; and n is 1 or 2, wherein when n is 2 and E is an Fc domain monomer, two E dimerize to form an Fc domain.

[0099] In some embodiments, in the conjugate represented by formula (II), A1 and A2 are each independently selected from formula (AI) to formula (A-III) and formula (A-VII),

[0100] wherein R1, R2, R3, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0101] In some embodiments, in the conjugate represented by formula (II), A1 and A2 are each independently selected from formula (AI), formula (A-III) and formula (A-VII),

[0102] wherein R1, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0103] In some embodiments, in the conjugate of formula (II), E comprises an Fc domain monomer (e.g., an Fc domain monomer having a sequence of any one of SEQ ID NOs: 1-68); n is 1 or 2, wherein when n is 2, two E dimerize to form an Fc domain.

[0104] In some embodiments, in the conjugate represented by formula (II), E is an Fc domain monomer, and the Fc domain monomer has an amino acid sequence selected from the group consisting of:

[0105] i) any one of the sequences shown in SEQ ID NO: 1-68;

[0106] ii) a sequence having one or more amino acid substitutions, deletions or additions (e.g., 1, 2, 3, 4 or 5 amino acid substitutions, deletions or additions) compared to any one of the sequences shown in SEQ ID NOs: 1-68; and

[0107] iii) a sequence that is at least 70% identical (e.g., 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identical) to any one of the sequences shown in SEQ ID NOs: 1-68.

[0108] In some embodiments, the substitutions described in ii) are conservative substitutions.

[0109] In some embodiments, in the conjugate of formula (II), E is an Fc domain monomer having a sequence that is at least 70% identical (e.g., 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identical) to SEQ ID NO: 64.

[0110] In some embodiments, in the conjugate represented by formula (II), E is an Fc domain monomer having the sequence of SEQ ID NO: 64.

[0111] In some embodiments, in the conjugate represented by formula (II), E is an Fc domain monomer having a sequence of SEQ ID NO: 64, n is 2, and two E's dimerize to form an Fc domain.

[0112] In some embodiments, R1 in the conjugate of formula (II) is selected from -OH, -NH2, and -NHC(=NH)NH2. In some embodiments, R1 in the conjugate of formula (II) is -NHC(=NH)NH2.

[0113] In some embodiments, R4 in the conjugate of formula (II) is selected from -C(=O)OH, -C(=O)OCH3 and -C(=O)OCF3. In some embodiments, R4 in the conjugate of formula (II) is selected from -C(=O)OH and -C(=O)OCH3.

[0114] In some embodiments, R5 in the conjugate of formula (II) is selected from -C(=O)CH3 and -C(=O)CF3. In some embodiments, R5 in the conjugate of formula (II) is -C(=O)CH3.

[0115] In some embodiments, R' in the conjugate of formula (II) is H or C1-C4 alkyl. In some embodiments, R' in the conjugate of formula (II) is H, methyl or ethyl. In some embodiments, R' in the conjugate of formula (II) is H or ethyl.

[0116] In some embodiments, in the conjugate represented by formula (II), X is -O-.

[0117] In some embodiments, Y in the conjugate of formula (II) is selected from -O-, -S-, and -NH-. In some embodiments, Y in the conjugate of formula (II) is selected from -O- and -NH-.

[0118] In some embodiments, the conjugate of formula (II) has the structure of formula (II-II-A), formula (II-II-B) or formula (II-II-C),

[0119] wherein R1, R4, R5, R', X, Y, E, n, L, and T are as defined in any embodiment of the present application.

[0120] In some embodiments, the conjugate represented by formula (II) has a structure represented by formula (II-II-A'), formula (II-II-B') or formula (II-II-C'),

[0121] wherein R1, R4, R5, R', X, Y, E, n, and T are as defined in any embodiment of the present application;

[0122] L1 is selected from:

[0123] wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)- or -CH2-; Z1 and Z2 are each independently selected from -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)- or -CH2-; m and p are each independently an integer from 1 to 20.

[0124] In some embodiments, in the conjugate represented by formula (II), L1 is selected from:

[0125] wherein V, p, m, and Z are defined as described in any embodiment of the present application.

[0126] In some embodiments, in the conjugate represented by formula (II), L1 is wherein V, p, m, and Z are defined as described in any embodiment of the present application.

[0127] In some embodiments, in the conjugate of formula (II), V is -CH2- or -O-. In some embodiments, in the conjugate of formula (II), V is -O-.

[0128] In some embodiments, in the conjugate of formula (II), Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, or -C(=O)-. In some embodiments, in the conjugate of formula (II), Z is -NH-C(=O)- or -C(=O)-.

[0129] In some embodiments, in the conjugate of formula (II), p is an integer between 1 and 10. In some embodiments, in the conjugate of formula (II), p is an integer between 1 and 6 (e.g., 1, 2, 3, 4, 5, 6).

[0130] In some embodiments, in the conjugate of formula (II), m is an integer between 1 and 12. In some embodiments, in the conjugate of formula (II), m is an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9).

[0131] In some embodiments, the conjugate of formula (II) has a structure represented by formula (II-II-A-1), formula (II-II-B-1), formula (II-II-B-2), or formula (II-II-C-1).

[0132] wherein E, n, T, and L1 are defined as described in any embodiment of the present application.

[0133] In some embodiments, the conjugate of formula (II) has a structure represented by formula (II-II-A-2), formula (II-II-B-3), formula (II-II-B-4) or formula (II-II-C-2),

[0134] Wherein, E, n, T, and L1 are as defined in any embodiment of the present application;

[0135] L2 is selected from:

[0136] wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)- or -CH2-; Z1 and Z2 are independently selected from -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)- or -CH2-; m and p are each independently an integer from 1 to 20;

[0137] L3 is Wherein U is -C(=O)-NH-, -NH-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)-, -CH2-; W is -CH2-, -O- or -S-; i and q are each independently an integer of 1-20, one end of L3 is covalently connected to E, and the other end is covalently connected to L2.

[0138] In some embodiments, L3 in the conjugate represented by formula (II) is covalently linked to E through an N atom, wherein the N atom is an N atom from E (e.g., an N atom on the side chain amino group of a lysine, arginine, asparagine, or glutamine residue).

[0139] In some embodiments, in the conjugate represented by formula (II), L2 is selected from:

[0140] wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)- or -CH2-; m and p are each independently an integer from 1 to 20.

[0141] In some embodiments, in the conjugate represented by formula (II), L1 is wherein V, p, m, and Z are defined as described in any embodiment of the present application. In some embodiments, V is -CH2- or -O-. In some embodiments, V is -O-. In some embodiments, Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, or -C(=O)-. In some embodiments, Z is -NH-C(=O)- or -C(=O)-. In some embodiments, p is an integer between 1 and 10. In some embodiments, p is an integer between 1 and 6 (e.g., 1, 2, 3, 4, 5, 6). In some embodiments, m is an integer between 1 and 12. In some embodiments, m is an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9);

[0142] In some embodiments, in the conjugate represented by formula (II), L2 is Wherein V, p, m, and Z are defined as described in any embodiment of the present application. In some embodiments, V is -CH2- or -O. In some embodiments, V is -O-. In some embodiments, Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, or -N(CH2CH3)-C(=O)-. In some embodiments, Z is -C(=O)-NH-. In some embodiments, p is an integer between 1 and 10. In some embodiments, p is an integer between 1 and 6 (e.g., 1, 2, 3, 4, 5, 6). In some embodiments, m is an integer between 1 and 12. In some embodiments, m is an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9).

[0143] In some embodiments, in the conjugate represented by formula (II), L3 is Wherein U, i, q are defined as described in any embodiment of the present application. In some embodiments, U is -NH-C(=O)-, -N(CH3)-C(=O)- or -N(CH2CH3)-C(=O)-. In some embodiments, U is -NH-C(=O)-. In some embodiments, the N atom in U is a N atom from E (e.g., a N atom on the side chain amino group of a lysine, arginine, asparagine, or glutamine residue). In some embodiments, i is an integer between 1-12. In some embodiments, i is an integer between 1-10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9). In some embodiments, q is an integer between 1-10. In some embodiments, q is an integer between 1-6 (e.g., 1, 2, 3, 4, 5, 6).

[0144] In some embodiments, T in the conjugate of formula (II) is a number between 1 and 10. In some embodiments, T in the conjugate of formula (II) is a number between 1 and 9. In some embodiments, T in the conjugate of formula (II) is a number between 1 and 7. In some embodiments, T in the conjugate of formula (II) is a number between 1 and 5. In some embodiments, T in the conjugate of formula (II) is a number between 3 and 7. In some embodiments, T in the conjugate of formula (II) is a number between 3 and 5.5.

[0145] In some embodiments, the conjugate of formula (II) has a structure represented by formula (II-II-A-3), formula (II-II-B-5), formula (II-II-B-6) or formula (II-II-C-3),

[0146] wherein E, n, and T are as defined in any embodiment of the present application; n1, n2, and n3 are each independently an integer between 1 and 20. In some embodiments, n1, n2, and n3 are each independently an integer between 1 and 12. In some embodiments, n1, n2, and n3 are each independently an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9).

[0147] In some embodiments, the conjugate represented by formula (II) is selected from:

[0148] wherein E, n, and T are defined as described in any embodiment of the present application.

[0149] On the other hand, the present application also provides a compound represented by formula (IV) or its salt, geometric or optical isomer, hydrate, solvate or polymorph,

[0150] wherein A1, A2 and A3 are each independently selected from formula (AI) to formula (A-XIV),

[0151] wherein L can be attached to any possible position of the compound of formula (A-XIV);

[0152] wherein R1 is selected from -OH, -NH2, -NHC(=NH)NH2 and -NHC(=NH)NHR6;

[0153] R2 and R3 are each independently selected from -H, -OH, -F, -Cl and -Br;

[0154] R4 is selected from -C(=O)OH, -P(=O)(OH)2, -SO3H, -C(=O)OCH3 and -C(=O)OCF3;

[0155] R5 is selected from -C(=O)CH3, -C(=O)CF3, -SO2CH3;

[0156] X is selected from -O- and -S-;

[0157] Y is selected from -O-, -S-, -NR7-, -OC(=O)NR7-, -OC(=S)NR7-, -OC(=O)O-, -OC(=O)-, -NHC(=O)O-, -NHC(=O)-, -NHC(=NH)-, -NHC(=O)NR7-, -NHC(=NH)NR7-, -NHC(=S)NR7-, -NHC(=S)-, -OCH2C(=O)NR7-, -NH(SO2)- and -NH(SO2)NR7-;

[0158] R' is H or C1-C6 alkyl;

[0159] R6 is selected from

[0160] R7 is selected from H, C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C3-C 20 Heterocycloalkyl; C5-C 15 Aryl and C5-C 15 Heteroaryl; preferably, R7 is H; preferably, C1-C6 alkyl;

[0161] L' is a linker covalently attached to each of A1, A2, and A3.

[0162] In some embodiments, in the compound represented by formula (IV), A1, A2, and A3 are each independently selected from formula (AI) to formula (A-XIII),

[0163] wherein R1, R2, R3, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0164] In some embodiments, A1, A2, and A3 in the compound represented by formula (IV) are each independently selected from formula (AI) to formula (A-IV) and formula (A-VII),

[0165] wherein R1, R2, R3, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0166] In some embodiments, A1, A2, and A3 in the compound represented by formula (IV) are each independently selected from formula (AI) to formula (A-III) and formula (A-VII),

[0167] wherein R1, R2, R3, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0168] In some embodiments, A1, A2, and A3 in the compound represented by formula (IV) are each independently selected from formula (AI), formula (A-III), and formula (A-VII).

[0169] wherein R1, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0170] In some embodiments, R1 in the compound of formula (IV) is selected from -OH, -NH2, and -NHC(=NH)NH2. In some embodiments, R1 in the compound of formula (IV) is -NHC(=NH)NH2.

[0171] In some embodiments, R4 in the compound of formula (IV) is selected from -C(=O)OH, -C(=O)OCH3 and -C(=O)OCF3. In some embodiments, R4 in the compound of formula (IV) is selected from -C(=O)OH and -C(=O)OCH3.

[0172] In some embodiments, R5 in the compound of formula (IV) is selected from -C(=O)CH3 and -C(=O)CF3. In some embodiments, R5 in the compound of formula (IV) is -C(=O)CH3.

[0173] In some embodiments, R' in the compound of formula (IV) is H or C1-C4 alkyl. In some embodiments, R' in the compound of formula (IV) is H, methyl or ethyl. In some embodiments, R' in the compound of formula (IV) is H or ethyl.

[0174] In some embodiments, X in the compound of formula (IV) is -O-.

[0175] In some embodiments, Y in the compound of formula (IV) is selected from -O-, -S-, and -NH-. In some embodiments, Y in the compound of formula (IV) is selected from -O- and -NH-.

[0176] In some embodiments, the compound represented by formula (IV) has the structure represented by formula (IV-I),

[0177] Wherein, the definitions of A1, A2 and A3 are as described in any embodiment of the present application,

[0178] L1 is selected from:

[0179] L2' is selected from:

[0180] wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)-, -CH2- or Z1 and Z2 are each independently selected from -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)- or -CH2-; W' is HC≡C-, -C(=O)OH, -NH2 or N3-; m and p are each independently an integer of 1-20.

[0181] In some embodiments, in the compound represented by formula (IV), L1 is selected from:

[0182] wherein V, p, m, and Z are defined as described in any embodiment of the present application.

[0183] In some embodiments, in the compound represented by formula (IV), L1 is wherein V, p, m, and Z are defined as described in any embodiment of the present application.

[0184] In some embodiments, L2' in the compound represented by formula (IV) is wherein W', V, p, m, and Z are defined as described in any embodiment of the present application.

[0185] In some embodiments, L2' in the compound represented by formula (IV) is wherein W', V, p, m, and Z are defined as described in any embodiment of the present application.

[0186] In some embodiments, L2' in the compound represented by formula (IV) is wherein W', p, m, and Z are defined as described in any embodiment of the present application.

[0187] In some embodiments, V in the compound of formula (IV) is -CH2- or -O-. In some embodiments, V in the compound of formula (IV) is -O-.

[0188] In some embodiments, Z in the compound represented by formula (IV) is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)- or -CH2-.

[0189] In some embodiments, Z in the compound represented by formula (IV) is wherein p, V, m, and Z1 are as defined in any embodiment of the present application.

[0190] In some embodiments, Z in the compound of formula (IV) is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, or -C(=O)-. In some embodiments, Z in the compound of formula (IV) is -NH-C(=O)- or -C(=O)-. In some embodiments, Z in the compound of formula (IV) is -NH-C(=O)-.

[0191] In some embodiments, Z1 in the compound of formula (IV) is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, or -CH2CH2-C(=O)-. In some embodiments, Z1 in the compound of formula (IV) is -C(=O)-NH- or -CH2-C(=O)-NH-. In some embodiments, Z1 in the compound of formula (IV) is -C(=O)-NH-.

[0192] In some embodiments, W' in the compound of formula (IV) is HC≡C-, -C(=O)OH, -NH2 or N3-. In some embodiments, W' in the compound of formula (IV) is HC≡C-. In some embodiments, W' in the compound of formula (IV) is

[0193] In some embodiments, p in the compound of formula (IV) is an integer between 1 and 10. In some embodiments, p in the compound of formula (IV) is an integer between 1 and 6 (e.g., 1, 2, 3, 4, 5, 6).

[0194] In some embodiments, m in the compound of formula (IV) is an integer between 1 and 12. In some embodiments, m in the compound of formula (IV) is an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9).

[0195] In some embodiments, the compound represented by formula (IV) has the structure represented by formula (IV-I-1), formula (IV-I-2), or formula (IV-I-3):

[0196] wherein R1, R4, R5, R', X, Y, L1, and L2' are as defined in any embodiment of the present application.

[0197] In some embodiments, the compound shown in formula (IV) has the structure shown in formula (IV-I-1-1), formula (IV-I-2-1), formula (IV-I-2-2) or formula (IV-I-3-1):

[0198] Wherein, the definitions of L1 and L2' are as described in any embodiment of the present application.

[0199] In some embodiments, the compound represented by formula (IV) is selected from:

[0200] On the other hand, the present application also provides a compound represented by formula (V) or its salt, geometric or optical isomer, hydrate, solvate or polymorph,

[0201] wherein A1 and A2 are each independently selected from formula (AI) to formula (A-XIV),

[0202] wherein L can be connected to any possible position of the compound of formula (A-XIV); wherein R1 is selected from -OH, -NH2, -NHC(=NH)NH2 and -NHC(=NH)NHR6;

[0203] R2 and R3 are each independently selected from -H, -OH, -F, -Cl and -Br;

[0204] R4 is selected from -C(=O)OH, -P(=O)(OH)2, -SO3H, -C(=O)OCH3 and -C(=O)OCF3;

[0205] R5 is selected from -C(=O)CH3, -C(=O)CF3, -SO2CH3;

[0206] X is selected from -O- and -S-;

[0207] Y is selected from -O-, -S-, -NR7-, -OC(=O)NR7-, -OC(=S)NR7-, -OC(=O)O-, -OC(=O)-, -NHC(=O)O-, -NHC(=O)-, -NHC(=NH)-, -NHC(=O)NR7-, -NHC(=NH)NR7-, -NHC(=S)NR7-, -NHC(=S)-, -OCH2C(=O)NR7-, -NH(SO2)- and -NH(SO2)NR7-;

[0208] R' is H or C1-C6 alkyl;

[0209] R6 is selected from

[0210] R7 is selected from H, C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C3-C 20 Heterocycloalkyl; C5-C 15 Aryl and C5-C 15 Heteroaryl; preferably, R7 is H; preferably, C1-C6 alkyl;

[0211] L' is a linker covalently attached to each group in A1 and A2.

[0212] In some embodiments, in the compound represented by formula (V), A1 and A2 are each independently selected from formula (AI) to formula (A-XIII),

[0213] wherein R1, R2, R3, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0214] In some embodiments, in the compound represented by formula (V), A1 and A2 are each independently selected from formula (AI) to formula (A-IV) and formula (A-VII),

[0215] wherein R1, R2, R3, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0216] In some embodiments, A1 and A2 in the compound represented by formula (V) are independently selected from formula (AI) to formula (A-III) and formula (A-VII),

[0217] wherein R1, R2, R3, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0218] In some embodiments, A1 and A2 in the compound represented by formula (V) are independently selected from formula (AI), formula (A-III) and formula (A-VII),

[0219] wherein R1, R4, R5, R', X, and Y are as defined in any embodiment of the present application.

[0220] In some embodiments, R1 in the compound of formula (V) is selected from -OH, -NH2, -NHC(=NH)NH2. In some embodiments, R1 in the compound of formula (V) is -NHC(=NH)NH2.

[0221] In some embodiments, R4 in the compound of formula (V) is selected from -C(=O)OH, -C(=O)OCH3 and -C(=O)OCF3. In some embodiments, R4 in the compound of formula (V) is selected from -C(=O)OH and -C(=O)OCH3.

[0222] In some embodiments, R5 in the compound of formula (V) is selected from -C(=O)CH3 and -C(=O)CF3. In some embodiments, R5 in the compound of formula (V) is -C(=O)CH3.

[0223] In some embodiments, R' in the compound of formula (V) is H or C1-C4 alkyl. In some embodiments, R' in the compound of formula (V) is H, methyl or ethyl. In some embodiments, R' in the compound of formula (V) is H or ethyl.

[0224] In some embodiments, X in the compound of formula (V) is -O-.

[0225] In some embodiments, Y in the compound of formula (V) is selected from -O-, -S-, and -NH-. In some embodiments, Y in the compound of formula (V) is selected from -O- and -NH-.

[0226] In some embodiments, the compound of formula (V) has the structure of formula (VI),

[0227] Wherein the definitions of A1 and A2 are as described in any embodiment of this application,

[0228] L1 is selected from:

[0229] L2' is selected from:

[0230] wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)- or -CH2-; Z1 and Z2 are each independently selected from -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -OC(=O)-, -C(=O)- or -CH2-; W' is HC≡C-, -C(=O)OH, -NH2 or N3-; m and p are each independently an integer of 1-20.

[0231] In some embodiments, in the compound represented by formula (V), L1 is selected from:

[0232] wherein V, p, m, and Z are defined as described in any embodiment of the present application.

[0233] In some embodiments, in the compound represented by formula (V), L1 is wherein V, p, m, and Z are defined as described in any embodiment of the present application.

[0234] In some embodiments, L2' in the compound represented by formula (V) is wherein W', V, p, m, and Z are defined as described in any embodiment of the present application.

[0235] In some embodiments, L2' in the compound represented by formula (V) is wherein W', V, p, m, and Z are defined as described in any embodiment of the present application.

[0236] In some embodiments, V in the compound of formula (V) is -CH2- or -O-. In some embodiments, V in the compound of formula (V) is -O-.

[0237] In some embodiments, Z in the compound represented by formula (V) is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)- or -C(=O)-. In some embodiments, Z in the compound represented by formula (V) is -NH-C(=O)- or -C(=O)-.

[0238] In some embodiments, W' in the compound of formula (V) is HC≡C-, -C(=O)OH, -NH2 or N3-. In some embodiments, W' in the compound of formula (V) is HC≡C-.

[0239] In some embodiments, in the compound of formula (V), p is an integer between 1 and 10. In some embodiments, in the compound of formula (V), p is an integer between 1 and 6 (e.g., 1, 2, 3, 4, 5, 6).

[0240] In some embodiments, m in the compound of formula (V) is an integer between 1 and 12. In some embodiments, m in the compound of formula (V) is an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9).

[0241] In some embodiments, the compound represented by formula (V) has the structure represented by formula (VI-1), formula (VI-2), or formula (VI-3):

[0242] wherein R1, R4, R5, R', X, Y, L1, and L2' are as defined in any embodiment of the present application.

[0243] In some embodiments, the compound represented by formula (V) has the structure represented by formula (VI-1-1), formula (VI-2-1), formula (VI-2-2) or formula (VI-3-1):

[0244] Wherein, the definitions of L1 and L2' are as described in any embodiment of the present application.

[0245] In some embodiments, the compound represented by formula (V) is selected from:

[0246] On the other hand, the present application also provides a pharmaceutical composition comprising the conjugate represented by formula (I) or formula (II) or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, and a pharmaceutically acceptable carrier and / or excipient.

[0247] On the other hand, the present application also provides a pharmaceutical composition comprising the compound represented by formula (IV) or formula (V) or its salt, geometric or optical isomer, hydrate, solvate or polymorph, and a pharmaceutically acceptable carrier and / or excipient.

[0248] On the other hand, the present application also provides the use of the conjugate represented by formula (I) or formula (II) or its pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph in the preparation of a drug for treating or preventing viral infection.

[0249] On the other hand, the present application also provides the use of the compound represented by formula (IV) or formula (V) or its salt, geometric or optical isomer, hydrate, solvate or polymorph in the preparation of a drug for treating or preventing viral infection.

[0250] On the other hand, the present application also provides use of the pharmaceutical composition in preparing a medicament for treating or preventing viral infection.

[0251] On the other hand, the present application also provides a method for treating a subject having a viral infection or suspected of having a viral infection, the method comprising administering to the subject an effective amount of a conjugate represented by formula (I) or formula (II) described herein, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof.

[0252] On the other hand, the present application also provides a method for treating a subject having a viral infection or suspected of having a viral infection, the method comprising administering to the subject an effective amount of a compound represented by formula (IV) or formula (V) described herein, or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof.

[0253] On the other hand, the present application also provides a method for prophylactically treating a viral infection in a subject in need thereof, comprising administering to the subject an effective amount of a conjugate represented by formula (I) or formula (II) described herein, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof.

[0254] In some embodiments, the viral infection is an infection caused by influenza virus or parainfluenza virus. In some embodiments, the viral infection is an infection caused by influenza virus A, B or C or parainfluenza virus. In some embodiments, the viral infection is an infection caused by avian influenza.

[0255] In some embodiments, the subject may be further treated with an antiviral agent, wherein the antiviral agent is selected from oseltamivir, zanamivir, peramivir, laninamivir, amantadine, rimantadine, or mabaloxavir.

[0256] In some embodiments, the subject is immunocompromised. In some embodiments, the subject has been diagnosed with humoral immune deficiency, T cell deficiency, neutropenia, asplenia, or complement deficiency. In some embodiments, the subject is being treated with or is about to be treated with immunosuppressive therapy. In some embodiments, the subject has been diagnosed with a disease that causes immunosuppression. In some embodiments, the disease is cancer or acquired immunodeficiency syndrome. In some embodiments, the cancer is leukemia, lymphoma, or multiple myeloma. In some embodiments, the subject has undergone or is about to undergo a hematopoietic stem cell transplant. In some embodiments, wherein the subject has undergone or is about to undergo an organ transplant.

[0257] In some embodiments, the conjugates of formula (I) or (II) described herein are capable of binding to one or more targets (e.g., antigens). In some embodiments, the target is a viral (e.g., influenza) protein, such as neuraminidase or hemagglutinin.

[0258] In some embodiments, the conjugate of Formula (I) or Formula (II), or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate, or polymorph thereof, or a composition thereof, is administered intramuscularly, intravenously, intradermally, intraarterially, intraperitoneally, intralesionally, intracranially, intraarticularly, intraprostatically, intrapleurally, intratracheally, intranasally, intravitreally, intravaginally, intrarectally, topically, intratumorally, transperitoneally, subcutaneously, subconjunctivally, intracapsularly, transmucosally, intrapericardially, intraumbilically, intraocularly, orally, topically, by inhalation, by injection, or by infusion.

[0259] On the other hand, the application also provides the use of the compound shown in the formula (IV) or formula (V) or its salt, geometric or optical isomer, hydrate, solvate or polymorph as an intermediate in the preparation of a conjugate. The compound shown in the formula (IV) or formula (V) as an intermediate can be coupled to the Fc domain or Fc domain monomer (for example, by means of a linker) by any suitable method known to those skilled in the art, including any method described or exemplified herein. In some embodiments, the conjugate (for example, a conjugate shown in formula (I) or formula (II)) includes E, wherein E is an Fc domain monomer (when n is 2, E forms an Fc domain with dimerization, and each Fc domain monomer independently has a sequence of any one of SEQ ID NO: 1-68). In a preferred embodiment, one or more nitrogen atoms of one or more surface-exposed lysine residues of E are covalently coupled to a linker (for example, a PEG2-PEG20 linker). The linker coupled to E can be functionalized so that it can react to form a covalent bond with any intermediate described herein (e.g., a compound of formula (IV) or (V)). In a preferred embodiment, E is coupled to an azide-functionalized linker and the intermediate (e.g., a compound of formula (IV) or (V)) is functionalized with an alkynyl group. E is coupled to the alkynyl group of the intermediate via the azide group of the linker (e.g., by click chemistry) to form a conjugate of the present application, such as a conjugate of formula (I) or (II).

[0260] In some embodiments, in the conjugates of the present application, each E is an Fc domain monomer, comprising a hinge domain, a CH2 antibody constant domain, and a CH3 antibody constant domain. The Fc domain monomer can be an immunoglobulin antibody isotype IgG. The variant Fc domain monomer can also be any immunoglobulin antibody isotype (e.g., IgG1). The variant Fc domain monomer can be any immunoglobulin antibody allotype (e.g., IGHG1*01 (i.e., G1m(za)), IGHG1*07 (i.e., G1m(zax)), IGHG1*04 (i.e., G1m(zav)), IGHG1*03 (G1m(f)), IGHG1*08 (i.e., G1m(fa)), IGHG2*01, IGHG2*06, or IGHG2*02) (as described, for example, in Vidarsson et al. IgG subclasses and allotypes: from structure to effector function Frontiers in Immunology. 5(520): 1-17 (2014)). The variant Fc domain monomer can also be of any species, such as human, murine, or mouse. A dimer of the variant Fc domain monomer is a variant Fc domain that can bind to an Fc receptor, which is a receptor located on the surface of white blood cells.

[0261] In some embodiments, the Fc domain monomer comprises the quadruple mutation C220S / M252Y / S254T / T256E relative to a wild-type Fc domain monomer. In some embodiments, the Fc domain monomer comprises the quadruple mutation C220S / V309D / Q311H / N434S relative to a wild-type Fc domain monomer. In other embodiments, the Fc domain monomer comprises the C220S mutation relative to a wild-type Fc domain monomer. The mutations are relative to a wild-type Fc monomer amino acid sequence, e.g., wild-type human IgG1.

[0262] In some embodiments, the Fc domain monomer in the conjugate described herein may comprise one or more amino acid substitutions, additions, and / or deletions relative to an Fc domain monomer having a sequence as set forth in any one of SEQ ID NOs: 1-68. In some embodiments, the Fc domain monomer may comprise one or more amino acid substitutions, additions, and / or deletions relative to an Fc domain monomer having a sequence as set forth in any one of SEQ ID NOs: 1 to 29, 31 to 52, or 56 to 58. In some embodiments, Asn297 in an Fc domain monomer in a conjugate as described herein may be substituted with Ala to prevent N-linked glycosylation (see, e.g., SEQ ID NO: 4, wherein the substitution of Asn297 to Ala is marked (*)).

[0263] In some embodiments, the Fc domain monomer or Fc domain in the conjugate described herein is a non-glycosylated Fc domain monomer or Fc domain (e.g., an Fc domain monomer or Fc domain that maintains engagement with an Fc receptor (e.g., FcRn)). For example, the Fc domain is a non-glycosylated IgG1 variant that maintains engagement with an Fc receptor (e.g., an IgG1 having an amino acid substitution at N297 and / or T299 of a glycosylation motif). Exemplary non-glycosylated Fc domains and methods for preparing non-glycosylated Fc domains are known in the art, for example, as described in Sazinsky SL et al., Aglycosylated immunoglobulin G1 variants productively engage activating Fc receptors, PNAS, 2008, 105(51):20167-20172.

[0264] In some embodiments, the C-terminal Lys447 of the Fc domain monomer in the conjugates described herein may or may not be present without affecting the structure or stability of the Fc region, such as any one of SEQ ID NOs: 1 to 29 and 31 to 52 that do not include the C-terminal Lys residue. In some embodiments, the N-terminal Asn of the Fc domain monomer in the conjugates described herein may or may not be present without affecting the structure or stability of the variant Fc domain monomer, such as any one of SEQ ID NOs: 1 to 29, 31 to 52, and 56 to 58 that do not include the N-terminal Asn residue.

[0265] In some embodiments, the Fc domain monomer in the conjugate described herein includes an additional moiety attached to the N- or C-terminus of the Fc domain monomer, such as a purification peptide (e.g., a hexahistidine peptide (HHHHHH (SEQ ID NO: 59))) or a signal sequence (e.g., the IL2 signal sequence MYRMQLLSCIALSLALVTNS (SEQ ID NO: 60)). In some embodiments, the Fc domain monomer in the conjugate does not contain any type of antibody variable region, such as VH, VL, complementarity determining region (CDR), or hypervariable region (HVR).

[0266] In some embodiments, the Fc domain monomer in the conjugate described herein has a sequence that is at least 70% identical (e.g., 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identical) to the sequence of any one of SEQ ID NOs: 1-68 set forth below. In some embodiments, the Fc domain monomer has a sequence of any one of SEQ ID NOs: 1-68 set forth below.

[0267] SEQ ID NO: 1: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), X1 is Asp or Glu, and X2 is Leu or Met, N-terminal Fab residue is underlined, hinge residues are italicized

[0268] SEQ ID NO: 2: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(fa) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0269] SEQ ID NO: 3: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(f) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0270] SEQ ID NO:4: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), Asn to Ala substitution (*), X1 is Asp or Glu, and X2 is Leu or Met, N-terminal Fab residue is underlined, hinge residues are italicized

[0271] SEQ ID NO:5: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(fa) (bold italic), Asn to Ala substitution (*), N-terminal Fab residue is underlined, hinge residues are italicized

[0272] SEQ ID NO:6: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(f) (bold italic), Asn to Ala substitution (*), N-terminal Fab residue is underlined, hinge residues are italicized

[0273] SEQ ID NO:7: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), X6 is Asp or Glu, and X7 is Leu or Met, Z1 is Asn or absent, Z2 is Asn or Ala, Z3 is Lys or absent, N-terminal Fab residue is underlined, hinge residues are italicized

[0274] SEQ ID NO:8: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(fa) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0275] SEQ ID NO:9: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(f) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0276] SEQ ID NO: 10: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(fa) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0277] SEQ ID NO: 11: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(f) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0278] SEQ ID NO: 12: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(fa) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0279] SEQ ID NO: 13: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(f) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0280] SEQ ID NO: 14: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(fa) (bold italic), Asn to Ala substitution (*), N-terminal Fab residue is underlined, hinge residues are italicized

[0281] SEQ ID NO: 15: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(f) (bold italic), Asn to Ala substitution (*), N-terminal Fab residue is underlined, hinge residues are italicized

[0282] SEQ ID NO: 16: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(fa) (bold italic), Asn to Ala substitution (*), N-terminal Fab residue is underlined, hinge residues are italicized

[0283] SEQ ID NO: 17: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(f) (bold italic), Asn to Ala substitution (*), N-terminal Fab residue is underlined, hinge residues are italicized

[0284] SEQ ID NO: 18: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(fa) (bold italic), Asn to Ala substitution (*), N-terminal Fab residue is underlined, hinge residues are italicized

[0285] SEQ ID NO: 19: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(f) (bold italic), Asn to Ala substitution (*), N-terminal Fab residue is underlined, hinge residues are italicized

[0286] SEQ ID NO:20: Adult IgG1 Fc, Cys to Ser substitution (#), X4 is Asp or Glu, X5 is Leu or Met; Z1 is Asn or absent, Z3 is Lys or absent, N-terminal Fab residue is underlined, hinge residues are italicized

[0287] SEQ ID NO:21: Adult IgG1 Fc, Cys to Ser substitution (#), allotype G1m(fa) (bold italics), N-terminal Fab residues are underlined, hinge residues are italics

[0288] SEQ ID NO:22: Adult IgG1 Fc, Cys to Ser substitution (#), allotype G1m(f) (bold italics), N-terminal Fab residues are underlined, hinge residues are italics

[0289] SEQ ID NO:23: Adult IgG1 Fc, Cys to Ser substitution (#), X1 is Met or Tyr, X2 is Ser or Thr, X3 is Thr or Glu, X6 is Asp or Glu, X7 is Leu or Met, Z1 is Asn or absent, Z2 is Asn or Ala, and Z3 is Lys or absent, N-terminal Fab residue is underlined, hinge residues are italicized

[0290] SEQ ID NO:24: Adult IgG1 Fc, Cys to Ser substitution (#), X1 is Met or Tyr, X2 is Ser or Thr, X3 is Thr or Glu, X6 is Asp or Glu, X7 is Leu or Met, and Z2 is Asn or Ala, N-terminal Fab residue is underlined, hinge residues are italicized

[0291] SEQ ID NO:25: Adult IgG1 Fc, Cys to Ser substitution (#), X1 is Met or Tyr, X2 is Ser or Thr, X3 is Thr or Glu, and Z2 is Asn or Ala, N-terminal Fab residue is underlined, hinge residues are italicized

[0292] SEQ ID NO:26: Adult IgG1 Fc, Cys to Ser substitution (#), X1 is Met or Tyr, X2 is Ser or Thr, X3 is Thr or Glu, and Z2 is Asn or Ala, N-terminal Fab residue is underlined, hinge residues are italicized

[0293] SEQ ID NO:27: Adult IgG1 Fc, Cys to Ser substitution (#), X1 is Met or Tyr, X2 is Ser or Thr, X3 is Thr or Glu, X6 is Asp or Glu, X7 is Leu or Met, and Z2 is Asn or Ala, N-terminal Fab residue is underlined, hinge residues are italicized

[0294] SEQ ID NO:28: Adult IgG1 Fc, Cys to Ser substitution (#), X1 is Met or Tyr, X2 is Ser or Thr, X3 is Thr or Glu, and Z2 is Asn or Ala, N-terminal Fab residue is underlined, hinge residues are italicized

[0295] SEQ ID NO:29: Adult IgG1 Fc, Cys to Ser substitution (#), X1 is Met or Tyr, X2 is Ser or Thr, X3 is Thr or Glu, and Z2 is Asn or Ala, N-terminal Fab residue is underlined, hinge residues are italicized

[0296] SEQ ID NO:30: Adult human IgG1 Fc with mouse heavy chain MigG Vh signal sequence (bold), Cys to Ser substitution (#), allotype G1m(fa) (bold italic), N-terminal Fab residues underlined, hinge residues italicized

[0297] SEQ ID NO:31: Adult Fc IgG1, Z1 is Asn or absent, Z3 is Lys or absent, J1 is Cys or Ser, and wherein X1 is Met or Tyr, X2 is Ser or Thr, X3 is Thr or Glu, Z3 is Asn or Ala, X4 is Leu or Asp, X5 is Gln or His, X6 is Asp or Glu, and X7 is Leu or Met, X8 is Met or Leu, and X9 is Asn or Ser, Z2 is Asn or Ala, N-terminal Fab residue is underlined, hinge residues are italicized

[0298] SEQ ID NO:32: Adult Fc IgG1, Cys to Ser substitution (#), Z1 is Asn or absent, Z3 is Lys or absent, and wherein Z2 is Asn or Ala, X4 is Leu or Asp, X5 is Gln or His, X6 is Asp or Glu, X7 is Leu or Met, X8 is Met or Leu, and X9 is Asn or Ser, N-terminal Fab residue is underlined, hinge residues are italicized

[0299] SEQ ID NO:33: Adult Fc IgG1, Cys to Ser substitution (#), DHS triple mutation (bold and underlined), Z1 is Asn or absent, Z3 is Lys or absent, and wherein Z2 is Asn or Ala, X6 is Asp or Glu, and X7 is Leu or Met, X8 is Met or Leu, and X9 is Asn or Ser, N-terminal Fab residue is underlined, hinge residues are italicized

[0300] SEQ ID NO:34: Adult Fc IgG1, Cys to Ser substitution (#), DHS triple mutation (bold and underlined), wherein Z2 is Asn or Ala, X6 is Asp or Glu, and X7 is Leu or Met, N-terminal Fab residue is underlined, hinge residues are italicized

[0301] SEQ ID NO:35: Adult Fc IgG1, Cys to Ser substitution (#), DHS triple mutation (bold and underlined), wherein X6 is Asp or Glu and X7 is Leu or Met, N-terminal Fab residue is underlined, hinge residues are italicized

[0302] SEQ ID NO:36: Adult Fc IgG1, Cys to Ser substitution (#), DHS triple mutation (bold and underlined), allotype G1m(fa) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0303] SEQ ID NO:37: Adult Fc IgG1, Cys to Ser substitution (#), DHS triple mutation (bold and underlined

[0304] SEQ ID NO:38: Adult Fc IgG1, Cys to Ser substitution (#), DHS triple mutation (bold and underlined), allotype G1m(fa) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0305] SEQ ID NO:39: Adult Fc IgG1, Cys to Ser substitution (#), DHS triple mutation (bold and underlined), allotype G1m(f) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0306] SEQ ID NO:40: Adult Fc IgG1, Cys to Ser substitution (#), DHS triple mutation (bold and underlined), allotype G1m(fa) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0307] SEQ ID NO:41: Adult Fc IgG1, Cys to Ser substitution (#), DHS triple mutation (bold and underlined)

[0308] SEQ ID NO:42: Adult Fc IgG1, Cys to Ser substitution (#), DHS triple mutation (bold and underlined), allotype G1m(fa) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0309] SEQ ID NO:43: Adult Fc IgG1, Cys to Ser substitution (#), DHS triple mutation (bold and underlined), allotype G1m(f) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0310] SEQ ID NO:44: Adult Fc IgG1, Cys to Ser substitution (#), Asn to Ala substitution (*), DHS triple mutation (bold and underlined), wherein X6 is Asp or Glu and X7 is Leu or Met, N-terminal Fab residue is underlined, hinge residues are italicized

[0311] SEQ ID NO:45: Adult Fc IgG1, Cys to Ser substitution (#), Asn to Ala substitution (*), DHS triple mutation (bold and underlined), allotype G1m(fa) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0312] SEQ ID NO:46: Adult Fc IgG1, Cys to Ser substitution (#), Asn to Ala substitution (*), DHS triple mutation (bold and underlined), allotype G1m(f) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0313] SEQ ID NO:47: Adult Fc IgG1, Cys to Ser substitution (#), Asn to Ala substitution (*), DHS triple mutation (bold and underlined), allotype G1m(fa) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0314] SEQ ID NO:48: Adult Fc IgG1, Cys to Ser substitution (#), Asn to Ala substitution (*), DHS triple mutation (bold and underlined), allotype G1m(f) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0315] SEQ ID NO:49: Adult Fc IgG1, Cys to Ser substitution (#), Asn to Ala substitution (*), DHS triple mutation (bold and underlined), allotype G1m(fa) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0316] SEQ ID NO:50: Adult Fc IgG1, Cys to Ser substitution (#), Asn to Ala substitution (*), DHS triple mutation (bold and underlined), allotype G1m(f) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0317] SEQ ID NO:51: Adult Fc IgG1, Cys to Ser substitution (#), Asn to Ala substitution (*), DHS triple mutation (bold and underlined), allotype G1m(fa) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0318] SEQ ID NO:52: Adult Fc IgG1, Cys to Ser substitution (#), Asn to Ala substitution (*), DHS triple mutation (bold and underlined), allotype G1m(f) (bold italic), N-terminal Fab residues are underlined, hinge residues are italicized

[0319] SEQ ID NO:53: Adult Fc IgG1, added N-terminal ISAMVRS amino acid residues (italics), C-terminal G4S linker (italics), C-terminal myc tag (underlined), allotype G1m(f) (bold italics)

[0320] SEQ ID NO:54: Adult Fc IgG1, added N-terminal ISAMVRS amino acid residues (italics), allotype G1m(fa) (bold italics)

[0321] SEQ ID NO:55: Adult Fc IgG1, added N-terminal amino acid residues (italics), hinge residues (italics), allotype G1m(fa) (bold italics)

[0322] SEQ ID NO:56: Adult IgG1 Fc, Cys to Ser substitution (#), allotype G1m(fa) (bold italics), N-terminal Fab residues are underlined, hinge residues are italics

[0323] SEQ ID NO:57: Adult IgG1 Fc, Cys to Ser substitution (#), allotype G1m(f) (bold italics), N-terminal Fab residues are underlined, hinge residues are italics

[0324] SEQ ID NO:58: Adult IgG1 Fc, Cys to Ser substitution (#), M428L, N434S (bold / underlined), allotype G1m(fa) (bold italic), N-terminal Fab residue underlined, hinge residues italicized

[0325] SEQ ID NO:59: Adult human IgG1 with mouse heavy chain MigG1 signal sequence (bold), with Cys to Ser substitution (#), with M428L, N434S mutations (bold / underlined), with C-terminal G4S (italics) and with C-terminal IgA peptide (underlined), with allotype G1m(fa) (bold italics)

[0326] SEQ ID NO:60: Adult Fc IgG1, Z1 is Cys or Ser, and wherein X1 is Met or Trp, X2 is Ser or Thr, X3 is Thr or Glu, X4 is Asp or Glu, and X5 is Leu or Met, X6 is Met or Leu, and X7 is Asn or Ser

[0327] SEQ ID NO:61: Adult Fc IgG1, Cys to Ser substitution (#), and wherein X1 is Met or Trp, X2 is Ser or Thr, X3 is Thr or Glu, X4 is Asp or Glu, and X5 is Leu or Met, X6 is Met or Leu, and X7 is Asn or Ser

[0328] SEQ ID NO:62: Adult IgG1 Fc, Cys to Ser substitution (#), X4 is Asp or Glu, and X5 is Leu or Met

[0329] SEQ ID NO:63: Adult IgG1 Fc, Cys to Ser substitution (#), allotype G1m(f) (bold italics)

[0330] SEQ ID NO:64: Adult IgG1 Fc, Cys to Ser substitution (#), allotype G1m(fa) (bold italics)

[0331] SEQ ID NO:65: Adult IgG1 Fc, Cys to Ser substitution (#), M428L, N434S mutations (bold / underlined), allotype G1m(fa) (bold italics)

[0332] SEQ ID NO:66: Adult IgG1 Fc, Cys to Ser substitution (#), M428L, N434S mutations (bold / underlined), allotype G1m(f) (bold italics)

[0333] SEQ ID NO:67: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(fa) (bold italics)

[0334] SEQ ID NO:68: Adult IgG1 Fc, Cys to Ser substitution (#), YTE triple mutation (bold and underlined), allotype G1m(f) (bold italics)

[0335] In some embodiments, in the conjugates of the present application, each E is a naturally occurring albumin or a variant thereof, such as an engineered variant of a naturally occurring albumin. The variants include polymorphisms, fragments such as domains and subdomains, and fusion proteins. The albumin may include a sequence of an albumin obtained from any source. Preferably, the source is a mammal, such as a human or a cow. Most preferably, the albumin is human serum albumin (HSA) or a variant thereof. Human serum albumin includes any albumin and its variants having an amino acid sequence naturally occurring in humans. Albumin coding sequences can be obtained by methods known to those skilled in the art for isolating cDNA corresponding to human genes and sequencing the cDNA. The albumin of the present application may include the amino acid sequence of human serum albumin (HSA) shown in SEQ ID NO: 69 or SEQ ID NO: 70, or the amino acid sequence of mouse serum albumin (MSA) shown in SEQ ID NO: 71, or a variant or fragment thereof, preferably a variant or fragment having the function thereof. The fragment or variant may or may not be functional, or may retain the function of albumin to some extent. For example, a fragment or variant may retain at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, or 105% of the ability of the parent albumin (e.g., the parent albumin from which the fragment or variant was derived) to bind to an albumin receptor (such as HSA or MSA). Relative binding ability can be determined by methods known in the art, such as by surface plasmon resonance.

[0336] SEQ ID NO: 69 (human serum albumin (HSA), variant 1)

[0337] SEQ ID NO:70 (human serum albumin (HSA), variant 2)

[0338] SEQ ID NO:71 (mouse serum albumin (MSA))

[0339] In some embodiments of any aspects of the present application, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 1. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 1.

[0340] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 2. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 2.

[0341] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 3. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 3.

[0342] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 4. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 4.

[0343] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 5. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 5.

[0344] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 6. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 6.

[0345] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 7. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 7.

[0346] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 8. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 8.

[0347] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 9. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 9.

[0348] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 10. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 10.

[0349] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 11. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 11.

[0350] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 12. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 12.

[0351] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 13. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 13.

[0352] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 14. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 14.

[0353] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 15. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 15.

[0354] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 16. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 16.

[0355] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 17. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 17.

[0356] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 18. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 18.

[0357] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 19. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 19.

[0358] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 20. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 20.

[0359] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 21. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 21.

[0360] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 22. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 22.

[0361] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 23. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 23.

[0362] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 24. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 24.

[0363] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 25. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 25.

[0364] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 26. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 26.

[0365] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 27. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 27.

[0366] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 28. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 28.

[0367] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 29. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 29.

[0368] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 30. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 30.

[0369] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 31. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 31.

[0370] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 32. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 32.

[0371] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 33. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 33.

[0372] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 34. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 34.

[0373] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 35. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 35.

[0374] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 36. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 36.

[0375] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 37. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 37.

[0376] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 38. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 38.

[0377] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 39. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 39.

[0378] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 40. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 40.

[0379] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 41. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 41.

[0380] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 42. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 42.

[0381] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 43. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 43.

[0382] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 44. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 45.

[0383] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 46. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 46.

[0384] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 47. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 47.

[0385] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 48. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 48.

[0386] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 49. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 49.

[0387] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 50. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 50.

[0388] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 51. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 51.

[0389] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 52. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 52.

[0390] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 53. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 53.

[0391] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 54. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 54.

[0392] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 55. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 55.

[0393] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 56. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 56.

[0394] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 57. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 57.

[0395] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 58. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 58.

[0396] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 59. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 59.

[0397] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 60. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 60.

[0398] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 61. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 61.

[0399] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 62. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 62.

[0400] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 63. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 63.

[0401] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 64. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 64.

[0402] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 65. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 65.

[0403] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 66. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 66.

[0404] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 67. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 67.

[0405] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 68. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 68.

[0406] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 69. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 69.

[0407] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 70. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 70.

[0408] In some embodiments of any aspect described herein, E (e.g., each E) comprises the amino acid sequence set forth in SEQ ID NO: 71. In some embodiments, E comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 71.

[0409] definition

[0410] As used herein, the term "half maximal inhibitory concentration" refers to the concentration of a drug required for 50% inhibition in vitro.

[0411] As used herein, the term "viral infection" means the pathogenic growth of a virus (e.g., influenza virus) in a host organism (e.g., a mouse). A viral infection can be any situation in which the presence of a viral population is damaging the host body. Thus, a subject is "suffering from" a viral infection when an excess viral population is present in or on the body of a host organism, or when the presence of a viral population is damaging cells or other tissues of the subject.

[0412] As used herein, the term "neuraminidase inhibitor" refers to a compound that reduces the activity of influenza virus neuraminidase (e.g., from influenza A, B, or C viruses). Viral neuraminidase inhibitors known to those skilled in the art include zanamivir, peramivir, oseltamivir, and analogs thereof. The neuraminidase inhibitors described herein include zanamivir, peramivir, oseltamivir, and analogs thereof, such as the neuraminidase inhibitors shown in formula (AI)-(A-XIII) in the conjugate.

[0413] As used herein, the term "Fc domain monomer" refers to a polypeptide chain comprising at least one hinge domain and second and third antibody constant domains (CH2 and CH3) or a functional fragment thereof (e.g., a fragment capable of (i) dimerizing with another Fc domain monomer to form an Fc domain, and (ii) binding to an Fc receptor). The Fc domain monomer may be of any immunoglobulin antibody isotype, including IgG, IgE, IgM, IgA, or IgD (e.g., IgG). In addition, the Fc domain monomer may be an IgG subtype (e.g., IgG1) including IgG1, IgG2a, IgG2b, IgG3, or IgG4. The Fc domain monomer does not include any portion of an immunoglobulin that can serve as an antigen-recognition region, such as a variable domain or a complementarity-determining region (CDR). The Fc domain monomer in the conjugate as described herein may contain one or more changes (e.g., 1-10, 1-8, 1-6, 1-4 amino acid substitutions, additions or deletions) relative to the wild-type Fc domain monomer sequence that alter the interaction between the Fc domain and the Fc receptor. Examples of suitable changes are known in the art. In certain embodiments, a human Fc domain monomer (e.g., an IgG heavy chain, such as IgG1) comprises a region extending from any one of Asn208, Glu216, Asp221, Lys222, or Cys226 to the heavy chain carboxyl terminus at Lys447. The presence or absence of Lys447 at the C-terminus of the Fc region does not affect the structure or stability of the Fc region. Unless otherwise specified herein, the numbering of amino acid residues in the IgG or Fc domain monomer is according to the EU numbering system for antibodies, also known as the Kabat EU index, as described, e.g., in Kabat et al., Sequences of Proteins of Immunological Interest, 5th ed. Public Health Service, National Institutes of Health, Bethesda, MD, 1991.

[0414] As used herein, the term "Fc domain" refers to a dimer of two Fc domain monomers that is capable of binding to an Fc receptor. In a wild-type Fc domain, the two Fc domain monomers dimerize through the interaction between the two CH3 antibody constant domains. In some embodiments, one or more disulfide bonds are formed between the hinge domains of the two dimerized Fc domain monomers.

[0415] As used herein, the term "covalently linked" refers to two parts of a conjugate being linked to each other by a covalent bond formed between two atoms in the two parts of the conjugate.

[0416] As used herein, the term "Fc-binding peptide" refers to a polypeptide having an amino acid sequence of 5 to 50 (e.g., 5 to 40, 5 to 30, 5 to 20, 5 to 15, 5 to 10, 10 to 50, 10 to 30, or 10 to 20) amino acid residues that has affinity for an Fc domain (e.g., any Fc domain described herein) and has the function of binding to the Fc domain. Fc-binding peptides may be of different origins, such as synthetic, human, mouse, or rat. The Fc-binding peptides of the present application include Fc-binding peptides that have been engineered to include one or more (e.g., two, three, four, or five) solvent-exposed lysine residues, which may provide a site for coupling to a compound of the present application (e.g., a dimer or trimer of a neuraminidase inhibitor shown in Formula (IV) or Formula (V), for example, via a linker). Most preferably, the Fc-binding peptide will contain a single solvent-exposed lysine, thereby enabling site-specific coupling of the compound of the present application. Fc binding peptides may include only naturally occurring amino acid residues or may include one or more non-naturally occurring amino acid residues. Non-naturally occurring amino acid residues (e.g., side chains of non-naturally occurring amino acid residues) can be used as attachment points for compounds of the present invention (e.g., neuraminidase inhibitor dimers or trimers shown in formula (IV) or (V), for example, via a linker). The Fc binding peptides of the present application may be linear or cyclic. The Fc binding peptides of the present application include any Fc binding peptides known to those skilled in the art.

[0417] As used herein, the term "albumin" refers to a polypeptide comprising amino acids corresponding to naturally occurring albumin (e.g., human serum albumin) or variants thereof (e.g., engineered variants of naturally occurring albumin). Variants of albumin include polymorphisms, fragments such as domains and subdomains, and fusion proteins (e.g., albumin with a C-terminal or N-terminal fusion such as a polypeptide linker). Preferably, the albumin has the amino acid sequence of human serum albumin (HSA) or a variant or fragment thereof, most preferably the amino acid sequence of a functional variant or fragment thereof. The albumin of the present application includes proteins having at least 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identity to any one of SEQ ID NOs: 69-71. The albumins of the present application include albumins that have been engineered to include one or more (e.g., two, three, four, or five) solvent-exposed lysine residues that can provide sites for coupling to the compounds of the present application (e.g., coupling to a neuraminidase inhibitor dimer or trimer of Formula (IV) or (V), including via a linker). Most preferably, the albumin will contain a single solvent-exposed lysine, thereby enabling site-specific coupling of the compounds of the present application (neuraminidase inhibitor dimer or trimer of Formula (IV) or (V)). Albumin may include only naturally occurring amino acid residues or may include one or more non-naturally occurring amino acid residues. Non-naturally occurring amino acid residues (e.g., side chains of non-naturally occurring amino acid residues) can serve as attachment points for the compounds of the present application (e.g., neuraminidase inhibitor dimers or trimers of Formula (IV) or (V), including via a linker).

[0418] As used herein, the term "albumin-binding peptide" refers to a polypeptide having an amino acid sequence of 5 to 50 (e.g., 5 to 40, 5 to 30, 5 to 20, 5 to 15, 5 to 10, 10 to 50, 10 to 30, or 10 to 20) amino acid residues that has an affinity for and functions to bind to an albumin (e.g., any of the albumins described herein). Preferably, the albumin-binding peptide is conjugated to naturally occurring serum albumin, most preferably human serum albumin. The albumin-binding peptide may be of various origins, such as synthetic, human, mouse, or rat. The albumin-binding peptides of the present application include those that have been engineered to include one or more (e.g., two, three, four, or five) solvent-exposed lysine residues, which may provide a site for coupling to a compound of the present application (e.g., to a dimer or trimer of a neuraminidase inhibitor of Formula (IV) or Formula (V), including via a linker). Most preferably, the albumin-binding peptide will contain a single solvent-exposed lysine, thereby enabling site-specific coupling of the compounds of the present application (neuraminidase inhibitor dimers or trimers represented by formula (IV) or (V)). The albumin-binding peptide may comprise only naturally occurring amino acid residues or may comprise one or more non-naturally occurring amino acid residues. Non-naturally occurring amino acid residues (e.g., side chains of non-naturally occurring amino acid residues) may serve as attachment points for the compounds of the present application (neuraminidase inhibitor dimers or trimers represented by formula (IV) or (V)). The albumin-binding peptides of the present application may be linear or cyclic. The albumin-binding peptides of the present application include any albumin-binding peptide known to those skilled in the art.

[0419] As used herein, a "surface exposed amino acid" or "solvent exposed amino acid," such as surface exposed lysine, refers to an amino acid that is accessible to the solvent surrounding the protein. A surface exposed amino acid can be naturally occurring or an engineered variant (e.g., a substitution or insertion) of the protein. In some embodiments, a surface exposed amino acid is an amino acid that, when substituted, does not substantially alter the three-dimensional structure of the protein.

[0420] As used herein, the terms "linker," "L'," and "L'" refer to a covalent linkage between two or more components in a compound (e.g., between two neuraminidase inhibitors in a conjugate described herein, between a neuraminidase inhibitor and an Fc domain monomer, Fc domain, or albumin in a conjugate described herein, and between a multimer of two neuraminidase inhibitors and an Fc domain monomer, Fc domain, or albumin in a compound described herein).

[0421] In some embodiments, the compounds described herein may contain a linker having a trivalent structure (e.g., a trivalent linker). A trivalent linker has four arms, each of which is covalently linked to a component of the compound (e.g., a first arm that is bound to a first neuraminidase inhibitor (e.g., A1 in the conjugate of formula (I)), a second arm that is bound to a second neuraminidase inhibitor (e.g., A2 in the conjugate of formula (I)), a third arm that is bound to a third neuraminidase inhibitor (e.g., A3 in the conjugate of formula (I)), and a fourth arm that is bound to an Fc protein or albumin).

[0422] As used herein, the term "amino acid" means naturally occurring amino acids and non-naturally occurring amino acids.

[0423] As used herein, the term "naturally occurring amino acids" means amino acids including Ala, Arg, Asn, Asp, Cys, Gln, Glu, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr, and Val.

[0424] As used herein, the term "T" refers to the average number of Fc domain monomers of the conjugate, neuraminidase inhibitor dimers or neuraminidase inhibitor trimers conjugated to the Fc domain or albumin, and can be from 1 to 20 (e.g., T is 1 to 2, 1 to 3, 1 to 4, 1 to 5, 5 to 10, 10 to 15, or 15 to 20).

[0425] As used herein, the term "pharmaceutical composition" refers to a pharmaceutical or drug formulation containing at least one active ingredient (e.g., a conjugate represented by formula (I) and formula (II), or any of the compounds represented by formula (IV) and formula (V)) and one or more carriers and / or excipients to enable the active ingredient to be suitable for administration.

[0426] As used herein, the term "about" can be understood to mean within + / -10%, + / -9%, + / -8%, + / -7%, + / -6%, + / -5%, + / -4%, + / -3%, + / -2%, + / -1%, + / -0.5%, + / -0.4%, + / -0.3%, + / -0.2% or + / -0.1% of the stated value. For example, about 10% refers to 9% to 11%. Unless otherwise apparent from the context, all numerical values ​​provided herein are modified by the term "about."

[0427] As used herein, the term "identity" refers to the matching of sequences between two polypeptides or between two nucleic acids. When a position in both sequences being compared is occupied by the same base or amino acid monomer subunit (e.g., a position in each of the two DNA molecules is occupied by adenine, or a position in each of the two polypeptides is occupied by lysine), then the molecules are identical at that position. The "percent identity" between two sequences is a function of the number of matching positions shared by the two sequences divided by the number of positions compared x 100. For example, if 6 out of 10 positions in two sequences match, then the two sequences have 60% identity. For example, the DNA sequences CTGACT and CAGGTT share 50% identity (3 out of 6 total positions match). Typically, two sequences are compared when aligned for maximum identity. Such alignment can be achieved, for example, using the method of Needleman et al. (1970) J. Mol. Biol. 48:443-453, which can be conveniently performed using a computer program such as the Align program (DNAstar, Inc.). The percent identity between two amino acid sequences can also be determined using the algorithm of E. Meyers and W. Miller (Comput. Appl Biosci., 4:11-17 (1988)), which has been incorporated into the ALIGN program (version 2.0), using a PAM120 weight residue table, a gap length penalty of 12, and a gap penalty of 4. In addition, the percent identity between two amino acid sequences can be determined using the Needleman and Wunsch (J Mol Biol. 48:444-453 (1970)) algorithm, which has been incorporated into the GAP program in the GCG software package (available at www.gcg.com), using a Blossum 62 matrix or a PAM250 matrix and a gap weight of 16, 14, 12, 10, 8, 6, or 4 and a length weight of 1, 2, 3, 4, 5, or 6.

[0428] As used herein, the term "conservative substitution" means an amino acid substitution that does not adversely affect or change the essential properties of the protein / polypeptide comprising the amino acid sequence. For example, conservative substitutions can be introduced by standard techniques known in the art, such as site-directed mutagenesis and PCR-mediated mutagenesis. Conservative amino acid substitutions include substitutions in which amino acid residues are substituted with amino acid residues having similar side chains, such as substitutions with residues that are physically or functionally similar to the corresponding amino acid residues (e.g., having similar size, shape, charge, chemical properties, including the ability to form covalent bonds or hydrogen bonds, etc.). Families of amino acid residues with similar side chains have been defined in the art. These families include amino acids with basic side chains (e.g., lysine, arginine, and histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine, tryptophan), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine), beta-branched side chains (e.g., threonine, valine, isoleucine), and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). Thus, conservative substitutions generally refer to replacing the corresponding amino acid residue with another amino acid residue from the same side chain family. Methods for identifying conservative amino acid substitutions are well known in the art (see, e.g., Brummell et al., Biochem. 32: 1180-1187 (1993); Kobayashi et al. Protein Eng. 12(10): 879-884 (1999); and Burks et al. Proc. Natl Acad. Set USA 94: 412-417 (1997), which are incorporated herein by reference).

[0429] As used herein, the term "subject" can be a human, non-human primate, or other mammal, including but not limited to dogs, cats, horses, cows, pigs, turkeys, goats, fish, monkeys, chickens, rats, mice, and sheep.

[0430] As used herein, the term "effective amount" refers to an amount sufficient to achieve the desired therapeutic effect, for example, an amount to alleviate the symptoms associated with the disease to be treated. It should also be noted that the dosage and method of use of the conjugate or compound of the present application depend on many factors, including the patient's age, weight, sex, natural health, nutritional status, activity of the compound, time of administration, metabolic rate, severity of the disease, and the subjective judgment of the treating physician. The preferred dosage is between 0.001 and 1000 mg / kg body weight / day.

[0431] As used herein, the term "pharmaceutically acceptable carrier and / or excipient" refers to a carrier and / or excipient that is pharmacologically and / or physiologically compatible with the subject and the active ingredient, as is well known in the art (see, for example, Remington's Pharmaceutical Sciences. Edited by Gennaro AR, 19th ed. Pennsylvania: Mack Publishing Company, 1995). Pharmaceutically acceptable carriers and / or excipients include, but are not limited to, pH adjusters, surfactants, ionic strength enhancers, diluents, agents that maintain osmotic pressure, agents that delay absorption, preservatives, and stabilizers. For example, pH adjusters include, but are not limited to, phosphate buffers. Surfactants include, but are not limited to, cationic, anionic, or nonionic surfactants, such as Tween-80. Ionic strength enhancers include, but are not limited to, sodium chloride. Preservatives include, but are not limited to, various antibacterial and antifungal agents, such as parabens, chlorobutanol, phenol, sorbic acid, and the like. Agents that maintain osmotic pressure include, but are not limited to, sugars, NaCl, and the like. Agents that delay absorption include, but are not limited to, monostearate and gelatin. Diluents include, but are not limited to, water, aqueous buffers (such as buffered saline), alcohols and polyols (such as glycerol), etc. Preservatives include, but are not limited to, various antibacterial and antifungal agents, such as thimerosal, 2-phenoxyethanol, parabens, chlorobutanol, phenol, sorbic acid, etc. Stabilizers have the meaning commonly understood by those skilled in the art, and are capable of stabilizing the desired activity of the active ingredient in the drug, including, but not limited to, sodium glutamate, gelatin, SPGA, carbohydrates (such as sorbitol, mannitol, starch, sucrose, lactose, dextran, or glucose), amino acids (such as glutamic acid, glycine), proteins (such as dried whey, albumin or casein), or their degradation products (such as lactalbumin hydrolysate), etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0432] Figures 1 and 2 show that the conjugates of the present application exhibit good NA enzyme activity inhibition ability;

[0433] Figures 3 and 4 show that the conjugate of the present application exhibits good inhibitory ability against NA enzyme activity of drug-resistant strains;

[0434] Figure 5 shows that the conjugate of the present application has a good plasma half-life and can maintain above the effective drug concentration for a long time;

[0435] Figure 6 shows that the conjugate of the present application can maintain the same ADCC effect as Fc;

[0436] Figure 7 shows that at different challenge doses, a single administration of the conjugate of the present application can effectively inhibit viral replication;

[0437] Figure 8 shows that the conjugate of the present application can effectively alleviate the weight loss in the DBA / 2 mouse model of severe influenza;

[0438] Figures 9 and 10 show that the negative control group and the small molecule drugs oseltamivir and zanamivir failed to protect against severe influenza in the DBA / 2 mouse model;

[0439] FIG11 shows the survival curve results of the conjugate of the present application on the DBA / 2 mouse model of severe influenza, indicating that the conjugate of the present application has a good protective effect on DBA / 2 mice with severe influenza;

[0440] Figures 12 and 13 respectively show the HPLC chromatogram and mass spectrum (MS) of conjugate I-1 prepared in one example of the present application;

[0441] Figures 14 and 15 respectively show the HPLC chromatogram and mass spectrum (MS) of conjugate I-5 prepared in one example of the present application;

[0442] Figures 16 and 17 respectively show the HPLC chromatogram and mass spectrum (MS) of conjugate I-6 prepared in one example of the present application;

[0443] Figures 18 and 19 respectively show the HPLC chromatogram and mass spectrum (MS) of conjugate II-1 prepared in one example of the present application;

[0444] Figures 20 and 21 respectively show the HPLC chromatogram and mass spectrum (MS) of conjugate II-6 prepared in one example of the present application;

[0445] Figures 22 and 23 respectively show the HPLC chromatogram and mass spectrum (MS) of conjugate I-9 prepared in one example of the present application;

[0446] Figures 24 and 25 respectively show the HPLC chromatogram and mass spectrum (MS) of conjugate I-6 prepared in another example of the present application;

[0447] Figures 26-29 show the inhibition curves of the conjugates of the present application against A / Puerto Rico / 8 / 1934 (H1N1-PR8), A / Victoria / 2570 / 2019 (H1N1), A / Darwin / 9 / 2021 (H3N2), and B / Austria / 1359417 / 2021 (BV) viruses, respectively;

[0448] FIG30 shows that therapeutic administration of the conjugate of the present application can effectively alleviate the weight loss in the BALB / c mouse model infected with H1N1-PR8;

[0449] FIG31 shows that therapeutic administration of the conjugate of the present application has a protective effect on the BALB / c mouse model infected with H1N1-PR8 and improves the survival rate of the BALB / c mouse model;

[0450] FIG32 shows that therapeutic administration of the conjugate of the present application can effectively inhibit the replication of H1N1-PR8 virus in a BALB / c mouse model, **** indicates a significance level of P<0.0001;

[0451] FIG33 shows that prophylactic administration of the conjugate of the present application can effectively alleviate the weight loss in the BALB / c mouse model infected with H1N1-PR8;

[0452] FIG34 shows that prophylactic administration of the conjugate of the present application has a protective effect on the BALB / c mouse model infected with H1N1-PR8 and improves the survival rate of the BALB / c mouse model;

[0453] FIG35 shows that the prophylactic administration of the conjugate of the present application can effectively inhibit the replication of the H1N1-PR8 virus in the BALB / c mouse model, **** indicates a significance level of P<0.0001. DETAILED DESCRIPTION

[0454] Example 1 Synthesis of a divalent skeleton

[0455] 29) Preparation of Compound 2:

[0456] Dissolve 2-amino-1,3-dihydroxypropane (5 g, 54.9 mmol) in 150 ml of anhydrous ethanol. Add di-tert-butyl dicarbonate (Boc2O) (12 g, 54.98 mmol dissolved in 100 ml of anhydrous ethanol) and stir at room temperature. After 6 hours, dry the reaction mixture on a rotary evaporator. Recrystallize the product from n-heptane to obtain a white solid. Filter the solid and dry it in vacuo (7 mg, 90% yield). [M+H] + =192.2

[0457] 2) Preparation of compound 3:

[0458] Under ice-bath conditions, KOH (7.87 g, 140.18 mmol) was dispersed in 20 ml of ultra-dry DMF to obtain a DMF solution containing KOH. Compound 2 (5 g, 26.2 mmol) was dissolved in 20 ml of THF / 8 ml of DMF and then slowly added to the DMF solution containing KOH. 3-Bromopropyne (12.46 g, 104.7 mmol) was then added dropwise to the reaction solution, and the solution turned brown. The reaction was carried out at 0°C for 7 h. The mixture was extracted with 100 ml of H2O and 140 ml of DCM, respectively, and the DCM extracts were combined and washed with saturated brine. Anhydrous sodium sulfate was added and the mixture was allowed to stand for 8 h. Purification by column chromatography and vacuum drying gave 4 g of a brown solid with a yield of 50.2% and [M+H] + =268.31

[0459] 3) Preparation of compound 4:

[0460] Compound 3 (2 g, 7.49 mmol) was dissolved in 15 ml of HCl·EA and stirred at room temperature. After 3 h, the reaction solution was dried using a rotary evaporator to obtain a brown oily liquid. Since the reaction solution contained no other impurities, the next step of the reaction was directly carried out.

[0461] 4) Preparation of compound 5:

[0462] The brown oily liquid (Compound 4) obtained in the previous step was dissolved in 2 mL of MeOH and added with 15 mL of NaHCO₃. After reacting for 2 h, the solution was tested for pH 7. Extraction was repeated twice with 50 mL of DCM and 30 mL of H₂O. The combined DCM extracts were washed with saturated NaCl and dried over anhydrous sodium sulfate overnight. Purification by column chromatography and vacuum drying afforded 1.26 g of a yellow oily substance with an 85% yield. 1 H NMR(600MHz,DMSO-d6)δ4.13(d,4H),3.42(t,2H),3.38(dd,2H),3.29(dd,2H),2.97(tt,1H),1.55(s,2H).[M+H] + =168.01

[0463] Example 2 Synthesis of trivalent skeleton

[0464] 29) Preparation of compound 7:

[0465] Dissolve tris(hydroxymethyl)aminomethane (5g, 41.27mmol) in a mixture of 30ml of methanol and 30ml of tert-butanol to obtain a suspension. Add di-tert-butyl dicarbonate (Boc2O) (11.75g, 53.84mmol) dissolved in tert-butanol dropwise and stir at room temperature. A white precipitate gradually forms in the reaction solution. After 8 hours of reaction, dry the reaction solution on a rotary evaporator to obtain a white solid. Add ethyl acetate to the solid, cool to 0°C, and react for 2 hours. Filter to obtain a solid, which is then dried in vacuo (8.20mg, 90% yield). [M+H] + =222.80

[0466] 2) Preparation of compound 8:

[0467] Under ice-bath conditions, KOH (7.87 g, 140.18 mmol) was dispersed in 20 ml of ultra-dry DMF to obtain a DMF solution containing KOH. BOC-aminotris(hydroxymethyl)methane (Compound 7) (5 g, 22.61 mmol) was dissolved in 20 ml of THF / 8 ml of DMF and then slowly added to the DMF solution containing KOH. 3-Bromopropyne (16.68 g, 140.18 mmol) was then added dropwise to the reaction solution, causing the solution to turn brown. The reaction was allowed to proceed at 0°C for 6 h. Extraction was repeated twice with 100 ml of H2O and 140 ml of DCM, respectively. The combined DCM extracts were washed with saturated brine and allowed to stand for 8 h after addition of anhydrous sodium sulfate. Purification by column chromatography and vacuum drying gave 3.6 g of a brownish-yellow solid with a 47.5% yield, [M+H] + =336.29

[0468] 3) Preparation of compound 9:

[0469] Compound 8 (1 g, 2.98 mmol) was dissolved in 15 ml of HCl·EA and stirred at room temperature. After 3 h, the reaction solution was dried using a rotary evaporator to obtain a brown oily liquid. Since the reaction solution contained no other impurities, the next step of the reaction was directly carried out.

[0470] 4) Preparation of compound 10:

[0471] The brown oily liquid (Compound 9) obtained from the previous step was dissolved in 2 ml of MeOH and added with 15 ml of NaHCO₃. After reacting for 2 hours, the solution was tested for pH 7. Extraction was repeated twice with 50 ml of DCM and 30 ml of H₂O. The combined DCM extracts were washed with saturated NaCl and dried over anhydrous sodium sulfate overnight. Purification by column chromatography and vacuum drying afforded 0.58 g of a yellow oily substance with an 83% yield. 1H NMR(600MHz,DMSO-d6)δ4.14(d,6H),3.42(t,3H),3.32(s,6H),1.47(s,2H).[M+H] + =236.12

[0472] Example 3 Synthesis of Zanamivir Dimeric Derivatives

[0473] 29) Preparation of compound R2:

[0474] Methyl 5-acetamido-7,8,9-O-triacetyl-2,6-anhydro-4-azido-3,4,5-trideoxy-D-glycero-D-galacto-non-2-enoate (Compound R1, 2.28 g, 5.0 mmol) was dissolved in anhydrous THF (15 mL) and the solution was cooled to approximately 13°C. After 20 minutes, triphenylphosphine (1.58 g, 6 mmol) was added in portions. The resulting mixture was stirred at approximately 13°C to room temperature for 2 hours, followed by the dropwise addition of a solution of LiOH (12 mg, 0.5 mmol) in water (1 mL). After stirring for 28 hours, N,N'-bis-boc-1-amidinopyrazole (1.63 g, 5.25 mmol) and 4-dimethylaminopyridine (122.2 mg, 1 mmol) were added to the reaction mixture. The reaction was stirred for 1.5 days. It was then diluted with a 1:1 mixture of ethyl acetate: hexane (100 mL) and extracted with water (30 mL). The aqueous layer was back-extracted with ethyl acetate (30 mL). The organic layers were combined and concentrated by rotary evaporator. The residue was purified by C18 reverse phase column chromatography (150 g, 25 to 70% acetonitrile and water). The collected eluate was concentrated by rotary evaporator at room temperature. A turbid aqueous solution was produced and most of the product was deposited on the flask in the form of a gel. The solution was then extracted with ethyl acetate (150 mL). The organic layer was used to redissolve the gel material. It was then dried over Na2SO4, concentrated by rotary evaporator, and further dried under high vacuum to obtain the title compound in the form of a white foam. Yield 3 g, 90.2% yield. Ions found by LCMS: [M+H] + =673.2.

[0475] 2) Preparation of compound R3:

[0476] Compound R2 (3 g, 4.46 mmol) was cooled in anhydrous MeOH (15 mL) in an ice-water bath, and a 0.5 M solution of sodium methoxide in MeOH (13 mL, 6.5 mmol) was slowly added. The stirring was continued for 1 hour, and then the pH was carefully adjusted to 7 to 7.5 by dropwise addition of a solution of hydrochloric acid in 1,4-dioxane (4 M, 2 mL, Innochem, product number A18256). The solvent was removed by rotary evaporation at a temperature not higher than room temperature. The residue was diluted with a 2:1 mixture of ethyl acetate and hexane (150 mL), and the resulting solution was extracted with water (20 mL). The aqueous layer was back-extracted with ethyl acetate (30 mL). The organic layers were combined, dried over anhydrous Na2SO4, concentrated by rotary evaporation, and dried in vacuo. The product was used in the subsequent step without further purification. Yield 2.7 g, 98.4% yield. Ions found by LCMS: [M+H] + =547.26.

[0477] 3) Preparation of compound R4:

[0478] Compound R3 (1 g, 1.82 mmol) was dissolved in anhydrous DCM (6 mL) and cooled in an ice-water bath. 4-Dimethylaminopyridine (221.26 mg, 1.82 mmol) and DIPEA (728 mg, 5.6 mmol) were then added dropwise to the reaction solution. The ice-water bath was then removed, and the reaction solution was stirred for 3 h and monitored by LCMS (additional p-nitrochlorophenylformate was added as needed). After completion of the reaction, water (10 mL) was added to quench the reaction. The organic layer was separated and concentrated on a rotary evaporator, then purified by C18 reverse-phase chromatography (100 g, 20% to 70% acetonitrile and water). The collected eluate was subjected to a rotary evaporator to remove the acetonitrile, and then extracted with a 1:1 mixture of ethyl acetate and hexane (120 mL). The aqueous layer was repeatedly extracted with ethyl acetate (30 mL). The organic phases were combined, dried over anhydrous Na2SO4 for 8 h, concentrated on a rotary evaporator, and dried under vacuum to obtain the product as a white solid. Yield: 712 mg, 68.34%. 1 H NMR(600MHz,DMSO-d6)δ11.39(s,1H),8.26(d,2H),8.15(d,1H),5.80(d,1H),5.71(d,1H),4.98(m,1H),4.88(m,1H),4.5 9(m,1H),4.55(t,1H),4.17(dd,1H),4.10(m,1H),4.01(m,1H),3.73(s,3H),1.85(s,3H),1.47(s,9H),1.40(s,9H).[M+H]+ =573.24.

[0479] 4) Preparation of compound R5:

[0480] Compound R4 (700 mg, 1.22 mmol) was dissolved in 5 ml of extra-dry DCM and cooled in an ice-water bath. Phenyl p-nitrochloroformate (294.6 mg, 1.46 mmol) was then added, followed by dimethylaminopyridine (123.2 mg, 0.61 mmol). The mixture was protected by nitrogen. After removing the ice-water bath, stirring was continued for 3 hours. Phenyl p-nitrochloroformate (201.8 mg, 1 mmol) was further added, and the reaction was continued for 1 hour. After completion of the reaction, the solvent was removed on a rotary evaporator and purified by column chromatography to obtain 540 mg of the product with a 60% yield.

[0481] 5) Preparation of compound R6:

[0482] Compound R5 (240 mg, 0.33 mmol) was dissolved in 5 ml of anhydrous DCM, and triethylene glycol azidoamine (N3-PEG3-NH2, 2-(2-(2-azidoethoxy)ethoxy)ethoxy)ethylamine, 71 mg, 0.33 mmol), 1-hydroxybenzotriazole (HOBT, 43.96 mg, 0.33 mmol), and N,N-diisopropylethylamine (DIPEA, 84.11 mg, 0.65 mmol) were added in sequence. The mixture was protected by nitrogen and stirred at room temperature. After reacting for 8 h, the product was purified by column chromatography to obtain 140 mg of the product with a yield of 51%. 1 H NMR(600MHz,DMSO-d6)δ7.64(m,1H),7.30(m,1H),4.34(t,1H),3.72(d,1H),3.58(m,3H),3.32(m,1H),2.27(t,1H ),1.65(m,1H),1.56(m,1H),1.41(t,3H),1.35(m,2H),1.18(s,24H),0.89(t,2H),0.81(t,8H),0.77(t,2H),[M+H] + =817.34

[0483] Compounds R6-1 and R6-2 were prepared by replacing tripolyethylene glycol ammonia (N3-PEG3-NH2) with hexapolyethylene glycol ammonia (N3-PEG6-NH2) and nonapolyethylene glycol ammonia (N3-PEG9-NH2), respectively.

[0484] 6) Preparation of compound R7:

[0485] Compound R6 (140 mg, 0.168 mmol) and compound 5 (11.29 mg, 0.0672 mmol) were dissolved in 1.5 ml of tetrahydrofuran (THF) and stirred. An aqueous solution of CuSO4·5H2O (6.294 mg, 0.025 mmol) and sodium ascorbate (Na·VC, 9.98 mg, 0.05 mmol) were added to the reaction mixture. After reacting at room temperature for 3 h, the mixture was extracted with DCM and purified by column chromatography to obtain 100 mg of the product with a 33% yield. [M+H] + =1780.3

[0486] Compounds R7-1 and R7-2 were prepared by the same method by replacing compound R6 with compounds R6-1 and R6-2, respectively.

[0487] 7) Preparation of compound R8:

[0488] The raw material prop-2-yn-1-yloxy-PEG2-COOH (2-(2-(2-(prop-2-yn-1-yloxy)ethoxy)ethoxy)acetic acid, 14.68 mg, 0.168 mmol) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDCI, 28.31 mg, 0.145 mmol), HOBT (19.6 mg, 0.145 mmol), DMAP (2.96 mg, 0.024 mmol), and DIPEA (31.27 mg, 0.242 mmol) were added sequentially to 3 ml of ultra-dry DMF under argon protection and stirred at room temperature for 30 minutes. Compound R7 (80 mg, 0.048 mmol) was then added and the mixture was stirred at room temperature under argon protection for 12 hours. The product was purified by column chromatography to obtain 60 mg of the product with a 63% yield. [M+H] + =1984.6

[0489] Using the same method, compound R8-1 was prepared by substituting compound R7-1 for compound R7.

[0490] Compound R8-2 was prepared by using the same method, replacing prop-2-yn-1-yloxy-PEG3-COOH with prop-2-yn-1-yloxy-PEG2-COOH and replacing compound R7 with compound R7-2.

[0491] Compound R8-3 was prepared by using the same method, replacing prop-2-yn-1-yloxy-PEG6-COOH with prop-2-yn-1-yloxy-PEG2-COOH, and replacing compound R7 with compound R7-2.

[0492] 8) Preparation of compound R9:

[0493] Compound R8 (60 mg, 0.03 mmol) was dissolved in 2 ml of ultra-dry DMF, and 2 ml of trifluoroacetic acid (TFA) was added. The mixture was stirred at room temperature for 4 h. TFA was removed by rotary evaporation and purified by C18 reverse phase chromatography to obtain 46 mg of the product with a 97% yield. [M+H] + =1584.5

[0494] The same method was used to prepare compounds R9-1 to R9-3.

[0495] 9) Preparation of Compound R10

[0496] Compound R9 (46 mg, 0.029 mmol) was dissolved in 1.5 ml of methanol, and 200 μl of double-distilled water was added. The pH was adjusted to 12-13 with 10 mol / L NaOH, and the mixture was stirred at room temperature for 4 h. The pH of the reaction system was adjusted to 4 with 4 M hydrochloric acid in 1,4-dioxane. Finally, the product was purified by C18 reverse-phase chromatography to obtain 40 mg of the product with a yield of 91.7%. [M+H] + =1503.9

[0497] Compounds R10-1 to R10-3 were prepared using the same method.

[0498] Example 4. Synthesis of Zanamivir Trimeric Derivatives

[0499] 29) Preparation of compound R11:

[0500] Compound R6 (140 mg, 0.168 mmol) and compound 10 (12.34 mg, 0.0525 mmol) were separately dissolved in 1.5 ml of tetrahydrofuran (THF), mixed and stirred, and aqueous solutions of CuSO4·5H2O (6.294 mg, 0.025 mmol) and sodium ascorbate (Na·VC, 9.98 mg, 0.05 mmol) were added to the reaction solution in sequence. After reacting at room temperature for 3 h, the mixture was extracted with DCM and purified by column chromatography to obtain 106 mg of the product with a yield of 25.5%. 1H NMR (600MHz, CDCl3) δ11.38(s,2H),8.43(d,3H),7.88(s,2H),5.97(d,2H),5.68(s,2 H),5.62(t,2H),5.17(m,3H),5.12(s,2H),4.66(m,12H),4.54(m,8H),4.18(q,3H),3. 89(t,6H),3.78(s,8H),3.68(s,3H),3.57(m,32H),3.31(m,2H),3.23(m,3H),3.31(m ,2H),3.23(m,3H),1.91(s,7H),1.47(s,54H),1.29(d,4H),1.26(d,6H),0.87(m,3H). [M+2H] + =1343.51

[0501] Compounds R11-1 and R11-2 were prepared using the same method by replacing compound R6 with compounds R6-1 and R6-2, respectively.

[0502] 2) Preparation of compound R12:

[0503] The raw material prop-2-yn-1-yloxy-PEG2-COOH (2-(2-(2-(prop-2-yn-1-yloxy)ethoxy)ethoxy)acetic acid, 9.83 mg, 0.0486 mmol) and EDCI (18.96 mg, 0.0972 mmol), HOBT (13.127 mg, 0.0972 mmol), DMAP (1.979 mg, 0.0162 mmol), and DIPEA (20.94 mg, 0.1621 mmol) were added sequentially to 3 ml of ultra-dry DMF, protected by argon, and stirred at room temperature for 30 minutes. Compound R11 (80 mg, 0.03 mmol) was added, and stirring at room temperature under argon protection was continued. After reacting for 12 hours, the product was purified by column chromatography to obtain 82 mg of the product with a yield of 95.3%. 1H NMR(600MHz, CDCl3)δ11.38(s,1H),9.11(s,2H),8.45(d,2H),7.82(dt,2H),7.79(s,1H),7.67(dt,1H),7.37(m,3H),6.89(m,2H) ,5.94(d,2H),5.64(t,2H),5.57(m,1H),5.21(t,2H),5.02(m,2H),4.65(m,4H),4.56(m,9H),4.48(dd,2H),4.17(d,1H),4.14(d,1 H),3.88(t,6H),3.78(d,11H),3.66(m,2H),3.63(m,3H),3.59(m,21H),3.52(m,3H),3.18(m,4H),3.34(m,3H),3.26(dd,2H),1.9 0(s,6H),1.46(t,54H),1.43(d,3H),1.37(s,1H),1.33(s,1H),1.28(d,4H),1.27(s,2H),1.25(s,13H),1.88(t,4H),0.84(m,2H). [M+3H] + =957.42

[0504] Compound R12-1 was prepared by using the same method, substituting compound R11-1 for compound R11.

[0505] Compound R12-2 was prepared by using the same method, replacing compound R11-2 with compound R11.

[0506] Compound R12-3 was prepared by using the same method, replacing prop-2-yn-1-yloxy-PEG6-COOH with prop-2-yn-1-yloxy-PEG2-COOH and replacing compound R11-2 with compound R11.

[0507] 3) Preparation of compound R13:

[0508] Compound R12 (60 mg, 0.028 mmol) was dissolved in 2 ml of ultra-dry DMF, and 2 ml of trifluoroacetic acid (TFA) was added. The mixture was stirred at room temperature for 4 h. TFA was removed by rotary evaporation and purified by C18 reverse phase chromatography to obtain 41 mg of the product with a 64.5% yield. [M+H] + =2268.7

[0509] The same method was used to prepare compounds R13-1 to R13-3.

[0510] 4) Preparation of Compound R14

[0511] Compound R13 (41 mg, 0.018 mmol) was dissolved in 1.5 ml of methanol, and 200 μl of double-distilled water was added. The pH was adjusted to 12-13 with 10 mol / L NaOH, and the mixture was stirred at room temperature for 4 h. The pH of the reaction system was adjusted to 4 with 4 M hydrochloric acid in 1,4-dioxane. Finally, the product was purified by C18 reverse-phase chromatography to obtain 32 mg of the product with an 82.8% yield. [M+H] + =2148.9

[0512] Compounds R14-1 to R14-3 were prepared using the same method.

[0513] Example 5. Synthesis of Peramivir Dimeric Derivatives

[0514] 29) Preparation of compound P2:

[0515] Compound P1 (5 g, 16.7 mmol) was added to DCM (100 ml), and N,N'-bis(tert-butyloxycarbonyl)-1H-pyrazole-1-carboximidamide (7.77 g, 25 mmol) was added. Diisopropylethylamine DIEA (4.3 g, 33.3 mmol) and dimethylaminopyridine DMAP (0.1 g) were added. The reaction was stirred at room temperature for 24 h. TLC detection (DCM:MeOH=10:1) showed that compound P1 was completely reacted. Water (100 ml) was added to the reaction solution, stirred for 10 min, and allowed to stand. The aqueous phase was separated, and the organic phase was washed with 100 ml of water. The organic phase was collected, dried over anhydrous sodium sulfate, filtered, and the filtrate was collected. It was concentrated to dryness and purified by column chromatography (eluent: DCM / MeOH=50:1) to collect the target product to obtain 5.8 g of compound P2 with a yield of 66%.

[0516] 2) Preparation of compound P3:

[0517] Compound P2 (100 mg, 0.184 mmol) was dissolved in 3 ml of anhydrous DCM and stirred in an ice bath. P-nitrophenyl chloroformate (55.7 mg, 0.276 mmol) was added sequentially, followed by dimethylaminopyridine (DMAP) (45.03 mg, 0.368 mmol). Under nitrogen, the ice bath was removed and stirring was continued for 6 hours. P-nitrophenyl chloroformate (27.5 mg, 0.184 mmol) was further added and the reaction continued for 6 hours. After completion of the reaction, the solvent was removed on a rotary evaporator and purified by column chromatography to obtain 98 mg of the product with a 75.3% yield.

[0518] 3) Preparation of compound P4:

[0519] Compound P3 (60 mg, 0.0848 mmol) was dissolved in 5 ml of anhydrous DCM, and triethylene glycol azidoamine (N3-PEG3-NH2, 2-(2-(2-azidoethoxy)ethoxy)ethoxy)ethylamine, 27.783 mg, 0.127 mmol), HOBT (11.47, 0.0848 mmol), and DIPEA (21.94 mg, 0.1697 mmol) were added in sequence. The mixture was stirred at room temperature under nitrogen protection. After 8 h of reaction, the mixture was purified by column chromatography to obtain 62 mg of the product with a yield of 93.0%, [M+H] + =787.3

[0520] Using the same method, replacing tripolyethylene glycol ammonia (N3-PEG3-NH2) with hexapolyethylene glycol ammonia (N3-PEG6-NH2) or nonapolyethylene glycol ammonia (N3-PEG9-NH2) was used to prepare compound P4-1 or P4-2.

[0521] 4) Preparation of compound P5:

[0522] Compound P4 (60 mg, 0.076 mmol) and compound 5 (5.77 mg, 0.0345 mmol) were dissolved in 1.5 ml of tetrahydrofuran (THF) respectively, mixed and stirred, and aqueous solutions of CuSO4·5H2O (9.57 mg, 0.038 mmol) and sodium ascorbate (Na·VC, 15.12 mg, 0.076 mmol) were added to the reaction solution in sequence. After reacting at room temperature for 3 h, the mixture was extracted with DCM and purified by column chromatography to obtain 54 mg of the product with a yield of 40.8%. 1H NMR (600MHz, CDCl3) δ11.43(s,2H),8.56(d,2H),8.24(m,2H),7.97(s,1H),6.14(t,2H),5.18(dd,2H ),4.68(s,3H),4.56(t,4H),4.39(m,2H),4.24(m,2H),3.89(t,4H),3.80(s,2H),3.72(s,6H),3.61( m,17H),3.54(t,5H),3.33(m,5H),2.96(m,2H),2.50(m,2H),2.36(q,2H),2.05(d,6H),1.83(m,2H), 1.48(d,36H),1.41(d,3H),1.28(s,2H),1.25(s,4H),1.11(m,3H),1.05(m,2H),0.85(m,14H),[M+H] + =1741.0540

[0523] Compounds P5-1 and P5-2 were prepared using the same method by substituting compounds P4-1 and P4-2 for compound P4, respectively.

[0524] 5) Preparation of compound P6:

[0525] The starting material, prop-2-yn-1-yloxy-PEG2-COOH (2-(2-(2-(prop-2-yn-1-yloxy)ethoxy)ethoxy)acetic acid, 4.68 mg, 0.023 mmol), EDCI (8.868 mg, 0.046 mmol), HOBT (6.245 mg, 0.046 mmol), DMAP (0.942 mg, 0.008 mmol), and DIPEA (9.96 mg, 0.077 mmol) were added sequentially to 3 ml of ultra-dry DMF under argon protection and stirred at room temperature for 30 minutes. Compound P5 (40 mg, 0.023 mmol) was then added and the mixture was stirred at room temperature under argon protection for 12 hours. The product was purified by column chromatography to obtain 43 mg of the product with a 97.2% yield. [M+H] + =1925.4

[0526] Compound P6-1 was prepared by using the same method, replacing compound P5 with compound P5-1 and replacing prop-2-yn-1-yloxy-PEG2-COOH with prop-2-yn-1-yloxy-PEG6-COOH.

[0527] Compound P6-2 was prepared by using the same method, substituting compound P5-2 for compound P5.

[0528] 6) Preparation of compound P7:

[0529] Compound P6 (40 mg, 0.021 mmol) was dissolved in 2 ml of ultra-dry DMF, and 2 ml of trifluoroacetic acid (TFA) was added. The mixture was stirred at room temperature for 4 h, and the TFA was removed by rotary evaporation. The product was purified by C18 reverse phase chromatography to obtain 29 mg of the product with a yield of 92.0%. [M+H] + =1524.6

[0530] Compounds P7-1 to P7-2 were prepared using the same method.

[0531] 7) Preparation of Compound P8

[0532] Compound P7 (29 mg, 0.019 mmol) was dissolved in 1.5 ml of methanol, and 200 μl of double-distilled water was added. The pH was adjusted to 12-13 with 10 mol / L NaOH, and the mixture was stirred at room temperature for 4 h. The pH of the reaction system was adjusted to 4 with 4 M hydrochloric acid in 1,4-dioxane. Finally, the product was purified by C18 reverse-phase chromatography to obtain 20 mg of the product with a yield of 70.4%. [M+H] + =1496.3

[0533] Compounds P8-1 to P8-2 were prepared using the same method.

[0534] Example 6. Synthesis of Peramivir Trimeric Derivatives

[0535] 29) Preparation of compound P9:

[0536] Compound P4 (300 mg, 0.382 mmol) and compound 10 (28.06 mg, 0.119 mmol) were separately dissolved in 1.5 ml of tetrahydrofuran (THF) and mixed with stirring. An aqueous solution of CuSO4·5H2O (14.29 mg, 0.057 mmol) and sodium ascorbate (Na·VC, 22.68 mg, 0.115 mmol) were added to the reaction solution in sequence. After reacting at room temperature for 3 h, the mixture was extracted with DCM and purified by column chromatography to obtain 190 mg of the product with a yield of 57.5%. 1H NMR(600MHz, CDCl3)δ11.43(s,3H),8.55(d,3H),8.20(d,2H),7.85(s,2H),5.91(t,2H),5.15(dd,3H ),4.62(s,4H),4.55(t,6H),4.41(m,3H),4.22(m,3H),3.89(t,6H),3.72(s,9H),3.62(d,28H),3.54 (m,6H),3.32(q,6H),2.97(m,3H),2.49(m,3H),2.35(m,3H),2.06(s,8H),1.82(m,3H),1.48(d,54H) ,1.42(s,2H),1.38(m,4H),1.28(s,3H),1.25(s,8H),1.13(m,3H),1.04(m,3H),0.84(m,20H),[M+2H] + =1298.2681

[0537] Compounds P9-1 and P9-2 were prepared using the same method by substituting compounds P4-1 and P4-2 for compound P4, respectively.

[0538] 2) Preparation of compound P10:

[0539] The raw material 2-(2-(2-(prop-2-yn-1-yloxy)ethoxy)ethoxy)acetic acid (18.72 mg, 0.093 mmol) and EDCI (35.452 mg, 0.185 mmol), HOBT (24.98 mg, 0.185 mmol), DMAP (3.768 mg, 0.032 mmol), and DIPEA (39.8 mg, 0.308 mmol) were added sequentially to 3 ml of ultra-dry DMF under argon protection and stirred at room temperature for 30 minutes. Compound P9 (160 mg, 0.062 mmol) was added, and stirring at room temperature under argon protection was continued. After reacting for 12 hours, the product was purified by column chromatography to obtain 126 mg with a yield of 73.1%. 1H NMR(600MHz, CDCl3)δ11.43(s,2H),8.55(d,2H),8.20(d,2H),7.71(d,2H),7.36(m,1H),7.31(t,1H),5.79(m,2H),5.30(s, 3H),5.15(m,3H),4.58(s,4H),4.54(t,4H),4.41(m,3H),4.21(m,2H),4.17(d,1H),3.88(m,6H),3.80(s,4H),3.72(s,6H), 3.61(d,20H),3.52(m,4H),3.41(m,2H),3.32(m,6H),2.96(m,3H),2.48(m,3H),2.35(q,3H),2.31(t,1H),2.05(s,6H),1.8 2(m,3H),1.48(d,54H),1.42(s,3H),1.37(s,3H),1.28(s,5H),1.25(s,18H),1.13(m,4H),1.04(m,3H),0.84(m,26H),[M+H] + =2780.5539

[0540] Compound P10-1 was prepared by the same method, using Compound P9-1 instead of Compound P9 and using Prop-2-yn-1-yloxy-PEG6-COOH instead of Prop-2-yn-1-yloxy-PEG2-COOH.

[0541] Compound P10-2 was prepared by using the same method, substituting compound P9-2 for compound P9.

[0542] 3) Preparation of compound P11:

[0543] Compound P10 (120 mg, 0.043 mmol) was dissolved in 2 ml of ultra-dry DMF, and 2 ml of trifluoroacetic acid (TFA) was added. The mixture was stirred at room temperature for 4 h. TFA was removed by rotary evaporation and purified by C18 reverse phase chromatography to obtain 81 mg of the product with an 86.5% yield. [M+H] + =2179.3

[0544] Compounds P11-1 and P11-2 were prepared using the same method.

[0545] 4) Preparation of Compound P12

[0546] Compound P11 (80 mg, 0.036 mmol) was dissolved in 1.5 ml of methanol, and 200 μl of double-distilled water was added. The pH was adjusted to 12-13 with 10 N NaOH and stirred at room temperature for 4 h. The reaction pH was adjusted to 4 with dioxane·4 N HCl. Finally, the product was purified by C18 reverse-phase chromatography to obtain 36 mg of the product with a 46.8% yield. [M+H] + =2137.4

[0547] Compounds P12-1 and P12-2 were prepared using the same method.

[0548] Example 7 Synthesis of Oseltamivir Dimeric Derivatives

[0549] 29) Preparation of compound O2

[0550] The raw material N3-PEG2-(CH2)2-COOH (1.084 g, 5.34 mmol), EDCI (1.53 g, 8.01 mmol), HOBT (1.81 g, 8.01 mmol), and DIPEA (1.378 g, 10.68 mmol) were added sequentially to 10 ml of ultra-dry DMF. Under argon protection, the mixture was stirred at room temperature for 30 minutes. Compound O1 (2 g, 6.4 mmol) was then added. Stirring at room temperature under argon protection continued for 12 hours. The product was purified by column chromatography to obtain 1.76 g of the product with a yield of 60.65%. [M+H] + =498.53

[0551] Using the same method, replacing N3-PEG2-(CH2)2-COOH with N3-PEG6-(CH2)2-COOH, compound O2-1 was prepared.

[0552] 2) Preparation of compound O3

[0553] Compound O2 (430 mg, 0.865 mmol) and compound 5 (57.76 mg, 0.345 mmol) were dissolved in 2 ml of tetrahydrofuran (THF) and stirred. An aqueous solution of CuSO4·5H2O (86 mg, 0.345 mmol) and sodium ascorbate (Na·VC, 136.7 mg, 0.69 mmol) were added to the reaction mixture. After reacting at room temperature for 3 h, the mixture was extracted with DCM and purified by column chromatography to obtain 160 mg of the product with a yield of 79.69%. [M+H] + =1162.48

[0554] Compound O3-1 was prepared by the same method using compound O2-1 instead of compound O2.

[0555] 3) Preparation of compound O4:

[0556] The starting material, prop-2-yn-1-yloxy-PEG2-COOH (2-(2-(2-(prop-2-yn-1-yloxy)ethoxy)ethoxy)acetic acid, 41.8 mg, 0.2067 mmol), EDCI (80.62 mg, 0.4134 mmol), HOBT (55.81 mg, 0.4134 mmol), DMAP (8.42 mg, 0.0689 mmol), and DIPEA (89.05 mg, 0.6891 mmol) were added sequentially to 3 ml of ultra-dry DMF under argon protection and stirred at room temperature for 30 minutes. Compound O3 (160 mg, 0.1378 mmol) was then added and the mixture was stirred at room temperature under argon protection for 12 hours. The product was purified by column chromatography to obtain 170 mg of the product with a 91.72% yield. [M+H] + =1346.22

[0557] Compound O4-1 was prepared by the same method using compound O3-1 instead of compound O3.

[0558] 4) Preparation of compound O5:

[0559] Compound O4 (170 mg, 0.1264 mmol) was completely dissolved in 1 ml of methanol solution, and 5% aqueous NaOH solution was slowly added dropwise. A precipitate was produced, and then the solution gradually became clear. The reaction was continued for 1.5 h. The pH of the reaction was adjusted to 4 with 1N dilute hydrochloric acid in an ice bath. The reaction solution was extracted with n-butanol and purified by column chromatography to obtain 95 mg of the product with a yield of 62.58% [M+H] + =1202.03

[0560] Compound O5-1 was prepared by the same method using compound O4-1 instead of compound O4.

[0561] Example 8. Synthesis of Oseltamivir Trimeric Derivatives

[0562] 29) Preparation of compound O6

[0563] Compound O2 (1.76 g, 3.541 mmol) and compound 10 (250 mg, 1.063 mmol) were dissolved in 1.5 ml of tetrahydrofuran (THF) and stirred. An aqueous solution of CuSO4·5H2O (132.66 mg, 0.53 mmol) and sodium ascorbate (Na·VC, 210.60 mg, 1.06 mmol) were added to the reaction mixture. After reacting at room temperature for 3 h, the mixture was extracted with DCM and purified by column chromatography to obtain 1.28 g of the product with a 62.8% yield. [M+H] + =1727.34

[0564] Compound O6-1 was prepared by the same method using compound O2-1 instead of compound O2.

[0565] 2) Preparation of compound O7:

[0566] The starting material, prop-2-yn-1-yloxy-PEG2-COOH (2-(2-(2-(prop-2-yn-1-yloxy)ethoxy)ethoxy)acetic acid, 57.99 mg, 0.2868 mmol), EDCI (111.85 mg, 0.5736 mmol), HOBT (77.436 mg, 0.5736 mmol), DMAP (11.68 mg, 0.0956 mmol), and DIPEA (123.55 mg, 0.956 mmol) were added sequentially to 3 ml of ultra-dry DMF under argon protection and stirred at room temperature for 30 minutes. Compound O6 (330 mg, 0.1912 mmol) was then added and the mixture was stirred at room temperature under argon protection for 12 hours. The product was purified by column chromatography to obtain 305 mg of the product with an 89.72% yield. [M+H] + =1779.4

[0567] Compound O7-1 was prepared by the same method using compound O6-1 instead of compound O6.

[0568] 3) Preparation of compound O8:

[0569] Compound O7 (150 mg, 0.078 mmol) was completely dissolved in 1 ml of methanol solution, and 5% aqueous NaOH solution was slowly added dropwise. A precipitate was produced, and then the solution gradually became clear. The reaction was continued for 1.5 h. The pH of the reaction was adjusted to 4 with 1N dilute hydrochloric acid in an ice bath. The reaction solution was extracted with n-butanol and purified by column chromatography to obtain 95 mg of the product with a yield of 71.89%. [M+H] + =1695.79

[0570] Compound O8-1 was prepared by the same method using Compound O7-1 instead of Compound O7.

[0571] Example 9 Synthesis of Conjugate

[0572] Compound R14 is coupled to Fc protein (SEQ ID NO: 64) to form conjugate I-1

[0573] The Fc protein (Fc domain, the sequence of which is shown in SEQ ID NO: 64) was replaced in PBS solution, and a 5 mg / ml DMSO stock solution of N3-PEG4-TFP (customized by Hunan Huateng Pharmaceutical Co., Ltd.) was prepared. 5 mg of Fc protein was added to N3-PEG4-TFP (0.278 mg, 0.633 μmol), and the reaction was allowed to proceed overnight at room temperature. The Fc protein was coupled to site # of N3-PEG4-TFP via its N atom. The product was purified by PD-10 desalting chromatography column and concentrated by ultrafiltration to obtain 4.6 mg of Fc-PEG4-N3. Compound R14 (R14: Fc = 20 eq: 1 eq) was then added, and CuSO4·5 was added in sequence. H2O (0.95 mg, 3.81 μmol), tris(3-hydroxypropyltriazolylmethyl)amine (THPTA, 1.66 mg, 3.81 μmol), and sodium ascorbate (Na·VC, 2.7 mg, 13.6 μmol) were reacted at room temperature for 4 h. The mixture was purified by PD-10 desalting chromatography and concentrated by ultrafiltration to obtain conjugate I-1. The HPLC chromatogram is shown in Figure 12, with a purity of 95.57%; the mass spectrum (MS) is shown in Figure 13. In conjugate I-1, E represents the Fc domain monomer (whose amino acid sequence is shown in SEQ ID NO: 64), I2 represents the Fc protein, and T is approximately 3.7.

[0574] In the same manner, compound R14-1 was subjected to a click reaction with Fc-PEG4-N3 to obtain conjugate I-2, wherein the Fc domain monomer (whose amino acid sequence is shown in SEQ ID NO: 64), I2 represents the Fc protein, and T is approximately 3.7.

[0575] In the same manner, compound R14-2 and Fc-PEG5-N3 were subjected to a click reaction to obtain conjugate I-3, wherein the Fc domain monomer (its amino acid sequence is shown in SEQ ID NO: 64), I2 represents the Fc protein, and T is about 3.7.

[0576] In the same manner, compound R14-3 and Fc-PEG6-N3 were subjected to a click reaction to obtain conjugate I-4, wherein the Fc domain monomer (its amino acid sequence is shown in SEQ ID NO: 64), I2 represents the Fc protein, and T is approximately 3.7.

[0577] Compound P11 was click-coupled with Fc-PEG4-N3 using the same method to obtain conjugate I-5. Its HPLC chromatogram is shown in Figure 14 , with a purity of 95.49%; its mass spectrum (MS) is shown in Figure 15 . In conjugate I-5, the Fc domain monomer (whose amino acid sequence is shown in SEQ ID NO: 64) and I2 represent the Fc protein, with a T of approximately 3.7.

[0578] Compound P12 was click-coupled with Fc-PEG4-N3 using the same method to obtain conjugate I-6. Its HPLC chromatogram is shown in Figure 16 , with a purity of 97.41%; its mass spectrum (MS) is shown in Figure 17 . In conjugate I-6, the Fc domain monomer (whose amino acid sequence is shown in SEQ ID NO: 64) is present, I2 represents the Fc protein, and T is approximately 3.5.

[0579] In the same manner, compound P12-1 was subjected to a click reaction with Fc-PEG6-N3 to obtain conjugate I-7, wherein the Fc domain monomer (its amino acid sequence is shown in SEQ ID NO: 64), I2 represents the Fc protein, and T is about 3.5.

[0580] In the same manner, compound P12-2 was subjected to a click reaction with Fc-PEG4-N3 to obtain conjugate I-8, wherein the Fc domain monomer (its amino acid sequence is shown in SEQ ID NO: 64), I2 represents the Fc protein, and T is approximately 3.5.

[0581] Compound O8 was click-coupled with Fc-PEG4-N3 using the same method to obtain conjugate I-9. Its HPLC chromatogram is shown in Figure 22 , with a purity of 93.22%; its mass spectrum (MS) is shown in Figure 23 . In conjugate I-9, E represents the Fc domain monomer (whose amino acid sequence is shown in SEQ ID NO: 64), I2 represents the Fc protein, and T is approximately 3.2.

[0582] In the same manner, compound O8-1 was subjected to a click reaction with Fc-PEG4-N3 to obtain conjugate I-10, wherein E is an Fc domain monomer (whose amino acid sequence is shown in SEQ ID NO: 64), I2 represents Fc protein, and T is approximately 3.2.

[0583] Compound R10 was click-coupled with Fc-PEG4-N3 using the same method to obtain conjugate II-1. The HPLC chromatogram is shown in Figure 18 , with a purity of 93.27%. The mass spectrum (MS) is shown in Figure 19 . In conjugate II-1, the Fc domain monomer (whose amino acid sequence is shown in SEQ ID NO: 64) and I2 represent the Fc protein, with a T of approximately 3.7.

[0584] In the same manner, compound R10-1 was subjected to a click reaction with Fc-PEG4-N3 to obtain conjugate II-2, wherein the Fc domain monomer (whose amino acid sequence is shown in SEQ ID NO: 64), I2 represents the Fc protein, and T is approximately 3.7.

[0585] In the same manner, compound R10-2 was subjected to a click reaction with Fc-PEG5-N3 to obtain conjugate II-3, wherein the Fc domain monomer (its amino acid sequence is shown in SEQ ID NO: 64), I2 represents the Fc protein, and T is approximately 3.7.

[0586] In the same manner, compound R10-3 was subjected to a click reaction with Fc-PEG6-N3 to obtain conjugate II-4, wherein the Fc domain monomer (its amino acid sequence is shown in SEQ ID NO: 64), I2 represents the Fc protein, and T is approximately 3.7.

[0587] Compound P8 was reacted with Fc-PEG4-N3 via click fusion reaction using the same method to obtain conjugate II-6. The HPLC chromatogram is shown in Figure 20 , with a purity of 100.00%; the mass spectrum (MS) is shown in Figure 21 . In conjugate II-6, the Fc domain monomer (whose amino acid sequence is shown in SEQ ID NO: 64) is present, I2 represents the Fc protein, and T is approximately 3.5.

[0588] In the same manner, compound P7 was subjected to a click reaction with Fc-PEG4-N3 to obtain conjugate II-5, wherein the Fc domain monomer (its amino acid sequence is shown in SEQ ID NO: 64), I2 represents the Fc protein, and T is about 3.5.

[0589] In the same manner, compound P8-1 and Fc-PEG6-N3 were subjected to a click reaction to obtain conjugate II-7, wherein the Fc domain monomer (its amino acid sequence is shown in SEQ ID NO: 64), I2 represents the Fc protein, and T is about 3.5.

[0590] In the same manner, compound P8-2 and Fc-PEG4-N3 were subjected to a click reaction to obtain conjugate II-8, wherein the Fc domain monomer (its amino acid sequence is shown in SEQ ID NO: 64), I2 represents the Fc protein, and T is about 3.5.

[0591] In the same manner, compound O5 was subjected to a click reaction with Fc-PEG4-N3 to obtain conjugate II-9, wherein the Fc domain monomer (its amino acid sequence is shown in SEQ ID NO: 64), I2 represents the Fc protein, and T is about 3.2.

[0592] In the same manner, compound O5-1 was reacted with Fc-PEG4-N3 by click reaction to obtain conjugate II-10, wherein the Fc domain monomer (its amino acid sequence is shown in SEQ ID NO: 64), I2 represents the Fc protein, and T is about 3.2.

[0593] Example 9-1 Synthesis of Conjugate II

[0594] 1. Preparation of Compound P12-A

[0595] To a solution of compound P12 (300 mg, 0.140 mmol) and 2,3,5,6-tetrafluorophenyl 1-azido-3,6,9,12-tetraoxopentadecane-15-oate (93 mg, 0.212 mmol) in N,N-dimethylformamide (2 mL), dimethyl sulfoxide (2 mL), and water (4 mL) was added copper sulfate pentahydrate (18 mg, 0.072 mmol) and an aqueous solution of sodium ascorbate (28 mg, 0.141 mmol) at room temperature. After the addition was complete, the mixture was stirred at room temperature for 30 min. The reaction mixture was directly subjected to HPLC preparative separation without treatment. Preparation conditions: Shim-pack GIST C18 (20 mm × 250 mm, 5 μm); A: 0.1% TFA in water, B: MeCN; 40 mL / min; 0-3 min, 10% B; 3-3.5 min, 10%-25% B; 3.5-14 min, 25%-60% B; 14-14.5 min, 60%-100% B; detector, UV 254 nm. The product P12-A (98.28 mg, 0.034 mmol, 24.03%) was obtained as a white solid. 1 H NMR(500MHz,DMSO-d6)δppm 12.64(br s,3H),8.01(s,3H),7.63(d,J=7.6Hz,3H),7.29(br s,4H),7.01(t,J=6.3Hz,3H),6.82-6.88(m,3H),6.70(br s,4H),5.14-5.20(m,3H),4.45-4.54(m,15H),4.34(t,J=10.4Hz,3H),3.75-3.85(m, 14H),3.66(s,6H),3.35-3.56(m,44H),3.06-3.18(m,6H),3.01(t,J=6.0Hz,2H),2.57 -2.69(m,7H),2.26-2.34(m,3H),1.96-2.04(m,2H),1.78(s,9H),1.52-1.60(m,3H), 1.40-1.48(m,5H),1.20-1.32(m,12H),1.01-1.08(m,4H),0.78-0.91(m,21H); ESI-MS m / z=1289.3[M / 2+H] + ;Calcu.=2575.3。

[0596] 2. Synthesis of Conjugate I-6

[0597] A 50 mg / mL stock solution of P12-A was prepared using DMSO. Fc protein (10 mg / mL, 37.32 mg, 0.67 μmol) was exchanged into 50 mM PBS (pH 7.4). 11 eq of P12-A small molecule stock solution (50 mg / mL, 19.05 mg, 7.4 μmol) was added, with DMSO accounting for 10% of the total system. The reaction was shaken at room temperature overnight. The sample was then exchanged into 20 mM histidine buffer (pH 5.0) using a 30 kD ultrafiltration centrifuge tube (Millipore) to obtain a total of 12.5 mg of conjugate I-6. The SEC-HPLC chromatogram is shown in Figure 1, indicating a purity of 99.6%. The mass spectrum (MS) is shown in Figure 2, indicating a DAR value of 3.8.

[0598] Conjugates I-1 to I-5, I-7 to I-10 and conjugates II-1 to II-10 can also be synthesized using the same method.

[0599] Example 10 Evaluation of NA enzyme activity inhibition

[0600] To verify the activity of inhibiting influenza virus at the enzyme level, the polymeric small molecule derivatives and conjugates provided in the examples of the present application and small molecule drugs (zanamivir (purchased from Adamas-beta, Catalog #C63-102157A), peramivir (Bidec Pharmaceuticals, Catalog #BD317210), and oseltamivir phosphate (purchased from Inocare, Catalog #A90108)) were tested for their half-maximal inhibitory concentration (IC50) against NA (A / California / 04 / 2009, H1N1, purchased from Sino Biological, Catalog #11058-VNAHC) 50 The drug was mixed with NA protein in a gradient dilution and incubated at room temperature for 30 minutes. Then, MUNANA substrate (purchased from Sigma, Catalog # M8639) was added and its fluorescence intensity was detected on a microplate reader (Molecular Devices, SpectraMax Gemini EM). Finally, IC 50 ,As shown in Figures 1 and 2, the conjugates all showed good ability to inhibit NA enzyme activity.

[0601] Example 11 Evaluation of NA enzyme activity inhibition in drug-resistant strains

[0602] To verify the activity of influenza virus inhibition at the enzyme level, the half-maximal inhibitory concentration (IC50) of the multi-small molecule derivatives and conjugates provided in the examples of the present application and small molecule drugs (zanamivir, peramivir, oseltamivir phosphate) against NA (A / California / 04 / 2009, H275Y, H1N1, purchased from Sino Biological, Catalog #11058-VNAHC) was tested. 50 The drug was mixed with NA protein in gradient dilution and incubated at room temperature for 30 minutes. Then MUNANA substrate was added and its fluorescence intensity was detected on a microplate reader. Finally, IC 50 ,As shown in Figures 3 and 4, the conjugates showed good inhibitory ability against the NA enzyme activity of drug-resistant strains.

[0603] Example 12 Evaluation of in vitro anti-influenza virus activity

[0604] To verify the activity of inhibiting influenza virus at the cellular level, A / Victoria / 2570 / 2009(H1N1) (kindly provided by Xiamen University), A / California / 04 / 2009(H1N1) (kindly provided by Xiamen University), A / Vietnam / 2004(H5N1), A / Shanghai / 02 / 2013(H7N9) (kindly provided by Xiamen University), B / Phuket / 3073 / 2013(BY) (kindly provided by Xiamen University), A / Puerto The antiviral activity was tested in the MDCK cell model (kindly donated by Xiamen University) infected with nine virus strains, including Rico / 8 / 1934 (H1N1-PR8) (purchased from NIBSC, NIBSC16 / 108), A / Victoria / 2570 / 2019 (H1N1) (purchased from NIBSC, NIBSC21 / 346), A / Darwin / 9 / 2021 (H3N2) (purchased from NIBSC, NIBSC21 / 214), and B / Austria / 1359417 / 2021 (BV) (purchased from NIBSC, NIBSC21 / 224). Different concentrations of the multi-small molecule derivatives or conjugates or small molecule drugs (zanamivir, peramivir, oseltamivir acid) provided in the examples of the present application were mixed with the virus and incubated at 37°C for one hour. The mixture was then added to a monolayer of 80-90% confluent MDCK cells and the cells were washed after 90 minutes of incubation. The monolayer cells were then covered with carboxymethylcellulose (purchased from Inochem, A05925) to minimize viral spread and the incubation was continued for two days. After two days of incubation, the effective drug concentration (EC) that could inhibit 50% CPE production was recorded. 50), and the results are shown in Tables 1 and 2. The inhibition curves of the drug against A / Puerto Rico / 8 / 1934 (H1N1-PR8), A / Victoria / 2570 / 2019 (H1N1), A / Darwin / 9 / 2021 (H3N2), and B / Austria / 1359417 / 2021 (BV) viruses are shown in Figures 26-29.

[0605] Table 1

[0606] Table 2

[0607] Example 13 Pharmacokinetic Analysis

[0608] In order to verify whether the conjugate drug provided in the embodiment of the present application has a long-lasting protective effect, the pharmacokinetics of the conjugate drug in mice were analyzed. Four healthy BALB / c mice (purchased from Weitong Lihua) were selected from each group and injected intravenously with 10 mg / kg of I-1, 1-6 or Fc protein (purchased from Yiqiao Shenzhou, customized, JS95A). 20 μL blood samples were taken from the mice at different time points to detect the concentration of the drug. Blood samples were taken at different time intervals. Anticoagulant (saturated EDTA-Na2) was immediately added to the collected blood samples, and the supernatant was extracted after centrifugation for standby use. 96-well plates were coated with NA protein (purchased from Sino Biological, 11058-V08B-(MF14DE2511)) and incubated with various concentrations of I-1 and I-6 at room temperature for 1 hour. Serum drug concentrations were then measured using a sandwich ELISA using a goat anti-human IgG (Fc) antibody, peroxidase-labeled (SeraCare, CAT: 5220-0279). The results, shown in Figure 5, demonstrate that the conjugate has a long plasma half-life and can maintain the drug at an effective concentration for a long time.

[0609] Example 14 ADCC effect analysis

[0610] Fc has certain biological functions and may activate the body's ADCC and ADCP effects to enhance antiviral activity. In order to verify whether the conjugate has this function, a virus-infected cell model was constructed and first cultured at 37°C and 5% CO2 for 18-24 hours. Then, an ADCC reporter cell line was added, which stably expressed the FcγRIIIa receptor. Finally, different concentrations of the test drug were added. After incubation at 37°C and 5% CO2 for 15 minutes, the fluorescence intensity emitted by the ADCC reporter cell line was detected, and then the intensity of the ADCC effect caused by the conjugate was detected. As shown in Figure 6, the conjugate provided in the embodiment of the present application can maintain the same ADCC effect as Fc.

[0611] Example 15 Evaluation of the Conjugate's Inhibition of Viral Replication in Mice

[0612] 1. In order to study whether the conjugate provided in the examples of the present application can inhibit the viral replication in the lungs and nasal concha of mice, about 1×10 6 PFU or approximately 1 × 10 7 PFU of H1N1 influenza virus (A / California / 07 / 2009, kindly donated by Xiamen University) was administered 2 hours after the challenge, and a single dose of conjugate (3, 9 mg / kg), PBS or negative control Fc protein (purchased from Yiqiao Shenzhou, customized, JS95A, 3 mg / kg) was intravenously injected. The positive control zanamivir (5 mg / kg) was intravenously injected 2 hours after the challenge, once a day, for 3 consecutive days. Oseltamivir phosphate (20 mg / kg) was orally administered 2 hours after the challenge, twice a day, for 3 consecutive days. All mice were euthanized on the fourth day after the challenge, and the viral load at the lungs and nasal concha was detected. The results are shown in Figure 7, which show that at different challenge doses, the conjugate provided in the examples of the present application can effectively inhibit the replication of the virus.

[0613] 2. BALB / c mice were inoculated with 10×LD 50 The mice were administered a single dose (3 mg / kg) of the conjugate intravenously 2 hours after the challenge with influenza virus (A / Puerto Rico / 8 / 1934 (H1N1-PR8)). Positive controls, oseltamivir (10 mg / kg) and mabaloxavir (5 mg / kg), were administered orally. The viral content in the bronchoalveolar lavage fluid was detected on the 6th day after administration, and the body weight and survival rate were monitored daily. The results are shown in Figures 30-32, indicating that therapeutic administration of the conjugates provided in the Examples of the present application, such as I-6, I-1, and II-6, can effectively inhibit viral replication with minimal toxic side effects. The mice can gain normal weight and have a high survival rate.

[0614] 3.BALB / c mice were intravenously injected with a single dose (3 mg / kg) of the conjugate, and the positive controls oseltamivir (10 mg / kg) and mabaloxavir (5 mg / kg) were orally administered. Fifteen days after administration, the mice were challenged with 10×LD 50 The mice were inoculated with influenza virus (A / Puerto Rico / 8 / 1934 (H1N1-PR8)). Viral levels in bronchoalveolar lavage fluid were measured six days after inoculation, and body weight and survival rate were monitored daily. The results, shown in Figures 33-35, demonstrate that prophylactic administration of the conjugates provided in the Examples of this application, such as I-6, I-1, and II-6, effectively inhibited viral replication with minimal toxic side effects, maintained normal weight gain, and maintained a high survival rate.

[0615] Example 16 Evaluation of the Anti-Influenza Virus Activity of the Conjugate in Vivo

[0616] In order to significantly compare the antiviral activity of the conjugates provided in the examples of this application, the influenza susceptible model DBA / 2 mouse model (purchased from Vital River) was selected. Compared with the BALB / c mouse model, this model can develop severe influenza symptoms at a lower challenge dose. 6-week-old female DBA / 2 mice (10 per group) were selected and 1×10 4 The dose of PFU was administered by nasal drop challenge (A / California / 07 / 2009), and the conjugate (I-1, I-5) (0.3, 3 mg / kg), PBS or negative control Fc protein (3 mg / kg, 9 mg / kg, purchased from Yiqiao Shenzhou, customized, JS95A) was injected into the tail vein once 2 hours after the challenge. The positive control zanamivir (5 mg / kg) was intravenously injected 2 hours after the challenge, once a day, for 5 consecutive days, and oseltamivir phosphate (20 mg / kg) was orally administered 2 hours after the challenge, twice a day, for 5 consecutive days. Body weight and survival rate were monitored every day (a 25% decrease in body weight was considered death) and observed for 14 days. The results are shown in Figures 9-12. In the DBA / 2 mouse model, it can be seen from Figure 8 that the body weight dropped to the lowest on the 7th day after the challenge, among which I-1 (3 mg / kg) can significantly alleviate the weight loss of mice. All mice in the PBS group and the Fc protein control group died on the fifth day (Figure 9), and all mice still died after high-dose, multiple-frequency administration of the positive control drugs oseltamivir phosphate and zanamivir (Figure 10). However, I-1 and I-5 were still able to achieve good protection rates at a single dose as low as 3 mg / kg (Figure 11), and I-5 was able to achieve a protection rate as high as 90%. The above results demonstrate the significant antiviral activity of the single-dose conjugate.

Claims

1. The conjugate represented by formula (I) or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein A1, A2 and A3 are each independently selected from Formula (A-I) to Formula (A-XIV), Among them, L can be linked to any possible site of the compound of formula (A-XIV); wherein R1 is selected from -OH, -NH2, -NHC(=NH)NH2 and -NHC(=NH)NHR6; R2 and R3 are each independently selected from -H, -OH, -F, -Cl and -Br; R4 is selected from -C(=O)OH, -P(=O)(OH)2, -SO3H, -C(=O)OCH3 and -C(=O)OCF3; R5 is selected from -C(=O)CH3, -C(=O)CF3, -SO2CH3; X is selected from -O- and -S-; Y is selected from -O-, -S-, -NR7-, -OC(=O)NR7-, -OC(=S)NR7-, -OC(=O)O-, -OC(=O)-, -NHC(=O)O-, -NHC(=O)-, -NHC(=NH)-, -NHC(=O)NR7-, -NHC(=NH)NR7-, -NHC(=S)NR7-, -NHC(=S)-, -OCH2C(=O)NR7-, -NH(SO2)- and -NH(SO2)NR7-; R' is H or C1-C6 alkyl; R6 is selected from R7 is selected from H, C1-C 20 alkyl, C3-C 20 cycloalkyl, C3-C 20 heterocycloalkyl; C5-C 15 aryl and C5-C 15 heteroaryl; preferably, R7 is H; preferably, C1-C6 alkyl; each E is a biological macromolecule; n is 1 or 2; T is a number between 1 and 20; The wavy lines connecting to each E represent each covalently linked (e.g., by means of a covalent bond or a linker) to the N atom in each E (e.g., the N atom on the side chain amino group of a lysine, arginine, asparagine or glutamine residue), and L is a linker covalently linked to each of the groups E, A1, A2 and A3.

2. The conjugate of claim 1 or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein A1, A2 and A3 are each independently selected from formula (A-I) to formula (A-XIII), Preferably, A1, A2, and A3 are each independently selected from Formula (A-I) to Formula (A-IV) and Formula (A-VII). wherein the definitions of R1, R2, R3, R4, R5, R', X, Y are as described in claim 1; each E comprises an Fc domain monomer (e.g., an Fc domain monomer having a sequence of any one of SEQ ID NOs: 1-68), albumin (e.g., albumin having a sequence of any one of SEQ ID NOs: 69-71), an albumin-binding peptide or an Fc-binding peptide; n is 1 or 2, and when n is 2 and E is an Fc domain monomer, two Es dimerize to form an Fc domain; L is a linker covalently linked to each of the groups E, A1, A2 and A3; Preferably, A1, A2 and A3 are each independently selected from Formula (A-I) to Formula (A-III) and Formula (A-VII). wherein the definitions of R1, R2, R3, R4, R5, R', X, Y are the same as above; Preferably, A1, A2 and A3 are each independently selected from formula (A-I), formula (A-III) and formula (A-VII), wherein the definitions of R1, R4, R5, R', X, Y are the same as above.

3. The conjugate of claim 1 or 2, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein E comprises an Fc domain monomer (e.g., an Fc domain monomer having a sequence of any one of SEQ ID NOs: 1-68); n is 1 or 2, and when n is 2, two Es dimerize to form an Fc domain; L is a linker covalently linked to each of the groups E, A1, A2 and A3; Preferably, the Fc domain monomer has an amino acid sequence selected from: i) any one of the sequences shown in SEQ ID NOs: 1-68; ii) a sequence having one or several amino acid substitutions, deletions or additions (such as 1, 2, 3, 4 or 5 amino acid substitutions, deletions or additions) compared with any one of the sequences shown in SEQ ID NO: 1-68; and iii) a sequence having at least 70% identity (such as 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity) with any one of the sequences shown in SEQ ID NO: 1-68; Preferably, the substitution described in ii) is a conservative substitution; Preferably, E is a monomer of the Fc domain of a sequence having at least 70% identity (such as 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity) with the sequence of SEQ ID NO: 64; Preferably, E is a monomer of the Fc domain having the sequence of SEQ ID NO: 64; Preferably, R1 is selected from -OH, -NH2, -NHC(=NH)NH2; more preferably, R1 is -NHC(=NH)NH2; Preferably, R4 is selected from -C(=O)OH, -C(=O)OCH3 and -C(=O)OCF3; more preferably, R4 is selected from -C(=O)OH and -C(=O)OCH3; Preferably, R5 is selected from -C(=O)CH3 and -C(=O)CF3; more preferably, R5 is -C(=O)CH3; Preferably, R' is H or C1-C4 alkyl; more preferably, R' is H, methyl or ethyl; more preferably, R' is H or ethyl; Preferably, X is -O-; Preferably, Y is selected from -O-, -S-, -NH-; more preferably, Y is selected from -O- and -NH-.

4. The conjugate of any one of claims 1-3, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the conjugate has a structure represented by formula (I-II-A), formula (I-II-B) or formula (I-II-C). Wherein the definitions of R1, R4, R5, R', X, Y, E, n, L, T are as described in any one of claims 1-3.

5. The conjugate according to any one of claims 1-4, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the conjugate has a structure represented by formula (I-II-A'), formula (I-II-B') or formula (I-II-C'), Wherein the definitions of R1, R4, R5, R', X, Y, E, n, T are as described in any one of claims 1-4. L1 is selected from: Wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)- or -CH2-; Z1 and Z2 are each independently selected from -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)- or -CH2-; m and p are each independently an integer from 1 to 20; Preferably, L1 is selected from: Wherein the definitions of V, p, m, Z are as described above; Preferably, L1 is Wherein the definitions of V, p, m, Z are as described above; Preferably, V is -CH2- or -O-; more preferably, V is -O-; Preferably, Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)- or -C(=O)-; more preferably, Z is -NH-C(=O)- or -C(=O)-; Preferably, p is an integer between 1 and 10; more preferably, p is an integer between 1 and 6 (e.g., 1, 2, 3, 4, 5, 6); Preferably, m is an integer between 1 and 12; more preferably, m is an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9).

6. The conjugate according to any one of claims 1-5, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the conjugate has a structure represented by formula (I-II-A'-1), formula (I-II-B'-1), formula (I-II-B'-2) or formula (I-II-C'-1); Wherein the definitions of E, n, and T are as described in any one of claims 1-4, and the definition of L1 is as described in claim 5.

7. The conjugate according to any one of claims 1-6, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the conjugate has a structure represented by formula (I-II-A-2), formula (I-II-B-3), formula (I-II-B-4) or formula (I-II-C-2), Wherein the definitions of E, n, and T are as described in any one of claims 1-4, and the definition of L1 is as described in claim 5; L2 is selected from: Wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)- or -CH2-; Z1 and Z2 are independently selected from -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)- or -CH2-; m and p are each independently an integer from 1 to 20; Preferably, L2 is selected from: Wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)- or -CH2-; m and p are each independently an integer from 1 to 20; L3 is Wherein U is -C(=O)-NH-, -NH-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)-, -CH2-; W is -CH2-, -O- or -S-; i and q are each independently an integer from 1 to 20, one end of L3 is covalently connected to E, and the other end is covalently connected to L2; Preferably, L1 is Wherein the definitions of V, p, m, and Z are as described above; preferably, V is -CH2- or -O-; more preferably, V is -O-; preferably, Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, or -C(=O)-; more preferably, Z is -NH-C(=O)- or -C(=O)-; preferably, p is an integer between 1 and 10; more preferably, p is an integer between 1 and 6 (e.g., 1, 2, 3, 4, 5, 6); preferably, m is an integer between 1 and 12; more preferably, m is an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9); Preferably, L2 is Wherein the definitions of V, p, m, and Z are as described above; preferably, V is -CH2- or -O-; more preferably, V is -O-; preferably, Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-; more preferably, Z is -C(=O)-NH-; preferably, p is an integer between 1 and 10; more preferably, p is an integer between 1 and 6 (e.g., 1, 2, 3, 4, 5, 6); preferably, m is an integer between 1 and 12; more preferably, m is an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9); Preferably, L3 is Wherein the definitions of U, i, and q are as described above; preferably, U is -NH-C(=O)-, -N(CH3)-C(=O)-, or -N(CH2CH3)-C(=O)-; more preferably, U is -NH-C(=O)-; preferably, i is an integer between 1 and 12; more preferably, i is an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9); preferably, q is an integer between 1 and 10; more preferably, q is an integer between 1 and 6 (e.g., 1, 2, 3, 4, 5, 6); Preferably, T is a number between 1 and 10; more preferably, T is a number between 1 and 9; more preferably, T is a number between 1 and 7; more preferably, T is a number between 1 and 5, more preferably, T is a number between 3 and 7, more preferably, T is a number between 3 and 5.

5.

8. The conjugate of any one of claims 1-7, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the conjugate has a structure represented by formula (I-II-A-3), formula (I-II-B-5), formula (I-II-B-6) or formula (I-II-C-3). Wherein the definitions of E, n, and T are as described in any one of claims 1-7; n1, n2, and n3 are each independently an integer between 1 and 20; Preferably, n1, n2, and n3 are each independently an integer between 1 and 12; more preferably, n1, n2, and n3 are each independently an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9).

9. The conjugate according to any one of claims 1-8, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the conjugate is selected from: Wherein the definitions of E, n, and T are as described in any one of claims 1-8.

10. The conjugate represented by formula (II) or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein A1 and A2 are each independently selected from Formula (A-I) to Formula (A-XIV), Among them, L can be linked to any possible site of the compound of formula (A-XIV); wherein R1 is selected from -OH, -NH2, -NHC(=NH)NH2 and -NHC(=NH)NHR6; R2 and R3 are each independently selected from -H, -OH, -F, -Cl and -Br; R4 is selected from -C(=O)OH, -P(=O)(OH)2, -SO3H, -C(=O)OCH3 and -C(=O)OCF3; R5 is selected from -C(=O)CH3, -C(=O)CF3, -SO2CH3; X is selected from -O- and -S-; Y is selected from -O-, -S-, -NR7-, -OC(=O)NR7-, -OC(=S)NR7-, -OC(=O)O-, -OC(=O)-, -NHC(=O)O-, -NHC(=O)-, -NHC(=NH)-, -NHC(=O)NR7-, -NHC(=NH)NR7-, -NHC(=S)NR7-, -NHC(=S)-, -OCH2C(=O)NR7-, -NH(SO2)- and -NH(SO2)NR7-; R' is H or C1-C6 alkyl; R6 is selected from R7 is selected from H, C1-C 20 alkyl, C3-C 20 cycloalkyl, C3-C 20 heterocycloalkyl; C5-C 15 aryl and C5-C 15 heteroaryl; preferably, R7 is H; preferably, C1-C6 alkyl; each E is a biological macromolecule; n is 1 or 2; T is a number between 1 and 20; The wavy line connected to each E indicates that each A1-L-A2 is covalently linked (e.g., by a covalent bond or a linker) to the N atom in each E (e.g., the N atom on the side chain amino group of a lysine, arginine, asparagine or glutamine residue), and L is a linker covalently linked to each of the groups E, A1, and A2.

11. The conjugate of claim 10 or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein A1 and A2 are each independently selected from formula (A-I) to formula (A-XIII), Preferably, A1 and A2 are each independently selected from Formula (A-I) to Formula (A-IV) and Formula (A-VII). wherein the definitions of R1, R2, R3, R4, R5, R', X, and Y are as described in claim 10; each E comprises an Fc domain monomer (e.g., an Fc domain monomer having a sequence of any one of SEQ ID NOs: 1-68), albumin (e.g., albumin having a sequence of any one of SEQ ID NOs: 69-71), an albumin-binding peptide or an Fc-binding peptide; n is 1 or 2, and when n is 2 and E is an Fc domain monomer, two Es dimerize to form an Fc domain; Preferably, A1 and A2 are each independently selected from Formula (A-I) to Formula (A-III) and Formula (A-VII). wherein the definitions of R1, R2, R3, R4, R5, R', X, and Y are the same as above; Preferably, A1 and A2 are each independently selected from formula (A-I), formula (A-III), and formula (A-VII). wherein the definitions of R1, R4, R5, R', X, and Y are the same as above.

12. The conjugate of claim 10 or 11, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein E comprises an Fc domain monomer (e.g., an Fc domain monomer having a sequence of any one of SEQ ID NOs: 1-68); n is 1 or 2, and when n is 2, two Es dimerize to form an Fc domain; Preferably, the Fc domain monomer has an amino acid sequence selected from: i) any one of the sequences shown in SEQ ID NOs: 1-68; ii) a sequence having one or several amino acid substitutions, deletions or additions (such as 1, 2, 3, 4 or 5 amino acid substitutions, deletions or additions) as compared with any one of the sequences shown in SEQ ID NO: 1-68; and iii) a sequence having at least 70% identity (such as 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity) with any one of the sequences shown in SEQ ID NO: 1-68; Preferably, the substitution described in ii) is a conservative substitution; Preferably, E is a monomer of the Fc domain of a sequence having at least 70% identity (such as 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity) with the sequence of SEQ ID NO: 64; Preferably, E is a monomer of the Fc domain having the sequence of SEQ ID NO: 64; Preferably, R1 is selected from -OH, -NH2, -NHC(=NH)NH2; More preferably, R1 is -NHC(=NH)NH2; Preferably, R4 is selected from -C(=O)OH, -C(=O)OCH3 and -C(=O)OCF3; More preferably, R4 is selected from -C(=O)OH and -C(=O)OCH3; Preferably, R5 is selected from -C(=O)CH3 and -C(=O)CF3; More preferably, R5 is -C(=O)CH3; Preferably, R' is H or a C1-C4 alkyl; More preferably, R' is H, methyl or ethyl; More preferably, R' is H or ethyl; Preferably, X is -O-; Preferably, Y is selected from -O-, -S-, -NH-; More preferably, Y is selected from -O- and -NH-.

13. The conjugate according to any one of claims 10 - 12, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the conjugate has a structure represented by formula (II-II-A), formula (II-II-B) or formula (II-II-C). Wherein the definitions of R1, R4, R5, R', X, Y, E, n, L, T are as described in any one of claims 10-12.

14. The conjugate according to any one of claims 10 - 13, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the conjugate has the structure shown by formula (II-II-A'), formula (II-II-B') or formula (II-II-C'), Wherein the definitions of R1, R4, R5, R', X, Y, E, n, T are as described in any one of claims 10-12; L1 is selected from: Wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)- or -CH2-; Z1 and Z2 are each independently selected from -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)- or -CH2-; m and p are each independently an integer from 1 to 20; Preferably, L1 is selected from: Wherein the definitions of V, p, m, Z are as described above; Preferably, L1 is Wherein the definitions of V, p, m, Z are as described above; Preferably, V is -CH2- or -O-; more preferably, V is -O-; Preferably, Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)- or -C(=O)-; more preferably, Z is -NH-C(=O)- or -C(=O)-; Preferably, p is an integer between 1 and 10; more preferably, p is an integer between 1 and 6 (e.g., 1, 2, 3, 4, 5, 6); Preferably, m is an integer between 1 and 12; more preferably, m is an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9).

15. The conjugate according to any one of claims 10-14, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the conjugate has a structure represented by formula (II-II-A-1), formula (II-II-B-1), formula (II-II-B-2) or formula (II-II-C-1). Wherein the definitions of E, n, and T are as described in any one of claims 10 - 13, and the definition of L1 is as described in claim 14.

16. The conjugate of any one of claims 10-15, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the conjugate has the structure shown in formula (II-II-A-2), formula (II-II-B-3), formula (II-II-B-4) or formula (II-II-C-2). Wherein the definitions of E, n, and T are as described in any one of claims 10 - 13, and the definition of L1 is as described in claim 14; L2 is selected from: Wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)- or -CH2-; Z1 and Z2 are independently selected from -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)- or -CH2-; m and p are each independently an integer from 1 to 20; Preferably, L2 is selected from: Wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)- or -CH2-; m and p are each independently an integer from 1 to 20; L3 is Wherein U is -C(=O)-NH-, -NH-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)-, -CH2-; W is -CH2-, -O- or -S-; i and q are each independently an integer from 1 to 20, one end of L3 is covalently connected to E, and the other end is covalently connected to L2; Preferably, L1 is Wherein the definitions of V, p, m, and Z are as described above; preferably, V is -CH2- or -O-; more preferably, V is -O-; preferably, Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)- or -C(=O)-; more preferably, Z is -NH-C(=O)- or -C(=O)-; preferably, p is an integer between 1 and 10; more preferably, p is an integer between 1 and 6 (such as 1, 2, 3, 4, 5, 6); preferably, m is an integer between 1 and 12; more preferably, m is an integer between 1 and 10 (such as 1, 2, 3, 4, 5, 6, 7, 8, 9); Preferably, L2 is Wherein the definitions of V, p, m, and Z are as described above; preferably, V is -CH2- or -O-; more preferably, V is -O-; preferably, Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-; more preferably, Z is -C(=O)-NH-; preferably, p is an integer between 1 and 10; more preferably, p is an integer between 1 and 6 (such as 1, 2, 3, 4, 5, 6); preferably, m is an integer between 1 and 12; more preferably, m is an integer between 1 and 10 (such as 1, 2, 3, 4, 5, 6, 7, 8, 9); Preferably, L3 is Wherein the definitions of U, i, and q are as described above; preferably, U is -NH-C(=O)-, -N(CH3)-C(=O)- or -N(CH2CH3)-C(=O)-; more preferably, U is -NH-C(=O)-; preferably, i is an integer between 1 and 12; more preferably, i is an integer between 1 and 10 (such as 1, 2, 3, 4, 5, 6, 7, 8, 9); preferably, q is an integer between 1 and 10; more preferably, q is an integer between 1 and 6 (such as 1, 2, 3, 4, 5, 6); Preferably, T is a number between 1 and 10; more preferably, T is a number between 1 and 9; more preferably, T is a number between 1 and 7; more preferably, T is a number between 1 and 5, more preferably, T is a number between 3 and 7, more preferably, T is a number between 3 and 5.

5.

17. The conjugate according to any one of claims 10-16, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the conjugate has the structure shown in formula (II-II-A-3), formula (II-II-B-5), formula (II-II-B-6) or formula (II-II-C-3). Wherein the definitions of E, n, and T are as described in any one of claims 10-16; n1, n2, and n3 are each independently an integer between 1 and 20; Preferably, n1, n2, and n3 are each independently an integer between 1 and 12; more preferably, n1, n2, and n3 are each independently an integer between 1 and 10 (such as 1, 2, 3, 4, 5, 6, 7, 8, 9).

18. The conjugate of any one of claims 10-17, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the conjugate is selected from: Wherein the definitions of E, n, and T are as described in any one of claims 10-17.

19. A compound of formula (IV) or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein A1, A2, and A3 are each independently selected from Formula (A-I) to Formula (A-XIV), Among them, L can be connected to any possible site of the compound of formula (A-XIV); wherein R1 is selected from -OH, -NH2, -NHC(=NH)NH2 and -NHC(=NH)NHR6; R2 and R3 are each independently selected from -H, -OH, -F, -Cl and -Br; R4 is selected from -C(=O)OH, -P(=O)(OH)2, -SO3H, -C(=O)OCH3 and -C(=O)OCF3; R5 is selected from -C(=O)CH3, -C(=O)CF3, -SO2CH3; X is selected from -O- and -S-; Y is selected from -O-, -S-, -NR7-, -OC(=O)NR7-, -OC(=S)NR7-, -OC(=O)O-, -OC(=O)-, -NHC(=O)O-, -NHC(=O)-, -NHC(=NH)-, -NHC(=O)NR7-, -NHC(=NH)NR7-, -NHC(=S)NR7-, -NHC(=S)-, -OCH2C(=O)NR7-, -NH(SO2)- and -NH(SO2)NR7-; R' is H or C1-C6 alkyl; R6 is selected from R7 is selected from H, C1-C 20 alkyl, C3-C 20 cycloalkyl, C3-C 20 heterocycloalkyl; C5-C 15 aryl and C5-C 15 heteroaryl; preferably, R7 is H; preferably, C1-C6 alkyl; L' is a linker covalently connected to each of the groups A1, A2 and A3.

20. The compound according to claim 19, or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein A1, A2 and A3 are each independently selected from formula (A-I) to formula (A-XIII), Preferably, A1, A2, and A3 are each independently selected from Formula (A-I) to Formula (A-IV) and Formula (A-VII). wherein the definitions of R1, R2, R3, R4, R5, R', X, Y are as described in claim 19; Preferably, A1, A2, and A3 are each independently selected from Formula (A-I) to Formula (A-III) and Formula (A-VII). wherein the definitions of R1, R2, R3, R4, R5, R', X, Y are as above; Preferably, A1, A2 and A3 are each independently selected from formula (A-I), formula (A-III) and formula (A-VII), wherein the definitions of R1, R4, R5, R', X, Y are as above.

21. The compound of claim 19 or 20, or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein R1 is selected from -OH, -NH2, -NHC(=NH)NH2; more preferably, R1 is -NHC(=NH)NH2; preferably, R4 is selected from -C(=O)OH, -C(=O)OCH3 and -C(=O)OCF3; more preferably, R4 is selected from -C(=O)OH and -C(=O)OCH3; preferably, R5 is selected from -C(=O)CH3 and -C(=O)CF3; more preferably, R5 is -C(=O)CH3; preferably, R' is H or C1-C4 alkyl; more preferably, R' is H, methyl or ethyl; more preferably, R' is H or ethyl; preferably, X is -O-; preferably, Y is selected from -O-, -S-, -NH-; more preferably, Y is selected from -O- and -NH-.

22. A compound according to any one of claims 19-21, or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the compound has the structure shown in formula (IV-I), wherein the definitions of A1, A2 and A3 are as described in any one of claims 19-21, L1 is selected from: L2' is selected from: wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)- or -CH2-; or Z is Z1 and Z2 are each independently selected from -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)- or -CH2-; W' is HC≡C-, -C(=O)OH, -NH2 or N3-; m, p are each independently an integer from 1 to 20; Preferably, L1 is selected from: wherein the definitions of V, p, m, Z are as above; Preferably, L1 is wherein the definitions of V, p, m, Z are as above; Preferably, L2' is wherein the definitions of W', V, p, m, Z are as above; Preferably, L2' is wherein the definitions of W', V, p, m, Z are as above; Preferably, L2' is wherein the definitions of W', p, m, Z are as above; Preferably, V is -CH2- or -O-; more preferably, V is -O-; Preferably, Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)- or -C(=O)-; more preferably, Z is -NH-C(=O)- or -C(=O)-; Preferably, W' is HC≡C-, -C(=O)OH, -NH2 or N3-; more preferably, W' is HC≡C-; Preferably, W’ is Preferably, Z is Preferably, Z1 is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)- or -CH2CH2-C(=O)-; more preferably, Z1 is -C(=O)-NH- or -CH2-C(=O)-NH-; even more preferably, Z1 is -C(=O)-NH-; Preferably, p is an integer between 1 and 10; more preferably, p is an integer between 1 and 6 (e.g., 1, 2, 3, 4, 5, 6); Preferably, m is an integer between 1 and 12; more preferably, m is an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9).

23. A compound or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof according to any one of claims 19 - 22, wherein the compound has the structure shown in formula (IV-I-1), formula (IV-I-2) or formula (IV-I-3): Wherein the definitions of R1, R4, R5, R', X, and Y are as described in any one of claims 19 - 21, and the definitions of L1 and L2' are as described in claim 22.

24. A compound or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof according to any one of claims 19-23, wherein the compound has a structure represented by formula (IV-I-1-1), formula (IV-I-2-1), formula (IV-I-2-2) or formula (IV-I-3-1): Wherein the definitions of L1 and L2' are as described in claim 22.

25. A compound according to any one of claims 19-24, or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the indicated compound is selected from:

26. A compound of formula (V) or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein A1 and A2 are each independently selected from Formula (A-I) to Formula (A-XIV), Among them, L can be connected to any possible site of the compound of formula (A-XIV); Wherein R1 is selected from -OH, -NH2, -NHC(=NH)NH2, and -NHC(=NH)NHR6; R2 and R3 are each independently selected from -H, -OH, -F, -Cl, and -Br; R4 is selected from -C(=O)OH, -P(=O)(OH)2, -SO3H, -C(=O)OCH3, and -C(=O)OCF3; R5 is selected from -C(=O)CH3, -C(=O)CF3, -SO2CH3; X is selected from -O- and -S-; Y is selected from -O-, -S-, -NR7-, -OC(=O)NR7-, -OC(=S)NR7-, -OC(=O)O-, -OC(=O)-, -NHC(=O)O-, -NHC(=O)-, -NHC(=NH)-, -NHC(=O)NR7-, -NHC(=NH)NR7-, -NHC(=S)NR7-, -NHC(=S)-, -OCH2C(=O)NR7-, -NH(SO2)-, and -NH(SO2)NR7-; R' is H or C1-C6 alkyl; R6 is selected from R7 is selected from H, C1-C 20 alkyl, C3-C 20 cycloalkyl, C3-C 20 heterocycloalkyl; C5-C 15 aryl and C5-C 15 heteroaryl; preferably, R7 is H; preferably, C1-C6 alkyl; L' is a linker covalently connected to each of the groups A1 and A2.

27. The compound of claim 26 or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein A1 and A2 are each independently selected from formula (A-I) to formula (A-XIII), Preferably, A1 and A2 are each independently selected from Formula (A-I) to Formula (A-IV) and Formula (A-VII). Wherein the definitions of R1, R2, R3, R4, R5, R', X, and Y are as described in claim 21; Preferably, A1 and A2 are each independently selected from formula (A-I) to formula (A-III) and formula (A-VII). Wherein the definitions of R1, R2, R3, R4, R5, R', X, and Y are the same as above; Preferably, A1 and A2 are each independently selected from Formula (A-I), Formula (A-III), and Formula (A-VII). Wherein the definitions of R1, R4, R5, R', X, and Y are the same as above.

28. A compound according to claim 26 or 27, or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein preferably, R1 is selected from -OH, -NH2, -NHC(=NH)NH2; more preferably, R1 is -NHC(=NH)NH2; preferably, R4 is selected from -C(=O)OH, -C(=O)OCH3 and -C(=O)OCF3; more preferably, R4 is selected from -C(=O)OH and -C(=O)OCH3; preferably, R5 is selected from -C(=O)CH3 and -C(=O)CF3; more preferably, R5 is -C(=O)CH3; preferably, R' is H or C1-C4 alkyl; more preferably, R' is H, methyl or ethyl; even more preferably, R' is H or ethyl; preferably, X is -O-; preferably, Y is selected from -O-, -S-, -NH-; more preferably, Y is selected from -O- and -NH-; 29. A compound or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof according to any one of claims 26 - 28, wherein the compound has the structure shown in formula (V-I) wherein A1 and A2 are as defined in any one of claims 26-28, L1 is selected from: L2’ is selected from: wherein V is -CH2-, -O- or -S-; Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)- or -CH2-; Z1 and Z2 are each independently selected from -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)-, -O-C(=O)-, -C(=O)- or -CH2-; W' is HC≡C-, -C(=O)OH, -NH2 or N3-; m and p are each independently an integer from 1 to 20; Preferably, L1 is selected from: wherein V, p, m and Z are as defined above; Preferably, L1 is wherein V, p, m and Z are as defined above; Preferably, L2' is wherein W', V, p, m and Z are as defined above; Preferably, L2' is wherein W', V, p, m and Z are as defined above; preferably, V is -CH2- or -O-; more preferably, V is -O-; preferably, Z is -C(=O)-NH-, -CH2-C(=O)-NH-, -NH-C(=O)-, -CH2CH2-C(=O)-, -N(CH3)-C(=O)-, -N(CH2CH3)-C(=O)- or -C(=O)-; more preferably, Z is -NH-C(=O)- or -C(=O)-; preferably, W' is HC≡C-, -C(=O)OH, -NH2 or N3-; more preferably, W' is HC≡C-; preferably, p is an integer between 1 and 10; more preferably, p is an integer between 1 and 6 (e.g., 1, 2, 3, 4, 5, 6); preferably, m is an integer between 1 and 12; more preferably, m is an integer between 1 and 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9).

30. A compound according to any one of claims 26-29, or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the compound has the structure shown in formula (V-I-1), formula (V-I-2) or formula (V-I-3): wherein R1, R4, R5, R', X and Y are as defined in any one of claims 26-28, and L1 and L2' are as defined in claim 29.

31. A compound according to any one of claims 26 - 30, or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the compound has a structure represented by formula (V-I-1-1), formula (V-I-2-1), formula (V-I-2-2) or formula (V-I-3-1): wherein L1 and L2' are as defined in claim 29.

32. A compound according to any one of claims 26 - 31, or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, wherein the indicated compound is selected from:

33. A pharmaceutical composition comprising a conjugate according to any one of claims 1 to 18, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, or a compound according to any one of claims 19-32, or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, and a pharmaceutically acceptable carrier and / or excipient. Use of the conjugate according to any one of claims 1 to 18, or a pharmaceutically acceptable salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, or the compound according to any one of claims 19 - 32, or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, or the pharmaceutical composition according to claim 33, in the preparation of a medicament for the treatment or prophylaxis of a viral infection, Preferably, the viral infection is an infection caused by an influenza virus or a parainfluenza virus; Preferably, the viral infection is an infection caused by an influenza A, B or C virus or a parainfluenza virus; Preferably, the viral infection is an infection caused by avian influenza.

35. The use according to claim 34, wherein the subject may be further treated with an antiviral agent selected from oseltamivir, zanamivir, peramivir, laninamivir, amantadine, rimantadine or baloxavir marboxil.

36. Use of a compound according to any one of claims 19 - 32, or a salt, geometric or optical isomer, hydrate, solvate or polymorph thereof, as an intermediate in the preparation of a conjugate.

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