Extended half-life antibodies and IgG fusion proteins

Abstract

The present invention provides antibodies or IgG Fc fusion proteins comprising a canine or feline fragment crystallizable region (Fc region) that have an enhanced half-life due to one or more specific amino acid substitutions in the Fc region. The increased half-life may be a function of increased binding affinity to the neonatal Fc receptor (FcRn) at moderately acidic pH relative to that of a corresponding antibody or IgG Fc fusion protein comprising an unsubstituted canine or feline Fc region. Pharmaceutical compositions comprising these antibodies and / or IgG fusion proteins are also provided.

Description

[Technical field]

[0001] Sequence Listing This application contains a Sequence Listing that has been submitted electronically in XML format and is incorporated herein by reference in its entirety. The filename of the XML file created on July 21, 2022 is "25530.xml". This Sequence Listing, submitted via EFS-Web, is a part of the present specification and is incorporated herein by reference in its entirety.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 63 / 341,443, filed May 13, 2022, U.S. Provisional Application No. 63 / 235,259, filed August 20, 2021, and U.S. Provisional Application No. 63 / 235,261, filed August 20, 2021.

[0003] The present invention relates to antibodies or IgG Fc fusion proteins comprising a canine or feline fragment crystallizable region (Fc region) that have an enhanced half-life due to one or more specific amino acid substitutions in the Fc region. The increased half-life may be a function of increased binding affinity to the neonatal Fc receptor (FcRn) at moderately acidic pH relative to that of the corresponding antibody or IgG Fc fusion protein comprising an unsubstituted canine or feline Fc region. Pharmaceutical compositions comprising these antibodies and / or IgG fusion proteins are also provided. [Background technology]

[0004] One important goal of pharmaceutical antibody research is to develop antibodies that are effective at relatively low doses and with low administration frequency. These attributes serve to lower the cost of treatment, which leads to greater patient access, while at the same time increasing patient convenience and enhancing patient compliance, thereby resulting in better treatment outcomes. To achieve this goal, many studies have focused on modulating the binding between therapeutic antibodies of the IgG isotype and the so-called neonatal Fc receptor (FcRn). This is because FcRn binding to IgG is thought to be a key factor in maintaining and extending antibody plasma half-life.

[0005] FcRn is a heterodimer composed of an MHC class I-like alpha domain and a B2-microglobulin (B2-m) subunit. FcRn is expressed in several tissues: most notably, vascular endothelium, kidney, bone marrow-derived cells, and the blood-brain barrier. FcRn binds IgG at a site on the IgG Fc that is distinct from the sites on other IgG Fc receptors. Binding of IgG to FcRn is highly pH dependent, with this binding occurring with high affinity at low pH (e.g., below pH 6.5) in endosomal compartments, but with significantly lower binding affinity at physiological pH (e.g., pH 7.4) on the cell surface [see, e.g., Borok et al., J. Biol. Chem. 290(7):4282-4290, (2015)]. The strong binding of IgG to FcRn in the endosomal compartment protects the antibody from degradation by proteolytic enzymes in the endosome and allows recycling of receptor-bound antibody to the cell surface, where the increase in pH weakens the interaction and allows release of the antibody into the circulation at physiological pH.

[0006] Previous studies have shown that certain mutations at certain positions alter the binding of human IgG to human FcRn [see, for example, U.S. Pat. No. 7,083,784, U.S. Pat. No. 7,658,921, U.S. Pat. No. 7,217,797, U.S. Pat. No. 7,217,798, U.S. Pat. No. 8,088,376, U.S. Pat. No. 10,336,818, and International Publication No. WO 2019 / 147973]. However, human and dog or cat IgG proteins have many differences in their amino acid sequences that give residues in the human sequence a different environment and / or a different identity than in the dog or cat sequence. This variability makes it difficult to directly transfer the properties of one species of IgG to another species of IgG. Consistently, a number of corresponding studies have been conducted recently on companion animals [see, for example, WO 2018073185, WO 2020082048, WO 20210116560, US Patent Application Publication No. 20200362035, US Patent Application Publication No. 20200216536, WO 2020191289, WO 2021231464, and US Patent Application Publication No. 20210347854]. However, any particular mutation or combination of mutations may have dramatically different effects on the prolongation of antibody half-life or other attributes, which also makes it difficult to predict the effect of such mutations on important antibody properties, including the potential to induce anti-drug (antibody) antibodies. Therefore, there remains a need to identify new specific substitutions / mutations in canine and / or feline IgG proteins that are capable of extending the half-life of therapeutic antibodies and / or corresponding therapeutic Fc-fusion proteins.

[0007] The citation of any reference herein should not be construed as an admission that such reference is available as "Prior Art" to the instant application. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Patent No. 7,083,784 [Patent Document 2] U.S. Pat. No. 7,658,921 [Patent Document 3] U.S. Patent No. 7,217,797 [Patent Document 4] U.S. Patent No. 7,217,798 [Patent Document 5] U.S. Pat. No. 8,088,376 [Patent Document 6] U.S. Pat. No. 10,336,818 [Patent Document 7] International Publication No. 2019 / 147973 [Patent Document 8] International Publication No. 2018073185 [Patent Document 9] International Publication No. 2020082048 [Patent Document 10] International Publication No. 20210116560 [Patent Document 11] US Patent Publication No. 20200362035 [Patent Document 12] US Patent Publication No. 20200216536 [Patent Document 13] International Publication No. 2020191289 [Patent Document 14] International Publication No. 2021231464 [Patent Document 15] US Patent Publication No. 20210347854 [Non-patent literature]

[0009] [Non-Patent Document 1] Borok et al.,J.Biol.Chem.290(7):4282-4290,(2015) Summary of the Invention

[0010] The present invention provides antibodies and IgG Fc fusion proteins with enhanced half-life. Thus, in one aspect of the present invention, an antibody is provided comprising a light chain and a heavy chain, wherein the heavy chain comprises a fragment crystallizable region (Fc region) comprising an amino acid substitution at amino acid residue position 252, amino acid residue position 254, amino acid residue position 256, amino acid residue position 308, amino acid residue position 433, amino acid residue position 434, amino acid residue position 436, or any combination of these amino acid positions, numbered according to the EU index as in Kabat. In certain embodiments of this type, the Fc region is a canine Fc region (cFc). In other embodiments of this type, the Fc region is a feline Fc region (fFc).

[0011] The invention also provides IgG Fc fusion proteins comprising a fragment crystallizable region (Fc region) comprising an amino acid substitution at an amino acid residue position numbered according to the EU index as in Kabat at amino acid residue position 252, amino acid residue position 254, amino acid residue position 256, amino acid residue position 308, amino acid residue position 433, amino acid residue position 434, amino acid residue position 436, or any combination of these amino acid positions. In certain embodiments of this type, the Fc region is a canine Fc region (cFc). In other embodiments of this type, the Fc region is a feline Fc region (fFc).

[0012] In certain embodiments, an antibody or IgG Fc fusion protein of the invention comprises one or more such amino acid substitutions. In certain embodiments, the substitution is with a tyrosine residue at amino acid residue position 252. In other embodiments, the substitution is with a threonine residue at amino acid residue position 254. In still other embodiments, the substitution is with an aspartic acid residue at amino acid residue position 256. In still other embodiments, the substitution is with a glutamic acid residue at amino acid residue position 256. In still other embodiments, the substitution is with a proline residue at amino acid residue position 308. In still other embodiments, the substitution is with a lysine residue at amino acid residue position 433. In still other embodiments, the substitution is with a leucine residue at amino acid residue position 433. In still other embodiments, the substitution is with a phenylalanine residue at amino acid residue position 434. In still other embodiments, the substitution is with a histidine residue at amino acid residue position 434. In still other embodiments, the substitution is with a tyrosine residue at amino acid residue position 434. In yet another embodiment, the substitution is with a threonine residue at amino acid residue position 436.

[0013] In related embodiments, an antibody or IgG Fc fusion protein of the invention comprises two or more of such amino acid substitutions. In certain embodiments, an antibody or IgG Fc fusion protein of the invention comprises a substitution at amino acid residue position 252 with a tyrosine residue and at amino acid residue position 256 with an aspartic acid residue. In other embodiments, the substitution is with a proline residue at amino acid residue position 308 and the substitution is with a tyrosine residue at amino acid residue position 434. In yet other embodiments, the substitution is with a lysine residue at amino acid residue position 433 and the substitution is with a phenylalanine residue at amino acid residue position 434. In yet other embodiments, the substitution is with a lysine residue at amino acid residue position 433 and the substitution is with a tyrosine residue at amino acid residue position 434. In yet other embodiments, the substitution is with a leucine residue at amino acid residue position 433 and the substitution is with a phenylalanine residue at amino acid residue position 434. In still other embodiments, the substitution is with a leucine residue at amino acid residue position 433 and the substitution is with a tyrosine residue at amino acid residue position 434. In yet other embodiments, the substitution is with an aspartic acid residue at amino acid residue position 256 and the substitution is with a tyrosine residue at amino acid residue position 434. In still other embodiments, the substitution is with a tyrosine residue at amino acid residue position 434 and the substitution is with a threonine residue at amino acid residue position 436. In still other embodiments, the substitution is with a tyrosine residue at amino acid residue position 252 and the substitution is with a threonine residue at amino acid residue position 254 and the substitution is with a glutamic acid residue at amino acid residue position 256. In still other embodiments, the substitution is with an aspartic acid residue at amino acid residue position 256 and the substitution is with a proline residue at amino acid residue position 308 and the substitution is with a tyrosine residue at amino acid residue position 434. In yet another embodiment, the substitution at amino acid residue position 433 is with a lysine residue, the substitution at amino acid residue position 434 is with a phenylalanine residue, and the substitution at amino acid residue position 436 is with a threonine residue.In still other embodiments, the substitution is with a lysine residue at amino acid residue position 433, the substitution is with a tyrosine residue at amino acid residue position 434, and the substitution is with a threonine residue at amino acid residue position 436. In yet other embodiments, the substitution is with a leucine residue at amino acid residue position 433, the substitution is with a phenylalanine residue at amino acid residue position 434, and the substitution is with a threonine residue at amino acid residue position 436. In still other embodiments, the substitution is with a leucine residue at amino acid residue position 433, the substitution is with a tyrosine residue at amino acid residue position 434, and the substitution is with a threonine residue at amino acid residue position 436.

[0014] The antibodies and IgG Fc fusion proteins of the present invention preferably have an increased half-life compared to the half-life of the corresponding antibody or corresponding IgG Fc fusion protein comprising the corresponding wild-type dog or cat Fc. In certain embodiments, the antibodies or IgG Fc fusion proteins have enhanced binding affinity to their neonatal Fc receptor (FcRn) at moderately acidic pH than the corresponding antibody or corresponding IgG Fc fusion protein comprising the corresponding wild-type dog or cat Fc.

[0015] In certain embodiments of the antibodies or IgG Fc fusion proteins of the invention, the Fc region is a feline Fc region (fFc). In certain embodiments, the fFc is an IgG-la Fc. In still other embodiments, the fFc is an IgG-1am Fc. In still other embodiments, the fFc is an IgG-lb Fc. In still other embodiments, the fFc is an IgG-1bm Fc. In still other embodiments, the fFc is an IgG-2 Fc. In still other embodiments, the fFc is an IgG-2m Fc.

[0016] In more particular embodiments of the antibody or IgG Fc fusion protein of the invention, fFc comprises an amino acid sequence having at least 90% identity to SEQ ID NO:9. In other embodiments, fFc comprises an amino acid sequence having at least 95% identity to SEQ ID NO:9. In yet other embodiments, fFc comprises an amino acid sequence having at least 97% identity to SEQ ID NO:9. In yet other embodiments, fFc comprises an amino acid sequence having at least 98% identity to SEQ ID NO:9. In yet other embodiments, fFc comprises an amino acid sequence having at least 99% identity to SEQ ID NO:9. In a specific embodiment, fFc comprises the amino acid sequence of SEQ ID NO:9.

[0017] In other specific embodiments of an antibody or IgG Fc fusion protein of the invention, fFc comprises an amino acid sequence having at least 90% identity to SEQ ID NO: 10. In other embodiments, fFc comprises an amino acid sequence having at least 95% identity to SEQ ID NO: 10. In yet other embodiments, fFc comprises an amino acid sequence having at least 97% identity to SEQ ID NO: 10. In yet other embodiments, fFc comprises an amino acid sequence having at least 98% identity to SEQ ID NO: 10. In yet other embodiments, fFc comprises an amino acid sequence having at least 99% identity to SEQ ID NO: 10. In a specific embodiment, fFc comprises the amino acid sequence of SEQ ID NO: 10.

[0018] In yet other specific embodiments of the antibody or IgG Fc fusion protein of the invention, fFc comprises an amino acid sequence having at least 90% identity to SEQ ID NO: 11. In other embodiments, fFc comprises an amino acid sequence having at least 95% identity to SEQ ID NO: 11. In yet other embodiments, fFc comprises an amino acid sequence having at least 97% identity to SEQ ID NO: 11. In yet other embodiments, fFc comprises an amino acid sequence having at least 98% identity to SEQ ID NO: 11. In yet other embodiments, fFc comprises an amino acid sequence having at least 99% identity to SEQ ID NO: 11. In a specific embodiment, fFc comprises the amino acid sequence of SEQ ID NO: 11.

[0019] In yet other specific embodiments of the antibody or IgG Fc fusion protein of the invention, fFc comprises an amino acid sequence having at least 90% identity to SEQ ID NO: 12. In other embodiments, fFc comprises an amino acid sequence having at least 95% identity to SEQ ID NO: 12. In still other embodiments, fFc comprises an amino acid sequence having at least 97% identity to SEQ ID NO: 12. In yet other embodiments, fFc comprises an amino acid sequence having at least 98% identity to SEQ ID NO: 12. In still other embodiments, fFc comprises an amino acid sequence having at least 99% identity to SEQ ID NO: 12. In a specific embodiment, fFc comprises the amino acid sequence of SEQ ID NO: 12.

[0020] In yet other specific embodiments of the antibody or IgG Fc fusion protein of the invention, fFc comprises an amino acid sequence having at least 90% identity to SEQ ID NO: 50. In other embodiments, fFc comprises an amino acid sequence having at least 95% identity to SEQ ID NO: 50. In yet other embodiments, fFc comprises an amino acid sequence having at least 97% identity to SEQ ID NO: 50. In yet other embodiments, fFc comprises an amino acid sequence having at least 98% identity to SEQ ID NO: 50. In yet other embodiments, fFc comprises an amino acid sequence having at least 99% identity to SEQ ID NO: 50. In a specific embodiment, fFc comprises the amino acid sequence of SEQ ID NO: 50.

[0021] In yet other specific embodiments of the antibody or IgG Fc fusion protein of the invention, fFc comprises an amino acid sequence having at least 90% identity to SEQ ID NO:51. In other embodiments, fFc comprises an amino acid sequence having at least 95% identity to SEQ ID NO:51. In still other embodiments, fFc comprises an amino acid sequence having at least 97% identity to SEQ ID NO:51. In yet other embodiments, fFc comprises an amino acid sequence having at least 98% identity to SEQ ID NO:51. In still other embodiments, fFc comprises an amino acid sequence having at least 99% identity to SEQ ID NO:51. In a specific embodiment, fFc comprises the amino acid sequence of SEQ ID NO:51.

[0022] In certain embodiments of the antibodies or IgG Fc fusion proteins of the invention, the Fc region is a canine Fc region (cFc). In certain embodiments, the cFc is an IgG-A Fc. In still other embodiments, the cFc is an IgG-Am Fc. In still other embodiments, the cFc is an IgG-B Fc. In still other embodiments, the cFc is an IgG-Bm Fc. In still other embodiments, the cFc is an IgG-C Fc. In still other embodiments, the cFc is an IgG-Cm Fc. In still other embodiments, the cFc is an IgG-D Fc. In still other embodiments, the cFc is an IgC-Dm Fc.

[0023] In more particular embodiments of the antibody or IgG Fc fusion protein of the invention, the cFc comprises an amino acid sequence having at least 90% identity to SEQ ID NO: 1. In other embodiments, the cFc comprises an amino acid sequence having at least 95% identity to SEQ ID NO: 1. In yet other embodiments, the cFc comprises an amino acid sequence having at least 97% identity to SEQ ID NO: 1. In yet other embodiments, the cFc comprises an amino acid sequence having at least 98% identity to SEQ ID NO: 1. In yet other embodiments, the cFc comprises an amino acid sequence having at least 99% identity to SEQ ID NO: 1. In a specific embodiment, the cFc comprises the amino acid sequence of SEQ ID NO: 1.

[0024] In other specific embodiments of the antibody or IgG Fc fusion protein of the invention, the cFc comprises an amino acid sequence having at least 90% identity to SEQ ID NO:2. In other embodiments, the cFc comprises an amino acid sequence having at least 95% identity to SEQ ID NO:2. In yet other embodiments, the cFc comprises an amino acid sequence having at least 97% identity to SEQ ID NO:2. In yet other embodiments, the cFc comprises an amino acid sequence having at least 98% identity to SEQ ID NO:2. In yet other embodiments, the cFc comprises an amino acid sequence having at least 99% identity to SEQ ID NO:2. In a specific embodiment, the cFc comprises the amino acid sequence of SEQ ID NO:2.

[0025] In yet other specific embodiments of the antibody or IgG Fc fusion protein of the invention, the cFc comprises an amino acid sequence having at least 90% identity to SEQ ID NO:3. In other embodiments, the cFc comprises an amino acid sequence having at least 95% identity to SEQ ID NO:3. In yet other embodiments, the cFc comprises an amino acid sequence having at least 97% identity to SEQ ID NO:3. In yet other embodiments, the cFc comprises an amino acid sequence having at least 98% identity to SEQ ID NO:3. In yet other embodiments, the cFc comprises an amino acid sequence having at least 99% identity to SEQ ID NO:3. In a specific embodiment, the cFc comprises the amino acid sequence of SEQ ID NO:3.

[0026] In yet other specific embodiments of the antibody or IgG Fc fusion protein of the invention, the cFc comprises an amino acid sequence having at least 90% identity to SEQ ID NO:4. In other embodiments, the cFc comprises an amino acid sequence having at least 95% identity to SEQ ID NO:4. In yet other embodiments, the cFc comprises an amino acid sequence having at least 97% identity to SEQ ID NO:4. In yet other embodiments, the cFc comprises an amino acid sequence having at least 98% identity to SEQ ID NO:4. In yet other embodiments, the cFc comprises an amino acid sequence having at least 99% identity to SEQ ID NO:4. In a specific embodiment, the cFc comprises the amino acid sequence of SEQ ID NO:4.

[0027] In yet other specific embodiments of the antibody or IgG Fc fusion protein of the invention, the cFc comprises an amino acid sequence having at least 90% identity to SEQ ID NO:5. In other embodiments, the cFc comprises an amino acid sequence having at least 95% identity to SEQ ID NO:5. In yet other embodiments, the cFc comprises an amino acid sequence having at least 97% identity to SEQ ID NO:5. In yet other embodiments, the cFc comprises an amino acid sequence having at least 98% identity to SEQ ID NO:5. In yet other embodiments, the cFc comprises an amino acid sequence having at least 99% identity to SEQ ID NO:5. In a specific embodiment, the cFc comprises the amino acid sequence of SEQ ID NO:5.

[0028] In yet other specific embodiments of the antibody or IgG Fc fusion protein of the invention, the cFc comprises an amino acid sequence having at least 90% identity to SEQ ID NO:6. In other embodiments, the cFc comprises an amino acid sequence having at least 95% identity to SEQ ID NO:6. In yet other embodiments, the cFc comprises an amino acid sequence having at least 97% identity to SEQ ID NO:6. In yet other embodiments, the cFc comprises an amino acid sequence having at least 98% identity to SEQ ID NO:6. In yet other embodiments, the cFc comprises an amino acid sequence having at least 99% identity to SEQ ID NO:6. In a specific embodiment, the cFc comprises the amino acid sequence of SEQ ID NO:6.

[0029] In yet other specific embodiments of the antibody or IgG Fc fusion protein of the invention, the cFc comprises an amino acid sequence having at least 90% identity to SEQ ID NO:7. In other embodiments, the cFc comprises an amino acid sequence having at least 95% identity to SEQ ID NO:7. In yet other embodiments, the cFc comprises an amino acid sequence having at least 97% identity to SEQ ID NO:7. In yet other embodiments, the cFc comprises an amino acid sequence having at least 98% identity to SEQ ID NO:7. In yet other embodiments, the cFc comprises an amino acid sequence having at least 99% identity to SEQ ID NO:7. In a specific embodiment, the cFc comprises the amino acid sequence of SEQ ID NO:7.

[0030] In yet other specific embodiments of the antibody or IgG Fc fusion protein of the invention, the cFc comprises an amino acid sequence having at least 90% identity to SEQ ID NO:8. In other embodiments, the cFc comprises an amino acid sequence having at least 95% identity to SEQ ID NO:8. In yet other embodiments, the cFc comprises an amino acid sequence having at least 97% identity to SEQ ID NO:8. In yet other embodiments, the cFc comprises an amino acid sequence having at least 98% identity to SEQ ID NO:8. In yet other embodiments, the cFc comprises an amino acid sequence having at least 99% identity to SEQ ID NO:8. In a specific embodiment, the cFc comprises the amino acid sequence of SEQ ID NO:8.

[0031] In related embodiments of the antibody or IgG Fc fusion protein of the invention, the cFc further comprises a canine hinge region. In certain embodiments, the canine hinge region comprises an amino acid sequence having at least 80% identity to SEQ ID NO: 13. In yet other embodiments, the canine hinge region comprises an amino acid sequence having at least 85% identity to SEQ ID NO: 13. In still other embodiments, the canine hinge region comprises an amino acid sequence having at least 90% identity to SEQ ID NO: 13. In still other embodiments, the canine hinge region comprises an amino acid sequence having at least 95% identity to SEQ ID NO: 13. In a specific embodiment, the canine hinge region comprises the amino acid sequence of SEQ ID NO: 13. In other embodiments, the canine hinge region comprises an amino acid sequence having at least 80% identity to SEQ ID NO: 14. In still other embodiments, the canine hinge region comprises an amino acid sequence having at least 85% identity to SEQ ID NO: 14. In still other embodiments, the canine hinge region comprises an amino acid sequence having at least 90% identity to SEQ ID NO: 14. In yet other embodiments, the canine hinge region comprises an amino acid sequence having at least 95% identity to SEQ ID NO: 14. In a specific embodiment, the canine hinge region comprises the amino acid sequence of SEQ ID NO: 14. In an alternative embodiment, the canine hinge region comprises an amino acid sequence having at least 80% identity to SEQ ID NO: 15. In still other embodiments, the canine hinge region comprises an amino acid sequence having at least 85% identity to SEQ ID NO: 15. In yet other embodiments, the canine hinge region comprises an amino acid sequence having at least 90% identity to SEQ ID NO: 15. In still other embodiments, the canine hinge region comprises an amino acid sequence having at least 95% identity to SEQ ID NO: 15. In a specific embodiment, the canine hinge region comprises the amino acid sequence of SEQ ID NO: 15. In other embodiments, the canine hinge region comprises an amino acid sequence having at least 80% identity to SEQ ID NO: 16. In still other embodiments, the canine hinge region comprises an amino acid sequence having at least 85% identity to SEQ ID NO: 16. In still other embodiments, the canine hinge region comprises an amino acid sequence having at least 90% identity to SEQ ID NO:16.In yet other embodiments, the canine hinge region comprises an amino acid sequence having at least 95% identity to SEQ ID NO: 16. In a specific embodiment, the canine hinge region comprises the amino acid sequence of SEQ ID NO:16.

[0032] In a particular embodiment, the IgG Fc fusion protein is a canine interleukin-13 receptor alpha1-canine IgG fusion protein (canine IL-13Rα1-canine IgG fusion protein) comprising the amino acid sequence of SEQ ID NO: 17. In other embodiments, the canine IL-13Rα1-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 17. In yet other embodiments, the canine IL-13Rα1-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 17. In yet other embodiments, the canine IL-13Rα1-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 17. In yet other embodiments, the canine IL-13Rα1-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 17. In still other embodiments, the canine IL-13Rα1-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO:17.

[0033] In another specific embodiment, the IgG Fc fusion protein is a canine interleukin-13 receptor alpha2-canine IgG fusion protein (canine IL-13Rα2-canine IgG fusion protein) comprising the amino acid sequence of SEQ ID NO: 18. In another embodiment, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 18. In yet another embodiment, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 18. In yet another embodiment, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 18. In yet another embodiment, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 18. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO:18.

[0034] In yet another specific embodiment, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO: 19. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 19. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 19. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 19. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 19. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 19.

[0035] In yet other specific embodiments, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO:20. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO:20. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO:20. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO:20. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO:20. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO:20.

[0036] In yet another specific embodiment, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO:21.

[0037] In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 21. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 21. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 21. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 21. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 21.

[0038] In yet other specific embodiments, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO:22. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO:22. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO:22. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO:22. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO:22. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO:22.

[0039] In yet another specific embodiment, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO:23. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO:23. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO:23. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO:23. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO:23. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO:23.

[0040] In yet other specific embodiments, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO:24. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO:24. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO:24. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO:24. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO:24. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO:24.

[0041] In yet another specific embodiment, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO:25. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO:25. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO:25. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO:25. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO:25. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO:25.

[0042] In yet other specific embodiments, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO:26. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO:26. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO:26. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO:26. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO:26. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO:26.

[0043] In yet another specific embodiment, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO:27. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO:27. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO:27. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO:27. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO:27. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO:27.

[0044] In yet other specific embodiments, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO:28. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO:28. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO:28. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO:28. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO:28. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO:28.

[0045] In yet another specific embodiment, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO:29. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO:29. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO:29. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO:29. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO:29. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO:29.

[0046] In yet other specific embodiments, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO: 30. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 30. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 30. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 30. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 30. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 30.

[0047] In yet another specific embodiment, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO:31. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO:31. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO:31. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO:31. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO:31. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO:31.

[0048] In yet other specific embodiments, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO: 32. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 32. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 32. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 32. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 32. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 32.

[0049] In yet another specific embodiment, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO: 33. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 33. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 33. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 33. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 33. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 33.

[0050] In yet other specific embodiments, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO: 34. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 34. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 34. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 34. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 34. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 34.

[0051] In yet another specific embodiment, the IgG Fc fusion protein is a canine IL-13Rα2-canine IgG fusion protein comprising the amino acid sequence of SEQ ID NO: 35. In other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 35. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 35. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 35. In yet other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 35. In still other embodiments, the canine IL-13Rα2-canine IgG fusion protein comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 35.

[0052] As noted below, unless specifically indicated otherwise, the antibodies of the invention are IgG antibodies. In specific embodiments, the antibodies of the invention are feline antibodies. In related embodiments, the antibodies are felineized antibodies. In other embodiments, the antibodies are canine antibodies. In yet other embodiments, the antibodies are canineized antibodies.

[0053] In certain embodiments, the caninized antibody is a caninized canine interleukin-31 receptor alpha (cIL-31RA) antibody. In more specific embodiments, the heavy chain of the cIL-31RA caninized antibody comprises a variable region comprising the amino acid sequence of SEQ ID NO: 44. In more specific embodiments, the antibody further comprises a light chain of a cIL-31RA caninized antibody. In certain embodiments, the light chain of the cIL-31RA caninized antibody comprises the amino acid sequence of SEQ ID NO: 45. In other embodiments, the light chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 45. In yet other embodiments, the light chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 45. In yet other embodiments, the light chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 45. In yet other embodiments, the light chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 45. In yet other embodiments, the light chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 45.

[0054] In certain embodiments, the heavy chain of the cIL-31RA caninized antibody comprises the amino acid sequence of SEQ ID NO: 36. In other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 36. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 36. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 36. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 36. In still other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 36.

[0055] In yet another specific embodiment, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence of SEQ ID NO: 37. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 37. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 37. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 37. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 37. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 37.

[0056] In yet another specific embodiment, the heavy chain of the cIL-31RA caninized antibody comprises the amino acid sequence of SEQ ID NO: 38. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 38. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 38. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 38. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 38. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 38.

[0057] In yet another specific embodiment, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence of SEQ ID NO: 39. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 39. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 39. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 39. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 39. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 39.

[0058] In yet another specific embodiment, the heavy chain of the cIL-31RA caninized antibody comprises the amino acid sequence of SEQ ID NO: 40. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 40. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 40. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 40. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 40. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 40.

[0059] In yet another specific embodiment, the heavy chain of the cIL-31RA caninized antibody comprises the amino acid sequence of SEQ ID NO: 41. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 41. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 41. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 41. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 41. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 41.

[0060] In yet another specific embodiment, the heavy chain of the cIL-31RA caninized antibody comprises the amino acid sequence of SEQ ID NO: 42. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 42. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 42. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 42. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 42. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 42.

[0061] In yet another specific embodiment, the heavy chain of the cIL-31RA caninized antibody comprises the amino acid sequence of SEQ ID NO: 43. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 43. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 95% identity to the amino acid sequence of SEQ ID NO: 43. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 97% identity to the amino acid sequence of SEQ ID NO: 43. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 98% identity to the amino acid sequence of SEQ ID NO: 43. In yet other embodiments, the heavy chain of the cIL-31RA caninized antibody comprises an amino acid sequence having at least 99% identity to the amino acid sequence of SEQ ID NO: 43.

[0062] The present invention further provides individual nucleic acids comprising individual nucleotide sequences encoding individual antibody heavy chains, antibody light chains or IgG fusion proteins of the present invention. Thus, the present invention provides nucleic acids comprising nucleotide sequences encoding antibody heavy chains, antibody light chains or IgG fusion proteins of the present invention. In certain embodiments, the present invention provides nucleic acids comprising nucleotide sequences encoding any one of the canine-13Rα1-canine IgG fusion proteins of the present invention. In related specific embodiments, the present invention provides nucleic acids comprising nucleotide sequences encoding any one of the canine-13Rα2-canine IgG fusion proteins of the present invention. In specific embodiments, the present invention provides nucleic acids comprising nucleotide sequences encoding a heavy chain of a cIL-31RA caninized antibody comprising a variable region comprising the amino acid sequence of SEQ ID NO: 44. In related embodiments, the present invention provides nucleic acids comprising nucleotide sequences encoding any one of the heavy chains of a cIL-31RA caninized antibody. The present invention also provides nucleic acids comprising nucleotide sequences encoding any one of the light chains of a cIL-31RA caninized antibody. In addition, the present invention provides nucleic acids comprising multiple nucleotide sequences encoding each of the antibody heavy and light chains of the present invention. The present invention further provides nucleic acids comprising multiple nucleotide sequences encoding each of the IgG fusion proteins of the present invention. The invention further provides vectors comprising these nucleic acids. In certain embodiments, the vector is an expression vector. The invention further provides host cells comprising any of the vectors of the invention.

[0063] The present invention also provides pharmaceutical compositions comprising the half-life enhanced antibodies and IgG Fc fusion proteins of the invention and a pharma- ceutically acceptable carrier. The enhanced half-life is attributable, at least in part, to the antibodies and IgG Fc fusion proteins comprising a fragment crystallizable region (Fc) that comprises one or more amino acid substitutions in the Fc region. In a more specific embodiment, the medicament comprises a canine-13Rα1-canine IgG fusion protein of the invention and a pharma- ceutically acceptable carrier. In a related embodiment, the medicament comprises a canine-13Rα2-canine IgG fusion protein of the invention and a pharma- ceutically acceptable carrier. In yet another embodiment, the medicament comprises a caninized cIL-31RA antibody of the invention and a pharma- ceutically acceptable carrier. The present invention also provides pharmaceutical compositions comprising a combination of a canine-13Rα1-canine IgG fusion protein, a canine-13Rα2-canine IgG fusion protein, and / or a caninized cIL-31RA caninized antibody. The present invention further provides a method of treating a dog with atopic dermatitis comprising administering to the dog any one or more of the pharmaceutical compositions of the present invention.

[0064] These and other aspects of the present invention will be better understood with reference to the detailed description and drawings. [Brief description of the drawings]

[0065] [Figure 1A]FIG. 1 shows an alignment of amino acid sequences of Fc regions from human IgG1 Fc [SEQ ID NO: 54], canine IgG-A [SEQ ID NO: 1], canine IgG-B [SEQ ID NO: 3], canine IgG-C [SEQ ID NO: 5], canine IgG-D [SEQ ID NO: 7], feline IgG-1a [SEQ ID NO: 52] and feline IgG-2 [SEQ ID NO: 53], together with the consensus sequence [SEQ ID NO: 55]. The depicted feline IgG-1a and feline IgG-2 Fc regions have two additional N-terminal amino acid residues relative to the corresponding feline Fc regions defined by Strietzel et al., [Vet Immunol&Immunpathol., 158:214-223 (2014)]. Solid arrows indicate specific amino acid residue positions reflecting the EU numbering scheme according to Sequences of Proteins of Immunological Interest, 5th ed., Kabat et al., National Institutes of Health, Bethesda, Md. (1991). The "x" reflects the lack of uniformity at position 252 in the consensus sequence for the seven amino acid sequences compared. [Figure 1B]FIG. 1 shows an alignment of amino acid sequences of Fc regions from human IgG1 Fc [SEQ ID NO: 54], canine IgG-A [SEQ ID NO: 1], canine IgG-B [SEQ ID NO: 3], canine IgG-C [SEQ ID NO: 5], canine IgG-D [SEQ ID NO: 7], feline IgG-1a [SEQ ID NO: 52] and feline IgG-2 [SEQ ID NO: 53], together with the consensus sequence [SEQ ID NO: 55]. The depicted feline IgG-1a and feline IgG-2 Fc regions have two additional N-terminal amino acid residues relative to the corresponding feline Fc regions defined by Strietzel et al., [Vet Immunol&Immunpathol., 158:214-223 (2014)]. Solid arrows indicate specific amino acid residue positions reflecting the EU numbering scheme according to Sequences of Proteins of Immunological Interest, 5th ed., Kabat et al., National Institutes of Health, Bethesda, Md. (1991). The "x" reflects the lack of uniformity at position 252 in the consensus sequence for the seven amino acid sequences compared. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0066] Binding of antibodies and / or IgG Fc fusion proteins to FcRn is highly pH dependent. Thus, binding occurs with high affinity at moderately acidic pH in endosomal compartments, but with significantly lower binding affinity at physiological pH on the cell surface. Strong binding of IgG antibodies to FcRn in endosomal compartments both protects the antibodies from the degradative action of proteolytic enzymes in endosomes and allows for recycling of receptor-bound antibodies at the cell surface, whereas higher pH at the cell surface (i.e., physiological pH) weakens the binding, thereby allowing release of the antibodies into circulation. Substitution of one or more amino acids into the Fc region may serve to increase the binding affinity of the antibodies and / or IgG Fc fusion proteins to FcRn at moderately acidic pH, thereby increasing the half-life of the antibodies and / or IgG Fc fusion proteins in vivo.

[0067] The present invention provides antibodies and IgG Fc fusion proteins comprising fragment crystallizable regions (Fc regions) that include one or more amino acid specific substitutions in the Fc region. In one aspect of the invention, these antibodies and IgG Fc fusion proteins have enhanced binding affinity for their neonatal Fc receptor (FcRn) at moderately acidic pH (pH 5.5-pH 6.5), extending the half-life of the antibody and / or IgG Fc fusion protein relative to corresponding antibodies and / or IgG Fc fusion proteins having unsubstituted Fc regions. In related embodiments, the antibodies and / or IgG Fc fusion proteins have enhanced binding affinity for their FcRn at moderately acidic pH, but unmodified or minimally modified binding affinity for their FcRn at physiological pH (pH 7.2-7.6). Thus, in one embodiment of the invention, specific amino acid substitutions in the Fc region of antibodies and / or IgG Fc fusion proteins do not appreciably affect the release of the antibodies and / or IgG Fc fusion proteins from their FcRn at physiological pH, but significantly increase the binding affinity of the antibodies and / or IgG Fc fusion proteins to their FcRn at moderately acidic pH.

[0068] Alternatively, or in combination, the relative in vivo half-life of the antibody and / or IgG Fc fusion protein can be extended by increasing the difference between the binding affinity at moderately acidic pH and the binding affinity at physiological pH of the antibody and / or IgG Fc fusion protein for FcRn. Thus, the present invention further provides antibodies and IgG Fc fusion proteins comprising fragment crystallizable regions (Fc), which comprise one or more amino acid substitutions in their Fc region, resulting in a greater difference in the binding affinity of the antibody and / or IgG Fc fusion protein for their neonatal Fc receptor (FcRn) at moderately acidic pH than their binding affinity at physiological pH, relative to the difference between their corresponding antibodies and IgG Fc fusion proteins that do not comprise amino acid substitutions in their Fc region. In certain embodiments of this type, the antibody and IgG Fc fusion protein also have an enhanced binding affinity for their neonatal Fc receptor (FcRn) at moderately acidic pH.

[0069] Abbreviation The following abbreviations are used throughout the detailed description and examples of the present invention: ADCC antibody-dependent cytotoxicity CDC Complement-dependent cytotoxicity CDR Complementarity determining region in an immunoglobulin variable region, as defined using the Kabat numbering system cFc dog fragment crystallizable region CHO Chinese hamster ovary EC50 Concentration that results in 50% efficacy or binding ECD extracellular domain ELISA Enzyme-Linked Immunosorbent Assay EU Index Also referred to as the EU Index, Kabat's EU Index, or EU numbering scheme, is a widely used numbering scheme according to Sequences of Proteins of Immunological Interest, 5th ed., Kabat et al., National Institutes of Health, Bethesda, Md. (1991).

[0070] fFc Cat fragment crystallizable region FR Antibody framework region: immunoglobulin variable region excluding the CDR regions.

[0071] IC50 Concentration that produces 50% inhibition IgG Immunoglobulin G The immunoglobulin alignment and numbering system pioneered by Elvin A. Kabat [Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991)] mAb Monoclonal antibody (also Mab or MAb) PCR Polymerase Chain Reaction PK Pharmacokinetics V region The segment of an IgG chain that is variable in sequence among different antibodies.

[0072] VH immunoglobulin heavy chain variable region VL immunoglobulin light chain variable region Vk immunoglobulin kappa light chain variable region Vl immunoglobulin lambda light chain variable region definition So that the present invention may be more readily understood, certain technical and scientific terms are specifically defined below. Unless specifically defined elsewhere herein, all other technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which this invention belongs.

[0073] As used in this specification, including the appended claims, the singular forms of words such as "a," "an," and "the" include their corresponding plural references unless the context clearly dictates otherwise.

[0074] The "activity" of a molecule may describe or refer to the binding of the molecule to a ligand or receptor, catalytic activity; the ability to stimulate gene expression or cell signaling, differentiation, or maturation; antigenic activity, modulation of the activity of other molecules, and the like. The "activity" of a molecule may also refer to the activity of modulating or maintaining cell-cell interactions, such as adhesion, or maintaining the structure of a cell, such as the cell membrane or cytoskeleton. "Activity" may also refer to specific activity, such as [catalytic activity] / [mg protein], or [immune activity] / [mg protein], concentration in a biological compartment, and the like. "Activity" may refer to the modulation of a component of the innate or adaptive immune system.

[0075] "Administration" and "treatment," as applied to an animal, e.g., canine or feline subject, cell, tissue, organ, or biological fluid, refer to contact of an exogenous medicinal, therapeutic, diagnostic agent, or composition with an animal, e.g., canine or feline subject, cell, tissue, organ, or biological fluid. Treatment of cells encompasses contact of a reagent to a cell, and contact of a reagent to a fluid where the fluid is in contact with a cell.

[0076] "Administration" and "treatment" also refer to in vitro and ex vivo treatments, for example, of a cell, with a reagent, diagnostic, binding compound, or by another cell. The term "subject" includes any organism, preferably an animal, more preferably a mammal (e.g., a dog, cat or human), most preferably a dog or cat.

[0077] "Treat" or "treatment" refers to administering a composition comprising a therapeutic agent, e.g., an IgG fusion protein (e.g., a canine or feline IgG fusion protein) and / or antibody (e.g., a caninized, felineized, canine or feline antibody) of the invention, internally or externally, to, e.g., a non-human subject, e.g., a dog or cat, or a canine or feline patient having one or more symptoms or suspected of having a condition for which the agent has therapeutic activity. Typically, the therapeutic agent is administered in an amount effective to alleviate and / or ameliorate one or more disease / condition symptoms (e.g., atopic dermatitis or cancer) in the treated subject or population, whether by inducing regression of such symptom(s) to any clinically measurable extent or inhibiting its progression. The amount of therapeutic agent effective to alleviate any particular disease / condition symptom (also referred to as a "therapeutically effective amount") may vary depending on factors such as the condition, age, and weight of the patient (e.g., dog or cat), and the ability of the pharmaceutical composition to elicit a desired response in the subject. Whether a disease / condition symptom has been alleviated or ameliorated can be assessed by any clinical measurement typically used by a veterinarian or other skilled health care provider to assess the severity or progression of that symptom. Although an embodiment of the present invention (e.g., a method of treatment or an article of manufacture) may not be effective in alleviating the target disease / condition symptom(s) in all subjects, it should alleviate the target disease / condition symptom(s) in a statistically significant number of subjects as determined by any statistical test known in the art, such as Student's t-test, chi-square test, Mann-Whitney U test, Kruskal-Wallis test (H test), Jonkheel-Terpstra test, and Wilcoxon test.

[0078] "Treatment" as applied to human, veterinary (e.g., dog or cat) or research subjects refers to therapeutic treatments as well as research and diagnostic applications, as set forth above, and includes, for example, contacting a dog, cat or other animal subject, cell, tissue, physiological compartment, or physiological fluid with an antibody and / or fusion protein of the invention.

[0079] As used herein, a "moderately acidic pH" is in the range of pH 5.5 to pH 6.5. In the examples below, pH 6.0 was used as the moderately acidic pH.

[0080] As used herein, "physiological pH" is in the range of pH 7.2 to pH 7.6. In the following examples, pH 7.4 was used as the physiological pH.

[0081] As used herein, the term "dog" includes all domestic dogs, Canis lupus familiaris or Canis familiaris, unless otherwise specified.

[0082] As used herein, the term "cat" refers to any member of the Felidae family. Members of this family include wild, zoo, and domestic members, including domestic cats, purebred and / or mixed breed companion cats, show cats, laboratory cats, cloned cats, and wild or feral cats.

[0083] As used herein, the term "antibody" refers to any form of antibody that exhibits the desired biological activity. Antibodies can be monomeric, dimeric or larger multimeric. It is therefore used in the broadest sense and specifically includes, but is not limited to, monoclonal antibodies (including full-length monoclonal antibodies), polyclonal antibodies, multispecific antibodies (e.g., bispecific antibodies), and camelized single domain antibodies. Unless otherwise specifically indicated, the antibody of the present invention is an IgG antibody.

[0084] As used herein, an "IgG antibody" is an immunoglobulin G antibody that contains two heavy chains and two light chains. The IgG antibodies of the present invention include caninized antibodies, fully canine antibodies, felineized antibodies, fully feline antibodies, and corresponding chimeric antibodies.

[0085] A "parent antibody" is an antibody obtained by exposing the immune system to an antigen prior to modification of the antibody for its intended use, such as caninization of the antibody for use as a canine therapeutic antibody.

[0086] As used herein, an antibody of the invention that, for example, "blocks" or is "blocking" a canine receptor to its binding partner (e.g., its ligand) or a feline receptor to its binding partner (e.g., its ligand) or that is "blocking the binding" of a canine receptor to its binding partner (e.g., its ligand) or a feline receptor to its binding partner (e.g., its ligand) is an antibody that blocks (partially or completely) the binding of a ligand to its receptor and vice versa, as determined by standard binding assays (e.g., BIACore®, ELISA or flow cytometry).

[0087] Typically, the antibody or antigen-binding fragment of the present invention retains at least 10% of its canine or feline antigen-binding activity (when compared to the parent antibody) when the activity is expressed on a molar basis. Preferably, the antibody or antigen-binding fragment of the present invention retains at least 20%, 50%, 70%, 80%, 90%, 95% or 100% or more of the canine antigen-binding affinity of the parent antibody. It is also contemplated that the antibody or antigen-binding fragment of the present invention may contain conservative or non-conservative amino acid substitutions (referred to as "conservative variants" or "functionally conserved variants" of the antibody) that do not substantially alter its biological activity.

[0088] "Isolated antibody" refers to a purified state, and in such context means that the molecule is substantially free of other biological molecules, such as nucleic acids, proteins, lipids, carbohydrates, or other materials, such as cell debris and growth medium. In general, the term "isolated" is not intended to refer to the complete absence of such materials, or the absence of water, buffers, or salts, unless present in amounts that would substantially interfere with the experimental or therapeutic use of the binding compounds described herein.

[0089] As used herein, a "chimeric antibody" is an antibody that has a variable domain from a first antibody and a constant domain from a second antibody, the first and second antibodies being from different species. [U.S. Pat. No. 4,816,567; and Morrison et al., Proc. Natl. Acad. Sci. USA 81:6851-6855 (1984)]. Typically, the variable domain is obtained from an antibody from a laboratory animal "parent antibody", such as a rodent, and the constant domain sequence is obtained from an animal subject antibody, such as a dog, cat or human, so that the resulting chimeric antibody is less likely to induce an adverse immune response in a dog, cat or human subject, respectively, than the parent (e.g., rodent) antibody.

[0090] The variable regions of each light / heavy chain pair form the antibody binding site. Thus, an intact antibody generally has two binding sites. Except for bifunctional or bispecific antibodies, the two binding sites are generally the same.

[0091] Typically, both heavy and light chain variable domains contain three hypervariable regions, also called complementarity determining regions (CDRs), located within relatively conserved framework regions (FRs). CDRs are usually aligned by framework regions, allowing binding to specific epitopes. Generally, from N-terminus to C-terminus, both light chain variable domains and heavy chain variable domains contain FR1, CDR1, FR2, CDR2, FR3, CDR3 and FR4. The assignment of amino acids to each domain is generally in accordance with Sequences of Proteins of Immunological Interest, Kabat, et al.; National Institutes of Health, Bethesda, Md.; 5th ed.; NIH Publ. No. 91-3242 (1991); Kabat, Adv. Prot. Chem. 32: 1-75 (1978); Kabat, et al., J. Biol. Chem. 252: 6609-6616 (1977)].

[0092] As used herein, the term "hypervariable region" refers to the amino acid residues of an antibody that are involved in antigen binding. Hypervariable region includes the amino acid residues from "complementarity determining region" or "CDR" [i.e., CDRL1 (or LCDR1), CDRL2 (or LCDR2) and CDRL3 (or LCDR3) in the light chain variable domain and CDRH1 (or HCDR1), CDRH2 (or HCDR2) and CDRH3 (or HCDR3) in the heavy chain variable domain]. [See Kabat et al. Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991), which defines the CDR region of an antibody by sequence; also see Chothia and Lesk, J. Mol. Biol. 196:901-917 (1987), which defines the CDR region of an antibody by structure].

[0093] As used herein, the terms "framework" or "FR" residues refer to variable domain residues other than the hypervariable region residues defined herein as CDR residues.

[0094] "Fragment crystallizable region", abbreviated as "Fc", and used interchangeably with "Fc region", corresponds to the CH2-CH3 portion of an antibody that interacts with cell surface receptors called Fc receptors.

[0095] As used herein, "wild-type Fc" is used interchangeably with "wild-type Fc region" and refers to an Fc region (e.g., cFc region or fFc region), e.g., an antibody or IgG Fc fusion protein comprising a wild-type Fc region, that is found in nature without any amino acid substitutions made to enhance the half-life of the antibody or IgG Fc fusion protein. As described below, an antibody or IgG fusion protein, e.g., an Fc region comprising one or more amino acid substitutions made to reduce antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) of a canine IgG-Bm region, is not found in nature and is therefore not a wild-type Fc region. However, an antibody or IgG fusion protein comprising such an Fc region (e.g., a canine IgG-Bm Fc region) should have the same half-life as a corresponding antibody or IgG Fc fusion protein comprising the corresponding wild-type Fc region found in nature (i.e., a canine IgG-B Fc region) in the absence of amino acid substitutions made to enhance the half-life of an antibody or IgG Fc fusion protein comprising a canine IgG-Bm region.

[0096] As used herein, the term "canine frame" refers to the amino acid sequences of the heavy and light chains of a canine antibody other than the hypervariable region residues defined herein as CDR residues. For caninized antibodies, in most embodiments, the amino acid sequences of the native canine CDRs are replaced in both chains with the corresponding foreign CDRs (e.g., from mouse, rat, or human). The heavy and / or light chains of the canine antibody may contain some foreign non-CDR residues to preserve the conformation of the foreign CDRs in the canine antibody and / or to modify Fc region function, for example, as exemplified below and / or as disclosed in U.S. Pat. No. 10,106,607 B2, the entirety of which is incorporated herein by reference. The present invention provides additional amino acid substitutions into the Fc region of the canine frame to enhance the half-life of the antibodies of the present invention.

[0097] As used herein, the term "cat frame" refers to the amino acid sequence of the heavy and light chains of a cat antibody other than the hypervariable region residues defined herein as CDR residues. For felineized antibodies, in most embodiments, the amino acid sequences of the native cat CDRs are replaced in both chains with the corresponding foreign CDRs (e.g., of mouse, rat, or human origin). The heavy and / or light chains of the cat antibody may contain some foreign non-CDR residues to preserve the conformation of the foreign CDRs in the cat antibody and / or to modify the Fc region function, for example, as exemplified below and / or as disclosed for caninized antibodies in U.S. Pat. No. 10,106,607 B2, the entirety of which is incorporated herein by reference. The present invention provides further amino acid substitutions in the Fc region of the cat frame to enhance the half-life of the antibodies of the present invention.

[0098] As used herein, "canine fragment crystallizable region" is interchangeably abbreviated as "cFc region" or simply "cFc" and corresponds to the canine fragment crystallizable region from a canine antibody. The canine fragment crystallizable region (cFc) of each of the four canine IgGs was first described by Tang et al. [Vet. Immunol. Immunopathol. 80:259-270 (2001); see also Bergeron et al., Vet. Immunol. Immunopathol. 157:31-41 (2014)].

[0099] As used herein, "feline fragment crystallizable region" is interchangeably abbreviated as "fFc region" or simply "fFc" and corresponds to the feline fragment crystallizable region from a feline antibody. The feline fragment crystallizable region (fFc) of each of the three feline IgGs was described by [Strietzel et al., Vet Immunol & Immunpathol. 158:214-223 (2014)].

[0100] There are four known IgG heavy chain subtypes and two known light chain subtypes of canine IgG. The four IgG heavy chains are designated A, B, C and D. These heavy chains represent four different subclasses of canine IgG, designated IgG-A (or IgGA), IgG-B (or IgGB), IgG-C (or IgGC) and IgG-D (or IgGD). Each heavy chain consists of one variable domain (VH) and three constant domains designated CH1, CH2 and CH3. The CH1 domain is connected to the CH2 domain via an amino acid sequence designated the "hinge" or alternatively the "hinge region". The DNA and amino acid sequences of these four heavy chain IgGs were first identified by Tang et al. [Vet. Immunol. Immunopathol. 80:259-270 (2001)]. The amino acid and DNA sequences of these heavy chain IgGs are also available from the GenBank database. For example, the amino acid sequence of the IgG-A heavy chain has the accession number AAL35301.1, IgG-B has the accession number AAL35302.1, IgG-C has the accession number AAL35303.1, and IgG-D has the accession number (AAL35304.1). Dog antibodies also contain two types of light chains, kappa and lambda. The DNA and amino acid sequences of these light chains can be obtained from the GenBank database. For example, the kappa light chain amino acid sequence has the accession number ABY 57289.1, and the lambda light chain has the accession number ABY 55569.1.

[0101] The constant regions of feline IgG subclasses and their hinge regions have been described [Strietzel et al., Vet Immunol & Immunpathol., 158:214-223 (2014)]. The amino acid sequences of the feline heavy chain constant regions are available in the Genbank database [IgG1a accession number BAA32229.1, IgG1b accession number BAA32230.1 and IgG2 accession number AHH34165.1]. IgG1a and IgG1b appear to be allelic variants and both bind strongly to human C1q, suggesting that they may be able to activate complement. In contrast, feline IgG2 has a divergent sequence, especially in the hinge region, and has negligible binding to C1q.

[0102] As used herein, a "substitution of an amino acid residue" in, for example, an amino acid sequence of an antibody by another amino acid residue is equivalent to a "replacement of an amino acid residue" by another amino acid residue, and indicates that a particular amino acid residue at a specific position in the amino acid sequence has been replaced (or substituted) by a different amino acid residue, for example by recombinant DNA techniques. Such substitutions can be specifically designed, i.e., deliberately replacing an asparagine (N) with a phenylalanine (F) at a specific position in the amino acid sequence of the Fc region, for example at position 434, numbered according to the EU index as in Kabat. Amino acid substitutions can be made, for example, to increase the half-life of a given antibody or IgG fusion protein and / or to decrease antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) of an antibody or IgG fusion protein, as described below.

[0103] An antibody or IgG Fc fusion protein of the invention comprising an Fc region (e.g., fFc or cFc) at, for example, positions 252, 254, 256, 308, 433, 434, 436, or any combination thereof, numbered according to the EU index as in Kabat, containing one or more amino acid substitutions, identified by its isotype or subtype (e.g., IgG-B), or by comprising a particular amino acid sequence in the absence of such substitutions (e.g., a cFc comprising the amino acid sequence of SEQ ID NO:2), or having a percent identity to a particular amino acid sequence in the absence of such substitutions (i.e., a cFc comprising 90% identity to the amino acid sequence of SEQ ID NO:2), as used herein means that the antibody or IgG Fc fusion protein comprises an IgG-B Fc region, a cFc comprising the amino acid sequence of SEQ ID NO:2, or a cFc comprising 90% identity to the amino acid sequence of SEQ ID NO:2, respectively, specifically containing one or more amino acid substitutions thereof. Although redundant, this can be reinforced by the statement that the Fc region (e.g., fFc or cFc) "retains said one or more amino acid substitutions." Thus, if the Fc region of an antibody or IgG Fc fusion protein is identified as comprising one or more amino acid substitutions, e.g., comprising an IgG-B Fc region, it is understood that the amino acid sequence of the IgG-B Fc region comprises those one or more amino acid substitutions. Similarly, if the Fc region of an antibody or IgG Fc fusion protein is identified as comprising one or more amino acid substitutions, e.g., comprising the amino acid sequence of SEQ ID NO:2, it is understood that the Fc region comprises the amino acid sequence of SEQ ID NO:2 comprising those one or more amino acid substitutions. In addition, if the Fc region of an antibody or IgG Fc fusion protein is identified as comprising one or more amino acid substitutions, and having at least 90% identity with the amino acid sequence of SEQ ID NO:2, it is understood that the amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO:2 retains those one or more amino acid substitutions, and the identity with the amino acid sequence is at least 90% with respect to the replacement / substitution in the remaining amino acid positions of the sequence.

[0104] As used herein, canine Fc (cFc) "IgG-Bm" comprises the amino acid sequence of SEQ ID NO: 4, which is the amino acid sequence of canine IgG-B Fc, but contains two amino acid residue substitutions, D31A and N63A, in the amino acid sequence of SEQ ID NO: 3 of IgG-B (see below). Thus, the aspartic acid residue (D) at position 31 of SEQ ID NO: 3 and the asparagine residue (N) at position 63 of SEQ ID NO: 3 are both replaced with an alanine residue (A) in the amino acid sequence of IgG-Bm, i.e., SEQ ID NO: 4. These two amino acid residue substitutions serve to significantly reduce the antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) of naturally occurring canine IgG-B [see U.S. Patent No. 10,106,607, the entire contents of which are incorporated herein by reference]. Similar substitutions can be made in the IgG-A, IgG-C, and IgG-D Fc regions, hereinafter designated IgG-Am, IgG-Cm, and IgG-Dm. In addition, analogous changes in the amino acid sequences of the feline Fc regions, IgG1a, IgG1b, and IgG2, are provided in the examples below, where such modifications are designated "IgG1am," "IgG1am," or "IgG2bm," respectively.

[0105] As used herein, the "extracellular domain" or "ECD" of a transmembrane protein, such as canine interleukin-13 receptor alpha 1 or canine interleukin-13 receptor alpha 2, refers to the portion of the transmembrane protein that naturally protrudes into the environment surrounding the cell. The ECD does not include the transmembrane portion of the transmembrane protein. The ECDs of canine interleukin-13 receptor alpha 1 and canine interleukin-13 receptor alpha 2 both bind canine IL-13.

[0106] As used herein, "artificial protein" and "artificial protein molecule" are used interchangeably to refer to a protein (or multimer of proteins, such as dimers, heterodimers, tetramers and heterotetramers) that does not naturally occur in nature, such as a man-made fusion protein.

[0107] As used herein, a "fusion protein" is an artificial protein that contains amino acid sequences from two or more different proteins joined together by peptide bonds.

[0108] As used herein, an "Fc fusion protein", which is used interchangeably with the term "IgG Fc fusion protein", is an artificial protein that combines the Fc region of an IgG antibody, which may further include a hinge region, e.g., canine IgG-B hinge region-CH2-CH3 or feline IgG1a hinge region-CH2-CH3, with another biologically active protein domain to generate a molecule with unique structure and therapeutic utility.

[0109] As used herein, a "cFc fusion protein" is used interchangeably with the term "canine IgG Fc fusion protein" and is an artificial protein that combines the cFc of a canine IgG antibody, which may include a hinge region, e.g., IgG-B hinge region-CH2-CH3, with another biologically active protein domain to generate a molecule with unique structure and therapeutic utility. For example, a canine IL-13Rα2-cFc fusion protein (cIL-13Rα2-cFc fusion protein) comprises the extracellular domain (ECD) of canine IL-13Rα2 linked to the N-terminus of canine IgG Fc (cFc). The ECD of IL-13Rα2 may be linked to the N-terminus of cFc by a canine hinge region. The cFc fusion proteins of the present invention are exemplified by the use of an IgGB hinge region and an IgGB cFc, but are in no way so limited, rather they include corresponding fusion proteins having cFcs of IgGA, IgGC and IgGD and may have hinge regions of IgGA, IgGC and IgGD. Thus, the canine Fc fusion protein cIL-13Rα2-cIgGB-Fc is one species of the cIL-13Rα2-cFc genus, which also includes cIL-13Rα2-cIgGA-Fc, cIL-13Rα2-cIgGC-Fc, cIL-13Rα2-cIgGD-Fc, and modified fusion proteins thereof.

[0110] As used herein, "canine interleukin-13 receptor alpha1-canine fragment crystallizable region fusion protein," "canine interleukin-13 receptor alpha1-cFc fusion protein," "canine IL-13Rα1-cFc fusion protein," or "cIL-13Rα1-cFc fusion protein," all used interchangeably, comprise the extracellular domain (ECD) of cIL-13Rα1 [or a fragment of the ECD that binds canine interleukin-13 (cIL-13)] connected via a peptide bond to a canine IgG Fc (cFc). In certain embodiments, the cIL-13Rα1-cFc fusion protein further comprises a canine hinge region linking the ECD of cIL-13Rα1 (or a fragment of the ECD that binds cIL-13) to the cFc. A cIL-13Rα1-cFc fusion protein can be generated by genetic engineering from a chemically synthesized nucleic acid encoding the cIL-13Rα1 ECD (or a fragment of the ECD that binds cIL-13) together with cFc (with or without a linking hinge region).

[0111] As used herein, "canine interleukin-13 receptor alpha2-canine fragment crystallizable region fusion protein," "canine interleukin-13 receptor alpha2-cFc fusion protein," "canine IL-13Rα2-cFc fusion protein" or "cIL-13Rα2-cFc fusion protein," all used interchangeably, comprise the extracellular domain (ECD) of cIL-13Rα2 [or a fragment of the ECD that binds canine interleukin-13 (cIL-13)] connected via a peptide bond to a canine IgG Fc (cFc). In certain embodiments, the cIL-13Rα2-cFc fusion protein further comprises a canine hinge region linking the ECD of cIL-13Rα2 (or a fragment of the ECD that binds cIL-13) to the cFc. A cIL-13Rα2-cFc fusion protein can be generated by genetic engineering from a chemically synthesized nucleic acid that encodes the cIL-13Rα2 ECD (or a fragment of the ECD that binds cIL-13) together with cFc (with or without a linking hinge region).

[0112] As used herein, a cIL-13Rα2-cFc fusion protein comprising a "fragment of the ECD of cIL-13Rα2 that binds to cIL-13" (or, interchangeably, a "fragment of the ECD of cIL-13Rα2 that binds to cIL-13) has a binding affinity for cIL-13 that is up to 100-fold lower than the binding affinity of a corresponding cIL-13Rα2-cFc fusion protein comprising a full-length ECD, i.e., the dissociation constant is up to 10 2 In certain embodiments, a cIL-13Rα2-cFc fusion protein comprising a fragment of the ECD of cIL-13Rα2 that binds cIL-13 has a binding affinity for cIL-13 that is up to 10-fold lower than the binding affinity of a corresponding cIL-13Rα2-cFc fusion protein comprising a full-length ECD, i.e., the dissociation constant is up to 10-fold higher. In yet other embodiments, a cIL-13Rα2-cFc fusion protein comprising a fragment of the ECD of cIL-13Rα2 that binds cIL-13 has a binding affinity for cIL-13 that is up to 5-fold lower than the binding affinity of a corresponding cIL-13Rα2-cFc fusion protein comprising a full-length ECD, i.e., the dissociation constant is up to 5-fold higher.

[0113] As used herein, a cIL-13Rα1-cFc fusion protein comprising a "fragment of the ECD of cIL-13Rα1 that binds to cIL-13" (or, interchangeably, a "fragment of the ECD of cIL-13Rα1 that binds to cIL-13) has a binding affinity for cIL-13 that is up to 100-fold lower than the binding affinity of a corresponding cIL-13Rα1-cFc fusion protein comprising a full-length ECD, i.e., the dissociation constant is up to 10 2In certain embodiments, a cIL-13Rα1-cFc fusion protein comprising a fragment of the ECD of cIL-13Rα1 that binds cIL-13 has a binding affinity for cIL-13 that is up to 10-fold lower than the binding affinity of a corresponding cIL-13Rα1-cFc fusion protein comprising a full-length ECD, i.e., the dissociation constant is up to 10-fold higher. In yet other embodiments, a cIL-13Rα1-cFc fusion protein comprising a fragment of the ECD of cIL-13Rα1 that binds cIL-13 has a binding affinity for cIL-13 that is up to 5-fold lower than the binding affinity of a corresponding cIL-13Rα1-cFc fusion protein comprising a full-length ECD, i.e., the dissociation constant is up to 5-fold higher.

[0114] As used herein, a "homodimer" of the canine interleukin receptor-cFc fusion protein of the present invention is a dimer of two monomeric fusion proteins that have minimally the same ECD (or a fragment of that ECD that binds to the corresponding ligand). The two monomeric fusion proteins also generally have the same cFc and the same hinge region. For example, if the canine interleukin receptor-cFc fusion protein is a cIL-13Rα2-cFc fusion protein, the ECD is cIL-13Rα2 ECD and the ligand is cIL-13. The two monomers of the homodimer are held together by disulfide bonds formed by cysteine ​​residues in the hinge region of each monomer. For example, a homodimer of a cIL-13Rα2-cFc fusion protein comprises two cIL-13Rα2-cFc fusion protein monomers, and a homodimer of a cIL-13Rα1-cFc fusion protein comprises two cIL-13Rα1-cFc fusion protein monomers.

[0115] As used herein, the IgG Fc fusion proteins of the invention, the antibodies of the invention, and / or antigen-binding fragments of antibodies "block" or are "blocking" one binding partner to another binding partner (e.g., a receptor for its ligand), or are "blocking the binding" of one binding partner to another binding partner (e.g., a receptor for its ligand). Antibodies and / or fusion proteins that block (partially or completely) the binding of two binding partners, e.g., a receptor to its ligand, and vice versa, can be determined by standard binding assays (e.g., BIACore®, ELISA, or flow cytometry).

[0116] As used herein, the term "caninized antibody" refers to a form of an IgG antibody that contains amino acid sequences derived from both canine and non-canine (e.g., mouse, rat, or human) IgG antibodies, whereas the term "felineized antibody" as used herein refers to a form of an IgG antibody that contains amino acid sequences derived from both feline and non-feline (e.g., mouse, rat, or human) IgG antibodies. Generally, a caninized or felineized antibody comprises substantially all of at least one or more, typically two, variable domains, with all or substantially all of the hypervariable loops corresponding to those of a non-canine or non-feline immunoglobulin, respectively (e.g., including six CDRs as exemplified below), and all or substantially all of the framework (FR) regions (and typically all or substantially all of the remaining frame) being of a canine or feline immunoglobulin sequence, respectively. A modified canine frame comprises one or more amino acid changes exemplified herein that further optimize the effectiveness of the caninized antibody, for example, to increase its binding to a canine antigen and / or its ability to block binding of the canine antigen to its natural binding partner. As exemplified below, the caninized antibody contains both the three heavy chain CDRs and the three light chain CDRs from a mouse anti-canine antigen antibody, along with a modified canine frame. As detailed below, the cFc of the caninized antibody may also contain amino acid substitutions that result in a longer half-life of the caninized antibody, i.e., increased binding affinity for its neonatal Fc receptor (FcRn) at pH 5.5 to pH 6.5.

[0117] Similarly, a felineized antibody can contain both three heavy chain CDRs and three light chain CDRs, e.g., from mouse, rat, or human, with a feline frame or, more commonly, a modified feline frame. The modified feline frame contains one or more amino acid changes that further optimize the effectiveness of the felineized antibody, e.g., to increase its binding to the feline antigen and / or its ability to block the binding of the feline antigen to its natural binding partner. Similarly, the fFc of the feline antibody can also contain amino acid substitutions that result in a longer half-life of the feline antibody, i.e., increased binding affinity for its neonatal Fc receptor (FcRn) at pH 5.5 to pH 6.5.

[0118] As used herein, a "fFc fusion protein", which is used interchangeably with the term "feline IgG Fc fusion protein", is an artificial protein that combines the fFc of a feline IgG antibody, which may include a hinge region, e.g., the IgG-1a hinge region-CH2-CH3, with another biologically active protein domain to generate a molecule with unique structure and therapeutic utility.

[0119] Caninized mouse or rat anti-dog antibodies that bind canine interleukin-31 (cIL-31) or canine interleukin-31 receptor alpha (cIL-31RA or cIL-31Rα) include, but are not limited to, antibodies for use in the invention comprising canine IgGA, IgGB, IgGC or IgGD heavy chains, and modified forms of canine IgGA, IgGB, IgGC or IgGD heavy chains that contain modified Fcs as disclosed herein, particularly caninized antibodies that also exhibit increased binding affinity for their neonatal Fc receptor (FcRn) at pH 5.5 to pH 6.5.

[0120] As used herein, the term "caninized antibody against canine interleukin-31 receptor alpha" is used interchangeably with "caninized cIL-31RA antibody" and "cIL-31RA caninized antibody" and is a caninized version of a mammalian antibody raised in a non-canine mammal (e.g., mouse or rat) against cIL-31RA.

[0121] Typically, an antibody or antigen-binding fragment of an antibody of the present invention retains at least 10% of its antigen-binding activity (when compared to the parent antibody) when that activity is expressed on a molar basis. Preferably, an antibody or antigen-binding fragment of the present invention retains at least 20%, 50%, 70%, 80%, 90%, 95% or 100% or more of the antigen-binding affinity as the parent antibody. It is also intended that an antibody or antigen-binding fragment of an antibody of the present invention may contain conservative or non-conservative amino acid substitutions (referred to as "conservative variants" or "functionally conserved variants" of an antibody) that do not substantially alter its biological activity.

[0122] As used herein, an "antipruritic agent" is a compound, polymer, and / or formulation that tends to inhibit, reduce, and / or prevent pruritus. Antipruritic agents are colloquially referred to as antipruritic agents.

[0123] As used herein, an "antipruritic antibody" is an antibody that can act as an antipruritic agent in animals, including mammals such as humans, dogs and / or cats, particularly with respect to atopic dermatitis. In certain embodiments, the antipruritic antibody binds to a specific protein of the IL-31 signaling pathway, such as IL-31 or its receptor IL-31RA. The binding of the antipruritic antibody to its corresponding antigen (e.g., IL-31 or IL-31RA) inhibits, for example, the binding of IL-31 to IL-31RA, disrupting and / or preventing successful signaling of this pathway, thereby inhibiting, reducing and / or preventing pruritus that would otherwise be caused by the IL-31 signaling pathway.

[0124] As used herein, an "anti-inflammatory agent" is a compound, macromolecule, and / or preparation that reduces inflammation by blocking the interaction of certain substances in the body that cause inflammation. The anti-inflammatory agent may be a cFc fusion protein that can act as an anti-inflammatory agent in animals, including mammals such as humans, dogs, and / or cats, particularly with respect to atopic dermatitis. In certain embodiments, the anti-inflammatory cFc fusion protein binds to a specific protein in the IL-4 / IL-13 signaling pathway, such as IL-4 or IL-13. The binding of the anti-inflammatory cFc fusion protein to its corresponding antigen (e.g., IL-4) inhibits, for example, the binding of IL-4 to IL-4Rα, disrupting and / or preventing signaling of this pathway, thereby disrupting or preventing chronic inflammation associated with atopic dermatitis. The combination of a homodimer of a cIL-4Rα-cFc fusion protein and a homodimer of a cIL-13Rα2-cFc fusion protein acts as an anti-inflammatory agent in the treatment of atopic dermatitis.

[0125] "Isolated nucleic acid molecule" means DNA or RNA of genomic, mRNA, cDNA or synthetic origin or some combination thereof, where the isolated polynucleotide is not associated with all or a portion of a polynucleotide with which it is found in nature or linked to a polynucleotide with which it is not linked in nature. For the purposes of this disclosure, it should be understood that a "nucleic acid molecule comprising" a particular nucleotide sequence does not encompass an intact chromosome. An isolated nucleic acid molecule "comprising" a specified nucleic acid sequence may, in addition to the specified sequence, include coding sequences for up to 10 or even up to 20 or more other proteins or portions or fragments thereof, or may include operably linked regulatory sequences that control expression of the coding region of the recited nucleic acid sequence, and / or may include vector sequences.

[0126] The phrase "control sequence" refers to a DNA sequence required for the expression of an operably linked coding sequence in a particular host organism. Control sequences suitable for prokaryotes include, for example, promoters, and may include operator sequences and ribosome binding sites. Eukaryotic cells are known to use promoters, polyadenylation signals, and enhancers.

[0127] A nucleic acid is "operably linked" when it is placed into a functional relationship with another nucleic acid sequence. For example, DNA for a presequence or secretory leader is operably linked to DNA for a polypeptide if it is expressed as a preprotein that participates in the secretion of the polypeptide; a promoter or enhancer is operably linked to a coding sequence if it affects the transcription of the sequence; or a ribosome binding site is operably linked to a coding sequence if it is positioned so as to promote translation. Generally, "operably linked" means that the DNA sequences being linked are contiguous, and in the case of a secretory leader, contiguous and in reading phase. Enhancers, however, need not be contiguous. Linking is accomplished by ligation at convenient restriction sites. If such sites do not exist, synthetic oligonucleotide adaptors or linkers are used in accordance with conventional practice.

[0128] As used herein, the terms "cell", "cell line" and "cell culture" are used interchangeably, and all such designations include progeny. Thus, the words "transformant" and "transformed cell" include the primary subject cell and cultures derived therefrom, regardless of the number of transfers. It is also understood that not all progeny have exactly the same DNA content due to deliberate or inadvertent mutations. Mutant progeny that have the same function or biological activity as screened for in the originally transformed cell are included. Where a clear designation is intended, it will be clear from the context.

[0129] Sequence identity refers to the degree to which the amino acids of two polypeptides are the same at equivalent positions when the two sequences are optimally aligned. As used herein, an amino acid sequence is 100% "identical" to a second amino acid sequence if the amino acid residues of both sequences are identical. Thus, an amino acid sequence is 50% "identical" to a second amino acid sequence if 50% of the amino acid residues of the two amino acid sequences are identical. Sequence comparison is performed over a contiguous block of amino acid residues contained in a given protein, e.g., a protein or portion of a polypeptide to be compared. In certain embodiments, selected deletions or insertions that would otherwise change the correspondence between the two amino acid sequences are taken into account.

[0130] Sequence similarity includes identical residues and non-identical biochemically related amino acids that share similar properties and may be interchangeable.

[0131] "Conservatively modified variants" or "conservative substitutions" refer to the substitution of amino acids in proteins with other amino acids having similar properties (e.g., charge, side chain size, hydrophobicity / hydrophilicity, main chain conformation and rigidity, etc.), such that changes can occur frequently without changing the biological activity of the protein. Those skilled in the art generally recognize that single amino acid substitutions in non-essential regions of a polypeptide do not substantially alter biological activity [see, for example, Watson et al., Molecular Biology of the Gene, The Benjamin / Cummings Pub.Co., p.224 (4th Ed.; 1987)]. In addition, substitutions of structurally or functionally similar amino acids are unlikely to destroy biological activity. Exemplary conservative substitutions are shown in Table A immediately below. [Table 1] Function-conservative variants of the IgG Fc fusion proteins of the present invention are also contemplated by the present invention. As used herein, "function-conservative variants" refers to IgG Fc fusion proteins or antibodies in which one or more amino acid residues are altered without altering the desired properties, such as antigen affinity and / or specificity. Such variants include, but are not limited to, replacement of amino acids with those having similar properties, such as the conservative amino acid substitutions in Table A above.

[0132] nucleic acid The present invention includes IgG Fc fusion proteins, antibodies and antigen-binding fragments of antibodies of the invention, and compositions comprising IgG Fc fusion proteins, antibodies and antigen-binding fragments of antibodies (see, for example, the Examples below).

[0133] Also included in the present invention are nucleic acids encoding IgG Fc fusion proteins, antibodies, and antigen-binding fragments of antibodies provided by the present invention that contain an amino acid sequence that is at least about 70% identical, preferably at least about 80% identical, more preferably at least about 90% identical, and most preferably at least about 95% identical (e.g., 95%, 96%, 97%, 98%, 99%, 100%) to the amino acid sequence of a caninized antibody provided herein, when the comparison is performed by a BLAST algorithm, with the algorithm parameters selected to give an exact match between the respective sequences over the entire length of the respective reference sequences, i.e., 95% identical means that 95% of the amino acids in the two sequences are identical. The present invention further provides nucleic acids encoding fusion proteins and / or immunoglobulin polypeptides comprising a nucleic acid sequence that is at least about 70% identical, preferably at least about 80% identical, more preferably at least about 90% identical, and most preferably at least about 95% identical (e.g., 95%, 96%, 97%, 98%, 99%, 100%) to any of the reference nucleic acid sequences when the comparison is performed by the BLAST algorithm, where the algorithm parameters are selected to give an exact match between the respective nucleotide sequences over the entire length of the respective reference sequence, i.e., at least 98% identical, meaning that at least 98% of the nucleotides in the two nucleic acid sequences are identical, and are also encompassed by the present invention.

[0134] As used herein, the percent sequence identity of nucleotides and amino acids can be determined using the C, MacVector (MacVector, Inc. Cary, NC 27519), Vector NTI (Informax, Inc. MD), Oxford Molecular Group PLC (1996) and ClustalW algorithms with alignment default parameters and identity default parameters. These commercially available programs can also be used to determine sequence similarity with the same or similar default parameters. Alternatively, advanced Blast search can be used under default filter conditions, for example, using the GCG (Genetics Computer Group, Program Manual for the GCG Package, Version 7, Madison, Wisconsin) pileup program with default parameters.

[0135] The following references relate to the BLAST algorithm, which is often used for sequence analysis: BLAST Algorithm: Altschul, SF, et al., J. Mol. Biol. 215:403-410 (1990); Gish, W., et al., Nature Genet. 3:266-272 (1993); Madden, TL, et al., Meth. Enzymol. 266:131-141 (1996); Altschul, SF, et al., Nucleic Acids Res. 25:3389-3402 (1997); Zhang, J., et al., Genome Res. 7:649-656 (1997); Wootton, JC, et al., Comput. Chem. 17:149-163 (1993); Hancock, JMet al., Comput. Appl. Biosci. 10:67-70(1994);Alignment scoring systems: Dayhoff, MO, et al., "A model of evolutionary change in proteins." Atlas of Protein Sequence and Structure, vol. 5, suppl. 3. MO Dayhoff (ed.), pp. 345-352, (1978); Natl. Biomed. Res. Found., Washington, DC; Schwartz, RM, et al., "Matrices for detecting distant relationships." Atlas of Protein Sequence and Structure, vol. 5, suppl. 3." (1978), MO Dayhoff (ed.), pp. 353-358(1978), Natl. Biomed. Res. Found., Washington, DC; Altschul, SF, J. Mol. Biol. 219:555-565(1991); States, DJ, et al. al.,Methods 3:66-70(1991);Henikoff,S.,et al.,Proc.Natl.Acad.Sci.USA 89:10915-10919(1992);Altschul,SF,et al.,J.Mol.Evol.36:290-300(1993);Alignment statistics: Karlin, S., et al., Proc. Natl. Acad. Sci. USA 87:2264-2268(1990); Karlin, S., et al., Proc. Natl. Acad. Sci. USA 90:5873-5877(1993); Dembo, A., et al., Ann. Prob. 22:2022-2039(1994); and Altschul, S. F. "Evaluating the statistical significance of multiple distinct local alignments." Theoretical and Computational Methods in Genome Research (S. Suhai, ed.), pp. 1-14, Plenum, New York (1997).

[0136] The IgG Fc fusion proteins, antibodies and antigen-binding fragments of antibodies of the present invention can be recombinantly produced by methods known in the art. Mammalian cell lines available as hosts for the expression of the antibodies or fragments disclosed herein are well known in the art and include many immortalized cell lines available from the American Type Culture Collection (ATCC). These include, among others, Chinese hamster ovary (CHO) cells, NSO, SP2 cells, HeLa cells, baby hamster kidney (BHK) cells, monkey kidney cells (COS), human hepatocellular carcinoma cells (e.g., Hep G2), A549 cells, 3T3 cells, HEK-293 cells and several other cell lines. Mammalian host cells include human, mouse, rat, dog, monkey, pig, goat, cow, horse and hamster cells. A particularly preferred cell line is selected by determining which cell line has a high expression level. Other cell lines that may be used are insect cell lines such as Sf9 cells, amphibian cells, bacterial cells, plant cells and fungal cells. When recombinant expression vectors encoding the heavy chain or antigen-binding portion or fragment thereof, the light chain and / or antigen-binding fragment thereof are introduced into a mammalian host cell, the antibody is produced by culturing the host cell for a period of time sufficient to allow for expression of the antibody in the host cell, or more preferably, secretion of the antibody into the medium in which the host cell is growing.

[0137] The antibody can be recovered from the culture medium using standard protein purification methods. Furthermore, expression of the antibody of the present invention (or other moieties therefrom) from the production cell line can be enhanced using several known techniques. For example, the glutamine synthetase gene expression system (GS system) is a common approach to enhance expression under certain conditions. The GS system is discussed in whole or in part in connection with European Patent Nos. 0216846, 0256055 and 0323997, and European Patent Application No. 89303964.4.

[0138] Pharmaceutical Compositions and Administration To prepare pharmaceutical or sterile compositions containing the IgG Fc fusion proteins, antibodies and antigen-binding fragments of antibodies of the present invention, they can be mixed with pharma- ceutically acceptable carriers or excipients. [See, for example, Remington's Pharmaceutical Sciences and US Pharmacopeia: National Formulary, Mack Publishing Company, Easton, PA (1984)].

[0139] Formulations of therapeutic and diagnostic agents can be prepared, for example, by mixing with acceptable carriers, excipients, or stabilizers in the form of lyophilized powders, slurries, aqueous solutions, or suspensions [see, for example, Hardman, et al. (2001) Goodman and Gilman's The Pharmacological Basis of Therapeutics, McGraw-Hill, New York, NY; Gennaro (2000) Remington: The Science and Practice of Pharmacy, Lippincott, Williams, and Wilkins, New York, NY; Avis, et al. (eds.) (1993) Pharmaceutical Dosage Forms: Parenteral Medications, Marcel Dekker, NY; Lieberman, et al. (eds.) (1990) Pharmaceutical Dosage Forms: Tablets, Marcel Dekker, NY; Lieberman, et al. (eds.) (1990) Pharmaceutical Dosage Forms: See, for example, Fischer, NY: Disperse Systems, Marcel Dekker, NY; Weiner and Kotkoskie (2000) Excipient Toxicity and Safety, Marcel Dekker, Inc., New York, NY. In one embodiment, the pharmaceutical composition comprising the IgG Fc fusion protein, antibody and / or antigen-binding fragment of antibody of the present invention is diluted to an appropriate concentration with sodium acetate solution pH 5-6, and NaCl or sucrose is added for isotonicity. Additional agents such as polysorbate 20 or polysorbate 80 may be added to enhance stability.

[0140] The toxicity and therapeutic efficacy of the IgG Fc fusion proteins, antibodies, and antigen-binding fragments of the antibodies of the compositions, administered alone or in combination with another agent, may be determined, for example, by LD 50 (a dose lethal to 50% of the population) and ED 50The dose that is therapeutically effective in 50% of the population can be determined by standard pharmaceutical procedures in cell cultures or experimental animals. The dose ratio between toxic and therapeutic effects is called the therapeutic index (LD 50 / ED 50 In certain embodiments, IgG Fc fusion proteins, antibodies, or antigen-binding fragments of antibodies of the invention that exhibit high therapeutic indices are desirable. The data obtained from these cell culture assays and animal studies can be used to formulate a range of dosages for use in subjects, e.g., dogs or cats. The dosage of such compounds is preferably within the ED with little or no toxicity. 50 The dosage may vary within this range depending upon the dosage form and route of administration used.

[0141] The mode of administration may vary. Suitable routes of administration include oral, rectal, mucosal, intestinal, parenteral, intramuscular, subcutaneous, intradermal, intramedullary, intrathecal, direct intracerebroventricular, intravenous, intraperitoneal, intranasal, intraocular, inhalation, insufflation, topical, dermal, transdermal, or intraarterial. In certain embodiments, pharmaceutical compositions comprising the IgG Fc fusion proteins, antibodies and / or antigen-binding fragments of antibodies of the present invention can be administered by invasive routes, such as by injection. In further embodiments of the present invention, pharmaceutical compositions comprising the IgG Fc fusion proteins, antibodies and / or antigen-binding fragments of antibodies of the present invention are administered intravenously, subcutaneously, intramuscularly, intraarterially, or by aerosol delivery by inhalation. Administration by non-invasive routes (e.g., oral; e.g., pills, capsules, or tablets) is also within the scope of the present invention.

[0142] Composition can be administered using medical equipment known in the art.For example, pharmaceutical composition of the present invention can be administered by injection with hypodermic needle, including prefilled syringe or autoinjector.Pharmaceutical composition disclosed herein can also be administered using needleless hypodermic injection device, such as the device disclosed in U.S. Patent No. 6,620,135; No. 6,096,002; No. 5,399,163; No. 5,383,851; No. 5,312,335; No. 5,064,413; No. 4,941,880; No. 4,790,824 or No. 4,596,556.

[0143] The pharmaceutical composition disclosed herein can also be administered by injection.The examples of well-known implant and module forms for administering pharmaceutical compositions include: US Patent No. 4,487,603, which discloses an implantable microinfusion pump for dispensing pharmaceuticals at a controlled rate; US Patent No. 4,447,233, which discloses a pharmaceutical infusion pump for delivering pharmaceuticals at a precise infusion rate; US Patent No. 4,447,224, which discloses a variable flow rate implantable infusion device for continuous drug delivery; US Patent No. 4,439,196, which discloses an osmotic drug delivery system with multi-chamber compartments.Many other such implants, delivery systems, and modules are well known to those skilled in the art.

[0144] Alternatively, compositions containing the IgG Fc fusion proteins, antibodies and / or antigen-binding fragments of antibodies of the present invention may be administered locally rather than systemically, often in a depot or sustained release formulation.

[0145] The dosing regimen depends on several factors, including the serum or tissue turnover rate of the therapeutic IgG Fc fusion protein, antibody, and / or antigen-binding fragment of the antibody, the level of symptoms, the immunogenicity of the therapeutic IgG Fc fusion protein, antibody, and / or antigen-binding fragment of the antibody, and the accessibility of the target cells in the biological matrix. Preferably, the dosing regimen delivers enough of the therapeutic IgG Fc fusion protein, antibody, and / or antigen-binding fragment of the antibody to bring about improvement of the target disease / condition while minimizing undesirable side effects. Thus, the amount of biologic delivered depends, in part, on the particular therapeutic antibody and / or fusion protein and the severity of the condition being treated. Guidance on selecting appropriate doses of therapeutic antibodies is available [e.g., Wawrzynczak Antibody Therapy, Bios Scientific Pub. Ltd, Oxfordshire, UK (1996); Kresina (ed.) Monoclonal Antibodies, Cytokines and Arthritis, Marcel Dekker, New York, NY (1991); Bach (ed.) Monoclonal Antibodies and Peptide Therapy in Autoimmune Diseases, Marcel Dekker, New York, NY (1993); Baert, et al. New Engl. J. Med. 348:601-608 (2003); Milgrom et al. New Engl. J. Med. 341:1966-1973 (1999); Slamon et al. New Engl. J. Med. 344:783-792 (2001); Beniaminovitz et al. New Engl. J. Med. 344:783-792 (2001); See Engl. J. Med. 342:613-619 (2000); Ghosh et al. New Engl. J. Med. 348:24-32 (2003); Lipsky et al. New Engl. J. Med. 343:1594-1602 (2000)].

[0146] The determination of the appropriate dose is made by a veterinarian, for example, using parameters or factors known or suspected in the art to affect treatment. Generally, the dose is started at a somewhat lower amount than the optimal dose, and then increased in small increments until the desired or optimal effect is achieved relative to any negative side effects. Important diagnostic procedures include diagnosis of symptoms.

[0147] Compositions comprising the IgG Fc fusion proteins, antibodies and / or antigen-binding fragments of antibodies of the invention, alone or together with any of the antibodies used in the invention, can be provided by continuous infusion or by doses administered, e.g., daily, 1-7 times per week, weekly, biweekly, monthly, bimonthly, quarterly, semi-annually, yearly, etc. Doses can be provided, for example, intravenously, subcutaneously, topically, orally, nasally, rectally, intramuscularly, intracerebrally, intraspinally, or by inhalation. The total weekly dose is generally at least 0.05 μg / kg body weight, more generally at least 0.2 μg / kg, 0.5 μg / kg, 1 μg / kg, 10 μg / kg, 100 μg / kg, 0.25 mg / kg, 1.0 mg / kg, 2.0 mg / kg, 5.0 mg / ml, 10 mg / kg, 25 mg / kg, 50 mg / kg, or more [e.g., Yang, et al. New Engl. J. Med. 349:427-434 (2003); Herold, et al. New Engl. J. Med. 346:1692-1698 (2002); Liu, et al. J. Neurol. Neurosurg. Psych. 67:451-456 (1999); Portielji, et al. Cancer Immunol. Immunother. 52:133-144 (2003)]. Doses may also be provided to achieve a predetermined target concentration of the IgG Fc fusion proteins, antibodies, and / or antigen-binding fragments of antibodies of the invention in the serum of a subject, e.g., 0.1, 0.3, 1, 3, 10, 30, 100, 300 μg / ml or more. In other embodiments, the IgG Fc fusion proteins, antibodies, and / or antigen-binding fragments of antibodies of the invention are administered subcutaneously or intravenously at 10, 20, 50, 80, 100, 200, 500, 1000 or 2500 mg / subject weekly, biweekly, "every four weeks," monthly, bimonthly or quarterly.

[0148] As used herein, "inhibit" or "treat" or "treatment" includes postponing the onset of symptoms associated with a disorder or condition and / or reducing the severity of symptoms of such a disorder or condition. The term further includes ameliorating existing uncontrolled or undesirable symptoms, preventing further symptoms, and ameliorating or preventing the underlying cause of such symptoms. Thus, the term indicates that a beneficial result is imparted to a vertebrate subject (e.g., a dog) having a disorder, condition, and / or condition, or having a potential for developing such a disorder, disease, or condition.

[0149] As used herein, the terms "therapeutically effective amount", "therapeutically effective dose" and "effective amount" refer to an amount of the IgG Fc fusion protein, antibody and / or antigen-binding fragment of the antibody of the present invention that is effective when administered alone or in combination with an additional therapeutic agent to a cell, tissue or subject, e.g., a dog or cat, to cause a measurable improvement in one or more of the symptoms of a disease or condition or the progression of such a disease or condition. A therapeutically effective dose further refers to an amount of the IgG Fc fusion protein, antibody and / or antigen-binding fragment of the antibody sufficient to cause at least a partial improvement of a symptom, e.g., treatment, cure, prevention or amelioration of an associated medical condition, or an increase in the rate of treatment, cure, prevention or amelioration of such a condition. When applied to a combination, a therapeutically effective dose refers to the combined amount of the active ingredients that produces a therapeutic effect, whether administered in combination, sequentially, or simultaneously. An effective amount of a therapeutic agent will cause an improvement of at least 10%; usually at least 20%; preferably at least about 30%; more preferably at least 40%, and most preferably at least 50% of a diagnostic measure or parameter. An effective amount may also result in an improvement in a subjective scale when a subjective scale is used to assess the severity of the condition.

[0150] [Example] [Example 1] Cloning and expression of the canine FcRn receptor. The subunits of the canine FcRn protein [IgG receptor and transporter (FCGRT) and β2-microglobulin (B2M)] have been described [Bergeron, et al., Vet Immunol and Immunopathol. 157:31-41 (2014)]. Their sequences can be found in the National Center for Biotechnology Information database and are provided below. DNA encoding FCGRT engineered with a c-terminal [GGGGS; SEQ ID NO: 46] x3 linker, AviTag, and 8xHis tag, as well as B2M prepared without a c-terminal tag, were cloned into the pcDNA3.4 vector with the artificial signaling peptide MGWSCIILFLVATATGVHS [SEQ ID NO: 47]. Equal amounts of each vector were co-transfected into Expi293F cells. To purify the FcRn heterodimer, a two-step purification was performed by HisTrapFF™ Crude and HiLoad™ 26 / 600 Superdex™ 200 prep grade columns.

[0151] XP_533618.2 IgG receptor FcRn large subunit p51 isoform X2 [Canis lupus familiaris]: [SEQ ID NO:48] MGVPRPRSWGLGFLLFLLPTLRADSHLSLLYHLTAVSAPPPGTPAFWASGWLGPQQYLSYNNLRAQAEPYGAWVWENQVSWYWEKETTDLRTKEGLFLEALKALGDGGPYTLQGLLGCELGPDNTSVPVAKFALNGEDFMTFDPKLGTWNGDWPETETVSKRWMQQAGAVSKERTFL LYSCPQRLLGHLERGNLEWKEPPSMRLKARPGSPGFSVLTCSAFSFYPPELQLRFLRNGLAAGSGEGDFGPNGDGSFHAWSSLTVKSGDEHHYRCLVQHAGLPQPLTVELESPAKSSVPVVGIVIGFLLLTAVAVGGALLWRRMRKGLPAPWMSLRGDDVGALLPTPGVPKDADS XP_535458.1 predicted: Similar to beta-2-microglobulin (B2M) precursor isoform 2 [Canis familiaris] [SEQ ID NO: 49] MAPRPALATAGFLALLLILLAACRLDAVQHPPKIQVYSRHPAENGKPNFLNCYVSGFHPPEIEIDLLKNGKEMKAEQTDLSFSKDWTFYLLVHTEFTPNEQDEFSCRVKHVTLSEPQIVKWDRDN [Example 2] In vitro binding to FcRn receptors The binding of antibodies and IgG Fc fusion proteins to FcRn protein was determined by Octet™ HTX using streptavidin (SA) biosensors. First, biotin-labeled FcRn / B2M was loaded onto pre-hydrated SA biosensors at a concentration of 10ug / mL for 60 seconds. Second, for the blocking step, the biosensors were placed into pH 6.0 TBS / casein buffer for 180 seconds. Third, for the association step, the FcRn / B2M-loaded biosensors were placed into two-fold serial dilutions of antibodies or IgG Fc fusion proteins from 500nM to 7.8nM in pH 6.0 or 7.4 TBS / casein buffer for 15 seconds. Finally, for the dissociation step, the biosensors were placed into either pH 6.0 or pH 7.4 TBS / casein buffer for 60 seconds. Analysis was performed using Octet Data Analysis 12.0 software, and curves were fitted using a 1:1 binding model.

[0152] [Example 3] Canine IgG Fc region and feline IgG Fc region Provided below are the amino acid sequences of four dog Fc regions and three cat Fc regions, as well as the corresponding amino acid sequences of modified Fc regions that contain two amino acid residue substitutions D31A and N63A, as exemplified in the amino acid sequence of SEQ ID NO:3 of IgG-B compared with the amino acid sequence of SEQ ID NO:4 of IgG-Bm. These two amino acid residue substitutions serve to significantly reduce the antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) of naturally occurring dog IgG-B (see U.S. Patent No. 10,106,607, the entire contents of which are incorporated herein by reference). According to the EU numbering scheme of Sequences of Proteins of Immunological Interest, 5th ed., Kabat et al., National Institutes of Health, Bethesda, Md. (1991), D31A and N63A correspond to amino acid positions D265A and N297A, respectively.

[0153] The amino acid sequences of the Fc regions from canine IgG-A [SEQ ID NO: 1], canine IgG-B [SEQ ID NO: 3], canine IgG-C [SEQ ID NO: 5], canine IgG-D [SEQ ID NO: 7], feline IgG-1a [SEQ ID NO: 52], feline IgG-2 [SEQ ID NO: 53], human IgG1 Fc [SEQ ID NO: 54], and the consensus sequence of these seven amino acid sequences [SEQ ID NO: 55] are shown in Figure 1. As shown by Strietzel et al., [Vet Immunol&Immunpathol., 158:214-223 (2014)], the amino acid sequences of the Fc regions of feline IgG-1a and feline IgG-2 Fc regions further include two additional N-terminal amino acid residues from their respective hinge regions. According to Strietzel et al., supra, the amino acid sequences of the feline Fc regions are [SEQ ID NO: 9] for feline IgG-1a, [SEQ ID NO: 50] for feline IgG-1b, and [SEQ ID NO: 11] for feline IgG-2.

[0154] Dog IgG Fc IgG-A [SEQ ID NO:1] LGGPSVLIFPPKPKDILRITRTPEVTCVVLDLGREDPEVQISWFVDGKEVHTAKTQSREQQFNGTYRVVSVLPIEHQDWLTGKEFKCRVNHIDLSPIERTISKARGRAHKPSVYVLPPSPKELLSSDTVSITCLIKDFYPPDIDVEWQSNGQQEPERKHRMTPPQLDEDGSYFLYSKLSVDKSRWQQGDPFTCAVMHETLQNHYTDLSLSHSPGK IgG Am LGGPSVLIFPPKPKDILRITRTPEVTCVVLALGREDPEVQISWFVDGKEVHTAKTQSREQQFAGTYRVVSVLPIEHQDWLTGKEFKCRVNHIDLSPIERTISKARGRAHKPSVYVLPPSPKELLSSDTVSITCLIKDFYPPDIDVEWQSNGQQEPERKHRMTPPQLDEDGSYFLYSKLSVDKSRWQQGDPFTCAVMHETLQNHYTDLSLSHSPGK IgG B LGGPSVFIFPKPKDTLLIARTPEVTCVVVDLDPEPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPDIVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALNHHYTQESLSHPGK IgG Bm LGGPSVFIFPKPKDTLLIARTPEVTCVVVALDPEVQISWFVDGKQMQTAKTQPREEQFAGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFPPDIVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALNHHYTQESLSHPGK IgG-C [SEQ ID NO:5] LGGPSVFIFPPKPKDILVTARTPTVTCVVVDLDPENPEVQISWFVDSKQVQTANTQPREEQSNGTYRVVSVLPIGHQDWLSGKQFKCKVNNKALPSPIEEIISKTPG QAHQPNVYVLPPSRDEMSKNTVTLTCLVKDFFPPEIDVEWQSNGQQEPESKYRMTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNHYTQISLSHSPGK IgG-Cm [SEQ ID NO:6] LGGPSVFIFPPKPKDILVTARTPTVTCVVVALDPENPEVQISWFVDSKQVQTANTQPREEQSAGTYRVVSVLPIGHQDWLSGKQFKCKVNNKALPSPIEEIISKTPG QAHQPNVYVLPPSRDEMSKNTVTLTCLVKDFFPPEIDVEWQSNGQQEPESKYRMTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNHYTQISLSHSPGK IgG-D [SEQ ID NO: 7] LGGPSVFIFPPKPKDILRITRTPEITCVVLDLGREDPEVQISWFVDGKEVHTAKTQPREQQFNSTYRVVSVLPIEHQDWLTGKEFKCRVNHIGLPSPIERTISKARGQ AHQPSVYVLPPSPKELSSSDTVTLTCLIKDFFPPEIDVEWQSNGQPEPESKYHTTAPQLDEDGSYFLYSKLSVDKSRWQQGDTFTCAVMHEALQNHYTDLSLSHSPGK IgG-Dm [SEQ ID NO: 8] LGGPSVFIFPPKPKDILRITRTPEITCVVLALGREDPEVQISWFVDGKEVHTAKTQPREQQFASTYRVVSVLPIEHQDWLTGKEFKCRVNHIGLPSPIERTISKARGQ AHQPSVYVLPPSPKELSSSDTVTLTCLIKDFFPPEIDVEWQSNGQPEPESKYHTTAPQLDEDGSYFLYSKLSVDKSRWQQGDTFTCAVMHEALQNHYTDLSLSHSPGK Feline IgG Fc IgG-1a [SEQ ID NO: 9] PPEMLGGPSIFIFPPKPKDTLSISRTPEVTCLVVDLGPDDSDVQITWFVDNTQVYTAKTSPREEQFNSTYRVVSVLPILHQDWLKGKEFKCKVNSKSLPSPIERTISKA KGQPHEPQVYVLPPAQEELSRNKVSVTCLIKSFHPPDIAVEWEITGQPEPENNYRTTPPQLDSDGTYFVYSKLSVDRSHWQRGNTYTCSVSHEALHSHHTQKSLTQSPGK IgG-1am [SEQ ID NO: 10] PPEMLGGPSIFIFPPKPKDTLSISRTPEVTCLVVALGPDDSDVQITWFVDNTQVYTAKTSPREEQFASTYRVVSVLPILHQDWLKGKEFKCKVNSKSLPSPIERTISKA KGQPHEPQVYVLPPAQEELSRNKVSVTCLIKSFHPPDIAVEWEITGQPEPENNYRTTPPQLDSDGTYFVYSKLSVDRSHWQRGNTYTCSVSHEALHSHHTQKSLTQSPGK IgG-1b [SEQ ID NO:50] PPEMLGGPSIFIFPPKPKDTLSISRTPEVTCLVVDLGPDDSDVQITWFVDNTQVYTAKTSPREEQFNSTYRVVSVLPILHQDWLKGKEFKCKVNSKSLPSPIERTISKD KGQPHEPQVYVLPPAQEELSRNKVSVTCLIEGFYPSDIAVEWEITGQPEPENNYRTTPPQLDSDGTYFLYSRLSVDRSRWQRGNTYTCSVSHEALHSHHTQKSLTQSPGK IgG-1bm [SEQ ID NO:51] PPEMLGGPSIFIFPPKPKDTLSISRTPEVTCLVVALGPDDSDVQITWFVDNTQVYTAKTSPREEQFASTYRVVSVLPILHQDWLKGKEFKCKVNSKSLPSPIERTISKD KGQPHEPQVYVLPPAQEELSRNKVSVTCLIEGFYPSDIAVEWEITGQPEPENNYRTTPPQLDSDGTYFLYSRLSVDRSRWQRGNTYTCSVSHEALHSHHTQKSLTQSPGK IgG-2 [SEQ ID NO: 11] VPEIPGAPSVFIFPPKPKDTLSISRTPEVTCLVVDLGPDDSNVQITWFVDNTEMHTAKTRPREEQFNSTYRVVSVLPILHQDWLKGKEFKCKVNSKSLPSAMERTISKA KGQPHEPQVYVLPPTQEELSENKVSVTCLIKGFHPPDIAVEWEITGQPEPENNYQTTPPQLDSDGTYFLYSRLSVDRSHWQRGNTYTCSVSHEALHSHHTQKSLTQSPGK IgG-2m [SEQ ID NO: 12] VPEIPGAPSVFIFPPKPKDTLSISRTPEVTCLVVALGPDDSNVQITWFVDNTEMHTAKTRPREEQFASTYRVVSVLPILHQDWLKGKEFKCKVNSKSLPSAMERTISKA KGQPHEPQVYVLPPTQEELSENKVSVTCLIKGFHPPDIAVEWEITGQPEPENNYQTTPPQLDSDGTYFLYSRLSVDRSHWQRGNTYTCSVSHEALHSHHTQKSLTQSPGK cIgG-A hinge region [SEQ ID NO: 13] FNECRCTDTPPCPVPEP cIgG-B hinge region [SEQ ID NO: 14] PKRENGRVPRPPDCPKCPT 1 PEM cIgG-C hinge region [SEQ ID NO: 15] AKECECKCNCNNCPCPGCGL cIgG-D hinge region [SEQ ID NO: 16] PKESTCKCISPCPVPES IgG-1a Fc+2 amino acid residues [SEQ ID NO:52] CPPPEMLGGPSIFIFPPKPKDTLSISRTPEVTCLVVDLGPDDSDVQITWFVDNTQVYTAKTSPREEQFNSTYRVVSVLPILHQDWLKGKEFKCKVNSKSLPSPIERTISK AKGQPHEPQVYVLPPAQEELSRNKVSVTCLIKSFHPPDIAVEWEITGQPEPENNYRTTPPQLDSDGTYFVYSKLSVDRSHWQRGNTYTCSVSHEALHSHHTQKSLTQSPGK IgG-2 Fc+2 amino acid residues [SEQ ID NO:53] CPVPEIPGAPSVFIFPPKPKDTLSISRTPEVTCLVVDLGPDDSNVQITWFVDNTEMHTAKTRPREEQFNSTYRVVSVLPILHQDWLKGKEFKCKVNSKSLPSAMERTISK AKGQPHEPQVYVLPPTQEELSENKVSVTCLIKGFHPPDIAVEWEITGQPEPENNYQTTPPQLDSDGTYFLYSRLSVDRSHWQRGNTYTCSVSHEALHSHHTQKSLTQSPGK Human IgG1 Fc [SEQ ID NO:54] PELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKA KGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK Consensus sequence: [SEQ ID NO:55] LGGPSVFIFPPKPKDTLXISRTPEVTCVVVDLGPEDPEVQISWFVDGKEVHTAKTQPREEQFNSTYRVVSVLPILHQDWLKGKEFKCKVNNKALPSPIERTISKAXGQ AHXPXVYVLPPSREELSKNXTVSLTCLIKDFFPPDIDVEWQSNGQPEPEXKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFTCAVMHEALHNHYTQKSLSHSPGK Figure 1 shows the EU numbering scheme according to Sequences of Proteins of Immunological Interest, 5th ed., Kabat et al., supra, as used herein. Amino acid residue numbers 252, 254, 256, 308, 428, 433, 434, and 436 are specifically identified in Figure 1 and are therefore amino acid residue positions that are constituted by the amino acid sequences of the cFc and fFc regions of the present invention according to the EU numbering scheme of Kabat et al., supra.

[0155] 1 This threonine (T) is also identified as alanine (A).

[0156] [Example 4] Construction, expression and purification of modified canine IgG Fc fusion proteins and antibodies Background Atopic dermatitis (AD) is a recurrent, pruritic and chronic inflammatory skin disease in humans and companion animals that is characterized by immune system dysregulation and epidermal barrier abnormalities. Both interleukin-4 (IL-4) and interleukin-13 (IL-13) are part of the signaling pathways involved in chronic inflammatory skin disease in atopic dermatitis. IL-4 binds to a heterodimeric receptor that contains a monomer of the common γc chain (γc) and a monomer of IL-4 receptor alpha (IL-4Rα). IL-13 binds to a heterodimeric receptor that contains a monomer of IL-13 receptor alpha1 (IL-13Rα1) and a monomer of IL-4Rα. Blocking the binding of IL-4 to IL-4Rα and IL-13 to IL-13Rα1 blocks the associated skin inflammation. IgG Fc fusion proteins containing either the extracellular domain (ECD) of IL-13Rα1 (e.g., cIL-13Rα1-cFc fusion protein) or the extracellular domain (ECD) of IL-13Rα2 (e.g., cIL-13Rα2-cFc fusion protein) can bind to IL-13. IgG Fc fusion proteins containing the ECD of IL-4Rα (e.g., canine IL-4Rα-cFc fusion protein) can bind to IL-4Rα. Combining both an IgG Fc fusion protein containing the ECD of either IL-13Rα1 or IL-13R Rα2 and an IgG Fc fusion protein containing the ECD of IL-4Rα can block signaling by IL-4Rα, thereby ameliorating the chronic inflammatory skin disease of atopic dermatitis.

[0157] Binding of interleukin-31 (IL-31) to its receptor, IL-31 receptor alpha (IL-31RA), initiates the pruritic effects of atopic dermatitis in both humans and dogs. Blocking the binding of IL-31 to IL-31RA with an antibody that binds to IL-31RA serves to block signaling by IL-31RA and ameliorate the pruritic effects of atopic dermatitis. Prolonging the half-life of IgG Fc IL-13Rα1 or IL-13R Rα2 IgG fusion proteins and / or IgG Fc IL-4Rα, and / or prolonging the half-life of IL-31RA antibodies, allows the use of lower doses and / or less frequent administration of the corresponding potential drugs.

[0158] method Amino acid residue modifications were engineered in the canine Fc region of the heavy chain of IgG antibodies and cFc fusion proteins to improve their affinity for the neonatal Fc receptor FcRn at pH 6. When the antibody contains a hinge region of canine IgG-B Fc and a canine IgG-Bm Fc region, the nucleic acid encoding the artificial signaling peptide peptide MGWSCIILFLVATATGVHS [SEQ ID NO: 16] and the amino acid sequence of the heavy chain. Alternatively, the extracellular domain of canine IL-13Ra2 was fused to a canine IgG-B Fc hinge region and a canine IgG-B Fc region. The nucleic acid encoding the antibody (canine heavy chain as above or the corresponding canine light chain) or the cFc fusion protein was cloned into the pcDNA3.4 vector. Each vector was transfected into ExpiCHO cells, and the collected supernatant was purified with a recombinant protein A affinity column. The protein was eluted in 0.1 M glycine-HCl (pH 2.7) and then adjusted to pH 6.0 using 1 M Tris buffer (pH 8.0).

[0159] Canine IL-13Rα1 and IL-13Rα2 Canine IL-13Rα1 [SEQ ID NO: 17] VLPAKPENISCIFYYEENFTCTWSPEKEASYTWYKVKRTYSYGYKSDICSTDNSTRGNHASCSFLPPTITNPDNYTIQVEAQNADGIMKSDITYWNLDAIMKIEPPEIFSVKSVLGIKRMLQIK WIRPVLAPHSSTLKYTLRFRTINSAYWMEVNFTKEDIDRDETYNLTELQAFTEYVMTLRCAPAESMFWSGWSQEKVGTTEEEAPYGLDLWRVLKPAMVDGRRPVQLMWKKATGAPVLEKALGYN IWYFPENNTNLTETVNTTNQTHELYLGGKTYWVYVVSYNSLGESPVATLRIPALNEKTFQCIEAMQACLTQDQLVVEWQSSAPEVDTWMVEWFPDVDSEPSSFSWESVSQARNWTIQKDELKPL WCYNISVYPVLRDRVGQPYSTQAYVQEGIPSAGPVTQADSIGVKTVTITWKEIPKSKRNGFIKNYTIFYQAEDGKEFSKTVNSNILQYRLESLTRRTSYSLQVMASTNAGGTNGTKINFKTLSIS Canine IL-13Rα2 [SEQ ID NO: 18] SMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCVYYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDH SAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVENEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKET Amino acid sequences of exemplary modified canine IL-13Rα1 and IL-13Rα2 IgG Fc fusion proteins Therefore, in order to increase the half-life of cFc fusion protein, the canine IgG-B Fc region of the fusion protein of the present invention is modified relative to the corresponding wild-type canine IgG-B Fc. Such modified cFc region comprises one or more amino acid substitutions at one or more amino acid residues 252, 254, 256, 433, 434 and 436 relative to the wild-type cFc region [Sequences of Proteins of Immunological Interest, 5th ed., Kabat et al., National Institutes of Health, Bethesda, Md. (1991); numbered according to the EU index]. Particular examples comprise modifications at one or more of the following positions: L252Y, A254T, T256D, T256E, I308P, H433K, H433L, N434H, N434F, N434Y and Y436T, numbered as shown in Figure 1 and provided in Table 1 below.

[0160] cIL-13Rα2-cIgGB-Fc-Y N434Y [SEQ ID NO: 19] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCVYYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKPMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVENEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHYHYTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-F N434F [SEQ ID NO: 20] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCVYYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKPMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVENEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHFHYTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-L H433L [SEQ ID NO: 21] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCVYYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKPMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVENEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALLNHYTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-K H433K [SEQ ID NO: 22] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCVYYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKPMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVENEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALKNHYTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-T Y436T [SEQ ID NO: 23] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCVYYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKPMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVENEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNHTTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-LY H433L / N434Y [SEQ ID NO: 24] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCVYYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKPMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVENEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALLYHYTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-KY H433K / N434Y [SEQ ID NO: 25] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCVYYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKPMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVENEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALKYHYTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-KF H433K / N434F [SEQ ID NO: 26] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCV YYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVE NEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSV LPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALKFHYTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-LF H433L / N434F [SEQ ID NO: 27] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCVYYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKPMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVENEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALLFHYTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-KYT H433K / N434Y / Y436T [SEQ ID NO: 28] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCVYYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKPMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVENEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALKYHTTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-LYT H433L / N434Y / Y436T [SEQ ID NO: 29] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCVYYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKPMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVENEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALLYHTTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-LFT H433L / N434F / Y436T [SEQ ID NO: 30] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCVYYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKPMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVENEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALLFHTTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-KFT H433K / N434F / Y436T [SEQ ID NO: 31] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCV YYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVE NEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSV LPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALKFHTTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-PY I308P / N434Y [SEQ ID NO: 32] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCV YYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVE NEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSV LPPGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHYTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-DPY T256D / I308P / N434Y [SEQ ID NO: 33] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCV YYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVE NEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARDPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSV LPPGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHYTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-DY T256D / N434Y [SEQ ID NO: 34] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCVYYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKPMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVENEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARDPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHYHYTQESLSHSPGK cIL-13Rα2-cIgGB-Fc-YT N434Y / Y436T [SEQ ID NO: 35] MGWSCIILFLVATATGVHSSMLSNAEIKVNPPQDFEIVDPGYLGYLSLQWQPPLFPDNFKECTIEYELKYRNIDSENWKTIITKNLHYKDGFDLNKGIEAKINTLLPAQCTNGSEVRSSWAETTYWTSPQGNRETKIQDMDCV YYNWQYLVCSWKPGMGVHFDTNYQLFYWYEGLDHSAECTDYIKVNGKNMGCRFPYLESSDYKDFYICVNGSSESQPIRPSYFIFQLQNIVKMPPDYLSLTVKNSEEINLKWNMPKGPIPAKCFIYEIEFTEDGTTWVTTTVE NEIQITRTSNESQKLCFLVRSKVNIYCSDDGIWSEWSDEQCWKGDIWKETPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSV LPIGHQDWLKGKQFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHYHTTQESLSHSPGK [Table 2] Exemplary antibody half-life enhancing modifications amino acid sequences In order to increase the half-life of the caninized mouse anti-canine IL-31RA antibody, the canine IgG-Bm Fc region of the canine heavy chain of the present invention is modified relative to the corresponding canine IgG-Bm Fc. Such modified cFc region comprises one or more amino acid substitutions at one or more amino acid residues 252, 256, 433 and 434 relative to the wild-type cFc region [Sequences of Proteins of Immunological Interest, 5th ed., Kabat et al., National Institutes of Health, Bethesda, Md. (1991); numbered according to the EU index]. Particular examples comprise modifications at one or more of the following positions: L252Y, T256D, T256E, H433K, H433L, N434F, and N434Y, numbered as shown in Figure 1 and provided in Table 2 below.

[0161] c218D9VH4-cIgGBm-F N434F [SEQ ID NO: 36] MGWSCIILFLVATATGVHSEVTLQESGPGLVKPSQTLSLTCSFSGFSLSTFGRGVGWIRQRPGRGLEWMGHIWWDDDKYYNPALKSRLSITKDTAKNQVFLQLSSMTTEDTAVYYCARI AGGLRRAPYAMDSWGQGTLVTVSSASTTAPSVFPLAPSCGSTSGSTVALACLVSGYFPEPVTVSWNSGSLTSGVHTFPSVLQSSGLYSLSSMVTVPSSRWPSETFTCNVAHPASKTKVDK PVPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVALDPEDPEVQISWFVDGKQMQTAKTQPREEQFAGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALP SPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHFHYTQESLSHSPGK c218D9VH4-cIgGBm-Y N434Y [SEQ ID NO: 37] MGWSCIILFLVATATGVHSEVTLQESGPGLVKPSQTLSLTCSFSGFSLSTFGRGVGWIRQRPGRGLEWMGHIWWDDDKYYNPALKSRLSITKDTAKNQVFLQLSSMTTEDTAVYYCARI AGGLRRAPYAMDSWGQGTLVTVSSASTTAPSVFPLAPSCGSTSGSTVALACLVSGYFPEPVTVSWNSGSLTSGVHTFPSVLQSSGLYSLSSMVTVPSSRWPSETFTCNVAHPASKTKVDK PVPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVALDPEDPEVQISWFVDGKQMQTAKTQPREEQFAGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALP SPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHYHYTQESLSHSPGK c218D9VH4-cIgGBm-KF H433K / N434F [SEQ ID NO: 38] MGWSCIILFLVATATGVHSEVTLQESGPGLVKPSQTLSLTCSFSGFSLSTFGRGVGWIRQRPGRGLEWMGHIWWDDDKYYNPALKSRLSITKDTAKNQVFLQLSSMTTEDTAVYYCARI AGGLRRAPYAMDSWGQGTLVTVSSASTTAPSVFPLAPSCGSTSGSTVALACLVSGYFPEPVTVSWNSGSLTSGVHTFPSVLQSSGLYSLSSMVTVPSSRWPSETFTCNVAHPASKTKVDK PVPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVALDPEDPEVQISWFVDGKQMQTAKTQPREEQFAGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALP SPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALKFHYTQESLSHSPGK c218D9VH4-cIgGBm-KY H433K / N434Y [SEQ ID NO: 39] MGWSCIILFLVATATGVHSEVTLQESGPGLVKPSQTLSLTCSFSGFSLSTFGRGVGWIRQRPGRGLEWMGHIWWDDDKYYNPALKSRLSITKDTAKNQVFLQLSSMTTEDTAVYYCARI AGGLRRAPYAMDSWGQGTLVTVSSASTTAPSVFPLAPSCGSTSGSTVALACLVSGYFPEPVTVSWNSGSLTSGVHTFPSVLQSSGLYSLSSMVTVPSSRWPSETFTCNVAHPASKTKVDK PVPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVALDPEDPEVQISWFVDGKQMQTAKTQPREEQFAGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALP SPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALKYHYTQESLSHSPGK c218D9VH4-cIgGBm-LF H433L / N434F [SEQ ID NO: 40] MGWSCIILFLVATATGVHSEVTLQESGPGLVKPSQTLSLTCSFSGFSLSTFGRGVGWIRQRPGRGLEWMGHIWWDDDKYYNPALKSRLSITKDTAKNQVFLQLSSMTTEDTAVYYCARI AGGLRRAPYAMDSWGQGTLVTVSSASTTAPSVFPLAPSCGSTSGSTVALACLVSGYFPEPVTVSWNSGSLTSGVHTFPSVLQSSGLYSLSSMVTVPSSRWPSETFTCNVAHPASKTKVDK PVPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVALDPEDPEVQISWFVDGKQMQTAKTQPREEQFAGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALP SPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALLFHYTQESLSHSPGK c218D9VH4-cIgGBm-LY H433L / N434Y [SEQ ID NO: 41] MGWSCIILFLVATATGVHSEVTLQESGPGLVKPSQTLSLTCSFSGFSLSTFGRGVGWIRQRPGRGLEWMGHIWWDDDKYYNPALKSRLSITKDTAKNQVFLQLSSMTTEDTAVYYCARI AGGLRRAPYAMDSWGQGTLVTVSSASTTAPSVFPLAPSCGSTSGSTVALACLVSGYFPEPVTVSWNSGSLTSGVHTFPSVLQSSGLYSLSSMVTVPSSRWPSETFTCNVAHPASKTKVDK PVPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVALDPEDPEVQISWFVDGKQMQTAKTQPREEQFAGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALP SPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALLYHYTQESLSHSPGK c218D9VH4-cIgGBm-YD L252Y / T256D [SEQ ID NO: 42] MGWSCIILFLVATATGVHSEVTLQESGPGLVKPSQTLSLTCSFSGFSLSTFGRGVGWIRQRPGRGLEWMGHIWWDDDKYYNPALKSRLSITKDTAKNQVFLQLSSMTTEDTAVYYCARI AGGLRRAPYAMDSWGQGTLVTVSSASTTAPSVFPLAPSCGSTSGSTVALACLVSGYFPEPVTVSWNSGSLTSGVHTFPSVLQSSGLYSLSSMVTVPSSRWPSETFTCNVAHPASKTKVDK PVPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLYIARDPEVTCVVVALDPEDPEVQISWFVDGKQMQTAKTQPREEQFAGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALP SPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNHYTQESLSHSPGK c218D9VH4-cIgGBm-H N434H [SEQ ID NO: 43] MGWSCIILFLVATATGVHSEVTLQESGPGLVKPSQTLSLTCSFSGFSLSTFGRGVGWIRQRPGRGLEWMGHIWWDDDKYYNPALKSRLSITKDTAKNQVFLQLSSMTTEDTAVYYCARI AGGLRRAPYAMDSWGQGTLVTVSSASTTAPSVFPLAPSCGSTSGSTVALACLVSGYFPEPVTVSWNSGSLTSGVHTFPSVLQSSGLYSLSSMVTVPSSRWPSETFTCNVAHPASKTKVDK PVPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVALDPEDPEVQISWFVDGKQMQTAKTQPREEQFAGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALP SPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHHHYTQESLSHSPGK c218D9VH4 [SEQ ID NO: 44] EVTLQESGPGLVKPSQTLSLTCSFSGFSLSTFGRGVGWIRQRPGRGLEWMGHIWWDDDKYYNPALKSRLSITKDTAKNQVFLQLSSMTTEDTAVYYCARIAGGLRRAPYAMDSWGQGTLVTVSS c218D9VL3-cCK [SEQ ID NO: 45] DIVMTQTPLSLSVSPGETASISCRASENIYSSLAWFRQKPGQSPQLLVYAATNLADGVPDRFSGSGSGTDYTLRISRVEADDTGVYYCQHFRDTPPTFGQGTKLEIKR NDAQPAVYLFQPSPDQLHTGSASVVCLLNSFYPKDINVKWKVDGVIQDTGIQESVTEQDKDSTYSLSSTLTMSSTEYLSHELYSCEITHKSLPSTLIKSFQRSECQRVD [Table 3] [Table 4] The present invention is not limited in scope by the specific embodiments described herein. Indeed, various modifications of the invention in addition to those described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are intended to be included within the scope of the appended claims.

Claims

1. 1. An antibody or IgG Fc fusion protein comprising a fragment crystallizable region (Fc region) comprising one or more amino acid substitutions, wherein each of said one or more amino acid residue substitutions is at an amino acid residue position in the Fc region selected from the group consisting of 252, 254, 256, 308, 433, 434 and 436, said amino acid residue positions numbered according to the EU index as in Kabat: if the substitution is at amino acid residue position 252, the substitution is with a tyrosine residue; if the substitution is at amino acid residue position 254, the substitution is with a threonine residue; If the substitution is at amino acid residue position 256, the substitution is with an aspartic acid residue or a glutamic acid residue; if the substitution is at amino acid residue position 308, the substitution is with a proline residue; if the substitution is at amino acid residue position 433, the substitution is with a lysine or leucine residue; If the substitution is at amino acid residue position 434, the substitution is with a phenylalanine residue, a histidine residue, or a tyrosine residue; if the substitution is at amino acid residue position 436, the substitution is with a threonine residue; the antibody comprises a heavy chain and a light chain; An antibody or IgG Fc fusion protein, wherein the Fc region is selected from the group consisting of a canine Fc region (cFc) and a feline Fc region (fFc).

2. The cFc or the fFc is selected from the following (a) to (q): (a) a substitution at amino acid residue position 252 with a tyrosine residue, at amino acid residue position 256 with an aspartic acid residue, and at amino acid residue position 434 with a histidine residue; (b) a substitution at amino acid residue position 252 with a tyrosine residue and at amino acid residue position 256 with an aspartic acid residue; (c) a substitution at amino acid residue position 252 with a tyrosine residue and at amino acid residue position 434 with a histidine residue; (d) a substitution at amino acid residue position 256 with an aspartic acid residue and at amino acid residue position 434 with a histidine residue; (e) a substitution at amino acid residue position 256 with an aspartic acid residue and at amino acid residue position 434 with a tyrosine residue; (f) a substitution at amino acid residue position 308 with a proline residue and at amino acid residue position 434 with a tyrosine residue; (g) a substitution at amino acid residue position 433 with a lysine residue and at amino acid residue position 434 with a phenylalanine residue; (h) a substitution at amino acid residue position 433 with a lysine residue and at amino acid residue position 434 with a tyrosine residue; (i) a substitution at amino acid residue position 433 with a leucine residue and at amino acid residue position 434 with a phenylalanine residue; (j) a substitution at amino acid residue position 433 with a leucine residue and at amino acid residue position 434 with a tyrosine residue; (k) a substitution at amino acid residue position 434 with a tyrosine residue and at amino acid residue position 436 with a threonine residue; (l) a substitution at amino acid residue position 252 with a tyrosine residue, at amino acid residue position 254 with a threonine residue, and at amino acid residue position 256 with a glutamic acid residue; (m) a substitution at amino acid residue position 256 with an aspartic acid residue, at amino acid residue position 308 with a proline residue, and at amino acid residue position 434 with a tyrosine residue; (n) a substitution at amino acid residue position 433 with a lysine residue, at amino acid residue position 434 with a phenylalanine residue, and at amino acid residue position 436 with a threonine residue; (o) a substitution at amino acid residue position 433 with a lysine residue, at amino acid residue position 434 with a tyrosine residue, and at amino acid residue position 436 with a threonine residue; (p) a substitution at amino acid residue position 433 with a leucine residue, a substitution at amino acid residue position 434 with a phenylalanine residue, and a substitution at amino acid residue position 436 with a threonine residue; and (q) a substitution at amino acid residue position 433 with a leucine residue, a substitution at amino acid residue position 434 with a tyrosine residue, and a substitution at amino acid residue position 436 with a threonine residue 2. The antibody or IgG Fc fusion protein of claim 1, comprising two or more amino acid residue substitutions selected from the group consisting of:

3. 3. The antibody or IgG Fc fusion protein of claim 1, wherein the fFc is selected from the group consisting of IgG-la Fc, IgG-lam Fc, IgG-lb Fc, IgG-lbm Fc, IgG-2 Fc, and IgG-2m Fc.

4. 4. The antibody or IgG Fc fusion protein of claim 3, wherein the fFc comprises an amino acid sequence selected from the group consisting of SEQ ID NO:9, an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:9, SEQ ID NO:10, an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:10, SEQ ID NO:11, an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:11, SEQ ID NO:12, an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:12, SEQ ID NO:50, an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:50, SEQ ID NO:51, and an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:

51.

5. 3. The antibody or IgG Fc fusion protein of claim 1 or 2, wherein the cFc is selected from the group consisting of IgG-A Fc, IgG-Am Fc, IgG-B Fc, IgG-Bm Fc, IgG-C Fc, IgG-Cm Fc, IgG-D Fc, and IgG-Dm Fc.

6. The cFc is selected from the group consisting of SEQ ID NO:1, an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:1, SEQ ID NO:2, an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:2, SEQ ID NO:3, an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:3, SEQ ID NO:4, an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:4, SEQ ID NO:5, an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:5, 6, an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:6, SEQ ID NO:7, an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:7, SEQ ID NO:8, and an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:

8.

7. 2. The antibody or IgG Fc fusion protein of claim 1, wherein the cFc further comprises a canine hinge region comprising an amino acid sequence having at least 80%, 85%, 90%, or 95% identity to an amino acid sequence selected from the group consisting of SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, and SEQ ID NO: 16, or wherein the canine hinge region comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, and SEQ ID NO:

16.

8. (a) has an increased half-life compared to the half-life of an antibody or IgG Fc fusion protein comprising a corresponding wild-type canine or feline Fc region; or (b) have enhanced binding affinity for the neonatal Fc receptor (FcRn) at moderately acidic pH; The antibody or IgG Fc fusion protein of claim 1 .

9. the Fc region is fused to a canine interleukin-13 receptor alpha 1 (IL-13Rα1) peptide comprising the amino acid sequence of SEQ ID NO: 17, or an amino acid sequence having at least 90%, 95%, 97%, 98%, or 99% identity to SEQ ID NO: 17; or the Fc region is fused to a canine interleukin-13 receptor alpha 2 (IL-13Rα2) peptide comprising the amino acid sequence of SEQ ID NO: 18, or an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO: 18; The IgG Fc fusion protein of claim 1 .

10. (a) an amino acid sequence selected from the group consisting of SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:30, SEQ ID NO:31, SEQ ID NO:32, SEQ ID NO:33, SEQ ID NO:34, and SEQ ID NO:35; or (b) an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:30, SEQ ID NO:31, SEQ ID NO:32, SEQ ID NO:33, SEQ ID NO:34 or SEQ ID NO:

35.

10. The IgG Fc fusion protein of claim 9, comprising:

11. A nucleic acid encoding the antibody or IgG fusion protein of claim 1 or any combination thereof.

12. The antibody of claim 1 , which is selected from the group consisting of a canine antibody or a caninized antibody.

13. The caninized antibody of claim 12, which is capable of binding to canine interleukin-31 receptor alpha (cIL-31RA), and wherein the heavy chain comprises a variable region comprising the amino acid sequence of SEQ ID NO:

44.

14. The caninized antibody of claim 13, wherein the heavy chain comprises an amino acid sequence selected from the group consisting of SEQ ID NO:36, SEQ ID NO:37, SEQ ID NO:38, SEQ ID NO:39, SEQ ID NO:40, SEQ ID NO:41, SEQ ID NO:42 and SEQ ID NO:43, or an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:36, SEQ ID NO:37, SEQ ID NO:38, SEQ ID NO:39, SEQ ID NO:40, SEQ ID NO:41, SEQ ID NO:42 or SEQ ID NO:

43.

15. The caninized antibody of claim 13, wherein the light chain comprises the amino acid sequence of SEQ ID NO: 45, or an amino acid sequence having at least 90%, 95%, 97%, 98% or 99% identity to SEQ ID NO:

45.

16. A nucleic acid encoding the light chain of the caninized antibody of any one of claims 12 to 15.

17. A nucleic acid encoding the heavy chain of the caninized antibody of any one of claims 12 to 15.

18. A nucleic acid composition comprising a first nucleic acid encoding the light chain of the caninized antibody of any one of claims 12 to 15 and a second nucleic acid encoding the heavy chain of the caninized antibody of any one of claims 12 to 15.

19. An expression vector comprising the nucleic acid of claim 11.

20. A host cell comprising the expression vector of claim 19.

21. A pharmaceutical composition comprising the IgG Fc fusion protein of claim 9 or 10, or the caninized antibody of any one of claims 13 to 15, and a pharmaceutically acceptable carrier.

22. 22. A method of treating atopic dermatitis in a canine or feline subject, comprising administering to said subject the pharmaceutical composition of claim 21.

23. 22. The pharmaceutical composition of claim 21 for use in treating atopic dermatitis in a canine or feline subject.

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