Anti-factor IX Padua antibodies

1. An antibody or antigen-binding fragment thereof that binds a Factor IX Padua comprising the amino acid sequence of SEQ ID NO: 1 and does not bind to a wild-type (WT) Factor IX comprising the amino acid sequence (SEQ ID NO: 2), wherein the antibody or antigen-binding fragment thereof comprises:

(i) the amino acid sequences of: SSYAIS (SEQ ID NO: 6), GIVPAFGTANYAQKFQG (SEQ ID NO: 7), SWGVISFAY (SEQ ID NO: 8), RASQDISSYLN (SEQ ID NO: 9), AASNLQS (SEQ ID NO: 10), and MQYDSLPFTF (SEQ ID NO: 11); or

(ii) the amino acid sequences of SEQ ID NOs: 24 and 25; or

(iii) the amino acid sequences of SEQ ID NOs: 26 and 27.

2. The antibody or antigen-binding fragment of claim 1 , which binds an epitope of SEQ ID NO: 1, wherein the epitope is a linear epitope within the amino acid sequence DRATCLLSTKFT (SEQ ID NO: 3).

3. The antibody or antigen-binding fragment of claim 1 , which binds to an epitope of SEQ ID NO: 1, wherein the epitope is a conformational epitope of the folded structure of the amino acid sequence LVDRATCLLSTKFTIYNNMFCAGFH (SEQ ID NO: 5), optionally, wherein the folded structure comprises a disulfide bridge.

4. The antibody or antigen-binding fragment of claim 1 , which does not bind to the amino acid sequence of DRATCLRSTKFT (SEQ ID NO: 14) or LVDRATCLRSTKFTIYNNMFCAGFH (SEQ ID NO:15).

5. The antibody or antigen-binding fragment of claim 1 , wherein the antibody or antigen-binding fragment binds to the Factor IX Padua with a K D of about 100 nM or less.

6. The antibody or antigen-binding fragment of claim 5 , wherein the antibody or antigen-binding fragment binds to the Factor IX Padua with a K D within a range of about 25 to about 75 nM, optionally, wherein the antibody or antigen-binding fragment binds to the Factor IX Padua with a K D within a range of about 50 nM to about 60 nM.

7. The antibody or antigen-binding fragment of claim 1 , wherein the antibody or antigen-binding fragment binds to the Factor IX Padua and does not bind to a WT Factor IX in a sample comprising human plasma, optionally, wherein the sample comprises at least or about 5%, at least or about 10%, or at least or about 20% human plasma and the sample comprises at least or about 5 μg/mL WT Factor IX.

8. The antibody or antigen-binding fragment of claim 1 , wherein the antibody or antigen-binding fragment does not bind to a Factor II polypeptide or a Factor X polypeptide, optionally, wherein the antibody or antigen-binding fragment binds to neither Factor II nor Factor X.

9. The antibody or antigen-binding fragment of claim 1 , which is a Fab or Fab2′ antibody fragment.

10. The antibody or antigen-binding fragment of claim 1 , which is monospecific.

11. The antibody or antigen-binding fragment of claim 1 , which is fully human.

12. The antibody or antigen-binding fragment of claim 1 , which is bivalent.

13. The antibody or antigen-binding fragment of claim 1 , comprising dimerized Fab fragments or dimerized Fab mini antibody.

14. The antibody or antigen-binding fragment of claim 1 , which is a dimerized Fab fragment via a linker.

15. An antibody or antigen-binding fragment comprising an amino acid sequence comprising each of SEQ ID NOs: 6-11, wherein the antibody or antigen-binding fragment binds a Factor IX Padua comprising the amino acid sequence of SEQ ID NO: 1 and does not bind to a wild-type (WT) Factor IX comprising the amino acid sequence (SEQ ID NO: 2), and optionally, wherein the antibody or antigen-binding fragment further comprises a FLAG tag comprising DYKDDDDK (SEQ ID NO: 12) and/or a hexa-His tag comprising HHHHHH (SEQ ID NO: 13), optionally, wherein the FLAG tag and/or the hexa-His tag are located at the C-terminal end of the antibody or antigen-binding fragment.

16. A conjugate comprising the antibody or antigen-binding fragment of claim 1 , conjugated to a heterologous moiety, optionally selected from the group consisting of: a polymer, a carbohydrate, a lipid, a nucleic acid, an oligonucleotide, an amino acid, peptide, polypeptide, protein and a detecting agent.

17. The conjugate of claim 16 , wherein the antibody or antigen-binding fragment is conjugated to agarose, cellulose, dextran, polyacrylamide, latex or controlled pore glass.

18. The conjugate of claim 16 , wherein the antibody or antigen-binding fragment is conjugated to a fluorophore, chromophore, radioisotope, enzymatic label, or biotin.

19. The conjugate of claim 16 , comprising a homodimer, which is a dimerized Fab fragment via a linker, optionally, wherein the polypeptides of the dimer are linked via a helix-turn-helix structure.

20. A nucleic acid comprising a nucleotide sequence encoding the antibody or antigen-binding fragment of claim 1 .

21. A vector comprising the nucleic acid of claim 20 .

22. A host cell comprising the nucleic acid of claim 20 .

23. A kit comprising (i) the antibody or antigen-binding fragment of claim 1 , and optionally, instructions for use, and optionally, (ii) a secondary antibody which binds to the antibody or antigen-binding fragment of (i).

24. The kit of claim 23 , further comprising a solid support.

25. The kit of claim 24 , wherein the antibody or antigen-binding fragment is pre-coated on the solid support.

26. The kit of claim 24 , wherein the solid support is a polymer bead, a microtiter plate, a membrane, or a filter.

27. The kit of claim 26 , comprising a solid support pre-coated with a solution comprising about 50 ng to about 500 ng of the antibody or antigen binding fragment.

28. A composition comprising an antibody or antigen-binding fragment of claim 1 admixed with a biological sample obtained from a human comprising human plasma, or a diluted fraction thereof, and/or human tissue, or cells thereof, wherein, optionally, the composition comprises a detecting agent.

29. A composition comprising an antibody or antigen-binding fragment of claim 1 admixed with a biological sample obtained from a human comprising human plasma proteins, wherein at least one of the human plasma proteins is selected from the group consisting of Factor IX, or a variant thereof, Factor II, and Factor X, wherein, optionally, the composition comprises a detecting agent.

30. A method of detecting Factor IX Padua in a sample obtained from a subject, comprising (i) contacting the sample with the antibody or antigen-binding fragment of claim 1 to form a complex comprising the Factor IX Padua and the antibody or antigen-binding fragment, and (ii) detecting the complex in the sample.

31. The method of claim 30 , wherein the antibody or antigen-binding fragment is conjugated to a detecting agent and/or a solid support.

32. The method of claim 30 , comprising contacting the sample with a secondary antibody comprising a detecting agent, wherein the secondary antibody binds to the antibody or antigen-binding fragment.

33. The method of claim 31 , wherein detecting the complex comprises detecting a signal of the detecting agent.

34. The method of claim 33 , wherein the signal is an enzymatic activity, binding activity and/or chromogenic activity.

35. The method of claim 30 , wherein the sample is a blood sample, a serum sample, or a plasma sample.

36. The method of claim 30 , wherein the subject has been treated with a vector comprising a nucleotide sequence encoding Factor IX Padua.

37. A method of detecting Factor IX Padua in a sample obtained from a subject, comprising (i) contacting the sample with the antibody or antigen-binding fragment of claim 15 to form a complex comprising the Factor IX Padua and the antibody or antigen-binding fragment, and (ii) detecting the complex in the sample.

38. The method of claim 33 , wherein the antibody or antigen-binding fragment is conjugated to a detecting agent and/or a solid support.

39. The method of claim 33 , comprising contacting the sample with a secondary antibody comprising a detecting agent, wherein the secondary antibody binds to the antibody or antigen-binding fragment.

40. The method of claim 38 , wherein detecting the complex comprises detecting a signal of the detecting agent.

41. The method of claim 40 , wherein the signal is an enzymatic activity, binding activity and/or chromogenic activity.

42. The method of claim 33 , wherein the sample is a blood sample, a serum sample, or a plasma sample.

43. The method of claim 33 , wherein the subject has been treated with a vector comprising a nucleotide sequence encoding Factor IX Padua.

44. A method of detecting Factor IX Padua in a sample obtained from a subject, comprising (i) contacting the sample with the conjugate of claim 16 to form a complex comprising the Factor IX Padua and the conjugate, and (ii) detecting the complex in the sample.

45. The method of claim 44 , wherein the conjugate comprises a detecting agent.

46. The method of claim 44 , comprising contacting the sample with a secondary antibody comprising a detecting agent, wherein the secondary antibody binds to the conjugate.

47. The method of claim 45 , wherein detecting the complex comprises detecting a signal of the detecting agent.

48. The method of claim 47 , wherein the signal is an enzymatic activity, binding activity and/or chromogenic activity.

49. The method of claim 44 , wherein the sample is a blood sample, a serum sample, or a plasma sample.

50. The method of claim 44 , wherein the subject has been treated with a vector comprising a nucleotide sequence encoding Factor IX Padua.

51. A kit comprising (i) the antibody or antigen-binding fragment of claim 15 , and optionally, instructions for use, and optionally, (ii) a secondary antibody which binds to the antibody or antigen-binding fragment of (i).

52. A kit comprising (i) the conjugate of claim 16 , and optionally, instructions for use, and optionally, (ii) a secondary antibody which binds to the conjugate of (i).