Chimeric human-llama antigens and methods of use
Provided are chimeric, camelid-human (e.g., llama-human) polypeptides comprising a first antigenic polypeptide portion and a second antigenic polypeptide portion wherein the first antigenic portion is a derived from a first portion of a camelid (e.g., llama) and the second antigenic portion is a human polypeptide homolog of a second portion of the camedid antigen. The chimeric polypeptides are useful inter alia for epitope mapping and generation of antibodies that bind to a desired region of human antigen.
1. A method for generating a heterotetrameric camelid antibody against a conformational epitope of a non-camelid antigen, the method comprising
immunizing a camelid with a chimeric polypeptide comprising a first portion derived from a camelid polypeptide and a second portion derived from a non-camelid polypeptide homologue of the camelid polypeptide, wherein the chimeric polypeptide is a cell surface receptor, receptor ligand, or fragment thereof, and wherein the second portion of the chimeric polypeptide comprises the portion of the non-camelid antigen; and
isolating the heterotetrameric camelid antibody.
2. The method of claim 1 , wherein the non-camelid antigen is a human antigen.
3. The method of claim 1 , wherein the camelid being immunized is a llama.
4. The method of claim 1 , wherein the camelid portion of the chimeric polypeptide is from the same species of camelid as the camelid being immunized.
5. The method of claim 1 , wherein the camelid portion of the chimeric polypeptide is not immunogenic in the immunized camelid.
6. The method of claim 1 , wherein the receptor ligand is a cytokine, chemokine, hormone, growth factor, or fragment thereof.
7. The method of claim 1 , wherein the first portion and the second portion are derived from corresponding regions of the camelid polypeptide and the non-camelid polypeptide homologue.
8. The method of claim 1 , wherein the first portion and the second portion are derived from non-corresponding regions of the camelid polypeptide and the non-camelid polypeptide homologue.
9. The method of claim 1 , wherein the chimeric polypeptide is a chimeric c-Met, CD70, CXCR4, or IL-1beta polypeptide, or a fragment thereof.
10. The method of claim 1 , wherein the chimeric polypeptide comprises the amino acid sequence selected from the group consisting of SEQ ID NOs 3-13.
11. The method of claim 1 , wherein the camelid polypeptide is a llama polypeptide.
12. The method of claim 1 , wherein the non-camelid polypeptide homologue is a human polypeptide homologue of the camelid polypeptide.
13. The method of claim 1 , wherein the camelid polypeptide and the non-camelid polypeptide homologue are directly linked.
14. The method of claim 1 , wherein the camelid polypeptide and the non-camelid polypeptide homologue are linked though an intervening linker moiety.
15. The method of claim 1 , wherein the camelid polypeptide and the non-camelid polypeptide homologue are genetically linked.
16. The method of claim 1 , wherein the camelid polypeptide and the non-camelid polypeptide homologue are chemically linked.
17. The method of claim 1 , wherein the camelid polypeptide is a llama polypeptide, the non-camelid polypeptide homologue is a human polypeptide, and the chimeric polypeptide has a similar structural conformation to the llama or human polypeptide.
18. The method of claim 1 , wherein the camelid polypeptide is a llama polypeptide, the non-camelid polypeptide homologue is a human polypeptide, and the chimeric polypeptide shares at least one functional property with the llama or human polypeptide.