Methods for displaying (poly)peptides/proteins on bacteriophage particles via disulfide bonds

1. An isolated host cell comprising:

(i) a nucleic acid sequence encoding a variant of a wild type coat protein of a bacteriophage,

(aa) wherein said nucleic acid sequence encoding said variant comprises a nucleic acid sequence encoding at least one part of said wild type coat protein of a bacteriophage, wherein said at least one part comprises at least that part which causes or allows the incorporation of said coat protein into the phage coat, and

(ab) wherein said variant comprises a cysteine residue, wherein said cysteine residue is present at, or in the vicinity of, the C- or the N-terminus of said at least one part of said wild type coat protein,

(ii) one or more nucleic acid sequences encoding a (poly)peptide/protein comprising a cysteine residue,

wherein upon expression of said nucleic acid sequence encoding said variant of a wild type coat protein and said one or more nucleic acid sequences encoding a (poly)peptide/protein comprising a cysteine residue, attachment of said variant of a wild type coat protein and said (poly)peptide/protein occurs by formation of a disulfide bond between said cysteine residue in said variant of a wild type coat protein and said cysteine residue comprised in said (poly)peptide/protein,

wherein said nucleic acid sequence encoding a variant of a wild type coat protein does not encode an interaction domain for interaction with a second domain present in said (poly)peptide/protein, and

wherein the expression product of said nucleic acid sequence encoding said variant of a wild type coat protein and the expression product or products of any of said one or more nucleic acid sequences encoding a (poly)peptide/protein do not form a genetic fusion protein.

2. The isolated host cell of claim 1 , wherein said nucleic acid sequence encoding said variant of said wild type coat protein further encodes:

(b) one or more peptide sequences for purification and/or detection purposes, wherein said one or more peptide sequences are fused to said variant of said wild type coat protein.

3. The isolated host cell of claim 1 , wherein the variant of a wild type coat protein comprises a modified variant, wherein the modified variant comprises:

(a) up to seven additional amino acid residues not present at the corresponding amino acid positions in a wild type coat protein of a bacteriophage, wherein one of said additional amino acid residues is said cysteine residue.

4. The isolated host cell of claim 3 , wherein said host cell is a bacterial host cell.

5. The isolated host cell of claim 3 , wherein said bacteriophage is a filamentous bacteriophage.

6. The isolated host cell of claim 3 , wherein said (poly)peptide/protein comprises an immunoglobulin or a functional fragment thereof.

7. The isolated host cell of claim 6 , wherein said immunoglobulin or a functional fragment thereof is selected from the group consisting of immunoglobulins, VH, VL, Fv, scFv, disulfide-linked Fv, Fab and F(ab′) 2 .

8. The isolated host cell of claim 1 , wherein the variant of a wild type coat protein comprises a truncated variant of a wild type coat protein, wherein said truncated variant comprises said cysteine residue which is present at a corresponding amino acid position in a wild type coat protein of a bacteriophage.

9. The isolated host cell of claim 8 , wherein said host cell is a bacterial host cell.

10. The isolated host cell of claim 8 , wherein said bacteriophage is a filamentous bacteriophage.

11. The isolated host cell of claim 8 , wherein said (poly)peptide/protein comprises an immunoglobulin or a functional fragment thereof.

12. The isolated host cell of claim 11 , wherein said immunoglobulin or a functional fragment thereof is selected from the group consisting of immunoglobulins, VH, VL, Fv, scFv, disulfide-linked Fv, Fab and F(ab′) 2 .

13. The isolated host cell of claim 1 , wherein the variant of a wild type coat protein comprises a truncated variant of a wild type coat protein wherein said truncated variant comprises:

(a) up to seven additional amino acid residues not present at the corresponding amino acid positions in a wild type coat protein of a bacteriophage, wherein one of said additional amino acid residues is said cysteine residue.

14. The isolated host cell of claim 13 , wherein said host cell is a bacterial host cell.

15. The isolated host cell of claim 13 , wherein said bacteriophage is a filamentous bacteriophage.

16. The isolated host cell of claim 13 , wherein said (poly)peptide/protein comprises an immunoglobulin or a functional fragment thereof.

17. The isolated host cell of claim 16 , wherein said immunoglobulin or a functional fragment thereof is selected from the group consisting of immunoglobulins, VH, VL, Fv, scFv, disulfide-linked Fv, Fab and F(ab′) 2 .

18. The isolated host cell of claim 1 , wherein said host cell is a bacterial host cell.

19. The isolated host cell of claim 1 , wherein said bacteriophage is a filamentous bacteriophage.

20. The isolated host cell of claim 1 , wherein said (poly)peptide/protein comprises an immunoglobulin or a functional fragment thereof.

21. The isolated host cell of claim 20 , wherein said immunoglobulin or a functional fragment thereof is selected from the group consisting of immunoglobulins, VH, VL, Fv, scFv, disulfide-linked Fv, Fab and F(ab′) 2 .

22. The isolated host cell according to claim 1 , wherein said cysteine residue in said variant of a wild type coat protein is present at, or in the vicinity of, the N-terminus of said at least one part of said wild type coat protein.

23. An isolated bacterial host cell comprising:

(i) a nucleic acid sequence encoding a variant of a wild type coat protein of a bacteriophage, wherein said nucleic acid sequence encoding said variant encodes:

(a) at least that part of said wild type coat protein which causes or allows the incorporation of said coat protein into the phage coat,

(b) a signal sequence for transport of said variant to the periplasm of the host cell and

(c) a cysteine residue present at, or in the vicinity of, the C- or the N-terminus of said at least one part of said wild type coat protein;

(ii) one or more nucleic acid sequences encoding a (poly)peptide/protein comprising a cysteine residue,

wherein upon expression of said nucleic acid sequence encoding said variant of a wild type coat protein and said one or more nucleic acid sequences encoding a (poly)peptide/protein comprising a cysteine residue, attachment of said variant of a wild type coat protein and said (poly)peptide/protein occurs by formation of a disulfide bond between said cysteine residue in said variant of a wild type coat protein and said cysteine residue comprised in said (poly)peptide/protein,

wherein no interaction domain for interaction with a second domain present in said (poly)peptide/protein has been genetically fused to said variant of a wild type coat protein, and

wherein the expression product or products of said one or more nucleic acid sequences encoding a (poly)peptide/protein do not form a genetic fusion protein with said variant of a wild type coat protein of a bacteriophage.

24. The isolated host cell of claim 23 , wherein said nucleic acid sequence encoding said variant of said wild type coat protein further encodes one or more peptide sequences for purification and/or detection purposes, wherein said one or more peptide sequences are fused to said variant of said wild type coat protein.

25. The isolated host cell of claim 23 , wherein said variant of a wild type coat protein comprises up to seven additional amino acid residues not present at the corresponding amino acid positions in a wild type coat protein of a bacteriophage, wherein one of said additional amino acid residues is said cysteine residue.

26. The isolated host cell of claim 23 , wherein the variant of a wild type coat protein comprises a truncated variant of a wild type coat protein, wherein said truncated variant comprises said cysteine residue, which is present at a corresponding amino acid position in a wild type coat protein of a bacteriophage.

27. The isolated host cell of claim 23 , wherein the variant of a wild type coat protein comprises a truncated variant of a wild type coat protein, wherein said truncated variant comprises up to seven additional amino acid residues not present at the corresponding amino acid positions in a wild type coat protein of a bacteriophage, wherein one of said additional amino acid residues is said cysteine residue.

28. The isolated host cell of claim 23 , wherein said bacteriophage is a filamentous bacteriophage.

29. The isolated host cell of claim 23 , wherein said (poly)peptide/protein comprises an immunoglobulin or a functional fragment thereof.

30. The isolated host cell of claim 29 , wherein said immunoglobulin or a functional fragment thereof is selected from the group consisting of, VH, VL, Fv, scFv, disulfide-linked Fv, Fab and F(ab′) 2 .

31. The isolated host cell of claim 29 , wherein said immunoglobulin or a functional fragment thereof is a Fab wherein the heavy and light chain are not linked via a disulfide bond.

32. The isolated bacterial host cell according to claim 23 , wherein said cysteine residue in said variant of a wild type coat protein is present at, or in the vicinity of, the N-terminus of said at least one part of said wild type coat protein.