Immunogenic peptides for use in the prevention and/or treatment of infectious diseases, autoimmune diseases, immune responses to allofactors, allergic diseases, tumors, graft rejection and immune responses against viral vectors used for gene therapy or gene vaccination

1. An isolated immunogenic peptide consisting of:

(1) a natural killer T (NKT) cell epitope having a [F, W, H or Y]-XX-[I, L, M or V]-XX-[F, W, H or Y] (SEQ ID NO: 23) motif of an antigenic protein;

(2) a thioreductase [C, S or T]-XX-C (SEQ ID NO: 19) or C-XX-[C, S or T] (SEQ ID NO: 18) motif, which is either immediately adjacent to said NKT cell epitope, or separated from said NKT cell epitope by a linker of at most 7 amino acids, and

(3) an optional flanking amino acid sequence of up to 10 amino acids at the N and/or C terminus of the peptide, wherein said antigenic protein does not comprise in its natural sequence a [C, S or T]-XX-C (SEQ ID NO: 19) or C-XX-[C, S or T] (SEQ ID NO: 18) motif within 11 amino acids N- or C terminally adjacent to said NKT cell epitope,

wherein X stands for any amino acid, and wherein said antigenic protein is not survivin.

2. The isolated immunogenic peptide according to claim 1 , capable of NKT cell activation.

3. The isolated immunogenic peptide according to claim 1 , wherein the antigenic protein is selected from the group consisting of: a tumour associated antigenic protein, a viral protein, an autoantigen, an allofactor, an allergen, an alloantigen shed by a graft, an antigen of an intracellular pathogen, and an antigen from a viral vector used for gene therapy or gene vaccination.

4. The isolated immunogenic peptide according to claim 1 , wherein the natural killer T (NKT) cell epitope consists of 7 amino acids with a [F, W, H or Y]-XX-[I, L, M or V]-XX-[F, W, H or Y] (SEQ ID NO: 23) motif of an antigenic protein.

5. The isolated immunogenic peptide according to claim 1 , wherein said NKT cell epitope has a [F or W]-XX-[I, L, M or V]-XX-[F or W] (SEQ ID NO: 13) motif.

6. The isolated immunogenic peptide according to claim 1 , wherein said thioreductase motif is C-XX-C (SEQ ID NO: 14).

7. A nucleic acid encoding an isolated immunogenic peptide according to claim 1 .

8. A pharmaceutical composition comprising an isolated immunogenic peptide according to claim 1 and at least one pharmaceutically acceptable carrier.

9. A pharmaceutical composition comprising a nucleic acid encoding an isolated immunogenic peptide according to claim 1 and at least one pharmaceutically acceptable carrier.

10. A method of treating a subject for a disease selected from the group consisting of: an infection with an intracellular pathogen, a tumour, an autoimmune disease, an immune response to an allofactor or to allergen exposure, an allograft rejection, and an immune response against a viral vector used for gene therapy or gene vaccination, comprising administrating a therapeutic amount of an isolated immunogenic peptide according to claim 1 to said subject.

11. The isolated immunogenic peptide according to claim 1 , wherein said antigenic protein is a multiple sclerosis autoantigen.

12. The isolated immunogenic peptide according to claim 1 , wherein said antigenic protein is myelin oligodendrocyte glycoprotein (MOG).

13. The isolated immunogenic peptide according to claim 1 , wherein said NKT cell epitope is FLRVPCWKI (SEQ ID NO: 38).

14. A composition comprising the isolated immunogenic peptide according to claim 1 loaded on an isolated CD1d tetramer.

15. A method of treating a subject for a disease selected from the group consisting of: an infection with an intracellular pathogen, a tumour, an autoimmune disease, an immune response to an allofactor or to allergen exposure, an allograft rejection, and an immune response against a viral vector used for gene therapy or gene vaccination, comprising administrating a therapeutic amount of a nucleic acid encoding the isolated immunogenic peptide according to claim 1 to said subject.