Fusion proteins for use as immunogenic enhancers for inducing antigen-specific T cell responses

A fusion protein consisting of:

• (a) an antigen-presenting cell (APC)-binding domain or a CD91 receptor-binding domain, located at the N-terminus of the fusion protein;
• (b) a protein transduction domain, located at the C-terminus of the APC-binding domain or the CD91 receptor-binding domain, wherein the protein transduction domain is selected from the group consisting of:
• (i) a T cell-sensitizing signal-transducing peptide consisting of 28-53 amino acid residues in length, comprising the amino acid sequence of SEQ ID NO:
• 31, in which Xaa8 is I;
• Xaa10 is V, F or A, Xaa11 is M or L, Xaa17 is L or I;
• and
• (ii) a translocation peptide of 34-46 amino acid residues in length, comprising an amino acid sequence that is at least 90% identical to SEQ ID NO:
• 3 or 20;
• and
• (c) an antigen of a pathogen, located at the C-terminus of the protein transduction domain:
• wherein:
• the APC-binding domain or the CD91 receptor-binding domain is free of the amino acid sequence of Pseudomonas exotoxin A (PE) binding domain I if the protein transduction domain is the translocation peptide.

A fusion protein consisting of:

• (a) an antigen-presenting cell (APC)-binding domain or a CD91 receptor-binding domain, located at the N-terminus of the fusion protein;
• (b) a protein transduction domain, located at the C-terminus of the APC-binding domain or the CD91 receptor-binding domain, wherein the protein transduction domain is selected from the group consisting of:
• (i) a T cell-sensitizing signal-transducing peptide consisting of 28-53 amino acid residues in length, comprising the amino acid sequence of SEQ ID NO:
• 31, in which Xaa8 is I;
• Xaa10 is V, F or A, Xaa11 is M or L, Xaa17 is L or I;
• and
• (ii) a translocation peptide of 34-46 amino acid residues in length, comprising an amino acid sequence that is at least 90% identical to SEQ ID NO:
• 3 or 20;
• and;
• (c) an antigen of a pathogen, located at the C-terminus of the protein transduction domain;
• and
• (d) an endoplasmic reticulum retention sequence located at the C-terminus of the fusion protein.

A fusion protein comprising:

• (a) an antigen-presenting cell (APC)-binding domain or a CD91 receptor-binding domain, located at the N-terminus of the fusion protein;
• (b) a protein transduction domain, located at the C-terminus of the APC-binding domain or the CD91 receptor-binding domain, wherein the protein transduction domain is a fusion polypeptide consisting of:
• (1) a T cell sensitizing signal-transducing peptide of 28 amino acid residues in length, consisting of the amino acid sequence of SEQ ID NO:
• 31, in which Xaa8 is I or L;
• Xaa10 is V, F or A, Xaa11 is M or L, Xaa17 is L or I, being located at the N-terminus of the fusion polypeptide;
• (2) a translocation peptide consisting of 34-112 amino acid residues in length, comprising an amino acid sequence that is at least 90% identical to SEQ ID NO:
• 3, 20 or 4;
• and
• (3) a linker, comprising SEQ ID NO:
• 15 linking the T cell sensitizing signal-transducing peptide and the translocation peptide;
• and
• (c) an antigen of a pathogen, located at the C-terminus of the protein transduction domain.