Immunogenicity of recombinant chaperone-complexed antigens
Final Report Abstract
Hsp73-capturing fusion antigens with a NH2-terminal J domain have surprisingly long half-lifes (>24 h) and accumulate to high steady state levels (0.5 – 2 µg per 107 cells) in eukaryotic cells. In experimental vaccinology, the hsp-capturing system we describe can be used either as an expression system to deliver antigens to T cells in vivo, or for the production of recombinant antigens. The expression system has three unique advantages: (i) it can express proteins that are either unstable, or toxic to the cell; (ii) it can incorporate a large amount of (T or B cell-stimulating) antigenic information into the hsp-capturing fusion protein thereby overcoming current limitations (that largely used single epitope antigenic peptides); (iii) the system can be used to produce recombinant antigens in eukaryotic cells because the bound hsp can be easily removed from the complexes. We designed informative hsp/antigen complexes and characterized their immunogenicity in mice using DNA- adenovector- and protein-based vaccination approaches. We showed that vaccines encoding hsp73-bound fusion antigen efficiently elicit humoral or cellular immunogenicity to viral or tumor-associated ´self´ antigens: (i) hsp/antigen complexes efficiently display antigen- but not hsp-specific immunogenicity for B cells. Notably, we found evidence that hsp-mediated, heterologous CD4 T cell ‘help’ facilitates priming of antibody responses; (ii) the hsp-binding expression system is exceptionally potent to induce mono- and multispecific CD8 T cell responses. We identified immunodominance hierarchies in antigen-specific CD8 T cell responses; (iii) using the hsp/antigen expression system, we identified CD8 T cell responses to epitopes of antigens expressed from alternative open reading frames of a single coding sequence; (iv) recombinant hsp/antigen vaccines efficiently induced CD8 T cell responses in mice; (v) We demonstrated the usefulness of the hsp/antigen expression system to elicit tumorprotective T cell responses in mice. The described vaccine formulation may imitate natural ways of cross priming CD8 T cell responses and seems to be an attractive option for the rational design of novel generations of T cell-stimulating vaccines.
Publications
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2008. Recombinant complexes of antigen with stress proteins are potent CD8 T- cell-stimulating immunogens. J.Mol.Med. 86:1067-1079
Wieland, A., M. Denzel, E. Schmidt, S. Kochanek, F. Kreppel, J. Reimann, and R. Schirmbeck
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2008. The immunogenicity of adenovirus vectors limits the multispecificity of CD8 T-cell responses to vector-encoded transgenic antigens. Mol.Ther. 16:1609-1616
Schirmbeck, R., J. Reimann, S. Kochanek, and F. Kreppel
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2009. Elimination of immunodominant epitopes from multispecific DNA- based vaccines allows induction of CD8 T cells that have a striking antiviral potential. J.Immunol. 183:370-380
Riedl, P., A. Wieland, K. Lamberth, S. Buus, F. Lemonnier, K. Reifenberg, J. Reimann, and R. Schirmbeck
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2009. Processing in the endoplasmic reticulum generates an epitope on the insulin A chain that stimulates diabetogenic CD8 T cell responses. J.Immunol. 183:7187-7195
19. Brosi, H., M. Reiser, T. Rajasalu, A. Spyrantis, F. Oswald, B. O. Boehm, and R. Schirmbeck
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2009. Silencing an immunodominant epitope of hepatitis B surface antigen reveals an alternative repertoire of CD8 T cell epitopes of this viral antigen. Vaccine 28:114-119
Wieland, A., P. Riedl, J. Reimann, and R. Schirmbeck
