The goal of the proposed research is to determine if the non-classical MHC class I molecule, Mamu-E, can present SIV-derived peptides to the immune system of the Indian rhesus macaque. We would then determine if the responses to these peptides can be elicited by vaccination and if they can control SIV replication. Mycobacterium tuberculosis (Mtb)-, Cytomegalovirus (CMV)- and Salmonella typhi-specific CD8+ T cells have been shown to recognize peptides bound by HLA-E. Furthermore, mice vaccinated with Transporter associated with antigen processing (TAP)-inhibited dendritic cells (DCs) develop Qa-1b- (the functional homologue of HLA-E) restricted CD8+ T cells that confer protection from challenge with a variety of tumors. CD8+ T cells that recognize HLA-E or its murine homologue Qa-1b may, therefore, play a critical role in immunological surveillance of both pathogens and tumors. Interestingly, HLA-E, unlike other classical MHC class I molecules, is well conserved across non-human primate species. This degree of conservation is most pronounced in the peptide-binding groove of these non-human primate MHC-E molecules suggesting that MHC-E plays an important role in binding peptides in both humans and non-human primate species. We have conducted preliminary studies in SIV-infected Indian rhesus macaques and have shown that SIV- derived peptides conforming to the HLA-E binding motif are recognized in IFN3 ELISPOT assays. We are proposing a series of experiments to explore the innovative hypothesis that SIV-specific Mamu-E- restricted CD8+ T cells play a role in immune surveillance against SIV. We will elute peptides from Mamu-E to define its peptide-binding motif, scan the SIVmac239 proteome for predicted Mamu-E binders and then screen these peptides using IFN3 ELISPOT with PBMC from SIV- infected Indian rhesus macaques. We will then grow cell lines that are stimulated by the reactive peptides and determine whether they are indeed Mamu-E-restricted using Mamu-E transfectants and Mamu-E tetramers. In the second part of our application we hypothesize that the generation of Mamu-E-specific CD8+ T cell responses by vaccination will broaden the repertoire of antiviral responses and aid in reducing viral replication after challenge with a pathogenic heterologous virus. !
Finding a vaccine for HIV is probably one of the most important goals of biomedical research. We will use approaches derived from cancer research to try to find new targets for an HIV vaccine. !