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#37-OR
HOST-DERIVED PEPTIDES ARE UNIQUELY PRESENTED BY MHC CLASS I MOLECULES DURING HIV INFECTION.
Heather D. Hickman , Angela D. Luis , Wilfried Bardet and William H. Hildebrand . Oklahoma City OK, USA, University of Oklahoma HSC, 73104, Microbiology and Immunology .
While it has been demonstrated that MHC molecules sample an array of endogenous proteins during the cellular lifecycle, class I presentation of host-protein derived peptides after HIV infection has not been characterized. Based upon the observation that HIV interacts with multiple host proteins inside the cell, we hypothesized that unique host-protein-derived peptides are presented during infection. Here, we use a bioreactor-HLA-protein-production method and a mass-spectrometric-ion mapping system for analyzing changes in host-encoded peptide presentation during infection. Human T cell-transfectants were produced expressing soluble HLA-A*0201 or B*0702. These transfectants were cultured in bioreactors before or after infection with HIV. Peptides eluted from class I molecules produced in infected or uninfected cells were then directly compared using mass spectrometry. Mapping of HIV-infected and uninfected peptides from A*0201 and B*0702 resulted in the identification of approximately 50 host-derived peptides unique to HIV-infected cells. Most of these peptides derived from proteins involved in RNA processing and transcription. We next utilized real-time PCR and Western blotting to determine whether HIV-induced changes in transcription and/or protein processing were leading to class I peptide presentation. Interestingly, there were no changes in transcription; however, a majority of the proteins tested were degraded during HIV infection. Thus, virus-mediated protein degradation contributes to altered class I peptide presentation on HIV-infected cells. Immunogenicity data indicate that these upregulated self-peptides are recognized by T lymphocytes, suggesting a novel mechanism for immune reactivity in virally infected individuals.