Identification of multiple HIV-1 cytotoxic T-cell epitopes presented by human leukocyte antigen B35 molecules

Objectives: To identify HIV-1 cytotoxic T lymphocyte (CTL) epitopes presented by human leukocyte antigen (HLA)-B35 molecules that are associated with the accelerated progression of AIDS using a reverse immunogenetic approach. Methods: 8-mer to 11-mer sequences carrying two anchor residues at position 2 and the carboxy-terminus were selected from HIV-1(SF2) strain. Sixty-four peptides matched to these sequences were synthesized and tested by a peptide binding assay using RMA-S-B(*)3501 cells. Peripheral blood lymphocytes (PBL) from two HIV-1-infected donors carrying HLA-B35 were stimulated once-weekly with each HLA-B(*)3501 binding peptide. The CTL activity of the cultured cells for the HLA-B35-positive target cells loaded with the corresponding peptides was examined after the second and fourth stimulation. Furthermore, the CTL activity of the cultured cells possessing HLA-B(*)3501-restricted HIV-1 peptide-specific CTL activity were examined for the HLA-B(*)3501-positive target cells infected with the recombinant vaccinia virus containing corresponding HIV-1 gene. Results: HIV-1 peptide-specific HLA-B(*)3501-restricted CTL was induced in PBL of HIV-1 infected donors by in vitro stimulation with 11 out of 27 HLA-B(*)3501-binding HIV-1 peptides. The specific CTL induced with 10 peptides killed the cells infected with recombinant vaccinia virus expressing the corresponding HIV-1 proteins. Out of these HIV-1 peptide epitopes, two epitopes were also presented by HLA-B51 molecules. Conclusion: In addition to the four HLA-B35-restricted HIV-1 CTL epitopes that have been previously reported, nine HLA-B35-restricted HIV-1 CTL epitopes were identified in the present study. These multiple epitopes will be useful in studies for immunopathogenesis of AIDS.