FINE-SPECIFICITY OF CYTOTOXIC T-LYMPHOCYTES WHICH RECOGNIZE CONSERVEDEPITOPES OF THE GAG PROTEIN OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1

Human immunodeficiency virus type 1 (HIV-1) Gag-specific cytotoxic T l ymphocyte (CTL) responses were studied in seven seropositive long-term asymptomatic individuals (CDCA1) with stable CD4 counts for more than 8 years, Using a set of partially overlapping peptides covering the w hole Gag, five 15-20-mer peptides were found to contain CTL epitopes, Further characterization of these epitopes revealed a new HLA-A25-rest ricted CTL epitope in p24, p24(203-212) ETINEEAAEW, This region of Gag is highly conserved in clades B and D of HIV-1. Naturally occurring a mino acid sequences, containing p24(203)D (consensus HIV-1 clades A, C , F, G and H) or p24(204)I (HIV-2(ROD)) were not recognized by CTL rec ognizing the index peptide, No virus variants with mutations in this s equence were found in peripheral blood mononuclear cells from the HIV- 1-infected individual concerned during the 8 year observation period, indicating that the virus had not escaped from the observed CTL respon se.