INDUCTION OF ANTI-GP160 CYTOTOXIC T-CELLS CROSS-REACTING WITH VARIOUSV3 LOOP P18 PEPTIDES IN HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 ENVELOPE-IMMUNIZED INDIVIDUALS

Cytotoxic T lymphocytes (CTL) may be important to prevent cell-to-cell transmission of human immunodeficiency virus type 1 (HIV-1), the agen t responsible for AIDS. In this study, we investigated the epitope spe cificity of CTLs induced in individuals immunized against the virus en velope glycoprotein gp160. The determinant of HIV-1 gp160 for the stim ulation of CTL is located in a region df high sequence variability amo ng HIV-1 isolates, the so-called V3 loop P18, Using a panel of P18 pep tides, we compared the CTL specificities of cells from two individuals immunized with vaccinia virus recombinants expressing the envelope gl ycoproteins from two different strains of HIV-1, IIIB and SIMI. For th is purpose, CTLs specific for the IIIB P18 peptide (RIQRGPGRAFVTIGK) w ere compared,vith CTLs for the site from the SIMI isolate (TLHMG PKRAF YATGD). The results indicate that in contrast to CD8(+) CTLs induced b y the glycoprotein from strain IIIB, CD8(+) CTLs induced by strain SIM I strongly cross-reacted with targets presenting P18 peptides as well as envelope proteins from the divergent MN and RF isolates but failed to cross-react with targets that presented the IIIB peptide, These dat a have implications for the design of an HIV vaccine.