Induction of anti-gp160 cytotoxic T cells cross-reacting with various V3 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 agent responsible for AIDS. In this study, we investigated the epitope specificity of CTLs induced in individuals immunized against the virus envelope glycoprotein gp160. The determinant of HIV-1 gp160 for the stimulation of CTL is located in a region df high sequence variability among HIV-1 isolates, the so-called V3 loop P18, Using a panel of P18 peptides, we compared the CTL specificities of cells from two individuals immunized with vaccinia virus recombinants expressing the envelope glycoproteins from two different strains of HIV-1, IIIB and SIMI. For this purpose, CTLs specific for the IIIB P18 peptide (RIQRGPGRAFVTIGK) were compared,vith CTLs for the site from the SIMI isolate (TLHMG PKRAFYATGD). The results indicate that in contrast to CD8(+) CTLs induced by the glycoprotein from strain IIIB, CD8(+) CTLs induced by strain SIMI 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 data have implications for the design of an HIV vaccine.