MEMORY CYTOTOXIC T-LYMPHOCYTE RESPONSES IN HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-I (HIV-1)-NEGATIVE VOLUNTEERS IMMUNIZED WITH A RECOMBINANT CANARYPOX EXPRESSING GP160 OF HIV-1 AND BOOSTED WITH A RECOMBINANT GP160

A vaccine against human immunodeficiency virus (HIV) should induce vir us-specific cytotoxic T lymphocyte (CTL) activity Immunization of unin fected volunteers with a canarypox virus expressing HIV envelope was c arried out in a phase I trial. Two injections of canarypox expressing HIV-1(MN) gp160 (months 0 and 1) were followed by two boosts of recomb inant envelope protein (months 3 and 6). HIV envelope-specific CTL wer e detected in peripheral blood mononuclear cells stimulated with autol ogous HIV-1-infected blast cells, T cell lines were obtained from 18 o f 20 donors: CTL were detected at least once following immunization in 7 (39%) of these 18. This activity was mediated by major histocompati bility complex class I-restricted CD3(+)CD8(+) T cells. For two subjec ts, this activity was still present 2 years after the initial immuniza tion, The CTL responses with this prime-boost regimen are the best obs erved with any HIV vaccine tested in humans.