Vaccine-induced cytotoxic T lymphocytes against human immunodeficiency virus type 1 using two complementary in vitro...

CD8+ cytotoxic T lymphocytes (CTL) against human immunodeficiency virus type 1 (HIV-1) induced by candidate HIV-1 vaccines may be a mechanism of immune protection against HIV-1 infection. We measured in vitro inducible CD8+ and CD4+ CTL using two in vitro effector cell stimulation strategies. Peripheral blood mononuclear cells (PBMC) for CTL assay were obtained after the third and/or fourth immunization timepoints from 23 healthy, uninfected adult volunteers, of whom 19 received a canarypox virus vaccine expressing HIV-1 env, gag, pol, nef and protease gene products (vCP300) with or without injections of HIV-1(SF-2) rgp120 subunit vaccine and four subjects received only control injections. CD8+ CTL activity was detected employing the two in vitro stimulation strategies against one or more HIV-1 antigens in 15 (79%) of 19 HIV-1 vaccine recipients on at least one occasion and repeatedly against the same antigen in 8 (42%). Canarypox virus-based HIV-1 vaccines represent a step forward in HIV-1 vaccine development.