HIV Type 1 Vaccine-Induced T Cell Memory and Cytotoxic T Lymphocyte Responses in HIV Type 1-Uninfected Volunteers

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Abstract
T cell memory to human immunodeficiency virus type 1 (HIV-1) antigens and anti-HIV-1 cytotoxic T lymphocyte (CTL) activity were assessed after administration of live canarypox virus (ALVAC) expressing HIV-1 env, gag, and protease (vCP205) vaccine given alone, vCP205 given with SF-2 recombinant gp120 (rgp120) vaccine, and placebos at 0, 1, 3, and 6 months. Healthy, HIV-1-uninfected subjects reporting high-risk and low-risk behavior for HIV-1 were enrolled. Anti-HIV-1 Env CD8+ CTLs (HIV-1MN and/or HIV-1 subtype B and C primary isolate sequences) were detected in 12 (60%) and anti-HIV-1 Gag CD8+ CTLs in 7 (35%) of the 20 vCP205 vaccine recipients tested by CTL assay 3.5 months after the final immunization. Fourteen days after the fourth immunization, lymphocyte proliferation in response to HIV-1 Gag antigen was detected in 14 (48%) of 29 vCP205 vaccine recipients, but secreted cytokine levels to HIV-1 Gag antigen were not above unstimulated levels. Coadministration of SF-2 rgp120 vaccine with vCP205 vaccine enhanced lymphocyte proliferation in response to HIV-1 envelope glycoprotein and broadened the envelope-stimulated cytokine secretion pattern, so that it consisted of both Th1 and Th2 cytokines compared with only interferon γ (IFN-γ) after vCP205 vaccine given alone. There was a possible association between HIV-1 envelope glycoprotein-stimulated interleukin 2 secretion and CD8+ CTLs against HIV-1 envelope glycoprotein, and an inverse relation between lymphocyte proliferation and CTLs against HIV-1 Gag antigens. Thus, a durable anti-HIV-1 CD8+ CTL response was detected after immunization with the live canarypox virus vaccine and preexisting helper T cell memory responses did not necessarily predict later CD8+ CTL activity.