HIV type 1 vaccine-induced T cell memory and cytotoxic T lymphocyte responses in HIV type 1-uninfected volunteers

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-1(MN) 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 gamma (IFN-gamma) 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.     

Delivery of liposome-encapsulated HIV type 1 proteins to human dendritic cells for stimulation of HIV type 1-specific memory cytotoxic T lymphocyte responses.

An important aspect of vaccine development involves delivery of antigens to antigen-presenting cells for the induction of potent antigen-specific T lymphocyte responses. We investigated the effect of a cationic liposome, lipofectin, on delivery of whole proteins to human dendritic cells (DCs) derived from blood mononuclear cells by culture in interleukin 4 and granulocyte-monocyte colony-stimulating factor for stimulation of human immunodeficiency virus type 1 (HIV-1)-specific memory cytotoxic T lymphocyte (CTL) responses. Delivery of HIV-1 Gag, Pol, and Env proteins to DCs by lipofectin stimulated greater anti-HIV-1 memory CTL responses in cells from HIV-1-infected subjects than those induced by DCs loaded with protein alone. The CTLs were CD8+ and HLA class I restricted. Antigen presentation was enhanced by chloroquine, but blocked by brefeldin A and peptide aldehyde inhibitors of proteasomes, indicating that the classic MHC class I cytosolic pathway was used for processing and presentation of HIV-1 protein by the DCs. Stimulation of anti-HIV-1 CTLs by this safe, inexpensive, and broadly applicable approach may be used in DC-based therapies for HIV-1 infection.     

A canarypox vaccine expressing multiple human immunodeficiency virus type 1 genes given alone or with rgp120 elicits broad and durable CD8+ cytotoxic T lymphocyte responses in seronegative volunteers.

Induction of CD8+ cytotoxic T cells is considered one of the important correlates for the protective efficacy of candidate human immunodeficiency virus type 1 (HIV-1) vaccines. To induce CD8+ cytotoxic T lymphocytes (CTLs) along with neutralizing antibody and CD4+ T cell help, a live canarypox virus construct expressing gp120, transmembrane gp41, the gag and protease genes, and sequences containing CTL epitopes in nef and pol was given simultaneously with, or followed by, rgp120 SF2. CD8+ CTLs were detected in 61% of volunteers at some time during the trial. Three to 6 months after the last immunization, the gene-specific responses were gag, 26/81; env, 17/77; nef, 12/77; and pol, 3/16. Simultaneous immunization with the canarypox vector and the subunit, beginning with the initial immunization, resulted in earlier antibody responses. In summary, a strategy of immunization with a canarypox vector expressing multiple genes of HIV-1 given with gp120 results in durable CD8+ CTL responses to a broad range of epitopes.