High-Level Primary CD8⁺T-Cell Response to Human Immunodeficiency Virus Type 1 Gag and Env Generated by Vaccination with Recombinant Vesicular Stomatitis Viruses

Abstract

We investigated the primary cellular immune responses to human immunodeficiency virus type 1 (HIV-1) Env and Gag proteins elicited by recombinant vesicular stomatitis viruses (rVSVs). The primary response to Env peaked 5 to 7 days after intraperitoneal vaccination, at which time 40% of CD8 ؉ cells were Env tetramer positive and activated (CD62L Lo ). These freshly isolated cells actively lysed target cells pulsed with the p18-I10 peptide and secreted gamma interferon and tumor necrosis factor alpha after stimulation with the Env p18-I10 peptide. The primary response to Env elicited by rVSVs was sixfold higher than that elicited by recombinant vaccinia viruses (rVVs) at 5 days postvaccination. An intranasal route of vaccination with VSV-Env also elicited a strong primary response to Env. The primary immune response to Gag elicited by rVSV peaked 7 days after vaccination, at which time 3% of CD8 ؉ cells were Gag tetramer positive and CD62L Lo and functional by intracellular cytokine staining. This response was eightfold higher than that elicited by rVV expressing Gag. VSV-GagEnv, which expresses both Gag and Env from a single recombinant, also induced strong cytotoxic T-lymphocyte (CTL) responses to both Env and Gag. Our quantitative analyses illustrate the potency of the VSV vector system in CTL induction.

Robust Recall and Long-Term Memory T-Cell Responses Induced by Prime-Boost Regimens with Heterologous Live Viral Vectors Expressing Human Immunodeficiency Virus Type 1 Gag and Env Proteins

“…The p18-I10 peptide is presented on several different MHC-I alleles, but it is most efficiently presented on the H-2D d class I molecule. Using H-2D d MHC-I tetramers containing the p18-I10 peptide (MHC-I Env tetramers), we previously showed that vaccination of mice with VSVEnv results in a strong primary response to Env that peaks 5 to 7 days after vaccination (16). The primary response rapidly declines to about one quarter of its peak level by 15 days after vaccination (16).…”

“…Using H-2D d MHC-I tetramers containing the p18-I10 peptide (MHC-I Env tetramers), we previously showed that vaccination of mice with VSVEnv results in a strong primary response to Env that peaks 5 to 7 days after vaccination (16). The primary response rapidly declines to about one quarter of its peak level by 15 days after vaccination (16). The magnitude of the peak primary response prompted us to determine if long-term memory cells specific for the p18-I10 peptide could be detected.…”

“…rVSVs expressing HIV-1 Env and Gag (VSVGag, VSV-Env, and VSV-GagEnv) have been described previously (15,16,21,22), as has the corresponding recovered wild-type VSV (VSV-rwt) control (27). Stocks of VSV and recombinants were grown on BHK-21 cells.…”

“…We previously reported that high-level primary responses were elicited to foreign viral proteins expressed in VSV (16). Here, using MHC-I tetramer staining and intracellular cytokine staining, we quantitated long-term memory and recall responses elicited in response to Gag and Env expressed in rVSVs by boosting with recombinant vaccinia viruses (rVVs) expressing these HIV proteins, as well as long-term memory to Env and Gag after boosting.…”

Long-Term Maintenance of gp120-Specific Immune Responses by Genetic Vaccination with the HIV-1 Envelope Genes Linked to the Gene Encoding Flt-3 Ligand

“…At the single-cell level, our study did not reveal any enhancement in the frequency of gp120-specific CD8 ϩ T cells in mice immunized with gp120 DNA in the presence and absence of DC expansion in vivo. These assays have proven to accurately measure T cell immune responses elicited by viral infections (47,67) or by the various modes of DNA vaccination (68,69). This could be due to a number of factors.…”