Abstract: Groups of rhesus macaques that had previously been immunized with HIV-1 envelope (env) peptides and first generation adenovirus serotype 5 (FG-Ad5) vaccines expressing the same peptides were immunized intramuscularly three times with helperdependent adenovirus (HD-Ad) vaccines expressing only the HIV-1 envelope from JRFL. No gag, pol, or other SHIV genes were used for vaccination. One group of the FG-Ad5-immune animals was immunized three times with HD-Ad5 expressing env. One group was immunized by serotype-switching with HD-Ad6, HD-Ad1, and HD-Ad2 expressing env. Previous work demonstrated that serum antibody levels against env were significantly higher in the serotype-switched group than in the HD-Ad5 group. In this study, neutralizing antibody and T cell responses were compared between the groups before and after rectal challenge with CCR5-tropic SHIV-SF162P3. When serum samples were assayed for neutralizing antibodies, only weak activity was observed. T cell responses against env epitopes were higher in the serotype-switched group. When these animals were challenged rectally with SHIV-SF162P3, both the Ad5 and serotype-switch groups significantly reduced peak viral loads 2 to 10-fold 2 weeks after infection. Peak viral loads were significantly lower for the serotype-switched group as compared to the HD-Ad5-immunized group. Viral loads declined over 18 weeks after infection with some animals viremia reducing nearly 4 logs from the peak. These data demonstrate significant mucosal vaccine effects after immunization with only env antigens. These data also demonstrate HD-Ad vectors are a robust platform for vaccination.
Keywords: HIV-1; SHIV; adenovirus; helper-dependent vector; mucosal challenge; serotype-switching
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Weaver, E.A.; Nehete, P.N.; Nehete, B.P.; Buchl, S.J.; Palmer, D.; Montefiori, D.C.; Ng, P.; Sastry, K.J.; Barry, M.A. Protection against Mucosal SHIV Challenge by Peptide and Helper-Dependent Adenovirus Vaccines. Viruses 2009, 1, 920-938.
Weaver EA, Nehete PN, Nehete BP, Buchl SJ, Palmer D, Montefiori DC, Ng P, Sastry KJ, Barry MA. Protection against Mucosal SHIV Challenge by Peptide and Helper-Dependent Adenovirus Vaccines. Viruses. 2009; 1(3):920-938.
Weaver, Eric A.; Nehete, Pramod N.; Nehete, Bharti P.; Buchl, Stephanie J.; Palmer, Donna; Montefiori, David C.; Ng, Philip; Sastry, K. Jagannadha; Barry, Michael A. 2009. "Protection against Mucosal SHIV Challenge by Peptide and Helper-Dependent Adenovirus Vaccines." Viruses 1, no. 3: 920-938.