title: Protection against Mucosal SHIV Challenge by Peptide and Helper-Dependent Adenovirus Vaccines.
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 helper-dependent 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.
authors.affiliation: Department of Internal Medicine, Division of Infectious Diseases, Translational Immunovirology Program, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Weaver
authors.forename: Pramod N
authors.initials: PN
authors.lastname: Nehete
authors.forename: Bharti P
authors.initials: BP
authors.lastname: Nehete
authors.forename: Stephanie J
authors.initials: SJ
authors.lastname: Buchl
authors.forename: Donna
authors.initials: D
authors.lastname: Palmer
authors.forename: David C
authors.initials: DC
authors.lastname: Montefiori
authors.forename: Philip
authors.initials: P
authors.lastname: Ng
authors.forename: K Jagannadha
authors.initials: KJ
authors.lastname: Sastry
authors.forename: Michael A
authors.initials: MA
authors.lastname: Barry