Protection against Mucosal SHIV Challenge by Peptide and Helper-Dependent Adenovirus Vaccines

Authors

• Eric A. Weaver, University of Nebraska-LincolnFollow
• Pramod N. Nehete, The University of Texas, Bastrop
• Bharti P. Nehete, The University of Texas, Bastrop
• Stephanie J. Buchl, The University of Texas, Bastrop
• Donna Palmer, Baylor College of Medicine, Houston
• David C. Montefiori, Baylor College of Medicine, Houston
• Philip Ng, Baylor College of Medicine, HoustonFollow
• K. Jagannadha Sastry, The University of Texas, Bastrop & The University of Texas, Houston
• Michael A. Barry, Mayo Clinic, RochesterFollow

Document Type

Article

Date of this Version

10-10-2009

Citation

2009 by the authors

doi:10.3390/v1030920

Comments

Viruses 2009, 1, 920-938

www.mdpi.com/journal/viruses

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.