This subproject is one of many research subprojects utilizing theresources provided by a Center grant funded by NIH/NCRR. The subproject andinvestigator (PI) may have received primary funding from another NIH source,and thus could be represented in other CRISP entries. The institution listed isfor the Center, which is not necessarily the institution for the investigator.This study is designed to evaluate the protective potential of the HIV-1 regulatory protein, Tat, as a purified biologically active protein (Tatwt protein) and as a gene product expressed by a recombinant replication-competent adenovirus vector (Ad5hr-HIVtatwt) in Macaca fascicularis of Mauritius origin. Two groups of nine macaques each received nine (weeks 0, 2, 6, 11, 15, 21, 28, 32, and 36) subcutaneous and intradermal vaccinations with Tat protein (Group 1) or two vaccinations, one intranasal (week 0) and the other intratracheal (week 12) with Ad5hr-HIVtat, plus two boosts with Tat protein (Group 2) at weeks 24 and 36. Two groups of three macaques that received alum only (Group 4) or empty vector (Group 3) serve as controls. Immune responses were assayed by ELISA, Luminex multianalyte profiling (xMAP), T-cell IFN- ELISPOT, intracellular cytokine staining, proliferation assays and HIV neutralization on blood obtained prior to, at the time of, and two weeks following each immunization. Mucosal secretions (rectal and nasal swabs and saliva) were assayed by xMAP. The xMAP system is being evaluated in comparison to the standard Tat ELISA. The results show that Group 1 animals mounted a rapid and sustained binding antibody response with titers increasing after each boost to peaks of 1:12,800. Group 2 animals had lower antibody levels following the adeno-recombinant immunizations that rose quickly following the protein boosts. Cellular immune response assays showed that T-cell responses were induced in both the adeno-recombinant group and the protein group with the former exhibiting higher activity. All animals were challenged at week 50 with a pathogenic SHIV, 89.6P. Viral loads were monitored by NASBA and RealTime PCR. Following challenge all macaques became infected. One adjuvant control animal and two animals each in the Tat protein and Ad-tat groups had undetectable viremia but were provirus positive. The CD4 counts mirrored the viral loads. Five animals, one each in Groups 1, 2, and 4 and two in Group 3 have been euthanized because of AIDS-related symptoms. Confounding variables uncovered in Mauritian macaques included significant associations of susceptibility to infection with MHC class IB and class II H2 and H5 haplotypes, and resistance to infection with class IB haplotypes H3 and H6. We are continuing to monitor the remaining animals to assess possible survival differences between the groups.
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