All ETDs from UAB

Advisory Committee Chair

Beatrice H Hahn

Advisory Committee Members

Paul A Goepfert

Olaf Kutsch

Elliot J Lefkowitz

Jamil S Saad

Document Type

Dissertation

Date of Award

2011

Degree Name by School

Doctor of Philosophy (PhD) Heersink School of Medicine

Abstract

Simian immunodeficiency virus of chimpanzees (SIVcpz) is the immediate precursor to human immunodeficiency virus type 1 (HIV-1), but even the most basic aspects of SIVcpz infection in its natural host are unknown. Here, we present the first comprehensive analysis of the natural history of SIVcpz infection in wild living chimpanzees. Using non-invasive (feces and urine based) methods, we studied two unique chimpanzee populations in Tanzania: the famous chimpanzees of Gombe National Park and the savanna chimpanzees of Ugalla, located about 135 km southeast of Gombe. Gombe chimpanzees are endemically infected with SIVcpz, and the park's established research infrastructure provides a unique opportunity to study this virus in its natural habitat. We found that SIVcpz is associated with a 10 to 16 fold increased risk of death, decreased female fertility, and increased infant mortality. CD4+ T cell depletion and overall immune system damage and dysfunction were observed in necropsied tissues of five SIVcpz infected chimpanzees but no uninfected chimpanzees. Next, we determined whether SIVcpz can negatively impact chimpanzee population size. In Gombe, one community with high prevalence (46%) suffered a population crash while the two neighboring communities with significantly lower prevalences (12% and 13%) remained stable in size. Demographic modeling allowed us to generalize the potential impacts of SIVcpz: SIVcpz can cause population decline, but in small communities connected via female immigration the virus is more likely to be driven to extinction than the population is. Finally, to examine of the geographic distribution and prevalence of SIVcpz in chimpanzee populations outside of Gombe, we surveyed a group of savanna chimpanzees who live in marginal habitats at significantly lower densities than the forest chimpanzees of Gombe. Despite their low population density, the savanna chimpanzees were infected with a high prevalence (31%) of SIVcpz. These chimpanzees are part of the larger Greater Mahale Ecosystem, meaning that additional nearby chimpanzee populations may be at risk for SIVcpz infection. Together, these studies show that SIVcpz is associated with an AIDS-like disease, that SIVcpz can but does not always negatively impact chimpanzee population size, and that SIVcpz is more widespread in Tanzania than previously appreciated.

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