Origins of HIV and the AIDS Epidemic

September 11-12, 2000, The Royal Society, London, United Kingdom

Jonathan Weber, FRCP, FRCPath, FmedSci, Keith Alcorn, Medical Writer

In This Article

Which Ape Holds the Smoking Gun?

What is the primate reservoir from which HIV emerged? Dr. Preston Marx of Tulane Regional Primate Research Center, Covington, Louisiana, pointed out that unless we understand how SIV turned into HIV we run the risk of new zoonoses; understanding which primates might present a future reservoir, were current variants of HIV ever to be controlled with vaccines, is thus a crucial area of HIV prevention research rather than simply an academic dispute. For example, smallpox has been eradicated by vaccinia immunization; however, a related virus, monkeypox, can infect humans and could theoretically re-emerge as a new zoonosis. We might be wise to continue vaccination for this reason.

Professor Beatrice Hahn of the University of Alabama, Birmingham, presented new data on her team's efforts to characterize the species reservoir of SIVcpz and its geographical range. SIVcpz is agreed to be the simian ancestor of HIV-1 group M, and Hahn has reported the reservoir to reside in Pan troglodytes troglodytes, the Central African chimpanzee that is largely confined to Gabon, Congo Brazzaville, Cameroon, and a small range of northern Congo (now the Democratic Republic of Congo).

Assessing SIVcpz prevalence in the wild is difficult because captured animals are invariably infants. Prevalence is very low among infant chimps, suggesting that maternal transmission is inefficient and rare. Hahn and colleagues developed fecal and urine antibody and HIV-1 RNA tests to measure prevalence, which were validated against Western Blot tests in 3 captive SIV-infected chimps.

The group then analyzed urine and fecal samples from Pan troglodytes troglodytes in Côte d'Ivoire and found no evidence of SIVcpz in West Africa. However, 1 infected chimp has been identified in East Africa at an unidentified location, and Dr. Hahn said that she expected to begin analysis of a viral sequence shortly. Western Blot analysis of the antibodies recovered shows a different reactivity from SIVcpz isolates recovered from chimps captured in Central and West Africa.


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