Scientists Find Wild Tanzanian Chimp With Simian Immunodeficiency Virus, Advance Search for HIV Origin
AIDS researchers have discovered simian immunodeficiency virus, an HIV-like virus, for the first time in the wild in a Tanzanian chimpanzee, the AP/New York Times reports (AP/New York Times, 1/18). The findings "bolster" the theory that HIV originated in chimps, Dr. Beatrice Hahn, a molecular geneticist at the University of Alabama-Birmingham, said in her report that appears in today's issue of the journal Science. After discovering SIVcpz -- a chimp strain of the virus "closely resembl[ing]" HIV -- in a captive chimp in 1999, Hahn reported that AIDS "most likely got its start when the virus leapt from apes to man in West Central Africa" (Sternberg, USA Today, 1/18). Hahn's critics, however, "rightfully pointed out" that Hahn had "no clue" about what was happening in the wild (Norton, Reuters Health, 1/17).
SIV in the Wild
Hahn and her team tested 58 chimpanzees for SIV in the Ivory Coast, Uganda and Tanzania by collecting the chimps' feces and urine, "a way to test wild chimpanzees ... without touching them." The chimp who tested SIV-positive, which belongs to the subspecies Pan troglodytes schweinfurthii, lives in the Kasakela chimp community in Gombe National Park. Although subspecies Pan troglodytes troglodytes, found mostly in western African and the species from which SIVcpz was isolated, is "believed to have passed SIV on to a human being," Hahn tested the east African chimpanzees because, after years of being studied by primatologist Jane Goodall, they "tolerat[e]" human observers. The SIV found in the Gombe chimp was "30% different, as measured by amino acid sequences, from the virus detected in captive animals of the subspecies Pan troglodytes troglodytes" (Brown, Washington Post, 1/18). The genetic difference in the two strains "ruled out" east African chimps as the source of HIV, Hahn said (New York Times, 1/18).
Researchers will now begin the more difficult task of collecting samples from wild P. troglodytes troglodytes, which are rarely seen by humans. "I believe that the chimps are a fantastic model for us -- more fantastic than ever, in fact. They got it by cross-species transmission, just like we did, but they have gotten to the point where it seems they can live with it," Hahn said. Researchers have reported finding SIV in about 30 species of captive chimps, sometimes infecting up to 30% of the population but causing "little or no illness." Although the infected chimp, who will continue to be observed "over time," has had "many sexual encounters," no other chimps were found to be infected (Washington Post, 1/18).