C hicago - Most AIDS researchers have long believed that HIV-1 the main form of the AIDS virus jumped from chimps to humans. But the data in support of this theory has been difficult to find. Now Beatrice Hahn of the University of Alabama at Birmingham and colleagues have reconstructed what is being hailed as the best case yet for the chimpanzee connection
Hahn genetic detective work -. She described in the speech here at the opening of the Sixth Conference on Retroviruses and Opportunistic Infections - indicates that a particular chimpanzee subspecies, found in an area that includes Gabon, Cameroon and Guinea Equatorial is the original source of the rights of HIV-1 infections. She speculates that butchering chimpanzees - a practice, she noted, is common in some West African equatorial regions - may have provided the route for transmission. A paper on the results will be published in Thursday's Nature
HIV virus as scientists had already found in only three chimpanzees :. Two of Gabon and a third of what was then Zaire. (Viruses appear to cause disease in animals.) An analysis of the genetic sequences of these viruses, called SIVcpz, revealed that both Gabon strains are closely related to HIV-1 strains found in humans, but the Zaire strain is quite different, leading some to doubt that chimpanzees were the original reservoir. Hahn has now isolated another strain SIVcpz from a tissue sample from a chimpanzee named Marilyn who died in a research colony in the United States in 1985; it was found that similarly to the Gabon strains.
Hahn and colleagues analyzed mitochondrial DNA of four chimpanzees and found that the Gabonese animals and Marilyn all belonged to a subspecies, Pan troglodytes troglodytes . The Zairian animal belonged to a different subspecies P.T. schweinfurthii . Hahn believes that SIVcpz perhaps chimpanzees for hundreds of thousands of years, and that the viral strains have evolved to be specific subspecies of chimpanzees, which are isolated from each other by rivers. Some subspecies can harbor the virus, she said, while others may be infected with a strain that is less likely to spread among humans.
Vanessa Hirsch, a primate researcher at the National Institute of Allergy and Infectious Diseases, said she is impressed by the data. "Everybody has somehow been pussy-foot around the issue of whether chimpanzees are the source," says Hirsch. "Like most isolates are studied, it becomes more credible."
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