Meet "Pan Troglodytes" the Chimp who Gave the World HIV

Scientists find missing link between HIV, chimpanzee virus

- Lawrence K. Altman

By studying chimpanzee droppings in remote African jungles, scientists have found direct evidence of a missing link between a chimpanzee virus and the one that causes human AIDS, they reported. Scientists have long suspected that chimpanzees are the source of the human AIDS pandemic because at least one subspecies carries a simian immune deficiency virus closely related to HIV, the human AIDS virus. But because the simian virus, known as SIVcpz, was identified in chimpanzees in captivity, researchers could not be sure that the same simian virus existed among these apes in the wild.

It does, according to a report Thursday by a team of American, European and Cameroon scientists in the journal Science. They found it by testing hundreds of chimpanzee droppings collected in Cameroon. The genetic and immunologic tests were developed in stages over the last seven years to help trace the evolution of HIV and solve the mysterious origins of AIDS, said Dr. Beatrice H. Hahn, a virologist at the University of Alabama in Birmingham who headed the international team that conducted the study.The new findings, she said in a telephone interview, do not explain the entire chain of events that led from the first human HIV infection to the infection of 65 million people around the world.

But, Hahn reported, the findings show "for the first time a clear picture of the origin of HIV-1 and the seeds of the AIDS pandemic." Studies estimate that the human AIDS virus jumped species between 50 and 75 years ago. But no one knows who the first infected person was or how that person acquired HIV. Hahn said her team theorizes that HIV was first transmitted locally somewhere in west central Africa.

Because the subspecies of chimpanzees, Pan troglodytes troglodytes, in which the simian virus had been found in captivity, lives in the wild in Cameroon, Gabon and Republic of Congo, the first infection could have been in any of those areas. Hahn's team found that the chimpanzee communities with a high prevalence of infected members were located south of the Sangha River, which flows into the Congo River and on to Kinshasa. That led Hahn's team to the theory that some infected person carried HIV from a remote area of Africa to Kinshasa and then it was transmitted elsewhere.