HIV-like virus found in Cameroon wild chimpanzees

The origin of the virus that causes Aids has been traced to chimpanzees living in the forests of southern Cameroon.

Photo: HIV-like virus found in Cameroon wild chimpanzees

HIV-like virus found in Cameroon wild chimpanzees

The closest known cousin of the Human Immunodeficiency Virus (HIV) has been identified among chimps living south of the West African country’s Sanaga River, allowing scientists to pinpoint where the germ jumped the species barrier to people.

The findings by an international research team fill a "missing link" in the evolution of HIV, the cause of the world’s most deadly infectious disease with an annual death toll of more than three million.

It bolsters the standard theory that Aids began when an ape version of HIV crossed into humans, probably first infecting a bushmeat hunter, and demolishes more sensational alternative explanations, reports Times Online.

According to Nature, r esearchers led by Beatrice Hahn of the University of Alabama at Birmingham travelled to Cameroon to collect droppings from the chimpanzee subspecies Pan troglodytes troglodytes.

The team knew that a few captive chimps of this subspecies have been found carrying a strain of simian immunodeficiency virus (SIV) almost identical to the HIV-1 strain, but it was not clear how these animals came to have the virus.

Better evidence that these creatures were responsible for the human AIDS pandemic would come from tracking down a reservoir of the human-like SIV in wild chimps in west Africa. The team's hopes of finding such a reservoir were high: a few years ago they found another version of SIV, one quite different from the human virus, in a different subspecies of wild chimp living in east Africa.

As hoped, analysis of the Cameroon samples revealed the presence of antibodies against human-like SIV and traces of the virus' genetic sequence. On the basis of their samples, the researchers calculate that some 30-35% of chimpanzees are carriers. The team reports the findings in Science.

The virus does not seem to cause any AIDS-like symptoms in the chimpanzees, says Hahn, as captive infected chimps do not seem to develop immune disease. "Lots of people are trying to find out why," says Paul Sharp, a viral geneticist at the University of Nottingham, UK, who also worked on the study.