Virus found in wild African chimp could hold Aids key

Scientists have detected a close relative of the Aids virus in a wild chimpanzee, raising the prospect that virologists may soon discover the source of HIV.

A few chimps kept in captivity have tested positive for the nearest simian relative of HIV, but finding the virus in wild animals supports the growing belief that Aids jumped from chimpanzee to man in the mid-20th century.

Aids researchers have been keen to discover the origin of HIV because that may lead to a group of wild chimpanzees with a natural immunity to the virus, which could help scientists to develop an effective vaccine for humans.

An international team of researchers found the Aids-like virus in a 23-year-old male chimpanzee living in the Gombe National Park on the eastern shore of Lake Tanganyika in Tanzania, an area studied by the primatologist Jane Goodall.

A genetic analysis of the simian immunodeficiency virus (SIV) isolated from the Gombe chimp revealed that it shared about 70 per cent of its identity with HIV, making it close enough to be related to the human virus but too distant to be its direct ancestor.

Although the researchers, led by Beatrice Hahn and George Shaw of the University of Alabama, have ruled out the virus as the ancestor of HIV, they believe its discovery increases the likelihood that other viruses which are direct progenitors to HIV exist in other parts of the central African jungle.

Dr Hahn said: "The finding of SIV in east African chimp indicates that chimps are naturally infected with SIV, that they are a natural host for the virus.

"We always assumed that the wild-caught captive chimps were infected in the wild but some people said that we couldn't prove it. This is now formal proof that wild chimps are infected."

If such viruses were found and proved to be genetically similar to HIV, infected chimps would be candidates for being the natural "reservoir" of the human virus, which has infected tens of millions of people over the past 20 years.

Dr Shaw said: "To find this virus for the first time in the wild opens a window of opportunity to begin to study the natural transmissibility of these types of viruses in their natural host.

"We also believe it may be important ultimately to understand the implications of the cross-species transmission that brought about the HIV epidemic."

- INDEPENDENT