AIDS Link Goes Back Millions Of Years

New research suggests that an ancestor to HIV may have existed millions of years ago.

An ancient predecessor to the virus that causes Aids evolved in wild primates many millions of years earlier than previously believed, according to research published yesterday by the Stanford University School of Medicine. The findings open a critical new avenue in the quest to understand the origins of the human immunodeficiency virus, or HIV, which unleashed a pandemic that since 1981 has claimed more than 25 million lives worldwide, and threatens millions more.

The discovery also bolsters scientific hunches that HIV-like viruses may be more broadly distributed among primates and other wildlife than previously thought, posing a potential risk for humans in close contact with these animals. Primates in Africa passed on the two strains of HIV circulating among humans, scientists are convinced.

"It points to the direction for future research, that we need to establish how widespread these viruses are," said Robert Gifford, an infectious disease researcher with Stanford, and lead author of the study. Gifford and his colleagues studied gray mouse lemurs, squirrel-sized, saucer-eyed primates found in Madagascar. They found that the lemur genomes they studied carried lentiviruses, which are among a family of viruses that include HIV. Lentiviruses have been intensely studied since the emergence of Aids. While the discovery of lentiviruses in lemurs surprised the researchers, what especially stunned them was the realisation that lemurs must have carried the virus for at least 14m years.

Scientists hope this discovery may help prevent other animal viruses from entering the human population. Further research may also discover "fixed features" of the ancient virus that could be the target of new AIDS drugs.