London: The origins of Human immunodeficiency virus (HIV) can be traced back millions rather than just tens of thousands of years, a new study has claimed.
The AIDS causing virus emerged in humans in the 20th Century, but scientists have long known that similar viruses in monkeys and apes have existed for much longer.
HIV-like viruses, according to a genetic study, arose in African monkeys and apes 5 million to 12 million years ago, `BBC News` reported.
"Our study reveals that, while primate lentiviruses may have modern consequences for human health, they have ancient origins in our non-human primate relatives," Dr Michael Emerman of the Fred Hutchinson Cancer Research Center said.
The research could lead to a better understanding of HIV and AIDS. The HIV virus affects 34 million people worldwide.
The disease emerged during the 20th century after a HIV like virus jumped from chimps to humans. Scientists have long known that similar viruses, known as lentiviruses, are widespread in African primates.
Previous studies have suggested these "cousins" of the HIV-virus arose tens of thousands of years ago, but some experts suspect this is an underestimate.
Scientists at the University of Washington and the Fred Hutchinson Cancer Research Center in Seattle, US looked at the genetic signatures of HIV-like viruses in a number of primates, including chimps, gorillas, orangutans and macaques.
Changes in genes that have evolved in the immune systems of monkeys and apes in Africa suggest the viruses arose between 5 and 16 million years ago.
The study, published in the journal PLOS Pathogens, gives clues to how the immune systems of our closest relatives evolved to fight infection, the report said.
"This kind of research helps us understand how the virus works. The hope is that one day this will translate into therapy," Dr Sam Wilson of the MRC - University of Glasgow Centre for Virus Research in Glasgow, said.