The origins of HIV can be traced back
millions rather than tens of thousands of
years, research suggests.
HIV, which causes Aids, emerged in humans
in the 20th Century, but scientists have long
known that similar viruses in monkeys and
apes have existed for much longer.
A genetic study shows HIV-like viruses arose
in African monkeys and apes 5 million to 12
million years ago.
The research may one day lead to a better
understanding of HIV and Aids.
HIV 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.
Past genetic research has suggested these
"cousins" of HIV arose tens of thousands of
years ago, but some experts have suspected
this is an underestimate.
Evolutionary arms race
Scientists at the University of Washington in
Seattle, US, and the Fred Hutchinson Cancer
Research Center, also in Seattle, looked at the
genetic signatures of HIV-like viruses in a
number of primates, including chimps,
gorillas, orang utans 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 research, published in the journal PLOS
Pathogens, gives clues to how the immune
systems of our closest relatives evolved to
fight infection.
Dr Michael Emerman of the Fred Hutchinson
Cancer Research Center said: "Our study
reveals that, while primate lentiviruses may
have modern consequences for human
health, they have ancient origins in our non-
human primate relatives."
Commenting on the study, Dr Sam Wilson of
the MRC - University of Glasgow Centre for
Virus Research in Glasgow, said: "This kind
of research helps us understand how the
virus works.
"The hope is that one day this will translate
into therapy."