Scientists Pursue Origins of HIV
have identified another piece in the puzzle of how HIV emerged
from the wilderness to spawn one of the most devastating
epidemics humanity has ever known.
same researchers who in 1999 traced the disease in humans to
chimpanzees in west central Africa have now discovered how the
chimps got the disease in the first place. They report their
results in Friday's issue of Science.
researchers found that chimps acquired the disease from eating
one of their favorite prey: monkeys. The primate version of
HIV, called SIV (simian immunodeficiency virus), emerged in
chimps apparently through a commingling of two monkey viruses
from the red-capped mangabey and the greater spot-nosed
is similar to the means by which humans probably first became
infected, by butchering chimpanzees for bushmeat,'" said
Paul M. Sharp, one of the researchers involved in the study,
and a professor at the Institute of Genetics at the University
of Nottingham in the United Kingdom.
are 98 percent genetically the same as humans, and they don't
get sick from SIV. This is an especially important clue for
developing an HIV vaccine, the researchers said. Understanding
what prevents chimps from getting sick would help scientists
duplicate resistance to AIDS symptoms in humans.
likely picked up viruses from both types of monkeys, and
eventually a hybrid formed, the researchers said. That
probably happened tens of thousands of years ago, which may
have given chimps an opportunity to evolve resistance to an
the new virus was transmitted to humans and became HIV-1.
(Researchers have traced HIV-2, another version of the human
virus, to the sooty mangabey).
16,000 people become infected with HIV -- the virus that
causes AIDS -- every day, according to the Joint United
Nations Programme on HIV/AIDS, or UNAIDS. About half the 38.6
million adults with HIV or AIDS worldwide are women, and 3.2
million are children younger than the age of 15.
the United States, 900,000 people have HIV and 40,000 new
infections appear annually, according to NAIAD, the National
Institute of Allergy and Infectious Diseases. More than half
those infected are people of color, and half of all new cases
are people under 25.
new study further debunks a theory that HIV may have emerged
from the polio vaccine, Sharp said. The Science study shows
that the virus likely developed through natural processes
rather than as an accident of medicine.
get me started!" Sharp said in an e-mail response to
questions about the polio vaccine hypothesis. "That
'theory' is already essentially dead in the minds of all but a
few individuals -- who lack expertise in the relevant
theory suggests the polio vaccine was created using chimpanzee
cells infected with a virus that became HIV. But it places the
chimps in eastern Africa in the late 1950s. Sharp's research,
however, has found that HIV-1 was derived from SIV in
chimpanzees from west central Africa around 1930.
wrong chimps, wrong time," he said.
groups have studied samples of the old oral polio vaccines,
Sharp said, finding no sign of SIV. They did find DNA from
macaques (but not from chimps), and it was no secret the
vaccine developers used macaque kidney cells.
new study means researchers should focus more on studying the
natural SIV infection in wild chimpanzees, Sharp said.
example, it would be interesting to learn whether they have
picked up SIVs from any other monkey species," Sharp
said. "Because of the similarity between chimpanzees and
humans, any virus that successfully adapts to spreading among
chimpanzees would be a candidate for a further jump to humans:
a potential HIV-3."
Hahn, a professor of medicine at the University of Alabama at
Birmingham and co- author of the new study, said that while a
mysterious HIV-3 is not likely to be infecting people now,
it's something researchers should keep an eye out for, and try
question is, because of practices currently ongoing, are we
creating more opportunities for cross-species transfer of
these and other infections?" Hahn asked. "We just
had SARS and yesterday we had monkey pox."