"The date when SIV first evolved to HIV makes it "unlikely'' that a
polio vaccination campaign in the late 1950s can be blamed for the rise of
AIDS.
"Some researchers have suggested that a polio vaccine made using
chimpanzee kidney cells could have transferred HIV into humans between 1957
and 1960."
Study: HIV Began in 1930s Africa
By PAUL RECER
WASHINGTON (AP) - AIDS evolved from a benign simian infection into a
human-killer in the early 1930s, long before it was recognized as a disease,
but it stayed in remote Africa until jet travel, big cities and the sexual
revolution spread it worldwide, a new study suggests.
Researchers measuring the rate of genetic change in HIV, the virus that
causes AIDS, found the current strains originated from a common ancestor that
first evolved from a simian virus in southwest Africa between 1915 and 1941,
with 1931 the most likely year.
``It could have been in humans even before that,'' said Tanmoy Bhattachary, a
researcher at the Los Alamos National Laboratory in Los Alamos, N.M. The
study appears Friday in the journal Science.
Bhattachary said the most common form of HIV worldwide evolved from simian
immunodeficiency virus, or SIV, that was in the chimpanzee. SIV genetically
converted to HIV either while it was in the chimp or after a human contracted
SIV.
The disease did not become a worldwide menace, he said, until people left the
isolated areas of Africa and carried the virus around the globe.
``It could have evolved in humans and stayed in a very small population, such
as a village,'' said Bhattachary. ``That is typically what most new diseases
do. They are in an isolated population and then something happens and it
starts spreading all over.''
The findings are consistent with earlier studies that suggested that HIV
originated early in this century and then was spread when Africa became less
isolated.
Bhattachary said the date when SIV first evolved to HIV makes it ``very
unlikely'' that a polio vaccination campaign in the late 1950s can be blamed
for the rise of AIDS. Some researchers have suggested that a polio vaccine
made using chimpanzee kidney cells could have transferred HIV into humans
between 1957 and 1960.
Although the new research could not eliminate that possibility entirely,
Bhattachary said, the fact that HIV originated before the polio vaccine means
``you can probably discount that scenario''
A type of AIDS virus called HIV2, which occurs mostly in Africa, may have
originated from sooty mangabeys, a type of African monkey, the study says.
But HIV1, the virus that has caused a pandemic, came from the chimpanzee, a
primate more closely related to humans.
A form of HIV1 called Group M is the major virus spreading throughout the
world. It has infected about 50 million people and killed 16 million.
Bhattachary said Group M may have crossed over from chimp to humans only
once, or evolved from SIV in only one patient.
``Our study shows that the M group had a single origin,'' he said. ``It could
have come from one animal or from one human.''
Other forms of HIV, he said, had ``multi-introductions.''
The most common form HIV in the United States, called subgroup B, first
evolved between 1960 and 1971, with 1967 being the most likely year, said
Bhattachary.
Clinical symptoms of what later became known as AIDS were reported in the
United States in the late 1970s. AIDS was formally diagnosed and named in
1981. The HIV1 virus was isolated and confirmed in 1983.
John P. Moore, a microbiologist and AIDS researcher at Cornell University in
New York, said the study by Bhattachary and his colleagues is ``outstanding
and significant. They have looked into this very carefully.''
Moore said the findings emphasizes how science needs to be concerned and
alert to the risks of cross-species viral transmissions, many of which are
lethal or cause serious illness in humans.
Another researcher, Jim Moore of the University of California, San Diego,
said the Los Alamos study is consistent with his findings that conditions in
colonial Africa were ripe, starting in the late 19th century, for a new virus
to take hold and spread.
Colonial powers forced people out of villages, causing many to live in the
jungles, surviving by hunting and gathering, said Moore, who is unrelated to
the Cornell scientists. A major food was meat from chimps and monkeys.
``This created conditions ideal for the transfer (of a virus) from chimps and
a spread into small populations,'' said Moore.
Later, he said, large work gangs were organized to build roads and mines,
with some construction organizations promoting prostitution to keep the
isolated workers content. HIV is a sexually transmitted disease.
In more recent decades, an age with easy transoceanic travel and the sexual
revolution, millions of people have been in and out of Africa.
Moore said campaigns to vaccinate the African population against small pox
and other diseases may even have helped HIV spread, saying, ``They weren't
using sterilized needles all the time.''
