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1999: Origin of HIV-1 Discovered
To place any conspiracy theory into perspective, consider the following media release
from scientists at the University of Alabama at Birmingham, titled "Origin of HIV-1 Discovered" (posted on January 31, 1999 at 1:52 p.m.):
BIRMINGHAM, AL — Scientists at the University of Alabama at Birmingham (UAB) have
discovered the origin of Human Immunodeficiency Virus Type 1 (HIV-1), the virus that
causes AIDS in humans. This finding by an international team of scientists led by
Dr. Beatrice H. Hahn of
UAB, solves a 20-year-old puzzle regarding the beginnings of the AIDS
epidemic which now afflicts some 30 million people worldwide. Hahn presented her
study today at the 6th Conference on Retroviruses and Opportunistic Infections in
Chicago. A paper detailing the discovery appears in the February 4 issue of the journal
UAB AIDS Researchers Dr. Beatrice Hahn
and George Shaw, M.D., Ph.D.
Image Source: UAB Media Relations
Hahn, a professor of medicine and microbiology at UAB, is senior author of the paper.
Dr. Feng Gao, research assistant professor of medicine at UAB, is the paper's lead
The researchers identified a subspecies of chimpanzee (Pan troglodytes troglodytes)
native to West-Central Africa as the natural reservoir for HIV-1. "We have long
suspected a virus from African primates to be the cause of human AIDS, but exactly
which animal species was responsible was unknown," says Gao. Viruses related
to HIV-1 had previously been found in chimpanzees and were given the designation
SIVcpz (for Simian Immunodeficiency Virus). However, only three such infected animals
were identified, and one of these harbored a virus so different from HIV-1 that most
scientists questioned a direct relationship to the human virus.
The recent breakthrough came when Hahn and her colleagues identified a fourth SIVcpz
infected chimpanzee and used sophisticated molecular techniques to analyze all four
viruses and the animals from which they were derived. The researchers found that
three of the four SIVcpz strains came from chimpanzees that belonged to one particular
subspecies, termed Pan troglodytes troglodytes, which is native to West-Central Africa.
The fourth virus strain, which was genetically divergent from the other three, came
from an animal that belonged to a different chimpanzee subspecies, termed Pan troglodytes
schweinfurthi, which is native to East Africa. The scientists then discovered that
all known strains of HIV-1, including the major group M (responsible for the global
AIDS epidemic) as well as groups N and O (found only in West-Central Africa), were
closely related only to SIVcpz strains infecting Pan troglodytes troglodytes.
The final piece of the puzzle was put in place when the researchers realized that
the natural habitat for Pan troglodytes troglodytes overlaps precisely with the region
in West-Central Africa where all three groups of HIV-1(M, N, and O) were first recognized.
Based on these findings, Hahn and her colleagues concluded that Pan troglodytes troglodytes
is the origin of HIV-1 and has been the source of at least three independent cross-species
transmission events of SIVcpz.
While the origin of the AIDS epidemic has been clarified, an explanation for why
the epidemic arose in the mid-20th century, and not before, remains a matter of speculation.
"Chimpanzees are frequently hunted for food, especially in West-Central Africa,
and we believe that HIV-1 was introduced into the human population through exposure
to blood during hunting and field dressing of these animals," says Hahn. She
further believes that while incidental transmissions of chimpanzee viruses to humans
may have occurred throughout history, it was the socio-economic changes in post-World
War II Africa that provided the particular circumstances leading to the spread of
HIV-1 and the development of the AIDS epidemic. "Increasing urbanization, breakdown
of traditional lifestyles, population movements, civil unrest, and sexual promiscuity
are all known to increase the rates of sexually transmitted diseases and thus likely
triggered the AIDS pandemic," adds Hahn.
"The importance of the current findings could be far reaching," says Dr.
George Shaw, a Howard Hughes Medical Institute Investigator at UAB and a principal
author of the paper. "Chimpanzees are identical to humans in over 98 percent
of their genome, or hereditary material, yet they appear to be resistant to the damaging
effects of the AIDS virus on the immune system. By studying the biological reasons
for this difference, we may be able to obtain important clues concerning the pathogenic
basis of HIV-1 in humans and possibly new strategies for treating the disease more
effectively." He further added that a better understanding of exactly how the
chimpanzee's immune system responds to SIVcpz infection compared to that of humans
is likely to lead to the development of more effective strategies for an HIV-1 vaccine.
Finally, the authors of the paper note that transmission of SIVcpz could still be
ongoing. "The bushmeat trade — the hunting and killing of chimpanzees and other
endangered animals for human consumption — is a common practice in West-Central Africa
and represents an ongoing risk for humans," says Hahn. "Subsistency hunting
has always been a part of West-Central African culture, but increasing logging activities
in the past decade have provided unprecedented access to remote forest regions and
have led to the commercialized killing of thousands of chimpanzees, gorillas, and
monkeys. It took us 20 years to find where HIV-1 came from, only to realize that
the very animal species that harbors it is at the brink of extinction," says
"We cannot afford to lose these animals, either from an animal conservation
or a medical investigative standpoint," she says. "It is quite possible
that the chimpanzee, which has served as the source of HIV-1, also holds the clues
to its successful control." Hahn and her colleagues hope that as a consequence
of their research, there will be additional measures taken to discourage chimpanzee
poaching and to preserve this and other endangered primate species.
The team of scientists responsible for the AIDS discovery included UAB's Ya-Lu Chen,
Cynthia Rodenburg and Scott Michael as well as Paul Sharp and Elizabeth Bailes from
the University of Nottingham in England; David Robertson from the Laboratory of Structural
and Genetic Information in Marseilles, France; Larry Cummins from the Southwest Foundation
for Biomedical Research in Texas; Larry Arthur from the Frederick Cancer Research
and Development Center in Frederick, Maryland; and Martine Peeters from the Laboratory
of Retroviruses at ORSTOM in Montpellier, France.
The research was funded by the National Institute of Allergy and Infectious Diseases
and the Howard Hughes Medical Institute.
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