News: Lemur virus gives clues to evolution of HIV
- From: Ye Old One <usenet@xxxxxxxxx>
- Date: Sun, 21 Dec 2008 01:27:10 GMT
Lemur virus gives clues to evolution of HIV
http://www.plusnews.org/Report.aspx?ReportId=81980
ANTANANARIVO, 16 December 2008 (PlusNews) - A squirrel sized lemur
from Madagascar has given scientists new evidence about the origins of
the HI virus and opened up promising new avenues for investigation.
Robert Shafer, a senior author of the research, told IRIN/PlusNews
that the discovery "is one of the most important missing links"
required for understanding the evolutionary history of HIV-related
viruses.
It is widely believed that the two strains of HIV prevalent in humans,
HIV-1 and HIV-2, were passed on by primates from Africa, and that
these primates have harboured the disease for a million years at the
most. But the discovery of a virus related to HIV in the genetic
make-up of the tiny grey mouse lemur, found only in Madagascar, has
turned these beliefs on their head.
The new findings, published in the Proceedings of the National Academy
of Sciences on 1 December, suggest that lentiviruses, the family of
viruses to which the HIV-1 and HIV-2 belong, have been present in
primates for at least 14 million years. That was the last time the
Indian Ocean island of Madagascar was linked to mainland Africa,
allowing the disease to pass to lemurs.
"Our discovery means that primate lentiviruses have been present in
Madagascar historically and may still be circulating there," Robert
Gifford, an infectious disease researcher at the Stanford School of
Medicine and lead author of the research, told IRIN/PlusNews. "Since
Madagascar has been very isolated throughout evolutionary history,
it's not clear how we could have these viruses present both there and
in Africa, unless they are in fact many millions of years old."
Scientists now believe that lentiviruses could be at least 50 million
years old, and that they may be found in primates throughout the
world.
More than 25 million people across the world have died of AIDS-related
illnesses since the HI virus was first identified in the United States
27 years ago. Two-thirds of the 33 million people infected with HIV
globally live in sub-Saharan Africa, but Madagascar's HIV prevalence
rate has so far remained below 1 percent. The prevalence of syphilis
and other sexually transmitted diseases, however, suggest that the
virus could spread rapidly.
The recent findings from Stanford University are unlikely to radically
change the course of research into HIV and AIDS in the short term, but
are expected to have a major impact on scientists' broader
understanding of the virus.
"If we are ever going to properly understand the relationships between
lentiviruses and disease, assess the risk of new epidemics occurring,
and harness the body's natural defences to prevent and control HIV
infections, we need to establish the proper ecological and
evolutionary contexts," Gifford said.
He described the lentivirus material found in the genetic make-up of
the grey mouse lemur as "molecular fossils" that show how viruses
looked hundreds of thousands or even millions of years ago. This is
important, as it helps scientists understand the functions of
different genes within a virus, and to assess the limits of virus
adaptation and potential vulnerabilities - information that could be
used to help develop new ways to prevent and treat infections in
humans.
However, Gifford warned that there was still a long road ahead. "Like
many things in science, our findings raise as many questions as they
provide answers," he said. "But the important thing is that they
reveal something new and completely unexpected about the evolutionary
relationship between primates and lentiviruses."
--
Bob.
.
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