http://www.prohealth.com/fibromyalgia/blog/boardDetail.cfm?id=3D1368010
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'Retrovirus might be culprit in chronic fatigue syndrome'
People with the condition are much more likely than others to harbor a
little-known pathogen
By Nathan Seppa
Web edition : 1:50 pm
http://www.sciencenews.org/view/generic/id/48157/title/Retrovirus_might_be_=
culprit_in_chronic_fatigue_syndrome
The long, fruitless search for the cause of chronic fatigue syndrome
has taken a curious turn. Scientists report online October 8 in
Science that an obscure retrovirus shows up in two-thirds of people
diagnosed with the condition. The researchers also show the retrovirus
can infect human immune cells.
These findings don=92t establish that the pathogen, called
gammaretrovirus XMRV, causes chronic fatigue, cautions study coauthor
Robert Silverman, a molecular biologist at the Lerner Research
Institute of the Cleveland Clinic. =93Nevertheless, it=92s exciting
because it is a viable candidate for a cause.=94
Roughly 1 to 4 million people in the United States have chronic
fatigue syndrome, according to the Centers for Disease Control and
Prevention. The condition shows up as mental and physical exhaustion,
memory lapses, muscle pain, insomnia, digestive distress and other
health problems. Doctors often diagnose chronic fatigue only after
ruling out everything else. Its cause is unknown.
In the new study, the researchers tested blood from 101 people with
chronic fatigue syndrome and found that 68 were infected with XMRV.
When the scientists analyzed blood from 218 healthy people as a
control group, only eight had the virus =97 4 percent. The study
participants lived in various parts of the United States.
=93This is a very striking association =97 two-thirds of the patients,=94
says John Coffin, a virologist at Tufts University in Boston who
wasn=92t involved in the study. A 4 percent infection rate in the
healthy controls is also substantial, he notes, because it suggests
that 10 million people in the United States are harboring this hidden
infection.
If the retrovirus indeed is found to cause chronic fatigue, the
infected 4 percent in the control group might represent people who
have been infected for a short time and haven=92t developed symptoms, or
who have kept the virus in check, says study coauthor Judy Mikovits, a
cell biologist at Whittemore Peterson Institute in Reno and at the
University of Nevada, Reno.
Based on its genetic makeup, XMRV arose from a mouse retrovirus that
somehow jumped to humans.
Mikovits asserts that the retroviral infection might result in an
immune deficiency that leads to chronic fatigue symptoms. Retroviruses
are known to attack the immune system, with HIV being the best-known
example. In this study, researchers showed that XMRV infected immune
cells in the blood.
=93This may end the controversy as to whether there is an underlying
infection in some cases of chronic fatigue syndrome, but is unlikely
to explain all cases,=94 says internist Dedra Buchwald of the University
of Washington in Seattle. Retroviruses can awaken latent viruses
already in cells. It is possible that chronic fatigue symptoms are
caused not by XMRV but by other viruses that it activates, she says.
Meanwhile, retroviruses harbor pro-growth genes, and some cause the
blood cancer leukemia in animals and people. XMRV =97 or xenotropic
murine-leukemia-virus=96related virus =97 itself shows up in some men with
prostate cancer, particularly those with aggressive malignancies,
another research team reported last month in the Proceedings of the
National Academy of Sciences.
Gammaretroviruses, a subset of retroviruses, also cause disease in
gibbons, cats and koalas, Silverman says. =93XMRV is the first member of
this genus of retrovirus to be found in humans,=94 he notes.
In the new study, the researchers also found hints that the retrovirus
is transmitted by blood, as are some other viruses, including HIV. But
it=92s probably not spreading very fast, because people with chronic
fatigue =93are too sick to do anything,=94 Mikovits says.
Further research is under way to fine-tune testing for the retrovirus,
and more blood analyses are planned that will clarify its occurrence
rate in the general population. Mikovits and her colleagues are
investigating already-approved antiretroviral drugs to see if these
will benefit people who have chronic fatigue.
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