October 9, 2009

Virus May Play Role In Chronic Fatigue Syndrome

A new breakthrough study finds that a virus linked to prostate cancer may also be linked to Chronic Fatigue Syndrome (CFS), a disorder characterized by unexplained and debilitating exhaustion that is not alleviated by sleep.

The research could pave the way to new treatments for the condition, which affects some 17 million people throughout the world, scientists said Thursday.

The virus, known as XMRV, was found in the blood of 68 out of 101 chronic fatigue syndrome patients, but just 8 of 218 healthy people, the researchers said.

However, the study only demonstrates a link between the virus and CFS, and does not prove that the pathogen causes the condition, said Judy Mikovits of the Whittemore Peterson Institute in Nevada and colleagues at the National Cancer Institute (NCI) and the Cleveland Clinic.

Although additional research is needed to show a direct link, the study offers hope that those with CFS could ultimately find relief from a cocktail of drugs used to fight AIDS, cancer and inflammation, Mikovits said.

"You can imagine a number of combination therapies that could be quite effective and could at least be used in clinical trials right away," said Mikovits during an interview with Reuters.

AIDS drugs such as reverse transcriptase inhibitors and integrase inhibitors, and nonsteroidal anti-inflammatory drugs (NSAIDs) and cancer-fighting proteasome inhibitors could be tested as possible treatments for CFS, she added.

But NCI biochemist Stuart Le Grice, who was involved in the study, said some AIDS drugs might be ineffective against XMRV because many are custom-made to treat HIV.

"But we've learned a lot from HIV, and if XMRV does become a serious issue, we can bring that to bear very quickly," he told Reuters.

XMRV, a retrovirus known formally as xenotropic murine leukemia virus-related virus, copies its genetic code into the DNA of its host but uses RNA -- a working form of DNA -- to do so.  It has been found in some prostate tumors, and is also known to cause leukemia and tumors in animals.

Additional research must now determine whether XMRV directly causes CFS, Mikovits' team said, or whether it is merely a passenger virus in the suppressed immune systems of those with CFS.  The virus may also be a pathogen that acts along with other viruses that previous research suggests may play a role in the disorder.

"Conceivably these viruses could be co-factors in pathogenesis, as is the case for HIV-mediated disease, where co-infecting pathogens play an important role," the researchers wrote in a report about the study.

Since 3.7 percent of the healthy test population tested positive for XMRV, several million otherwise healthy people could be infected with it, the researchers said.

CFS impairs the immune system and causes incapacitating fatigue.  The disorder can also cause memory loss, concentration problems, joint and muscle aches, tender lymph nodes, sore throats and headaches.

Symptoms last six months or longer and can be just as crippling as multiple sclerosis or rheumatoid arthritis, according to the U.S. Centers for Disease Control and Prevention.

Although cognitive behavioral therapy can help patients cope with the disorder's effects, there are no current treatments for CFS, Mikovits said.

The study was published Thursday in the journal Science.


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