New studies question chronic fatigue syndrome's link to infection

From The NY Times:

In a blow to patients with chronic fatigue syndrome, two new studies published on Tuesday raised serious doubts about earlier reports that the disabling disease is linked to infection with XMRV, a poorly understood retrovirus.

The new papers were posted online in the journal Science, which in October 2009 published the initial research linking XMRV to chronic fatigue syndrome. In an “editorial expression of concern” accompanying the two new studies, Bruce Alberts, editor in chief of the journal, declared that the earlier finding “is now seriously in question” and was most likely due to laboratory contamination.

Based on those earlier findings, some people with chronic fatigue syndrome tried to obtain access to antiretroviral drugs used to treat H.I.V., which had been shown in laboratory studies to inhibit the replication of XMRV.

But in one of the two new studies, researchers found no trace of XMRV or related viruses in the blood of 43 patients who had previously tested positive for XMRV. In the second study, scientists reported evidence that XMRV was likely a recombination of two mouse leukemia viruses created accidentally in laboratory experiments.

The new studies are the latest in a series of disappointments for people struggling with chronic fatigue syndrome. Other researchers have been unable to duplicate the original findings implicating XMRV, although none of their studies fully replicated the methods of the original research from the Cleveland Clinic, the National Cancer Institute and the Whittemore Peterson Institute for Neuro-Immune Disease in Reno, Nev.

Dr. Vincent Racaniello, a microbiology professor at Columbia University, said in an interview that it now appeared unlikely that XMRV infection is a cause of chronic fatigue syndrome. But it also would be wrong to conclude that chronic fatigue syndrome is not an infectious disease, he added.

“These patients have a lot of signs of hyper-immune activation, with their immune systems firing almost constantly,” he said.

Dr. Jay Levy, a professor of medicine at the University of California, San Francisco, and the senior author of one of the new studies, said he nonetheless believed that many or most people with chronic fatigue syndrome are suffering from a disease initiated by one or more viruses.

Many of the disease’s symptoms are likely caused by the immune systems’ response to an infection, rather than to the pathogens themselves, he said.

“The immune system pours out its toxins to stop this agent, and then the immune system doesn’t calm down,” he said, adding that environmental toxins could also play a role in the illness.

Last week, the editors of Science asked the authors of the original research if they would retract their paper in view of the new findings about to be published. The senior author, Dr. Judy Mikovits, research director at the Whittemore Peterson Institute, responded that such a step was “premature” and that she knew of other investigators planning to publish research backing the original findings.

Some patients reacted angrily to the news that Science had asked for a retraction. “The patient community is shocked,” Rivka Solomon, a largely homebound Boston-area writer with chronic fatigue syndrome, said in an e-mail. “Most of us feel that the scientific inquiry necessary to bring this to conclusion has not yet been played out.”

Ms. Solomon recently organized small demonstrations in Washington, D.C., and San Francisco to focus attention on the small amount of financing the government has allocated to the disease in recent years. If the XMRV association does not pan out, she wrote, patients like her “worry that we will once again be abandoned.”

The government is supporting additional studies to determine whether XMRV plays any role in chronic fatigue syndrome at all. The retrovirus had also been linked to prostate cancer, an association also challenged by the research published on Tuesday.