Researchers link chronic fatigue syndrome to class of virus

The researchers, from the National Institutes of Health, the Food and Drug Administration, and Harvard Medical School, analyzed blood samples that had been collected 15 years ago from 37 patients with chronic fatigue syndrome. Most of the subjects—32, or 86.5 percent—tested positive for a virus known as a murine leukemia virus-related virus, the researchers found. In contrast, tests on 44 healthy blood donors detected evidence of the virus in only three of the subjects, or 6.8 percent.

While providing more evidence that a virus may play a role in the mysterious condition, the researchers said the findings, published in the Proceedings of the National Academy of Sciences, are nowhere near proving that the virus causes the syndrome.

But the findings are being hailed by advocates for chronic fatigue syndrome patients, such as the CFID Association of America. The head of that group, Kim McCleary, said the findings are a potentially important step toward finding the cause of the condition and possibly developing treatments, as well as dispelling the notion that the condition is only psychological.

Between 1 million to 4 million Americans are believed to suffer from the syndrome, which causes prolonged and severe fatigue, body aches, and other symptoms. The cause has long been a mystery. Over the years, many viruses have been linked to the syndrome, but no conclusive evidence was found.

But in 2009, Judy Mikovits and colleagues at the Whittemore Peterson Institute in Reno published a paper in the journal Science. That paper reported that many syndrome patients appeared to be infected with a little-known virus called the xenotrophic murine leukemia virus-related virus, or XMRV. XMRV is a retrovirus, which is the same type of virus as HIV, which causes AIDS. XMRV had also been found in some prostate cancer patients.

Four other groups, including a team at the federal Centers for Disease Control and Prevention in Atlanta, subsequently failed to duplicate the findings in other patients, raising deep suspicions on this premise involving the retrovirus.

The new findings will probably revive interest in the virus. The virus detected in the new study does not appear to be the same one the Reno group found, but it is closely related. In addition to detecting evidence of the microbe in an overwhelming majority of the stored blood samples, the researchers found evidence of virus in fresh blood samples from seven of eight of the patients, indicating that the infection persists. Harvey Alter of the National Institutes of Health, who helped conduct the study, said there were also indications that the virus had evolved slightly, which is what would be expected from a retrovirus.

The paper’s publication was delayed because of questions about whether the findings could have been the result of laboratory contamination. That prompted the researchers to conduct a series of additional tests to try to rule that out, and rumors that the research was being suppressed.