It’s been two years since a study linking chronic fatigue syndrome (CFS) with the retrovirus xenotropic murine leukemia virus-related virus (XMRV) was published in the journal Science. The authors of that study reported finding XMRV in blood samples of 68 of 101 individuals with CFS, compared with just 8 of 218 samples from people without the illness.
Those results led the American Red Cross to announce last year that it would no longer accept blood donations from individuals with CFS. It also led some people with CFS to experiment off-label with antiretroviral drugs, which pose health risks of their own, including kidney damage.
As I’ve reported here before, the 2009 study was controversial from the start, and grew even more so as an increasing number of scientists were unable to replicate its findings. (One group of scientists did find a possible association last summer between CFS and an XMRV-related class of viruses that causes leukemia in mice, but they did not find a link to XMRV.)
The possibility that the genesis of CFS had finally been identified had raised the hopes of many of the more than 1 million Americans with this debilitating illness, which is characterized not only by severe and prolonged tiredness, but also by joint and muscle pain, headaches, sore throat, insomnia, difficulty with concentration and memory, and other symptoms.
For all too long, the medical community had treated CFS as a psychological disorder. Although that attitude no longer prevails, scientists remained baffled by what causes CFS as well as how to effectively treat it. (A new randomized clinical trial suggests cognitive behavior therapy and gradual exercise therapy may help patients recover.)
But those hopes surrounding the discovery of the XMRV link received a serious setback this week with the publication of two new studies in Science. One, using the same methodology as the 2009 study, was unable to find any evidence of XMRV or any other related virus in the blood samples of 61 people with CFS, including 43 individuals whose samples had tested positive in the earlier study.
The second study was even more damning. It found strong evidence that the XMRV found in the 2009 study originated not in the blood of CFS patients, but in the laboratory, the result of contamination from cell lines and chemicals used in the lab.
Journal sought retraction
Science has asked the authors of the 2009 study, which was led by Vincent Lombardi and other researchers at the Whittemore Peterson Institute for Neuro-Immune Disease in Reno, Nev., to voluntarily retract the paper. They have declined to do so.
“The authors of the Lombardi study believe that it is premature to conclude that the negative studies are accurate or change the conclusions of the original studies and we fully agree,” said the institute’s president, Annette Whittemore, in a press release [PDF] Tuesday.
Meanwhile, scientists at the National Institutes of Health are conducting a $1.3 million study on the subject. Results are expected within the next couple of years.