Meanwhile, the other new paper, by microbiologist John Coffin and his colleagues at Tufts University, the National Cancer Institute, and the University of California, Davis, puts the whole notion of human-contracted XMRV into question. Coffin's paper presents strong evidence that XMRV was created in the laboratory—the result of mouse virus that contaminated a prostate cancer cell line in the 1990s. There's still a possibility that a virus genetically related to XMRV could be involved with CFS, Coffin says. A paper published last year in Proceedings of the National Academy of Sciences suggested just that. But, he says, "it's getting more and more remote, I have to admit."
Levy goes a step further, calling for all research on chronic fatigue syndrome and XMRV to come to a halt. But Ian Lipkin, a virologist at Columbia University who is leading a $1.3 million National Institutes of Health study on the subject, thinks that would be premature. Lipkin concedes that Levy's and Coffin's papers cast doubt on the specific findings of the 2009 paper, but he maintains that there are still unanswered questions regarding XMRV-related viruses and CFS that are worth addressing. "We discussed the recent papers, and we're still full speed ahead [with the study]," he says.
In the meantime, researchers continue to search for new ways to treat chronic fatigue symptoms. For example, a clinical trial published in The Lancet earlier this year found that a combination of cognitive behavioral therapy and gradual exercise appeared to improve patient outcomes. The important message for chronic fatigue sufferers, Levy says, is that the new studies are not a knock against them or their condition. "There's no way we wrote this paper to tell CFS patients that we don't take them seriously," he says. "It's a very real disease."