It was just a snippet of news, reported by an obscure journal in the Netherlands. And yet it lit up the Internet. Twitter was all atwitter, scientists' mailboxes on both sides of the Atlantic began filling up, and dozens of bloggers started jubilating. "It's happened. I cannot tell you all how this changes the world as we have known it for 25+ years," one patient wrote on her blog. "Now to work on the vindication part!"
The reason for all the excitement? Scientists at the U.S. National Institutes of Health (NIH) and the Food and Drug Administration (FDA) were reported to have confirmed the link, first published in Science last year, between a human retrovirus and the elusive condition called chronic fatigue syndrome (CFS). Earlier this year, three other groups reported being unable to replicate such a connection. That federal scientists now confirmed it was huge mood-lifter for patients, many of whom are desperate to find a biological cause, and a cure, for their debilitating ailment.
But the story wasn't as simple as that. Science has learned that a paper describing the new findings, already accepted by the Proceedings of the National Academy of Sciences (PNAS), has been put on hold because it directly contradicts another as-yet-unpublished study by a third government agency, the U.S. Centers for Disease Control and Prevention (CDC). That paper, a retrovirus scientist says, has been submitted to Retrovirology and is also on hold; it fails to find a link between the xenotropic murine leukemia virus-related virus (XMRV) and CFS. The contradiction has caused "nervousness" both at PNAS and among senior officials within the Department of Health and Human Services, of which all three agencies are part, says one scientist with inside knowledge.
The debate over XMRV started in 2009 when a group of researchers led by Judy Mikovits of the Whittemore Peterson Institute (WPI) for Neuro-Immune Disease in Reno, Nevada, reported in Science finding traces of the virus in peripheral blood mononuclear cells, a type of white blood cell, of 67% of CFS patients. By contrast, only 3.4% of healthy controls were found to harbor the virus. The team also showed that XMRV could infect human cells and concluded that the virus—which had previously been linked to prostate cancer—might play a role in causing CFS (Science, 23 October 2009, p. 585).
Many scientists were skeptical, however, and in May, Science published three Technical Comments that tried to poke holes in the study, along with a rebuttal by Mikovits and first author Francis Ruscetti of the National Cancer Institute. By that time, two groups in the United Kingdom and one in the Netherlands had also published papers failing to find a link; in fact, they found little or no evidence of XMRV infection at all, either in patients or in healthy people. Three other groups, two from the United States and one from Europe, have also reported negative findings at meetings, says Kim McCleary, president of the Chronic Fatigue and Immune Dysfunction Syndrome Association of America, a patient advocacy group.
The FDA-NIH paper would offer fresh hope that Mikovits is on to something after all, but so far, details about the work are scant. Ortho, a Dutch magazine about nutrition and food supplements, last week issued a press release saying that Harvey Alter, a renowned virologist at NIH's Clinical Center, mentioned the study when he gave a talk at a blood safety meeting in the Croatian capital Zagreb in late May. In his PowerPoint presentation, Alter wrote that the data in the 2009 study in Science "are extremely strong and likely true, despite the controversy." Another bullet point said: "We (FDA & NIH) have independently confirmed the Lombardi group findings." (WPI's Vincent Lombardi was the paper's first author.) But the presentation offered no detail beyond that tantalizing summary, and an NIH spokesperson says Alter is not available for comment.
Meanwhile, a group working with retrovirologist William Switzer at CDC, which has done an independent study, has held its cards closer to its chest. But Science talked to several scientists who say they have seen the data, and they are negative. Although it's not unprecedented for government scientists to be on opposite ends of a scientific debate, two contradictory press releases on a flashpoint issue like CFS would look odd, scientists say. With publication deferred, "they want to find out what's going on first," says one researcher who says he has been briefed about the controversy.
Last week, the AABB, an international association of blood banks, recommended to its members that they discourage CFS patients from donating blood. A special task force on XMRV conceded that the evidence was preliminary but decided it's "prudent" to err on the side of caution, says task force member Louis Katz, the medical director at the Mississippi Valley Regional Blood Center in Davenport, Iowa. "If [XMRV] turns out to be important," says Katz, "I don't want to be criticized for doing nothing when I could have done something."
(This story is adapted from a longer one in the 2 July issue of Science.)