The authors of a controversial study linking a retrovirus called XMRV to chronic fatigue syndrome have partially retracted their findings. The retraction was published today by Science, along with another study, conducted by nine independent laboratories, that failed to confirm the link between the virus and chronic fatigue.
In 2009, a group of scientists led by Judy Mikovits (profiled here) of the Whittemore Peterson Institute in Reno, Nevada reported in Science the discovery of XMRV in blood samples from patients with chronic fatigue syndrome. Since then, the findings have come under attack as other laboratories were unable to reproduce the findings (see here, here, and here for examples), although one group found related viruses in samples from patients with chronic fatigue syndrome. In May, Science published an editorial expression of concern about the original 2009 paper.
The ensuing controversy kicked off two large-scale attempts to resolve the matter. One of those — the Blood XMRV Scientific Research Working Group — distributed patient samples used by Mikovits’ group to nine independent laboratories. The samples were blinded so that testers would not know which had previously tested positive.
In a paper published today, that group reported that only two of the nine laboratories detected XMRV or related viruses, and even those labs failed to reproduce their findings when given replicate samples. The results, authors said, argue against routine screening for XMRV and related viruses in the blood supply.
Meanwhile, the authors of the 2009 Science paper have determined that some of the samples they used for DNA testing were contaminated with XMRV plasmid DNA. As a result, they are retracting the data associated with those tests but continue to stand by the validity of the other two assays they performed — one to detect antibodies against the virus and the other to test for viral replication. Mikovits says they had discussions with editors at Science about whether the DNA contamination threatened the validity of the rest of the paper, and all agreed that it did not.
In fact, the retraction has done nothing to dampen Mikovits’ support for her original conclusion: that a gamma-retrovirus like XMRV is present in a disproportionate number of patients with chronic fatigue syndrome. But she does acknowledge that with the DNA sequence data now in question, the identity of the virus they found in samples from patients with chronic fatigue is unclear. In fact, Mikovits says this could account for some of the controversy: researchers who based their assays on that sequence data may well turn up empty-handed, she says, but that doesn’t rule out the presence of a related retrovirus.
Meanwhile, virus hunter Ian Lipkin of Columbia University in New York is heading up another multi-laboratory effort to bring some resolution to the matter. That project, which will also involve independent testing by multiple laboratories, is critical for chronic-fatigue research, says Mikovits: “Nobody has collected such well-controlled and defined samples before.” She anticipates that her lab will receive samples for testing in the coming weeks.
Micrograph of XMRV via Wikimedia Commons