By Amy Dockser Marcus
A second high-profile paper in the long-running XMRV saga has been retracted, although an NIH study looking at the issue will continue.
The paper in question, published in August of 2010 in the Proceedings of the National Academy of Sciences, looked at the blood of patients with chronic fatigue syndrome and healthy blood donors. The authors, which include NIH infectious-disease specialist Harvey Alter, found a family of retroviruses called MLV-like viruses in 32 of 37 patients with CFS, as well as in three of 44 healthy blood donors.
Although the PNAS paper did not find XMRV, it was seen by many as supporting the finding of a link between CFS and XMRV (which is in the same family of retroviruses described in the PNAS paper) reported in an earlier paper authored by a different group of scientists and published in Science. That journal’s editors retracted that paper last week, saying they no longer believed its conclusions were valid.
The retraction statement for the PNAS study, signed by all the paper’s authors, said that the published findings were reproducible in the authors’ labs, and that there had been no evidence of contamination in the testing or the blood samples. But mounting data from further studies in the authors’ labs as well as from other studies that “do not consistently demonstrate an association between MLV and CFS” mean that “any association is now viewed as tenuous” and that the paper should be retracted.
The statement cited a number of concerns, including an insufficient number of original CFS patient samples to distribute to independent labs for more testing. It also cited a September paper by the Blood XMRV Scientific Research Working Group that found nine labs — including one of the labs involved in the PNAS paper — testing for XMRV or evidence of XMRV infection in the blood of CFS patients and healthy donors either didn’t find the retrovirus or couldn’t reproduce their findings.
Randy Schekman,who was the editor of PNAS when the paper was published, tells the Health Blog that in late September, after the working group’s results were published and the authors of the Science paper issued a partial retraction of some of their data, he reached out to Alter to express his concerns.
Alter said that they had not found any evidence of contamination, but acknowledged that that they lacked enough original CFS patient samples to do additional testing.
At that point, Schekman says he said some sort of statement needed to be made. When the editors and scientists read it, Schekman says they realized it amounted to a retraction.
The retraction of the two key XMRV-related papers puts the spotlight on one remaining study: a large NIH-funded project directed by virus hunter Ian Lipkin. This study is taking new samples from CFS patients and healthy people in different locations around the country and looking for evidence of retroviruses and other viruses.
When the Health Blog asked Lipkin whether the latest retractions would derail that study — the results of which are expected in 2012 — he wrote, “I can’t keep track of who is retracting what. Editors are at odds with authors who are frequently at odds with one another.”
Lipkin added that there will be an opportunity to explore hypotheses other than that the disease is due to XMRV or MLV infection.
He said that all the scientists and doctors involved in the NIH study — including Alter, and other co-authors of the retracted PNAS and Science papers — “are committed to completing this study because none of us believes that the issue of retroviral infection in CFS/ME is resolved.”