A meticulous study has failed to confirm a connection between chronic fatigue syndrome and a family of viruses that includes XMRV. Nine laboratories — including the two that originally identified a link — could not reliably detect the viruses in blood cells from patients with the mysterious and controversial condition, researchers report online September 22 in Science.
In another blow, one of the labs that contributed to the original study retracted its key result because some of the samples used in the research were found to be contaminated with genetically engineered DNA from XMRV. The partial retraction also appears online September 22 in Science.
Together, the new data largely exonerate the virus as a cause of chronic fatigue syndrome — a disorder with a constellation of symptoms, no known cause and no effective treatment.
“The data certainly contradict the original findings,” says infectious disease specialist Michael Busch of the University of California, San Francisco and the Blood Systems Research Institute in San Francisco, who coordinated the new nine-lab study. “To me, it demonstrates that these labs have serious problems with false positive results and that those earlier data are not credible.”