At the time, the finding raised hopes that there might finally be a concrete cause for chronic fatigue syndrome and perhaps, down the line, treatments for the disease.
The illness affects an estimated 1 percent of people worldwide and, as its name implies, involves crippling fatigue as well as aching joints, headaches and various other symptoms.
Unfortunately, subsequent studies by other researchers failed to replicate the findings.
The authors of the new study looked at blood samples from 61 people with chronic fatigue syndrome. The samples came from the same source that had supplied samples for the 2009 study. Forty-three of the samples had earlier been diagnosed as positive for XMRV.
However, this time around the researchers avoided using any lab products derived from mice. This time, they found no evidence at all of XMRV in any of the 61 samples.
"We're learning a very important lesson that even some commonly used reagents [compounds used in scientific experiments] contain trace amounts of contaminating mouse DNA," said LeGrice, who is head of the Center of Excellence in HIV AIDS/Cancer Virology at the National Cancer Institute. "But, using diagnostic technologies that are ultra-sensitive, we can easily pick out the contaminating material. The contaminants somehow got into the samples [but] we have to be absolutely clear that this virus was never in humans."
A second study in the same issue of the journal had similar problems trying to replicate earlier research linking XMRV with prostate cancer tumors, for much the same reasons. That study was led by Jay Levy of the University of California, San Francisco.
A statement from the Chr
All rights reserved