By now, whenever the subject of XMRV raises its sleepy head, the reaction is somewhere between a yawn and a primal scream. Well, its time to examine some more data, this time by way of two studies published online in "Science".
In the study from the Wisconsin Virus Research Group, researchers attempted to replicate the results in the 2009 Lombardi study that found XMRV in 67% of patients with chronic fatigue syndrome, versus 3.7% of control patients. To this end, blood samples were examined from 61 patients with chronic fatigue syndrome from the same medical practice that had supplied samples in the original study; this group included 43 patients who had been earlier diagnosed as being XMRV-positive. The analysis of these samples, as presented in this latest "Science" article, revealed no viral genetic material, no infectious virus, and no virus-specific antibody evidence of XMRV in any of these samples.
Likewise, there was no evidence of other murine-like gammaretroviruses (MLVs), per investigators at the University of California, San Francisco. Scientists used the most sensitive assays available. The group in San Francisco had been asked by Dr. Peterson, a co-author of the Lombardi paper, to examine some blood samples from that 2009 study after several other groups had failed to replicate the positive findings published in 2009.
Interestingly, the "Wall Street Journal" reported that "Science" asked for the retraction of the Lombardi paper. However, Judy Mikovits, the director of research of the Institute involved in the 2009 work, has labeled talk of retraction as being premature.
The editor-in-chief of "Science" presented an "Expression of Editorial Concern" regarding the Lombardi study, and a statement of such concern has been retroactively attached to the Lombardi paper.
In the second study, XMRV DNA sequences were detected in commercial laboratory reagents. It was concluded that "evidence linking XMRV and ... chronic fatigue syndrome is likely attributable to laboratory contamination". Human cell lines that produce XMRV were studied and the authors "conclude that XMRV... was generated by recombination of two proviruses" and that "the association of XMRV with human disease is due to contamination of human samples with virus originating from this recombination event".
In a press statement, Dr. Pathak of the National Cancer Institute concluded that the scientific community needs to focus on finding the actual cause of chronic fatigue syndrome, and "stop wasting time and resources on the laboratory-derived virus known as XMRV". He added that "XMRV has nothing to do with prostate cancer".
By way of contrast, Dr. Mikovits remains the optimist, with patents still pending for the detection of XMRV seroconversion in several diseases.
The science in "Science" is what it is. Until another study is published. Pass the earplugs.