A multicenter blinded case-control study has confirmed that chronic fatigue syndrome (CFS) is not associated with xenotropic murine leukemia virus-related virus (XMRV) or polytropic murine leukemia virus (pMLV). These results effectively resolve debate sparked by two major studies published in 2009 and 2010, which first reported a link between CFS and these viruses. Concerns about XMRV and potential transmission through blood transfusion subsequently prompted AABB and the FDA to recommend that CFS patients be discouraged from donating blood. However, the associations reported in these studies could not be replicated by other laboratories, and it was later shown that the findings were generated through provirus recombination in mice models. In this issue of the journal mBio, Dr. Harvey Alter at the National Institutes of Health and colleagues from six clinical research sites report results from an analysis of peripheral blood samples from 147 CFS patients, who met both 1994 Fukuda and 2003 Canadian CFS criteria, and 146 frequency-matched controls. The analysis incorporated PCR and serology-based testing of samples by the investigators originally reporting XMRV or pMLV in CFS patients, as well as by the Centers for Disease Control, which first reported failure to replicate these results. Each laboratory independently found that no case or control sample was PCR positive for XMRV or pMLV, except for spiked positive controls. There were also no differences between cases and controls in serology outcomes. Thus, the authors concluded that no link exists between CFS and either XMRV or pMLV.
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3. Lombardi VC, Ruscetti FW, Das Gupta J, Pfost MA, Hagen KS, Peterson DL, Ruscetti SK, Bagni RK, Petrow-Sadowski C, Gold B, Dean M, Silverman RH, Mikovits JA. Detection of an infectious retrovirus, XMRV, in blood cells of patients with chronic fatigue syndrome. Science 2009;326: 585-9.