WEDNESDAY, June 1 (HealthDay News) -- Murine-like gammaretroviruses (MLVs), including xenotropic murine leukemia virus-related virus (XMRV), are unlikely to cause either prostate cancer or chronic fatigue syndrome (CFS) in humans, and their detection in human beings is likely due to sample contamination, according to two studies published online May 31 in Science.
Tobias Paprotka, Ph.D., from the National Cancer Institute in Frederick, Md., and colleagues conducted experiments to identify how and when XMRV arises and whether it is associated with prostate cancer. They studied human prostate cancer cell lines from patient samples and progenitor human prostate tumor xenografts in mice. XMRV infection was detected from the two cell lines in the xenografts but was not detected in patient samples. Two proviruses, PreXMRV-1 and PreXMRV-2, were detected in host mice, which were 99.92 percent identical to XMRV over more than 3.2- kilobase stretches of their genomes.
Konstance Knox, Ph.D., from the Wisconsin Viral Research Group in Milwaukee, and colleagues evaluated blood samples from 61 patients with CFS, of which 43 were previously identified as positive for XMRV. No evidence of XMRV or other MLVs were identified in these blood samples, but MLV sequences were detected in commercial laboratory reagents. Xenotropic-MLV was strongly inactivated and XMRV was partially inactivated by sera from CFS patients and healthy controls.
"Our results indicate that previous evidence linking XMRV and MLVs to CFS is likely attributable to laboratory contamination," Knox and colleagues write.
Abstract - Paprotka
Abstract - Knox