Xenotropic murine leukemia virus-related virus(XMRV) is a gammaretrovirus that was first described in 2006. Initial reports linked the virus to prostate cancer, and later to chronic fatigue syndrome (CFS), but these were followed by a large number of studies in which no association was found. It has not been established that XMRV can infect humans, nor has it been demonstrated that XMRV is associated with or causes human disease. Numerous researchers have suggested that XMRV detection may result from contamination of clinical specimens and laboratory reagents with mouse retroviruses or related nucleic acids. Nevertheless, public health officials have voiced concerns about the donated blood supply, citing the potential dangers should XMRV prove to be an infectious human pathogen.
XMRV has been proposed as a cause for conditions including autism, fibromyalgia, multiple sclerosis,amyotrophic lateral sclerosis, and Parkinson’s disease. However, there is currently no evidence to support these hypotheses. No XMRV was found in 230 autistic children or in 204 controls, nor was XMRV detected in fibromyalgia or MS patients or in children with idiopathic diseases. In one study, XMRV was detected in a small percentage of patients with weakened immune systems, but other studies found no evidence of XMRV in immunosuppression. Out of more than 500 HIV-1-positive people, none was positive for XMRV, nor was XMRV found in systemic lupus erythematosispatients.