Xenotropic murine leukemia virus–related virus

Xenotropic murine leukemia virus–related virus (XMRV) is a retrovirus which was first described in 2006 as an apparently novel human pathogen found in tissue samples from people with prostate cancer. Initial reports erroneously linked the virus to prostate cancer and later to chronic fatigue syndrome (CFS), leading to considerable interest in the scientific and patient communities, investigation of XMRV as a potential cause of multiple medical conditions, and public-health concerns about the safety of the donated blood supply.

Xenotropic viruses replicate or reproduce in cells other than those of the host species. Murine refers to the rodent family Muridae, which includes common household rats and mice.

Subsequent research established that XMRV was in fact a laboratory contaminant, rather than a novel pathogen, and had been generated unintentionally in the laboratory through genetic recombination between two mouse retroviruses during propagation of a prostate-cancer cell line in the mid-1990s. These findings raised serious questions concerning the findings of XMRV-related studies which purported to find connections between XMRV and human diseases. There is no evidence that XMRV infects humans, nor that XMRV is associated with or causes any human disease.