Xenotropic murine leukemia virus-related virus | |
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Virus classification | |
Group: | Group VI (ssRNA-RT) |
Family: | Retroviridae |
Subfamily: | Orthoretrovirinae |
Genus: | Gammaretrovirus |
Species: | Xenotropic MuLV-related virus |
Xenotropic murine leukemia virus-related virus (XMRV) is "a laboratory-derived mouse virus that was generated through recombination between two endogenous murine retroviruses during propagation of a prostate cancer xenograft in the mid-1990's." The chimeric virus was first described in 2006 as an apparently novel retrovirus and potential human pathogen. 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.
XMRV has now been established as a laboratory contaminant. False positive detection of XMRV may also occur because of contamination of clinical specimens and laboratory reagents with other mouse retroviruses or related nucleic acids. Most scientific publications claiming an association of XMRV with CFS or prostate cancer have been retracted, and allegations of research misconduct were leveled against at least one CFS investigator. There is no evidence that XMRV can infect humans, nor has it been demonstrated that XMRV is associated with or causes any human disease.
XMRV is a murine leukemia virus (MLV) that formed through the recombination of the genomes of two parent MLVs known as preXMRV-1 and preXMRV-2. MLVs belong to the virus family Retroviridae and the genus gammaretrovirus and have a single-stranded RNA genome that replicates through a DNA intermediate. The name XMRV was given because the discoverers of the virus initially thought that it was a novel potential human pathogen that was related to but distinct from MLVs. The XMRV particle is approximately spherical and 80 to 100 nm in diameter.
Several XMRV genomic sequences have been published to date. These sequences are almost identical, an unusual finding as retroviruses replicate their genomes with relatively low fidelity, leading to divergent viral sequences in a single host organism. In 2010 the results of phylogenetic analyses of XMRV and related murine retroviruses led a group of researchers to conclude that XMRV "might not be a genuine human pathogen".