On the contrary, recent evidence indicates that XMRV is a contaminant originating from the recombination of two
mouse endogenous retroviruses during passaging of a prostate tumor xenograft (CWR22) in mice, generating laboratory - derived cell lines that are XMRV - infected.
Finally, a 2011 study from Paprotka, et al. provided strong evidence that XMRV is a 22Rv1 - derived laboratory contaminant originating from recombination of two
mouse endogenous retroviruses during serial passage of CWR22 in nude mice [38].
Not exact matches
Phylogenetic analyses place XMRV firmly within the murine
endogenous retroviruses [3] even though no identical element has so far been identified within the
mouse genome [4].