A recently identified novel human retrovirus (xenotropic murine
leukemia virus related retrovirus, XMRV) has been found in some
forms of prostate cancers and chronic fatigue syndrome in man
(13, 20, 22) although causal association has not been proven yet.
XMRV is almost undistinguishable from an ERV present in mice
and it will be important to investigate how this virus passed into
the human population, regardless of its pathogenic potential.
Interestingly, the current methods used for screening human
vaccines for retroviral contaminants include extremely sensitive
PCR-based RT assays (not required for veterinary vaccines) that
are much more sensitive than conventional RT assays. Thus,
contamination of human vaccines with XMRV, would not pass
undetected with the currently available technology although
this may not be necessarily true for vaccines produced in previous
(c) 2010 American Society for Microbiology