A mouse leukemia retrovirus, xenotropic murine leukemia virus-related virus (XMRV retrovirus), has been under consideration as a possible cause of chronic fatigue syndrome (CFS, and also prostate cancer). In a study published in Science in October 2009, Lombardi et al. found XMRV in 67% of CFS patients and 3.7% of controls. Several subsequent studies in the UK, the Netherlands, and the US — by lead authors Erlwein, van Kuppleveld, Groom , Switzer and Henrich — failed to find XMRV at all.
Now a new study published in Retrovirology by Hue et al. shows that the original positive findings were likely erroneous and due to contamination in the lab. The complete article is available online.
We provide several independent lines of evidence that XMRV detected by sensitive PCR methods in patient samples is the likely result of PCR contamination with mouse DNA and that the described clones of XMRV arose from the tumour cell line 22Rv1, which was probably infected with XMRV during xenografting in mice. We propose that XMRV might not be a genuine human pathogen.