I got tagged to participate in a study done by the Univ of Ill and Tuffs Univ on a HERV K-18. It too, like XMRV, is a mouse virus. I don't know much details yet. Its funded by the NIH (National Institute of Health). I was asked if I would participate over a year ago. Viruses are known to alter DNA, these may be at a deeper cause of CFS, CFIDS, FM, ME. I still think that the root cause is metal toxicity like mercury and Lead. I have to fill out a lengthy questionairre on CFS and donate a blood sample. XMRV showed up in 66% of the CFS subjects maybe the other 33% had Lyme or HERV?!?