By Elie Dolgin

Last year, a Nevada team linked a peculiar retrovirus to chronic fatigue syndrome (CFS), an elusive condition with no known cause. The virus—known as xenotropic murine leukemia virus–related virus, or XMRV—had previously been implicated in an aggressive form of prostate cancer, but XMRV’s role in both diseases has been hotly contested, particularly with regard to CFS. (Click here to continue reading)