New mouse virus found in chronic fatigue patients

A team from the National Institutes of Health has found evidence of murine leukemia virus, which causes cancer in mice, in 86% of chronic fatigue patients they tested, but in fewer than 7% of healthy blood donors. This is the second mouse virus to be linked to CFS patients, but the findings do not yet provide a causative link.

Another study in 2009 found xenotropic murine leukemia virus-related virus or XMRV in some patients with chronic fatigue syndrome but several others since then have found no such link. Evidence of XMRV has also been found in prostate tumors, but again, scientists are unsure if the virus may actually be causing the tumors.

Scientists have been looking for a possible infectious disease as a cause of CFS but have never found anything definitive. However, Dr Shyh-Ching Lo of the U.S. Food and Drug Administration has studied frozen samples from 37 well-studied chronic fatigue patients taken years ago and found DNA sequences that looked something like XMRV, but they turned out to be from different types, although closely related, mouse leukemia viruses. They found these genetic sequences in 32 of 37 samples, or 86.5%. While 6.8% of 44 healthy blood donors had such genes.

However, more study is needed to show a causative link and the virus will need to be found in whole tissue samples, not just genetic sequences.

Proceedings of the National Academy of Sciences

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