Chronic fatigue syndrome not linked to virus

By Dr. Ananya Mandal, MDDec 21 2010

The latest research from the University College London, the Wellcome Trust Sanger Institute, and University of Oxford, England suggests that chronic fatigue syndrome (CFS) is not caused by the virus XMRV (xenotropic murine leukemia virus-related virus). The team says that earlier research that linked the virus to CFS was faulty because of contamination of mouse cell DNA samples in the laboratory.

CFS is usually manifested as chronic fatigue lasting six months or longer, with several additional symptoms that may include impaired memory, un-refreshing sleep, muscle pain, sore throat, and headache. XMRV is a recently discovered virus that is a relative of retroviruses called murine leukema viruses (MLVs), which are known to cause cancer in certain mice. In 2009 a study published showed that blood samples from chronic fatigue syndrome patients had traces of the virus. This new study published in Retrovirology, identifies the source of XMRV in CFS samples as being cells or mouse DNA rather than infection by XMRV.

The team says that there may be a link between the virus and the disease but XMRV is not the cause. Professor Greg Towers, a Wellcome Trust senior research fellow at University College London said, “Our conclusion is quite simple: XMRV is not the cause of chronic fatigue syndrome… All our evidence shows that the sequences from the virus genome in cell culture have contaminated human chronic fatigue syndrome and prostate cancer samples.” He added, “It is vital to understand that we are not saying chronic fatigue syndrome does not have a virus cause - we cannot answer that yet - but we know it is not this virus causing it.”

Professor Tim Peto, consultant in infectious diseases at the University of Oxford said, “It came as a great surprise when XMRV was first suggested as being linked to chronic fatigue syndrome and it was imperative that further tests be done to see if the findings could be repeated… There have now been a number of attempts which have failed to find the retrovirus in other samples, and this research suggests that in fact XMRV is probably a contamination from mouse DNA…These latest findings add to the evidence and it now seems really very, very unlikely that XMRV is linked to chronic fatigue syndrome.”