ME, Chronic Fatigue Syndrome, not from Suggested XMRV Virus
Researchers say chronic fatigue syndrome is not caused by the virus that has been suggested. The syndrome, also known as myalgic encephalomyelitis (ME) may come from a virus, but scientists say new research shows with certainty the XMRV virus, found in some patients with ME is not the culprit.
Researchers at University College London (UCL) found out lab samples taken from patients with ME and used in an October 2009 study had been contaminated by mouse cells or DNA and submitted. The findings have prompted the researchers to develop better testing methods that won't mix things up and produce false results.
The team from University College London, Wellcome Trust Sanger Institute and University of Oxford was able to show previous methods of extracting XMRV from other gene sequences include contaminated human chronic fatigue syndrome from mouse DNA and prostate cancer samples.
With new methods, they can prove whether they are picking up lab contamination to weed out the real cause of disease.
Dr Stéphane Hué, Post Doctoral Researcher at UCL says, "When we compare viral genomes, we see signs of their history, of how far they have travelled in space or time.
We would expect the samples from patients from around the world, collected at different times, to be more diverse than the samples from within a cell line in a lab, where they are grown under standard conditions. During infection and transmission in people, our immune system would push XMRV into new genetic variants.”
She adds, "Viral infection is a battle between the virus and the host and XMRV does not have the scars of a virus that transmits between people."
They say the findings show the XMRV doesn’t cause chronic fatigue syndrome nor does it cause prostate cancer and conclude "the ubiquitous presence of mouse DNA in laboratory specimens" makes it important to validate future studies using sensitive assays.
The lesson, say the researchers, is more vigorous methods are needed to prevent lab cells and DNA from becoming contaminated in addition to tight standards for identifying viruses and bacteria as a cause for disease.
In this case, the scientists were able to show the XMRV virus came from lab contamination of cell samples taken from patients with chronic fatigue syndrome. They also noted that one in 50 cell lines undergoing testing are contaminated with XMRV related viruses, including one commonly used in prostate cancer research.
Retrovirology 2010, 7:108doi:10.1186/1742-4690-7-108