CFS not caused by XMRV virus as recently thought

The role of virus -- XMRV known for causing chronic fatigue syndrome is under doubt again. According to a new study the syndrome which is also known as Myalgic Encephalomyelitis (ME), has turned out be laboratory malfunction and it says that XMRV does not cause infection in humans. The discovery is major setback for the scientists who said to have found the evidences to link the virus with the disease.

The recent research assessed the purity and ancestry of viral samples isolated from human cells. In their findings, researchers came to conclusion that the human cells in the previous study had been contaminated. Stating this as the reason rigorous detection methods were used during testing. The study was carried out by researchers from University College London, the Wellcome Trust Sanger Institute in Cambridge and the University of Oxford. The study was published in the peer-reviewed medical journal Retrovirology.

The 2009 study that first linked XMRV to ME involved examination of blood cells from ME patients, finding that most samples contained DNA from the virus. The new study examined the DNA from different types of mice to check the presence of virus. In the result they found all of them positive. In this study scientists also investigated human cells that were contaminated with XMRV virus. They then investigated the presence of the XMRV virus using complex methods of detection, and also set out to see whether the human cells included viruses that could be mistaken for XMRV.

In the results it was found that DNA in human cells was contaminated with DNA from different viruses, some which came from XMRV and others were mistaken for having XMRV origin. Further analysis suggesting that contamination was a likely reason for detection of this virus in human samples. Finally, the researchers found that the type of XMRV that is derived from human samples is less diverse than that from mouse cells. This is unexpected for a virus thought to cause an infectious disease.
In conclusion researchers said the XMRV found in patients is likely to have come either by mouse DNA or by other cells infected with viruses that originate in mouse DNA. They conclude that XMRV is unlikely to be a human pathogen.