Study finds contamination in virus link to fatigue
LONDON |
LONDON (Reuters) - A virus previously thought to be linked to a baffling condition known as chronic fatigue syndrome is not the cause of the disease, scientists said on Monday after their study found previous research was contaminated in the lab.
Researchers from University College London, the Wellcome Trust Sanger Institute and Oxford University said cell samples from patients in earlier studies were contaminated with the virus, known as XMRV, which is found in the DNA of mice.
This suggests the patients were not infected with XMRV and it could not have triggered their illness, the scientists said.
The finding, published in the journal Retrovirology, is the latest to contradict a U.S. study from 2009 which suggested a link between XMRV and chronic fatigue syndrome (CFS) when the virus was found in the blood of 68 out of 101 CFS patients. The XMRV virus has also been identified in samples from certain prostate cancer patients.
"Our conclusion is quite simple: XMRV is not the cause of chronic fatigue syndrome," said Greg Towers, of UCL, who worked on the latest study. "All our evidence shows that the sequences from the virus genome in cell culture have contaminated human chronic fatigue syndrome and prostate cancer samples."
CFS is a debilitating condition of disabling physical and mental fatigue that does not improve with rest. It also known as myalgic encephalomyelitis (ME) and affects around 17 million people worldwide. There is no cure for CSF and scientists don't know what causes it, but many sufferers say they think their illness started after a viral infection.
CELL LINE
Towers said it was vital to understand that this latest research did not suggest chronic fatigue syndrome is not caused by a virus of some sort. "We cannot answer that yet," he said. "But we know it is not this virus causing it."
The 2009 U.S. study that found a link had prompted hopes that CFS patients might benefit from a range of drugs designed to fight AIDS, cancer and inflammation.
But in January 2010, British researchers found no evidence of XMRV in 186 patients with chronic fatigue syndrome, and two separate studies published in February also failed to identify the virus in groups of ME patients.
Towers' team said their study found that the XMRV found in the studies that linked it to CFS was from contamination by a laboratory cell line or mouse DNA. The sequences from the contaminated cell line and chronic fatigue patient samples were very similar, they said, and this is contrary to what scientists would expect from a virus if it were spreading in humans.
Tim Peto, a consultant in infectious diseases at Oxford University who was not involved in the research, said Monday's findings meant "it now seems really very, very unlikely that XMRV is linked to chronic fatigue syndrome."
"It came as a great surprise when XMRV was first suggested as being linked to chronic fatigue syndrome," he said in an emailed statement. "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."
(Editing by Alison Williams)
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And why are patients testing antibody positive using a test that has been available since August? Mounting an antibody response to a lab contaminant is biologically impossible.
This is basic bio-science 101.
And why are you quoting as FACT papers that have yet to be properly peer reviewed or validated, seeing as “Retrovirology” is an open access, fee for publication journal?
Oh and by the way the X in XMRV stands for XENOTROPIC. This means that this is NOT a mouse virus any more than HIV is the exact same virus as SIV.
This is one of the worst cases of yellow journalism I’ve ever seen.
Just because contamination has been the cause in other studies does not prove that it was in the studies done by Whittemore Peterson Institute or the Lo Alter NIH/FDA study.
It is significant that the UK media rush to publish this but haven’t bothered to keep the public informed on the earlier significant research.
Before they continue publishing they should do their homework and I am sure the Whittemore Peterson Institute would be more than happy to share their findings especially on UK patients who have now tested positive to XMRV.
It’s time for good investagative Science Journalism and not just parrotting such a weak study touting it as conclusive without looking at alternate science.
Shame on our UK media they do not have a good track record with this illness ME/CFS if they did they would realise the huge controversy that has left patients struggling years without researching the cause.
The Lombardi et al. and Lo et al. studies were done using four different methods of detection. They were not simply PCR experiments, as were the studies by McClure et al. and others who have recently reported their difficulties with contamination. Experienced researchers such as Mikovits, Lombardi, Lo and their collaborators understand the limitations of PCR technology, especially the possibility of sample contamination. As a result, we and Lo et al. conducted rigorous studies to prevent and rule out any possibility that the results reported were from contamination. In addition to the use of PCR methodology, the Lombardi team used two other scientific techniques to determine whether, in fact, we had found new retroviruses in human blood samples. We identified a human antibody response to a gamma retroviral infection and we demonstrated that live gamma retrovirus isolated from human blood could infect human cells in culture. These scientific findings cannot be explained by contamination with mouse cells, mouse DNA or XMRV-related virus-contaminated human tumor cells. No mouse cell lines and none of the human cell lines reported today by Hue et al. to contain XMRV were ever cultured in the WPI lab where our PCR experiments were performed. Humans cannot make antibodies to viruses related to murine leukemia viruses unless they have been exposed to virus proteins. Therefore, recent publications regarding PCR contamination do not change the conclusions of the Lombardi et al. and Lo et al. studies that concluded that patients with ME/CFS are infected with human gammaretroviruses. We have never claimed that CFS was caused by XMRV, only that CFS patients possess antibodies to XMRV related proteins and harbor infectious XMRV, which integrates into human chromosomes and thus is a human infection of as yet unknown pathogenic potential.
“The coauthors stand by the conclusions of Lombardi et al. Nothing that has been published to date refutes our data.” Judy A. Mikovits
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