‘More questions over link between XMRV and chronic fatigue syndrome’; ‘Nature’ news blog, May 05, 2011

May 6, 2011

From the ‘Nature' news blog, 5 May 2011.

A comprehensive study on the purported link between XMRV and chronic fatigue syndrome (CFS) has failed to find any trace of the virus. The study published yesterday in the Journal of Virology also hints that contamination of laboratory reagents with mouse DNA may explain some of the previous positive results.

In 2009, a team led by Judy Mikovits at the Whittemore Peterson Institute for Neuro-Immune Disease in Reno, Nevada reported in Science the discovery of the retrovirus in up to two-thirds of patients with CFS, which is also known as myalgic encephalomyelitis (ME). The discovery raised the hopes of patients with CFS/ME because it offered a clear explanation for the mysterious condition, as well as hope of a treatment.

Over the last two years, however, the link between XMRV and CFS/ME has clouded considerably, and no lab has been able to replicate Mikovits' results. I covered this saga in a recent feature, “Fighting for A Cause”, which included the revelation that XMRV was created in a laboratory in the 1990s and therefore was extremely unlikely to underlie CFS/ME.

Mikovits's primary response has been that the studies failing to find XMRV have not replicated her lab’s methods precisely, which involved detecting virus genetic material, patient immune responses, as well as the ability of the virus to divide in cell culture.

The new study, led by Ila Singh at the University of Utah in Salt Lake City, has now done all that and still come up with no sign of XMRV in 100 CFS/ME patients as well as 200 healthy people. What’s more, Singh’s team failed to find the virus in 14 patients who previously tested positive for the virus in Mikovits’ lab. They also find evidence that mouse DNA contaminates some of the reagents used to search for XMRV DNA, offering a possible explanation for some positive results.

For a technical, yet highly readable explanation of Singh’s study, check out Vincent Racaniello’s Virology Blog, which covered the new paper yesterday.

Also significant is the fact that Singh has previously found XMRV in tissue from prostate cancer patients and shown that the virus is sensitive to antiretroviral drugs.

In the new paper, her team writes:

Given the lack of evidence for XMRV or XMRV-like viruses in our cohort of CFS patients, as well as the lack of these viruses in a set of patients previously tested positive, we feel that that XMRV is not associated with CFS. We are forced to conclude that prescribing antiretroviral agents to CFS patients is insufficiently justified and potentially dangerous.

While it’s tempting to call this paper the “nail in the coffin” for XMRV, other similarly thorough replication studies are in the works. The largest of those is a $1.3 million effort funded by the US National Institute of Allergy and Infectious Disease and being led by microbial epidemiologist W. Ian Lipkin at Columbia University in New York. Results from that study are expected by the end of this year.

2 thoughts on “‘More questions over link between XMRV and chronic fatigue syndrome’; ‘Nature’ news blog, May 05, 2011”

  1. “While it’s tempting to call this paper the “nail in the coffin” for XMRV, other similarly thorough replication studies are in the works.”

    That’s quite a telling statement really.

    It’s important to put these stories into context. The lobby that is supportive of the XMRV theory still has criticisms about the methodology of this test. (I’m not in a position to judge the quality of those criticisms but as ever I expect many of them to remain unanswered – which is what tends to breed scepticism of the medical ‘establishment’)

    For over a year now the medical media has tried to build a consensus driven opposition to the XMRV theory. It’s again important to note that a consensus of opinion is fallacious. You cannott ‘vote’ on science ultimately, it either proves right or wrong. Also if you actually take stock in a consensus, looking at the way in which both blood donations have been banned and that multiple, almost innumerable studies have been attempted since the two positive studies, then it shows just how seriously the medical establishment is actually taking the initial findings.

    It’s definitely worth waiting to see what the next big piece of work that comes out of the WPI tells us. Similarly the reaction of the medical establishment to it could be just as telling. So far the only criticism of their initial work has been to attempt to create a scenario where contamination could of happened, but as yet remain unable to prove it actually did happen in the initial study.

    If there’s one thing I’ve learnt from the XMRV story it’s that I find it very hard to trust medical journalism to deliver the full spectrum of criticism to everything it publishes. While many of us are at odds to understand what’s being said, when you abandon logic and fill the bottom ends of supposedly factual studies with opinions, the medically ignorant can still see what you’re doing there.

    So the jury is still out, I can neither responsibly claim to support or be against the XMRV theory. What I am supportive of is response to criticism and better medical journalism. Similarly I’m supportive of M.E patients having areas of interest for their condition fully explored and not abandoned to probability, potentially misappropriated probability at that.

    The time for scientists to play the victim over the fury of patients has ended. The time for patients to demand dignity from the medical establishment has begun.

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