A highly anticipated paper linking viral infection with chronic fatigue syndrome will at last see the light.
The paper, to be published online later today by Proceedings of the National Academy of Sciences USA (PNAS), is the first to back up a previous report that chronic fatigue syndrome may be linked to infection by a virus called XMRV (see ‘Virus linked to chronic fatigue syndrome’). Chronic fatigue patients and their advocates embraced the findings as a long-sought clue to the cause of the mysterious ailment, but several research teams have since tried and failed to reproduce this link.
The PNAS paper was originally accepted for publication on 27 May. But on 4 June, the authors, who work for the US National Institutes of Health and the US Food and Drug Administration, asked to delay publication while they considered conflicting results from a second paper authored by other government researchers. (For more see ‘Chronic fatigue findings were held back’.) That second paper appeared in the journal Retrovirology on 2 July, but there was still no sign of the first.
In an editorial accompanying the PNAS paper, journal editor-in-chief Randy Schekman explains what happened.
On 18 June, after the paper was accepted and while its authors were mulling over their Retrovirology preprint, PNAS provided the authors with an additional “recommendation” that they look for direct evidence that XMRV genes had integrated into their hosts’ genome. On 22 July, the authors submitted a revised paper with several sentences added to acknowledge that evidence of viral gene integration would indeed be nice to have, but finding it would “take more time and effort to investigate”.
Where does this leave the XMRV debate? The new paper supports the XMRV camp, but of course (say it with me now) more research is needed to sort through all of the conflicting results now in the literature. Interestingly, the new paper finds members of a broader collection of related viruses — all, like XMRV, related to murine leukemia virus — in chronic fatigue patients, not just XMRV itself. 86.5% of the chronic fatigue patients in the study had such viruses in their blood, compared to only 6.8% of healthy participants.
And if you’re frustrated by the lack of consensus among all of these studies, you’re not the only one. A network of research teams is now at work trying to standardize laboratory assays for XMRV in hopes that consistent methods might yield more consistent results. And in a commentary accompanying the new PNAS paper, Marc Sitbon of Montpellier University in France, Andrew Mason of the University of Alberta in Canada, and others, argue that scientists may not agree on the issue until anti-retroviral therapies are tested in chronic fatigue patients. The authors note the bacterium Helicobacter pylori was not accepted as the culprit behind peptic ulcers until after antibiotics were shown to cure the disease. Several anti-retroviral drugs have been shown to inhibit XMRV, but these can also have serious side effects so embarking on such clinical trials will be a delicate decision.