Tuesday, 21 August 2012

Resurrecting XMRV in Chronic Fatigue Syndrome?

The letters X-M-R-V in relation to Chronic Fatigue Syndrome (CFS) have had their fair share of controversy in recent years. For those who don't know about XMRV - xenotropic murine leukemia virus-related virus - there is ample discussion about this topic on the web or you can browse my past posts covering the story here and here. I'm sure that a feature film or TV mini-series will be made eventually about XMRV and CFS including the back-story of Dr Judy Mikovtis and the whole WPI saga. I'll leave you to make up your own film title.

After all the excitement of contamination, missing notebooks and scientific retractions, you'd think this would be a 'leave well alone' area for many researchers not really wanting to get involved, given the career-tarnishing effects it seems to have. It was with some interest therefore that I stumbled across this fairly recent article by Paolucci and colleagues* (full-text) and their findings on XMRV and CFS adding to the mix.

It is a short paper but nevertheless contains some interesting facts which I'll try and summarise:

  • Twelve participants diagnosed with CFS and some 40 controls (including asymptomatic, those confirmed as HIV positive or hepatitis C infection and transplant recipients) were investigated for the presence of XMRV "and polytropic MLV-related provirus". This last bit taps into some now author retracted research published by Lo and colleagues** (full-text).
  • I can't claim to understand all the ins-and-outs of the process for trying to detect XMRV or its friends but PCR was the name of the game, looking for fragments of DNA from the respective viruses.
  • Results: nothing for the control participants when it came to the potential presence of XMRV or its friends. For the CFS participants, in the majority nothing also except in two participants who "were positive for gag PCR and integrase PCR respectively". Further study of positive participant number 1 suggested that "the retrovirus was more closely related to the polytropic MLV rather than to XMRV (identity 100% vs. 96%)". For participant 2, further analysis "confirmed the similarity with the XMRV sequence".
  • Given the methods used by the authors, the contamination issue that overshadowed the previous research were excluded.

I'm not making too much of this paper at the current time given that other contemporary studies have reported no presence of XMRV in cohorts of participants with CFS (see here and here) alongside the relatively small participant group included as part of the Paolucci study. As per my previous reporting of this area of research, detecting such viruses is not by any means an easy task and no doubt there are still gaps in the methodology and science that need patching up. Even with the virus detected, there is a substantial leap to make before one is able to suggest the virus might be 'causative' of CFS or anything else.

What we can perhaps infer from the Paolucci paper is that the XMRV chapter of CFS research history might not be ready for the scientific scrapheap just yet. The big 'final say' study from virus hunter Ian Lipkin - yes, he of the autism and Sutterella research - has, at the time of writing, still not found its way into the peer-reviewed literature as far as I can see despite some signs it would be here already.

So we wait and see...

While waiting perhaps you would like to hear which Disney song currently fills my house. I've got a dream y'know..

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* Paolucci S. et al. Xenotropic and polytropic murine leukemia virus-related sequences are not detected in the majority of patients with chronic fatigue syndrome. New Microbiologica. 2012; 35: 341-344.

** Lo SC. et al. Detection of MLV-related virus gene sequences in blood of patients with chronic fatigue syndrome and healthy blood donors. PNAS. 2010. 107: 15874-9 [RETRACTED].

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ResearchBlogging.org Paolucci S, Piralla A, Zanello C, Minoli L, & Baldanti F (2012). Xenotropic and polytropic murine leukemia virus-related sequences are not detected in the majority of patients with chronic fatigue syndrome. The new microbiologica, 35 (3), 341-4 PMID: 22842604