XMRV and ME/CFS – second UK study fails to establish any link

ABSENCE OF XENOTROPIC MURINE LEUKAEMIA VIRUS-RELATED VIRUS (XMRV) IN UK PATIENTS WITH CHRONIC FATIGUE SYNDROME

RETROVIROLOGY: 2010, 7, 10


 A second UK research group has today (15 February 2010) reported that they have been unable to find any evidence of XMRV infection in people with ME/CFS.
 
The research, which has been published in the on-line edition of Retrovirology, was carried out by a collaborative of very reputable virologists and retrovirologists. The group includes two researchers (ie Professor John Gow and Dr Jonathan Kerr) who are already involved in biomedical research into various aspects of ME/CFS. Dr Jonathan Stoye, from the National Institute for Medical Research, co-authored the editorial in Science that accompanied the paper from the American group which first raised the possibility of a link between XMRV and ME/CFS back in October 2009.
 
The UK research involved the use of blood samples taken from two cohorts involving 170 people with CFS and 395 controls. 
 
They looked for evidence of XMRV infection using quantitative PCR (polymerase chain reaction) to check for the presence of viral nucleic acids (DNA) and a viral neutralisation assay to try and detect an anti-XMRV immune response.
 
The authors report that they have not identified XMRV DNA (ie genetic material) in any samples using PCR (0/299).  Some samples showed XMRV neutralising activity (26/565) but only one of these positive sera came from a CFS patient.
 
Those involved in this replication study concluded that:
 
No association between XMRV infection and CFS was observed in the samples tested, either by PCR or serological methodologies.  The non-specific neutralisation observed in multiple serum samples suggests that it is unlikely that these responses were elicited by XMRV and highlights the danger of over-estimating XMRV frequency based on serological assays.  In spite of this, we believe that the detection of neutralising activity did not inhibit VSV-G pseudotyped MLV in at least four human samples indicates that XMRV infection may occur in the general population, although with currently uncertain outcomes
 
 The ME Association advice on XMRV testing remains the same.  We do not believe there is any point, at present, in spending a large sum of money on a blood test that has not yet been shown to be a diagnostic marker for ME/CFS or an aid to management.  The ME Association will be issuing a more detailed position statement on this UK research later.
 
An abstract of the research paper can be accessed here. The full paper can be accessed via a provisional PDF on the Retrovirologity journal site.
 
The most recent MEA summary on XMRV can be accessed using the Quick Links section on the MEA website
 
Dr Charles Shepherd
Hon Medical Adviser, MEA

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