Absence of xenotropic murine leukemia virus-related virus in UK patients with chronic fatigue syndrome – Source: Retrovirology, Feb 15, 2010

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Background: Detection of a retrovirus, xenotropic murine leukemia virus-related virus (XMRV), has recently been reported in 67% of patients with chronic fatigue syndrome.

We have studied a total of 170 samples from chronic fatigue syndrome patients from two UK cohorts and 395 controls for evidence of XMRV infection by looking either for the presence of viral nucleic acids using quantitative PCR (limit of detection less than 16 viral copies) or for the presence of serological responses using a virus neutralization assay.

Results: We have not identified XMRV DNA in any samples by PCR (0/299). Some serum samples showed XMRV neutralizing activity (26/565), but only one of these positive sera came from a CFS patient.

Most of the positive sera were also able to neutralize MLV particles pseudotyped with envelope proteins from other viruses, including vesicular stomatitis virus, indicating significant cross-reactivity in serological responses. Four positive samples were specific for XMRV.

Conclusions: No association between XMRV infection and CFS was observed in the samples tested, either by PCR or serological methodologies. The non-specific neutralization 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 neutralizing activity that did not inhibit VSV-G pseudotyped MLV in at least four human serum samples indicates that:

• XMRV infection may occur in the general population,

• Although with currently uncertain outcomes.

Source: Retrovirology, Feb 15, 2010. DOI: 10.1186/1742-4690-7-10, by Groom HCT, Bocherit VC, Makinson K, Randal E, Baptista S, Hagan S, Gow JW, Mattes FM, Breuer J, Kerr JR, Stoye JP, Bishop KN. Division of Virology, MRC National Institute for Medical Research, London; CFS Group, Division of Cellular & Molecular Medicine, St. George’s University of London; Center for Forensic Investigation, Glasgow Caledonian University, Glasgow; Department of Virology, Barts and The London NHS trust, London; Division of Infection and Immunity, University College London, UK. [Email: john.gow@gcal.ac.uk; kbishop@nimr.mrc.ac.uk]

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2 thoughts on “Absence of xenotropic murine leukemia virus-related virus in UK patients with chronic fatigue syndrome – Source: Retrovirology, Feb 15, 2010”

  1. JeNeSuisPersonne says:

    One must remember that in the UK the people who are assigned a ME/CFS diagnosis are often those with depression-related fatigue. Because of this, they are even further off the mark as far as ME/CFS studies go than other countries. Another sad example of how even the shockingly small amount of research funds allotted to ME/CFS have been claimed by the psychiatric contingency who go hand-in-hand with insurance agencies to deny claims and insure that people with ME/CFS will continue to be classified as suffering from a state of ill-health that is “all in their head”.

  2. Sandy10m says:

    Dr. Mikovits addressed the question on why other labs have not yet found XMRV. She said that the results work in probabilities (Poisson distributions). There is a 1 in 4 chance, roughly, that the PCR technique will see the XMRV. She also indicated that the virus must be active at the time of blood draw. So, if the samples in the US have active virus, she has to test the samples up to 4 times (maybe more) to find the virus. And she is testing the samples many times to double-check if someone has the virus or not. If the UK is only testing their samples once, then they may never see any virus, even though it is there. If the UK blood samples do not contain active virus, then they may never see any virus. Or, the other possible theory is that the UK version of XMRV is missing a key genetic marker, it is a mutant strain, and the antigen tests won’t pick it up because of that. More research is obviously needed. Patients in the UK: don’t give up hope yet.

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