Date Published: January 6, 2010
Publisher: Public Library of Science
Author(s): Otto Erlwein, Steve Kaye, Myra O. McClure, Jonathan Weber, Gillian Wills, David Collier, Simon Wessely, Anthony Cleare, Douglas F. Nixon. http://doi.org/10.1371/journal.pone.0008519
Abstract: In October 2009 it was reported that 68 of 101 patients with chronic fatigue syndrome (CFS) in the US were infected with a novel gamma retrovirus, xenotropic murine leukaemia virus-related virus (XMRV), a virus previously linked to prostate cancer. This finding, if confirmed, would have a profound effect on the understanding and treatment of an incapacitating disease affecting millions worldwide. We have investigated CFS sufferers in the UK to determine if they are carriers of XMRV.
Partial Text: A recent study by Lombardi et al. describing a gamma-retrovirus infection in 68 of 101 chronic fatigue syndrome (CFS) patients was notable not only for its claim of a new viral aetiology of a hitherto controversial disease, but also for the fact that proviral DNA could be amplified from the peripheral blood mononuclear cells (PBMC) of 3.75% (8/218) of the healthy controls. This follows an earlier claim that 1.7% (5/300) of healthy Japanese blood donors carried antibodies to the same virus . The virus in question is a recently discovered retrovirus, Xenotropic Murine Leukaemia Virus (MLV)-Related Virus (XMRV).
Unlike the study of Lombardi et al., we have failed to detect XMRV or closely related MRV proviral DNA sequences in any sample from CFS cases. There have been numerous claims for an infective aetiology to CFS over the years, not least because, as in this sample, many patients report that their symptoms were triggered by an infective episode. Prospective epidemiological studies have confirmed that certain infective agents, for example Epstein Barr virus, are unequivocally associated with subsequent CFS , even if the mechanisms are unclear and almost certainly multi factorial. Nearly two decades ago, sequences from another retrovirus, the human T-lymphotropic virus type ll, were amplified from the PBMCs of 10/12 (83%) adult and 13/18 paediatric CFS patients, but not from healthy control subjects . However, subsequent studies carried out on small numbers (20–30) of CFS patients, failed to confirm evidence for HTLV (type 1 or 11) – or other retroviruses, including the closely-related simian T lymphotropic virus type l, the prototype foamy virus, simian retrovirus, bovine and feline leukaemia viruses  and HIV-1 .