Back in In the issue of 23 October 2009, Science published a study by Lombardi et al. purporting to show that a retrovirus called XMRV (xenotropic murine leukemia virus-related virus) was present in the blood of 67% of patients with chronic fatigue syndrome (CFS) compared with 3.7% of healthy controls.
This as everyone will recall, attracted a great deal of scientific and patient derived interest, but there has been considerable lack of success in the replication of these findings by other investigative groups.
The indication from these reports is that the findings of the XMRV retrovirus in cultures is due to its transfer by recombination of two mouse derived leukaemia viruses during a human prostate tumour graft back in the 1990’s.
Whilst this story still has some legs, and the main scientists still have faith in their original findings, and of course many patients hoped for a simple cause and effect outcome – with subsequent opportunity for resolution, I suspect that this may soon falter as a serious hypothesis.
The US National Institute of Health is sponsoring additional carefully designed studies to ascertain whether the association between XMRV and CFS can be confirmed. I am sure that like me, there are many who will look forward to their findings.
 Lombardi VC, Ruscetti FW, Das Gupta J, Pfost MA, Hagen KS, Peterson DL, Ruscetti SK, Bagni RK, Petrow-Sadowski C, Gold B, Dean M, Silverman RH, Mikovits JA.Detection of an infectious retrovirus, XMRV, in blood cells of patients with chronic fatigue syndrome. Science. 2009 Oct 23;326(5952):585-9. Epub 2009 Oct 8. View Full Paper
 Knox K, Carrigan D, Simmons G, Teque F, Zhou Y, Hackett J Jr, Qiu X, Luk KC, Schochetman G, Knox A, Kogelnik AM, Levy JA. No evidence of murine-like gammaretroviruses in CFS patients previously identified as XMRV-infected. Science. 2011 Jul 1;333(6038):94-7. Epub 2011 May 31. View Abstract
 Paprotka T, Delviks-Frankenberry KA, Cingöz O, Martinez A, Kung HJ, Tepper CG, Hu WS, Fivash MJ Jr, Coffin JM, Pathak VK. Recombinant origin of the retrovirus XMRV. Science. 2011 Jul 1;333(6038):97-101. Epub 2011 May 31. View Abstract