Since the original study suggesting a possible link between CFS/ME and the XMRV retrovirus, there have been six published reports from reputable groups in three continents that have failed to find evidence of this virus. These studies have used appropriate techniques in well characterised CFS/ME patients. One study found evidence of two different retroviruses, the significance of which is unclear.
Four very recent further studies (two of them including as author one of the original commentators on the first report) have provided strong evidence to suggest that laboratory and/or reagent contamination are the likely explanation for the original findings.
The current view of informed observers is that the research evidence does not support the idea that XMRV or other retroviruses have a role in the causation or manifestations of CFS/ME. This type of virus is especially liable to be found as a result of inadvertent laboratory contamination, and there is now direct evidence to support this explanation. There is an ongoing study in which samples from the same patients are sent to multiple laboratories, and this – together with the latest reports – may conclude the matter.
There is currently no basis for using tests or treatment based on the initial findings in clinical practise. The original findings raised high expectations, but the hopes now seem to have been dashed. We have been here many times before.
Professor Greg Towers, an author of one of the recent studies comments appropriately in a press release. “Our conclusion is quite simple: XMRV is not the cause of chronic fatigue syndrome. All our evidence shows that the sequences from the virus genome in cell culture have contaminated human chronic fatigue syndrome and prostate cancer samples. It is vital to understand that we are not saying chronic fatigue syndrome does not have a virus cause – we cannot answer that yet – but we know it is not this virus causing it.”
The main benefit of the episode has been an increased awareness of the need for more substantial understanding of the biological basis for CFS/ME, and for better tests and treatments. For the CFS/ME community, the strong health warning must be not to rush to embrace new research findings until they have been confirmed.
Professor Anthony J Pinching
21 December 2010
Prof Pinching is a medical advisor to the Sussex & Kent ME/CFS Society