New virus not linked to ME

Recent research suggesting a link between a recently discovered virus - XMRV - and Chronic Fatigue Syndrome has been thrown into doubt by UK scientists.

Chronic Fatigue Syndrome - also known as myalgic encephalomyelitis or ME - affects about 250,000 people in the UK.

Symptoms usually include severe fatigue, tiredness, muscle pain and aching joints. Although the cause of the condition is unknown, some scientists suspect a virus infection may trigger the condition.

In a recent study, a group of US scientists found a type of retrovirus called XMRV in blood samples of 68 out of 101 CFS patients. But in a joint study, scientists from Imperial College London and King's College have been unable to reproduce the results.

The UK scientists tested 186 CFS patient blood samples using an ultra-sensitive method called PCR which can detect minute amounts of virus genetic material. All the samples tested showed no sign of the XMRV virus.

Professor Myra McClure, from the Division of Medicine at Imperial College London and an expert in retroviruses, said: "Our research was carried out under rigorous conditions -- we looked at samples from well-studied patients, and we used very sensitive testing methods to look for the virus.

"If it had been there, we would have found it. The lab in which we carried out the analysis had never housed any of the murine leukaemia viruses related to XMRV, and we took great care to ensure there was no contamination (by other viral genetic material)."

The scientists say the latest findings mean that anti-retroviral drugs should not be used to treat CFS, as they would be unlikely to have an effect on the symptoms.

"We are confident that our results show there is no link between XMRV and Chronic Fatigue Syndrome, at least in the UK. The US study had some dramatic results that implied people with the illness could be treated with anti-retrovirals.

"Our recommendation to people with Chronic Fatigue Syndrome would be not to change their treatment regime, because our results suggest that anti-retrovirals would not be an effective treatment for the condition," said Professor McClure.

Dr Anthony Cleare, Reader in Psychiatric Neuroendocrinology from the Chronic Fatigue Syndrome Clinic at King's College London said: "Chronic Fatigue Syndrome is a serious and debilitating condition. It can also be extremely frustrating for people with the illness, as we have yet to identify its fundamental cause, or come up with any definitive treatments.

"The recent US study generated real excitement among doctors and patients alike as it seemed to open up a new line of research. Unfortunately, we have not been able to replicate those findings.

"It is important to emphasise that these findings do not invalidate all previous research, some of which has shown that CFS can be triggered by other infective agents, such as Epstein Barr Virus or Giardia parasites," Dr Cleare said.

This article was published on Wed 6 January 2010