WHERE NEXT?
Despite a series of 5 negative results the 'jury is still out' when it comes to drawing any firm conclusions about a possible link between XMRV and ME/CFS. And it looks as though this is going to take some time - probably until results from all the XMRV studies that have been completed, or are still underway, have been reported in the scientific journals. This may well mean 2011 rather than late in 2010.
Retrovirologists and ME/CFS researchers will then have to review all the evidence and try to reach a consensus on the possible link between XMRV and ME/CFS and decide on where we go next.
If it looks as though there is a definite link, possibly just in a sub-set of people with ME/CFS, researchers will then have to try and decide whether XMRV is a disease-causing virus or just a harmless passenger. If XMRV is a disease-causing virus in ME/CFS then the use of anti-viral drugs will need to be assessed in clinical trials. However, the use of anti-retroviral drug therapy would obviously have to proceed with great care given the fact that AZT can cause mitochondrial damage - see MEA website report (HIV and fatigue session) on the recent Newcastle University Symposium on fatigue research.
Newcastle Symposium: HIV AND MUSCLE - ASSOCIATIONS WITH FATIGUE: Dr Brendan Payne
Dr Payne explained that fatigue is a common problem in patients with HIV and AIDS. It does not appear to be linked to demographics (= age, sex and other population variables) or immune system cell markers. It does appear to be linked to lipodystrophy (= changes in body fat distribution caused by antiretroviral drug treatment), orthostatic intolerance, depression and sleep disturbance.
Of particular interest is the fact that patients who are treated with antiretroviral drugs such as AZT, which almost completely suppresses HIV replication, find that this has very little effect on fatigue levels. In other words, removing the HIV infection does not remove the fatigue. So, as with ME/CFS, the question is raised as to whether fatigue is being caused by immune activation that is triggered by an infection.
The session on HIV and fatigue also briefly covered the very important issue of muscle mitochondrial damage following antiretroviral therapy (AZT) which is related to the lipodystropy and appears to be permanent in some cases. This observation is obviously going to be very relevant if it turns out that XMRV is a causative factor in ME/CFS and clinical trials involving antiretroviral therapy take place.
There was a short discussion on the Science paper reporting XMRV in patients with ME/CFS and results of the four validation studies which have failed to find XMRV in other cohorts of people with ME/CFS.
On the other hand, a conclusion may be reached that XMRV is not linked to ME/CFS and further research is no longer justified.....
ROLE OF MEA RAMSAY RESEARCH FUND
In the meantime the MEA Ramsay Research Fund is very willing to consider UK applications relating to good quality research that will help to us to reach a satisfactory conclusion about a possible link between XMRV and ME/CFS.
XMRV TESTING IN THE UK
In our current state of knowledge there is no point in paying for individual XMRV testing through commercial laboratories because testing is not available on the NHS. This is not a diagnostic test for ME/CFS and a positive XMRV result is not at present a route to any form of drug treatment.
Full MEA statement on XMRV testing in the UK
Dr Charles Shepherd
Hon Medical Adviser, The ME Association
2 July 2010
