RETROVIRUS XMRV and ME/CFS: WHAT DO WE KNOW SO FAR? AND WHAT DON'T WE KNOW?
The Independent story was soon followed up by the rest of the UK media, including the BBC. Most of the news reports gave a balanced and accurate account of the research but some incorrectly inferred that the sole cause of ME/CFS had now been conclusively discovered. A selection of UK media reports can be found in the October news archive on the MEA website.
The actual research paper was published in the online edition of Science, along with a perspective written by John Coffin (Department of Molecular Microbiology, Tufts University, Boston, USA) and Jonathan Stoye (National Institute for Medical Research, London).
Detection of an infectious retrovirus, XMRV, in blood cells of patients with chronic fatigue syndrome. Lombardi V et al. Science October 8 2009
A new virus for old diseases? Coffin JM and Stoye JP. Science October 8 2009 326; p215
Abstract: click here
ME ASSOCIATION POSITION
These are clearly important research findings that could help with both the diagnosis and management of ME/CFS, and we congratulate all those involved.
However, a number of questions still have to be answered before anyone can conclude that this virus plays a significant role in either the cause, transmission, clinical assessment or management of ME/CFS. Much more epidemiology and laboratory work now needs to be done to answer the essential points set out below:
- Carrying out further and larger studies using different populations of people with ME/CFS, including people at different stages of the illness (to see if the virus is present in the same percentages in both early and late cases) and in all degrees of severity.
- Using different international laboratories to test for evidence of the virus.
- Assessing what, if any, correlation there is between the presence of this virus and (a) severity of symptoms, (b) a clear infectious onset with a known infection, and (c) various other factors involved in sub-grouping of people under the ME/CFS umbrella.
- Assessing to what extent this virus is also present in other chronic conditions, especially those such as multiple sclerosis and lymphoma where viral infections have been implicated as a causative factor.
- Assessing whether this virus is acting as a benign marker of disease or immune dysfunction, or is a ‘passenger virus', or whether it has a role in the actual disease process and development of symptoms.
- Investigating whether the presence of the virus in healthy people acts as a predisposing factor in the development of ME/CFS (possibly when another infective trigger appears) and/or prostate cancer – rather than being involved in the actual disease process.
- Investigating what effect, if any, the virus has in healthy people who carry it.
- Assessing whether people with evidence of the virus should be treated with antiretroviral medication, and if so developing a suitable antiviral drug.
- Assessing whether animal model studies would help to increase our understanding of the way in which this virus infects cells and possibly causes disease.
TESTING FOR XMRV
Until these research findings have been robustly replicated, and we have the answers to some of the above questions, there is no point in asking your doctor to be tested for XMRV. This is because the NHS does not currently have the facilities to do so and the testing procedures are only being used in a research capacity at present. But if it does turn out that there is a consistent and strong association with ME/CFS then testing for XMRV would almost certainly have to be made available.
We appreciate that people with ME/CFS may be very concerned about the possibility of transmission of XMRV through what are termed body fluids (ie blood, saliva, semen). However, until we know more about what this virus does in the body it would be premature to start arriving at firm conclusions and recommending all kinds of restrictions to normal daily living. Remember: we still do not know for certain whether this is a disease-causing virus in humans and whether it plays a role in causing or maintaining ME/CFS.
One simple way of obtaining some early clues about viral transmission would be to test for the presence of the virus in healthy partners and offspring of people who have the infection and compare the findings to a control group of people that have no such link.
If the virus is also present in up to 4% of the normal healthy population here in the UK (ie around 2.4 million, or ten times the number of people who have ME/CFS), as appears to be the case in America, there could be more widespread implications for public health, blood donation etc.
In relation to blood donation in the UK, current advice is that people with ME/CFS who have symptoms, or are receiving treatment, should not donate blood. It would seem sensible in the short term, until we know more about transmission and pathogenicity of XMRV, to consider extending this restriction to people who have recovered from ME/CFS.
ROLE OF THE MEA RAMSAY RESEARCH FUND
The ME Association is keen to progress this research here in the UK through any way we can help. We have already made contact with virologists who are interested in this virus here in the UK and funding from the Ramsay Research Fund (RRF) could be made available very quickly if we receive a good quality research proposal.
More information on the work of the RRF can be found here.
- An American group from the Whittemore Peterson Institute (www.wpinstitute.org), in collaboration with the National Cancer Institute and the Cleveland Clinic, have reported finding evidence of a human retrovirus known as XMRV in blood samples taken from people with ME/CFS.
- Using peripheral blood mononuclear cells, DNA (viral genetic material) from the virus was found in 67% of patients (68/101) compared to 3.7% in healthy controls (8/218).
- Further studies have found that 95% of people with ME/CFS have antibodies to the virus.
- Blood samples were collected from people with what is referred to in the paper as CFS who live in different parts of the United States, as well as from healthy controls.
- A more detailed, but easy to understand, summary of the XMRV research has been prepared by Dr Suzanne Vernon for the CFIDS Association in America. This can be read at their website.
- The paper in Sciencedoes not provide any detailed information about the patient or control groups. However, a report on the research in The Wall Street Journal states that 20/101 people in the CFS patient group also had a lymphoma, a type of cancer affecting the lymph nodes. Questions have therefore been raised about the inclusion of these patients in the CFS group, as well as the make up of the control group and how these people were selected. See commentary from Professor Andrew Lloyd published on the website of the ME/CFS Society of NSW.
- Retroviruses are a small group of human viruses that consist of HIV, HTLV-1 and HTLV-2.
- XMRV is retrovirus that was first described about three years ago in some men who have prostate cancer. It may also be linked to other medical conditions, including fibromyalgia.
- It is related to a group of viruses that can infect mice
- This type of virus is thought to be transmitted through body fluids such as blood, semen and breast milk. It is not transmitted through the air – like a flu virus.
- Testing for evidence of the virus in blood is currently only available at a few specialised laboratories here in the UK.
We will update this summary as further information becomes available.
If you want to comment to us, please do so via firstname.lastname@example.org
Dr Charles Shepherd
Hon Medical Adviser, ME Association
Summary 1 dated 14 October 2009.