The ME/CFS Society of NSW Inc
Web Page 3 November 2009
New Retrovirus - Comments by Professor Andrew Lloyd
I thought it might be helpful to get in early and arm you with a scientific
appraisal of the recent article in Science regarding a new retrovirus discovered
in patients with CFS. The first comment is that the findings are potentially
very important to our understanding of the illness.
The paper describes the detection of genetic material of a virus known as
xenotropic murine
leukemia virus-related virus (XMRV) in
68 of 101 (67%) patients in the US, described as having illness "fulfilling the
1994 CDC Fukuda Criteria for Chronic Fatigue Syndrome and the 2003 Canadian
Consensus Criteria for Chronic Fatigue Syndrome/Myalgic encephalomyelitis
(CFS/ME) and presenting with severe disability", compared to 8 of 218 (3.7%)
healthy individuals.
The significance of this finding was further supported by detection of XMRV
proteins in the blood of 19 0f 30 patients but none of 5 healthy subjects.
Antibodies against XMRV were found in the blood of 9 of 18 patients and none of
9 healthy individuals The XMRV was shown to grow in cell culture in the
laboratory.
As the retrovirus family also includes HIV, on face value this finding raises
the suggestion that CFS may be caused in some cases by infection with XMRV which
may affect both the immune system and the brain. However, several strong notes
of caution need to be applied:
(1) Research into CFS has been plagued over several decades by studies using
sophisticated laboratory techniques to examine poorly characterised subjects and
samples. In the recent study, the 101 patients are reported to have met
diagnostic criteria for CFS, but perplexingly no details of their age, gender,
or illness characteristics were provided - except the indication that the
illness in these patients was causing "severe disability". This information is
critical to allow the reader to understand how comparable the patients in the
study were to 'typical' patients with CFS in the USA and worldwide.
Disconcertingly, one of the authors of the study, Judy Mikovits has suggested
during interviews with the Amy Dockser Marcus in the Wall Street Journal, that
"20 patients of the 101 in the study have lymphoma"- if this statement is
accurate the reliability of the designation of the101 patients must be cast into
serious doubt (as diagnosis of lymphoma precludes a diagnosis of CFS).
Perplexingly, the paper also does not describe how the healthy control subjects
were selected - for instance if the controls were family members of the cases,
or individuals working in the laboratory where the studies were performed, this
would be inappropriate as they may have altered rates of contact with the XMRV.
(2) The finding of a retrovirus in the blood would seem to be highly
significant; however so called 'endogenous retroviruses' (ERVs) are actually
found commonly in humans and generally cause no ill effects. These retroviruses
are derived from ancient viral infections of germ cells in
humans, mammals and other vertebrates; and so are passed on through
generations and now remain in the human genome.
Some research suggests that human ERVs may cause certain autoimmune diseases and
cancers. XMRV has previously been associated with prostate cancer.
Accordingly, the finding of XMRV in the recent study raises the possibility that
infection with this virus may cause CFS in some patients -alternatively it may
become active as a result of CFS - or it may have no role whatsoever in the
illness (i.e it may be an epiphenomenon).
(3) Those of us who have been undertaking research into CFS for a long
period will remember the remarkably comparable "discovery" of a retrovirus in
patients with CFS made by Elaine
Defreitas which was published in the similarly prestigious journal. Proceedings
of the National Academy of Sciences in 1991.
In brief, the initial report was of a retrovirus with both genetic material and
viral proteins, as well as antibodies against the virus identified in a
significant proportion of patients and not in healthy individuals.
A series of subsequent studies failed to confirm the findings - or find evidence
for any known retroviral infection.
This outcome is an important reminder that biomedical research is highly complex
process and often uses new technologies to make discoveries - some are confirmed
and found to have lasting significance - many are not.
This process is a necessary element in the pathway to improved understanding of
disease.
There can be no doubt that CFS is one of the most challenging on the list of
unsolved medical conditions, hence the last two decades have witnessed many such
'discoveries' - time will tell whether this one stands the key test of
independent replication, which is verification of the same finding in other
laboratories and using other patient samples.
My research group will be one of many undertaking the task of confirming or
refuting the significance of this finding over the next several months until
these results are in - there is no likelihood of a meaningful
"diagnostic test".
If the findings are confirmed the likelihood of an effective treatment would be
several years away at the earliest.
Professor Andrew Lloyd AM
Director, Centre for Infection and Inflammation Research University of New South
Wales
This report appeared on the web page of the ME/CFS Society of NSW Inchttp://www.me-cfs.org.au
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