De "vermoeidheidsdeskundigen" uit Nijmegen hebben zoals verwacht
(klik hier
en
hier)
het XMRV-virus niet gevonden in het bloed van (32) "chronische vermoeide mensen".
De studie betrof géén ME/CVS-patiënten, maar mensen die voldeden aan de Oxford-criteria voor chronische vermoeidheid (die nog ruimer zijn dan de nietszeggende CVS-kriteria).
Ook de methode die gebruikt werd (bijv. de primers: DNA-sleutels) wijkt af van
die van de oorspronkelijke studie van het Whittemore-Peterson Instituut (klik hier).
De pr-machine van het Expertisecentrum Chronische Vermoeidheid draait op volle toeren.
En de media?
Die nemen klakkeloos de persberichten van de onderzoekers als waarheid aan.
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Het "objektieve" kommentaar van Simon Wessely...
Chronic fatigue syndrome and human retrovirus XMRV
BMJ 25 February 2010;340:c1099. doi:10.1136/bmj.c1099.
Editorials
Three studies now refute the original study reporting the link
The first 150 words of the full text of this article appear below.
In the linked case-control study (doi:10.1136/bmj.c1018),
van Kuppeveld and colleagues describe their failure to find evidence of
a new human retrovirus in Dutch patients with chronic fatigue syndrome.1
The study is the latest contribution to
a controversy that has surrounded
two conflicting publications on the retroviral aetiology of this syndrome.2 3
The saga started, not with chronic fatigue syndrome or a virus,
but with an enzyme (RNaseL)
that plays a pivotal role in antiviral defences
when activated by the interferon released in response to infection.
Variants of the gene encoding this enzyme
have been linked to an increased susceptibility to prostate cancer,
and this led to the identification of a new virus in prostate tissue
that was related to, but different from, known xenotropic murine leukaemia viruses4;
hence the designation
xenotropic murine leukaemia virus-related virus (XMRV).
Sequence analyses showed that it is not an endogenous human virus, and ...
Myra McClure, professor of retrovirology and honorary consultant in genitourinary medicine 1,
Simon Wessely, professor of psychological medicine 2.
- Jefferiss Research Trust Laboratories, Wright-Fleming Institute,
Faculty of Medicine, Imperial College London, London W2 1PG.
- Institute of Psychiatry, King’s College London, London SE5 8AF.
Editorial
(4) New study casts doubt over ME virus link
(Research: Prevalence of xenotropic murine leukaemia virus-related virus in patients with chronic fatigue syndrome in the Netherlands:
retrospective analysis of samples from an established cohort)
http://www.bmj.com/cgi/content/abstract/340/feb25_1/c1018
(Editorial: Chronic fatigue syndrome and human retrovirus XMRV)
http://www.bmj.com/cgi/content/extract/340/feb25_1/c1099
A new study published on bmj.com today casts doubt on recent claims
that a human retrovirus known as XMRV is linked to chronic fatigue syndrome or ME (myalgic encephalitis).
This is the third study to refute the original US study reporting the link.
Chronic fatigue syndrome is a debilitating condition that affects millions of people worldwide with disabling physical and mental fatigue that does not improve with rest.
Its causes remain unclear, but many people say their illness started after a viral infection.
A recent study from the United States detected XMRV in two thirds of patients with chronic fatigue syndrome,
but could not conclusively prove a direct (causal) link between the virus and the disease.
In January 2010, another research team found no evidence of XMRV in 186 patients with chronic fatigue syndrome in the United Kingdom.
A third study, published earlier this month, also failed to identify XMRV in 170 patients.
So a team from the Netherlands, led by Professors Frank van Kuppeveld and Jos van der Meer,
investigated whether this link could be confirmed in an independent European group of patients with chronic fatigue syndrome.
They examined the DNA from XMRV in the blood cells of 32 Dutch patients with chronic fatigue syndrome and 43 healthy controls, matched by age, sex and geographical area.
Two highly sensitive tests were performed on two different target genes.
They found no evidence of XMRV in any of the patients or the controls, adding to the negative evidence in the two previous studies.
"Although our patient group was relatively small and we cannot formally rule out a role of XMRV,
our data cast doubt on the claim that this virus is associated with chronic fatigue syndrome in the majority of patients," say the authors.
One reason why these results contradict the original findings may be that the US study involved patients
from a specific outbreak of chronic fatigue syndrome in the mid-80s that has already been linked to several viruses, explain the authors.
It is possible that XMRV is implicated in this outbreak,
but does not play a substantial role in most cases of chronic fatigue syndrome elsewhere, they conclude.
To reconcile these different findings,
other US laboratories are currently investigating XMRV and chronic fatigue syndrome,
and the results are eagerly awaited,
say researchers from Imperial College London and King's College London in an accompanying editorial.
"If the link fails to hold up, it will be another bitter disappointment to affected patients.
Nonetheless, the current debate will still bring critical attention to the causes of chronic fatigue syndrome,
and XMRV may turn out to be important in the pathogenesis of other diseases," they conclude.
Contact:
Research:
Frank van Kuppeveld, Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands,
Editorial:
Myra McClure, Professor of Retrovirology and Honorary Consultant in Genitourinary Medicine, Jefferiss Research Trust Laboratories, Wright-Fleming Institute, Faculty of Medicine, Imperial College London, UK
http://www.bmj.com/content/vol340/issue7744/press_release.dtl#4
Prevalence of xenotropic murine leukaemia virus-related virus in patients with chronic fatigue syndrome in the Netherlands:
retrospective analysis of samples from an established cohort
BMJ 2010;340:c1018.
van Kuppeveld FJM, de Jong AS, Lanke KH, Verhaegh GW, Melchers WJG, Swanink SMA, Bleijenberg G, Netea MG, Galama JMD, van der Meer JWM.
Research
Objective
The presence of
the retrovirus xenotropic murine leukaemia virus-related virus (XMRV)
has been reported
in peripheral blood mononuclear cells
of patients with chronic fatigue syndrome.
Considering
the potentially great medical and social relevance
of such a discovery,
we investigated whether this finding
could be confirmed in
an independent European cohort
of patients with chronic fatigue syndrome.
Design
Analysis of a well defined cohort of
patients and matched neighbourhood controls
by polymerase chain reaction.
Setting Certified (ISO 15189) laboratory
of clinical virology in a university hospital in the Netherlands.
Population
Between December 1991 and April 1992,
peripheral blood mononuclear cells
wwere isolated from
76 patients and 69 matched neighbourhood controls.
In this study we tested cells from
32 patients and 43 controls from
whom original cryopreserved phials were still available.
Main outcome measures
Detection of XMRV
in peripheral blood mononuclear cells
by real time polymerase chain reaction assay
targeting the XMRV integrase gene and/or
a nested polymerase chain reaction assay
targeting the XMRV gag gene.
Results
We detected
no XMRV sequences
in any of the patients or controls
in either of the assays,
in which relevant
positive and negative isolation controls and
polymerase chain reaction controls
were included.
Spiking experiments showed that
wewe were able to detect
at least 10 copies of XMRV sequences
per 105 peripheral blood mononuclear cells
by real time as well as
by nested polymerase chain reaction,
demonstrating high sensitivity of both assays.
Conclusions
This study failed to show the presence of XMRV
in peripheral blood mononuclear cells
of patients with chronic fatigue syndrome
from a Dutch cohort.
These data cast doubt on the claim that
XMRV is associated with chronic fatigue syndrome
in the majority of patients.
http://www.bmj.com/cgi/content/full/340/feb25_1/c1018 (html)
http://www.bmj.com/cgi/reprint/340/feb25_1/c1018.pdf (pdf)
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