Comments on Lombardi, et al in Science

[subtr4ct]

Abstract number 1: Comment on "Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome"
Cathie Sudlow, Malcolm Macleod, Rustam Al-Shahi Salman, Jon Stone

Lombardi et al. (Reports, 23 October 2009, p. 585) reported an association between the human gammaretrovirus XMRV and chronic fatigue syndrome. However, their results may be misleading because of various potential sources of bias and confounding. If real, the association may lack generalizability because of the specific characteristics of the cases studied and could be due to reverse causality.



Abstract number 2: Comment on "Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome"
Andrew Lloyd, Peter White, Simon Wessely, Michael Sharpe, Dedra Buchwald

Lombardi et al. (Reports, 23 October 2009, p. 585) reported a significant association between the human retrovirus XMRV and chronic fatigue syndrome (CFS). However, the cases with CFS and the control subjects in their study are poorly described and unlikely to be representative. Independent replication is a critical first step before accepting the validity of this finding.



Abstract number 3: Comment on "Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome"
Jos W. M. van der Meer, Mihai G. Netea, Jochem M. D. Galama, and Frank J. M. van Kuppeveld
Science 14 May 2010: 825.

Lombardi et al. (Reports, 23 October 2009, p. 585) reported detection of the human gammaretrovirus XMRV in the blood cells of patients with chronic fatigue syndrome (CFS). However, the patient description provided was incomplete. The inclusion of patients from a "CFS outbreak" previously linked with a viral infection, without confirmation in sporadic CFS cases, casts doubt on the role of XMRV in the pathogenesis of CFS.



Abstract number 4: Response to Comments on "Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome"
Judy A. Mikovits and Francis W. Ruscetti
Science 14 May 2010: 825.

We reported the detection of the human gammaretrovirus XMRV in 67% of 101 patients with chronic fatigue syndrome (CFS) and in 3.7% of 218 healthy controls, but we did not claim that XMRV causes CFS. Here, we explain why the criticisms of Sudlow et al., Lloyd et al., and van der Meer et al. regarding the selection of patients and controls in our study are unwarranted.

 

[_Kim_]

Thanks for being on top of this subtr4ct! You know we're all itching to see the rest of the text but...

The links you posted give this message:

[FONT=Arial, Helvetica, sans-serif] This item is Restricted to Maintenance Users Only.
[/FONT]

 

[subtr4ct]

Thanks for being on top of this subtr4ct! You know we're all itching to see the rest of the text but...

The links you posted give this message:

[FONT=Arial, Helvetica, sans-serif] This item is Restricted to Maintenance Users Only.
[/FONT]

Yes -- I cannot even reload the pages that loaded a few minutes ago. I think perhaps Science is having a meltdown at the moment.

 

[leelaplay]

Thanks for being on top of this subtr4ct! You know we're all itching to see the rest of the text but...

The links you posted give this message:

[FONT=Arial, Helvetica, sans-serif] This item is Restricted to Maintenance Users Only.
[/FONT]

thanks subtr4ct

boy - the gall of these "scientists".

Does anyone else find Andrew Lloyd, Peter White, Simon Wessely, Michael Sharpe, Dedra Buchwald saying " the cases with CFS and the control subjects in their study are poorly described and unlikely to be representative. Independent replication is a critical first step before accepting the validity of this finding." stomach churningly ironic double-speak??!! How do they get away with it? My respect for "Science" mag has gone downhill.

But, subtr4ct, while you're looking, it seems that there is also a response to these artcles here

Response to Comments on "Detection of an Infectious Retrovirus ...
Science Magazine (subscription)
We reported the detection of the human gammaretrovirus XMRV in 67% of 101
patients with chronic fatigue syndrome (CFS) and in 3.7% of 218 healthy
controls, ...
http://www.sciencemag.org/cgi/content/abstract/328/5980/825-d

that I am itching to see

thx for anything you can do

 

[_Kim_]

Yeah, looks like the Science website is undergoing maintenance.

Here is the page where you can see the list of technical comments on Lombardi et al.:

Technical Comments

Comment on "Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome"Cathie Sudlow, Malcolm Macleod, Rustam Al-Shahi Salman, and Jon Stone
Science 14 May 2010: 825.
Abstract | Full Text | PDF |

Comment on "Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome"Andrew Lloyd, Peter White, Simon Wessely, Michael Sharpe, and Dedra Buchwald
Science 14 May 2010: 825.
Abstract | Full Text | PDF |

Comment on "Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome"Jos W. M. van der Meer, Mihai G. Netea, Jochem M. D. Galama, and Frank J. M. van Kuppeveld
Science 14 May 2010: 825.
Abstract | Full Text | PDF |

Response to Comments on "Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome"Judy A. Mikovits and Francis W. Ruscetti
Science 14 May 2010: 825.
Abstract | Full Text | PDF | Supporting Online Material |

 

[subtr4ct]

Yeah, looks like the Science website is undergoing maintenance.

I wonder if they did not mean for this to be out until tomorrow -- the articles are dated May 14.

 

[_Kim_]

I wonder if they did not mean for this to be out until tomorrow -- the articles are dated May 14.

I just saw that. Now the current issue tab has been disabled. Yours was an especially good snag, then.

 

[subtr4ct]

Okay that is definitely the case -- the links redirect to a slightly different version of the address wherein "content" is replaced with "content-embargo". I guess we have to wait a few hours.

 

[oerganix]

WPIs response is available: http://www.sciencemag.org/cgi/data/328/5980/825-d/DC1/1
and: http://www.sciencemag.org/cgi/content/full/328/5980/825-d

 

[Lesley]

Kim's links are working for me.

 

[VillageLife]

look, what ever is written don't worry, remember what Dr holmberg said at cfsac, FDA, CDC and NIH are studying xmrv hard. and there's the xmrv meeting in September, things are getting looked at.

 

[leelaplay]

I guess they're up now. Here's one. Note the time lag from submission to acceptance. Wonder what happened in between.

Science 14 May 2010:
Vol. 328. no. 5980, p. 825
DOI: 10.1126/science.1183906


Comment on "Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome"
Jos W. M. van der Meer,1,3,* Mihai G. Netea,1,3 Jochem M. D. Galama,2,3 Frank J. M. van Kuppeveld2,3

Lombardi et al. (Reports, 23 October 2009, p. 585) reported detection of the human gammaretrovirus XMRV in the blood cells of patients with chronic fatigue syndrome (CFS). However, the patient description provided was incomplete. The inclusion of patients from a "CFS outbreak" previously linked with a viral infection, without confirmation in sporadic CFS cases, casts doubt on the role of XMRV in the pathogenesis of CFS.

1 Department of Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands.
2 Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands.
3 Nijmegen Institute for Infection, Inflammation and Immunity, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands.

* To whom correspondence should be addressed. E-mail: j.vandermeer@aig.umcn.nl

Chronic fatigue syndrome (CFS), a prolonged state of disabling physical and mental fatigue, has been linked often to an infectious etiology, with viruses such as Epstein-Barr virus, other herpesviruses, parvovirus B19 or enteroviruses, and bacteria such as Coxiella burnetti or Mycoplasma species being linked to the disease at one point or another (1). However, none of these associations have been confirmed in subsequent investigations, leaving the field and the patients in a continued state of uncertainty. At first glance, the recent study by Lombardi et al. describing the occurrence of the retrovirus xenotropic murine leukemia virusrelated virus (XMRV) in 67% of patients with CFS would seem to be a scientific breakthrough (2), as this would pinpoint a clear etiology and pathogenesis, with important implications for prevention and treatment. Strikingly, this study also reported a prevalence of 3.7% of this virus in healthy Americans, with unknown and possibly far-reaching public health implications.

Surprisingly, the study by Lombardi et al. (2) falls short in the description of the patients: What was the nature of the cohort, the age and gender distribution of the patients, and the duration of illness? Did the patients fulfill the criteria of the Centers for Disease Control and Prevention? Moreover, it was surprising to learn during the presentation of this study at the 2009 Tri-Society Annual Conference in Lisbon (3) that the material studied was derived from patients from the well-publicized "outbreak" of CFS from Incline Village, Nevada, dating back to the 1980s. This outbreak has long been suggested to be caused by a viral infection, most notably with Epstein-Barr virus (4) or human herpes virus 6 (5). As a consequence, it is surprising that no independent cohort of patients with sporadic CFS was investigated by Lombardi et al., as these CFS cases represent the majority of patients. Investigation of such an independent cohort is necessary before a claim regarding the presence of the XMRV retrovirus in CFS patients is justified. This assessment has been provided by three recent independent studies (68). Erlwein et al. (6) failed to detect XMRV in any of the patients investigated from a cohort of well-characterized CFS patients from the United Kingdom, thus raising doubt about the role of XMRV in CFS. In addition, Groom et al. (7) failed to find any support for XMRV presence in another cohort of CFS patients from the United Kingdom, assessed by both polymerase chain reaction (PCR) and serological tests, and van Kuppeveld et al. (8) failed to detect XMRV by two different PCR methodologies in a cohort of Dutch patients.

In their detailed presentation of the immunological abnormalities in the patients, Mikovits also reported a cytokine profile with high interleukin-8 and macrophage inflammatory protein1{alpha} and a low interferon-{alpha} concentration (3). The authors suggested that the selection of their group of CFS patients was partly based on reproducible immunological abnormalities and presented it as an additional argument for the viral etiology of CFS. Although this cytokine profile may be associated with a possible viral infection (while by no means being necessarily specific), it has not been reported previously as such in patients with CFS. The cytokine abnormalities in CFS patients are notoriously inconsistent (9), with some studies reporting increased (10), not different (11), or even lower (12) cytokine responses. Thus it is not possible to use "immunological abnormalities" as a selection criterion.

Therefore, we cannot but conclude that although the study of Lombardi et al. unravels the cause of an outbreak of viral infection, the etiology of sporadic CFS that represents the vast majority of patients remains uncertain. A note of caution should also be added regarding the putative geographic distribution of XMRV. XMRV was initially identified in prostate cancer patients in the United States (13), and this association was confirmed in a recent independent study from the United States (14). Remarkably, in three independent European cohorts of patients with prostate cancer, no XMRV was detected (1517). Along the same lines, it would be of interest to see studies of XMRV in sporadic cases of CFS patients in the United States and elsewhere.

Over the past few decades, we have witnessed a long series of papers claiming the discovery of the cause of CFS. None of these claims has been confirmed. Each time, this gives false hopes to large numbers of patients who seek a solution for their suffering. Shortcomings in the study by Lombardi et al. now raise concerns about the role of XMRV in the pathogenesis of CFS.

References and Notes

* 1. L. D. Devanur, J. R. Kerr, Chronic fatigue syndrome. J. Clin. Virol. 37, 139 (2006). [CrossRef] [Web of Science] [Medline]
* 2. V. C. Lombardi et al., Detection of an infectious retrovirus, XMRV, in blood cells of patients with chronic fatigue syndrome. Science 326, 585 (2009). [Abstract/Free Full Text]
* 3. J. A. Mikovits, presentation at Conference on Cellular and Cytokine Interactions in Health and Disease, Lisbon, Portugal, 17 to 21 October 2009.
* 4. G. P. Holmes et al., A cluster of patients with a chronic mononucleosis-like syndrome. Is Epstein-Barr virus the cause? JAMA 257, 2297 (1987). [Abstract/Free Full Text]
* 5. S. A. Daugherty et al., Chronic fatigue syndrome in northern Nevada. Rev. Infect. Dis. 13 (suppl. 1), S39 (1991). [Web of Science] [Medline]
* 6. O. Erlwein et al., Failure to detect the novel retrovirus XMRV in chronic fatigue syndrome. PLoS ONE 5, e8519 (2010). [CrossRef] [Medline]
* 7. H. C. Groom et al., Absence of xenotropic murine leukaemia virus-related virus in UK patients with chronic fatigue syndrome. Retrovirology 7, 10 (2010). [CrossRef] [Medline]
* 8. F. J. M. van Kuppeveld et al., 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 340, c1018 (2010). [Abstract/Free Full Text]
* 9. M. Lyall et al., A systematic review and critical evaluation of the immunology of chronic fatigue syndrome. J. Pysochosom. Res. 55, 79 (2003). [CrossRef] [Web of Science] [Medline]
* 10. M. A. Fletcher, X. R. Zeng, Z. Barnes, S. Levis, N. G. Klimas, Plasma cytokines in women with chronic fatigue syndrome. J. Transl. Med. 7, 96 (2009). [CrossRef] [Medline]
* 11. C. M. Swanink et al., Lymphocyte subsets, apoptosis, and cytokines in patients with chronic fatigue syndrome. J. Infect. Dis. 173, 460 (1996). [Web of Science] [Medline]
* 12. Y. Jammes, J. G. Steinberg, S. Delliaux, F. Brgeon, Chronic fatigue syndrome combines increased exercise-induced oxidative stress and reduced cytokine and Hsp responses. J. Intern. Med. 266, 196 (2009). [CrossRef] [Web of Science] [Medline]
* 13. A. Urisman et al., Identification of a novel gammaretrovirus in prostate tumors of patients homozygous for R462Q RNASEL variant. PLoS Pathog. 2, e25 (2006). [CrossRef] [Medline]
* 14. R. Schlaberg, D. J. Choe, K. R. Brown, H. M. Thaker, I. R. Singh, XMRV is present in malignant prostatic epithelium and is associated with prostate cancer, especially high-grade tumors. Proc. Natl. Acad. Sci. U.S.A. 106, 16351 (2009). [Abstract/Free Full Text]
* 15. N. Fischer et al., Prevalence of human gammaretrovirus XMRV in sporadic prostate cancer. J. Clin. Virol. 43, 277 (2008). [CrossRef] [Web of Science] [Medline]
* 16. O. Hohn et al., Lack of evidence for xenotropic murine leukemia virus-related virus(XMRV) in German prostate cancer patients. Retrovirology 6, 92 (2009). [CrossRef] [Medline]
* 17. F. DArcy et al., Eur. Urol. 7 (suppl.), 271 (2008).
* 18. M.G.N. is supported by a Vici grant of the Netherlands Organization for Scientific Research.

Received for publication 26 October 2009. Accepted for publication 18 April 2010.

 

[leelaplay]

Science 14 May 2010:
Vol. 328. no. 5980, p. 825
DOI: 10.1126/science.1183545

Comment on "Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome"
Cathie Sudlow,1,2,* Malcolm Macleod,1,3 Rustam Al-Shahi Salman,1 Jon Stone1

Lombardi et al. (Reports, 23 October 2009, p. 585) reported an association between the human gammaretrovirus XMRV and chronic fatigue syndrome. However, their results may be misleading because of various potential sources of bias and confounding. If real, the association may lack generalizability because of the specific characteristics of the cases studied and could be due to reverse causality.

1 Division of Clinical Neurosciences, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
2 Centre for Molecular Medicine, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
3 Department of Neurology, NHS Forth Valley, Stirling, UK

* To whom correspondence should be addressed. E-mail: cathie.sudlow@ed.ac.uk

Well-conducted case-control studies provide important insights into disease pathogenesis. Lombardi et al. (1) demonstrated an apparent association between chronic fatigue syndrome (CFS) and the presence, infectivity of, and immune response to the human gammaretrovirus, xenotropic murine leukemia virusrelated virus (XMRV). However, their report has few features of a well-conducted case-control study, making their findings potentially misleading. Here, we briefly discuss several issues of study design, analysis, and interpretation, which may have contributed to inappropriate conclusions.

First, although the CFS cases studied fulfilled broadly accepted diagnostic criteria, they were selected from regions of CFS "outbreaks" and had specific immunological abnormalities, making them potentially more susceptible to viral infections than most patients with CFS. This could limit the generalizability of the studys results. Second, to avoid selection bias, the CFS-free controls should have been drawn from the same background population as the cases and selected independent of the exposure (in this case, a viral infection) under study (2, 3). Put simply, the controls should ideally have been people who would have been cases in the study if they had CFS. However, the control subjects are not described in (1) beyond a mention that they were healthy donors. Third, the lack of clinical data for cases and controls makes it impossible to assess the potential for confounding by numerous other characteristics that may independently influence XMRV status, including age, sex, social deprivation status, medical history (e.g., of prostate cancer), and area of residence. Although confounding by demographic and clinical characteristics alone is unlikely to account for all of the observed difference in XMRV status between cases and controls, it could certainly be a contributory factor.

Fourth, Lombardi et al. do not explain whether identical and contemporaneous laboratory sample storage, handling, and analysis procedures were used for both cases and controls. Differences in these could be another potentially important source of confounding. Fifth, even if identical laboratory procedures for cases and controls were intended, researchers exploring an exciting new hypothesis of a viral cause for CFS in a laboratory established to explore biological causes of CFS will be understandably eager for positive results. This so-called "expectation bias" may lead to completely unconscious and nondeliberate differences in sample handling and data interpretation between cases and controls; it can be avoided only if researchers are blinded to the case-control status of the samples. However, this is not described in (1).

Finally, the criteria for selecting samples for further analyses (including XMRV protein expression in 30/101 cases and 16/218 controls, infectivity in 12 cases and 12 controls, and immune response in 18 cases and 7 controls) are not described and are another important source of potential bias. Was this selection made at random or without knowledge of case-control status? Were all case and control samples on which testing was performed included in data analyses?

Aside from these crucial methodological issues, other plausible alternative explanations for the findings are not explicitly discussed. Foremost among these is reverse causality: Patients with poor general health because of CFS may be more susceptible to viral and other infections. We welcome biological research in CFS but are concerned that Lombardi et al. (1) have not discussed the possibilities of bias, confounding, reverse causality, and lack of generalizability in their study. Patients with CFS, understandably desperate for answers, deserve high-quality research into their condition. Full details of the methodological issues described above should be published, so that the scientific community can properly assess the credibility of these findings. This is particularly important because three studies (including a total of 388 patients with CFS and 438 controls from the United Kingdom and the Netherlands) have now failed to demonstrate any link between XMRV and CFS (46).

References and Notes

* 1. V. C. Lombardi et al., Detection of an infectious retrovirus, XMRV, in blood cells of patients with chronic fatigue syndrome. Science 326, 585 (2009). [Abstract/Free Full Text]
* 2. K. F. Schulz, D. A. Grimes, Case-control studies: Research in reverse. Lancet 359, 431 (2002). [CrossRef] [Web of Science] [Medline]
* 3. D. A. Grimes, K. F. Schulz, Compared to what? Finding controls for case-control studies. Lancet 365, 1429 (2005). [CrossRef] [Web of Science] [Medline]
* 4. O. Erlwein et al., Failure to detect the novel retrovirus XMRV in chronic fatigue syndrome. PLoS ONE 5, e8519 (2010). [CrossRef] [Medline]
* 5. H. C. Groom et al., Absence of xenotropic murine leukaemia virus-related virus in UK patients with chronic fatigue syndrome. Retrovirology 7, 10 (2010). [CrossRef] [Medline]
* 6. F. J. M. van Kuppeveld et al., 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 340, c1018 (2010). [Abstract/Free Full Text]

Received for publication 19 October 2009. Accepted for publication 18 April 2010.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:

Response to Comments on "Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome".
J. A. Mikovits and F. W. Ruscetti (2010)
Science 328, 825

 

[oerganix]

Science 14 May 2010:
Vol. 328. no. 5980, p. 825
DOI: 10.1126/science.1184548
Prev | Table of Contents | Next

Technical Comments

Response to Comments on "Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome"

Judy A. Mikovits1,* and Francis W. Ruscetti2
We reported the detection of the human gammaretrovirus XMRV in 67% of 101 patients with chronic fatigue syndrome (CFS) and in 3.7% of 218 healthy controls, but we did not claim that XMRV causes CFS. Here, we explain why the criticisms of Sudlow et al., Lloyd et al., and van der Meer et al. regarding the selection of patients and controls in our study are unwarranted.

[SIZE=-1]1 Whittemore Peterson Institute, Reno, NV 89557, USA.
2 Laboratory of Experimental Immunology, National Cancer InstituteFrederick, Frederick, MD 21701, USA. [/SIZE]

* To whom correspondence should be addressed. E-mail: judym@wpinstitute.org
Our study (1) documented the presence of a recently discovered human retrovirus, XMRV, in a high proportion of patients with chronic fatigue syndrome (CFS) in comparison with healthy controls. Sudlow et al. (2), Lloyd et al. (3), and van der Meer et al. (4) raise concerns about the cases and controls described in our study and thus the validity of our results. First, we wish to emphasize that our study was not intended to be a detailed clinical description of CFS or an epidemiological study that would relate particular symptoms, demographics, duration, pattern of onset, and the like to the presence or viral load of XMRV. The study was not, nor was it designed to be, a case-control study as Sudlow et al. (2) imply, for it was the first demonstration of the replication and production of infectious XMRV in human blood cells. The fact that a number of the patients tested were from regions of CFS outbreaks does not invalidate the clinical diagnosis. We hope that our report will stimulate the performance of many case-control studies that use appropriate virus detection. We certainly recognize that such studies will be required to determine what role XMRV plays in the pathogenesis of CFS.
Samples included in our study (1) were from CFS patients who fulfilled both the Fukuda criteria and the Canadian Consensus Criteria (CCC), regardless of severity. We regret that a sentence in the original supporting online material in (1) implied that immunological abnormalities were part of the CFS diagnosis; indeed, while many such patients do exhibit such abnormalities (5, 6), they were not required for diagnosis. All patients that met Centers for Disease Control and Prevention and CCC criteria were accepted; none were excluded. Patient samples were obtained from 2006 to 2009 and stored in the Whittemore Peterson Institute (WPI) repository. We did not state in Lisbon (7) or elsewhere that the samples analyzed in (1) were only from patients from documented outbreaks of CFS, nor did we state that the 101 patients described in (1) exhibited all the immunological abnormalities described in our Lisbon conference presentation. In fact, only 25 samples in (1) came from patients identified during the 1984 to 1988 CFS outbreak in Incline Village, Nevada. The remaining 76 samples included patients with sporadic cases from 12 U.S. states and Canada, including California, New York, North Carolina, Wisconsin, Michigan, Oregon, New Mexico, New Jersey, North Dakota, Texas, and Florida. Patients in the study were 67% female, reflecting the reported gender incidence of CFS, with an age distribution of 19 to 75 years of age (mean of 55). The healthy control population, which was similar in age and gender to the patients, was composed of healthy people who visited doctors offices in the western United States between 2006 and 2008. The great majority, although not all, of the patients analyzed were matched in geographic location with controls. As this was not an epidemiological case-control study, we did not attempt to discern where the patients believed they contracted CFS; at the time of sample collection, some were undoubtedly living in an area different from the location where they first became ill.
The information we provide here and in the accompanying Supporting Online Material (8) should lay to rest any concerns about "bias" or "confounding." Again, the primary aim of the work described in (1) was not to characterize this clinical condition or to prove a cause for CFS but to demonstrate the existence of an infectious gammaretrovirus in patients who had been diagnosed with CFS. We achieved our goal using four different experimental strategies. The original description of HTLV-1 and HIV-1 involved only one or two patients (912), whereas we detected XMRV in 75 individuals.
We did not state that our study (1) proves the cause of CFS. A large number of infectious and noninfectious agents have been implicated in CFS, and it is that fact that makes the puzzle of CFS all the more difficult to solve. At no time have we wished to raise false hopes among a group of patients who, in general, have not been treated well by the medical research community. We are aware that many different pathogens have previously been reported to be associated with CFS but have not been proven to be causal.
We further note that no cytokine profiles were presented in (1), nor did we state that abnormal cytokine levels, altered natural killer cell activity, or particular RNase L profiles were a requirement for inclusion in the study. Unpublished comments made during a medical conference (7) exploring hypothetical connections with immune system defects, viral reactivation, and malignancies should not be used to judge the merits of the science in the published paper. Regarding the concern raised by Sudlow et al. (2) about potential "expectation bias," we point out that the National Cancer Institute (NCI) and the Cleveland Clinic, whose scientists independently performed experiments and coauthored (1), were certainly not "established" as laboratories for the purpose of studying CFS. All samples were blinded, as mandated by the NCI and WPI institutional review board approvals. All experimental procedures were done by the same personnel, in the same physical laboratory space, under identical protocols. Investigators at NCI received 100 samples from individuals without knowing their health status; furthermore, the samples were sent to NCI directly without passing through the WPI laboratory space. Laboratory workers at the NCI and the WPI who performed the polymerase chain reaction (PCR) and immunological studies used coded, blinded samples that did not reveal the CFS status of the individuals. The WPI has examined all 218 control and 101 patient samples by both PCR and serological methods for the presence of XMRV nucleic acid and antibodies. In addition, NCI used plasma from all 100 samples they received in infection experiments with LNCaP cells. It was not feasible to examine all 101 patient and 218 control samples with all four XMRV detection methods described in (1), due to time and resource constraints.
Of the technologies used to identify and isolate XMRV in patients with CFS, PCR from DNA or cDNA from unstimulated peripheral blood mononuclear cells is the least sensitive method. We contend that the three recently published negative PCR studies (1315) do not qualify as being studies that fail to replicate our study, as neither the same PCR methodologies were used nor did these studies draw on the additional cell culture and immunological methods that we employed to observe XMRV nucleic acids and proteins. Although we offer to send samples in which we have detected XMRV, the groups that published these results neither requested nor analyzed any samples we had found positive for XMRV in our laboratories.
Sudlow et al. erroneously state that we did not consider alternative explanations for the findings, namely that patients with poor general health may be more susceptible to viral and other infections. On the contrary, we raised as a question for future study: "Is XMRV infection a causal factor in the pathogenesis of CFS or a passenger virus in the immunosuppressed CFS patient population?" (1). We recognize that the presence of XMRV could be due to enhanced susceptibility to retroviral infection after development of CFS. A causal role of XMRV in CFS is an intriguing possibility, given the known immunosuppressive, neurotropic, and serious consequences of infection with other known retroviruses.
Supporting Online Material

www.sciencemag.org/cgi/content/full/328/5980/825-d/DC1
SOM Text
References

References and Notes

• 1. V. C. Lombardi et al., Detection of an infectious retrovirus, XMRV, in blood cells of patients with chronic fatigue syndrome. Science 326, 585 (2009). [Abstract/Free Full Text]
• 2. C. Sudlow, M. Macleod, R. Al-Shahi Salman, J. Stone, Science 328, 825 (2010); www.sciencemag.org/cgi/content/full/328/5980/825-a. [CrossRef]
• 3. A. Lloyd, P. White, S. Wessely, M. Sharpe, D. Buchwald, Science 328, 825 (2010); www.sciencemag.org/cgi/content/full/328/5980/825-b. [CrossRef]
• 4. J. W. M. van der Meer, M. G. Netea, J. M. D. Galama, F. J. M. van Kuppeveld, . Science 328, 825 (2010); www.sciencemag.org/cgi/content/full/328/5980/825-c. [CrossRef]
• 5. N. G. Klimas, F. R. Salvato, R. Morgan, M. A. Fletcher, Immunologic abnormalities in chronic fatigue syndrome. J. Clin. Microbiol. 28, 1403 (1990).[Abstract/Free Full Text]
• 6. K. J. Maher, N. G. Klimas, M. A. Fletcher, Chronic fatigue syndrome is associated with diminished intracellular perforin. Clin. Exp. Immunol. 142, 505 (2005). [Web of Science] [Medline]
• 7. J. A. Mikovits, presentation at Conference on Cellular and Cytokine Interactions in Health and Disease, Lisbon, Portugal, 17 to 21 October 2009).
• 8. Additional patient information is provided as Supporting Online Material.
• 9. F. Barr-Sinoussi et al., Isolation of a T-lymphotropic retrovirus from a patient at risk for acquired immune deficiency syndrome (AIDS). Science 220, 868 (1983). [Abstract/Free Full Text]
• 10. R. C. Gallo et al., Isolation of human T-cell leukemia virus in acquired immune deficiency syndrome (AIDS). Science 220, 865 (1983). [Abstract/Free Full Text]
• 11. B. J. Poiesz et al., Detection and isolation of type C retrovirus particles from fresh and cultured lymphocytes of a patient with cutaneous T-cell lymphoma. Proc. Natl. Acad. Sci. U.S.A. 77, 7415 (1980). [Abstract/Free Full Text]
• 12. B. J. Poiesz, F. W. Ruscetti, M. S. Reitz, V. S. Kalyanaraman, R. C. Gallo, Isolation of a new type C retrovirus (HTLV) in primary uncultured cells of a patient with Szary T-cell leukaemia. Nature 294, 268 (1981). [CrossRef] [Medline]
• 13. O. Erlwein et al., Failure to detect the novel retrovirus XMRV in chronic fatigue syndrome. PLoS ONE 5, e8519 (2010). [CrossRef] [Medline]
• 14. H. C. Groom et al., Absence of xenotropic murine leukaemia virus-related virus in UK patients with chronic fatigue syndrome. Retrovirology 7, 10 (2010). [CrossRef] [Medline]
• 15. F. J. M. van Kuppeveld et al., 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 340, c1018 (2010). [Abstract/Free Full Text]
• 16. Patent applications were submitted for XMRV detection methods in CFS by the WPI, a not-for-profit 501c3. J.A.M. has signed over any personal rights she may have on royalties from these patents to the WPI.

Received for publication 10 November 2009. Accepted for publication 19 April 2010.

 

[leelaplay]

Science 14 May 2010:
Vol. 328. no. 5980, p. 825
DOI: 10.1126/science.1183706

Comment on "Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome"
Andrew Lloyd,1 Peter White,2 Simon Wessely,3 Michael Sharpe,4 Dedra Buchwald5

Lombardi et al. (Reports, 23 October 2009, p. 585) reported a significant association between the human retrovirus XMRV and chronic fatigue syndrome (CFS). However, the cases with CFS and the control subjects in their study are poorly described and unlikely to be representative. Independent replication is a critical first step before accepting the validity of this finding.

1 Centre for Infection and Inflammation Research, University of New South Wales, Sydney, Australia 2052.
2 Wolfson Institute of Preventive Medicine, Barts and the London School of Medicine, Queen Mary University of London, London, UK.
3 Department of Psychological Medicine, Institute of Psychiatry, Kings College London, UK.
4 School of Molecular and Clinical Medicine, University of Edinburgh, UK.
5 Center for Clinical and Epidemiological Research, University of Washington, Seattle, WA 98101, USA.

* To whom correspondence should be addressed. E-mail: a.lloyd@unsw.edu.au

The finding of a significant association between xenotropic murine leukemia virusrelated virus (XMRV) and the enigmatic clinical illness, chronic fatigue syndrome (CFS), has the potential to revise our understanding of the pathogenesis of this condition and raise serious public health concerns (1). It is unusual to find such a strong association between an infectious agent and a well-defined chronic disease, much less an illness like CFS. As such, critical evaluation of the results is paramount. Experienced CFS researchers will remember the 1991 "discovery" of an HTLV-2like retrovirus in CFS (2), which subsequent studies failed to replicate (36).

For reliable results, clearly defined cases should be compared to a control group similar in all aspects other than the disease. The 101 patients studied in (1) were "patients fulfilling the 1994 CDC Fukuda criteria for chronic fatigue syndrome and the 2003 Canadian Consensus Criteria for chronic fatigue syndrome/myalgic encephalitis (CFS/ME) and presenting with severe disability" [supporting online material for (1)], but the latter requires physical signs precluded in the former. The patients were selected, in part, with immunologic perturbations such as in RNase L pathways, yet there are no biomarkers that have demonstrated reliability in affirming the diagnosis of CFS (7). Lombardi et al. (1) provided no description of demographics, illness duration, pattern of onset, or evaluation for exclusionary medical and psychiatric conditions. Likewise, the characteristics of the controls, and details of collection, handling, and storage of specimens, are not described. It is therefore impossible to critically evaluate the findings.

CFS is likely to arise from complex genes-x-environment risk factors, making a simple causative link between XMRV and CFS unlikely. Even if confirmed, further research will be needed to demonstrate causality. In relation to prostate cancer, with which a comparable association with XMRV was reported (8), negative replication studies are mounting (9). Similarly, three negative replication studies in well-characterized cases of CFS have now been published (1012). This outcome serves as a cogent reminder of the need for independent replication before findings such as this can be accepted.

References and Notes

* 1. V. C. Lombardi et al., Detection of an infectious retrovirus, XMRV, in blood cells of patients with chronic fatigue syndrome. Science 326, 585 (2009). [Abstract/Free Full Text]
* 2. E. DeFreitas et al., Retroviral sequences related to human T-lymphotropic virus type II in patients with chronic fatigue immune dysfunction syndrome. Proc. Natl. Acad. Sci. U.S.A. 88, 2922 (1991). [Abstract/Free Full Text]
* 3. J. W. Gow et al., Search for retrovirus in the chronic fatigue syndrome. J. Clin. Pathol. 45, 1058 (1992). [Abstract/Free Full Text]
* 4. M. Honda et al., Japanese patients with chronic fatigue syndrome are negative for known retrovirus infections. Microbiol. Immunol. 37, 779 (1993). [Web of Science] [Medline]
* 5. A. S. Khan et al., Assessment of a retrovirus sequence and other possible risk factors for the chronic fatigue syndrome in adults. Ann. Intern. Med. 118, 241 (1993).[Abstract/Free Full Text]
* 6. W. Heneine et al., Lack of evidence for infection with known human and animal retroviruses in patients with chronic fatigue syndrome. Clin. Infect. Dis. 18 (suppl. 1), S121 (1994). [Web of Science] [Medline]
* 7. M. Lyall, M. Peakman, S. Wessely, A systematic review and critical evaluation of the immunology of chronic fatigue syndrome. J. Psychosom. Res. 55, 79 (2003). [CrossRef] [Web of Science] [Medline]
* 8. R. Schlaberg, D. J. Choe, K. R. Brown, H. M. Thaker, I. R. Singh, XMRV is present in malignant prostatic epithelium and is associated with prostate cancer, especially high-grade tumors. Proc. Natl. Acad. Sci. U.S.A. 106, 16351 (2009). [Abstract/Free Full Text]
* 9. O. Hohn et al., Lack of evidence for xenotropic murine leukemia virus-related virus(XMRV) in German prostate cancer patients. Retrovirology 6, 92 (2009). [CrossRef] [Medline]
* 10. O. Erlwein et al., Failure to detect the novel retrovirus XMRV in chronic fatigue syndrome. PLoS ONE 5, e8519 (2010). [CrossRef] [Medline]
* 11. H. C. Groom et al., Absence of xenotropic murine leukaemia virus-related virus in UK patients with chronic fatigue syndrome. Retrovirology 7, 10 (2010). [CrossRef] [Medline]
* 12. F. J. M. van Kuppeveld et al., 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 340, c1018 (2010). [Abstract/Free Full Text]
* 13. M.S. has been paid by insurers for independent advice on medical claims that might include CFS. He has also been paid by lawyers for independent advice on litigation that might include CFS.

Received for publication 22 October 2009. Accepted for publication 18 April 2010.

 

[oerganix]

1,2,3 punch, punch,punch, take that you denialists

WPIs response to the criticisms of the Science paper:

1)"The study was not, nor was it designed to be, a case-control study as Sudlow et al. (2) imply, for it was the first demonstration of the replication and production of infectious XMRV in human blood cells."

2)"We did not state in Lisbon (7) or elsewhere that the samples analyzed in (1) were only from patients from documented outbreaks of CFS, nor did we state that the 101 patients described in (1) exhibited all the immunological abnormalities described in our Lisbon conference presentation."

3)"At no time have we wished to raise false hopes among a group of patients who, in general, have not been treated well by the medical research community. We are aware that many different pathogens have previously been reported to be associated with CFS but have not been proven to be causal.

We further note that no cytokine profiles were presented in (1), nor did we state that abnormal cytokine levels, altered natural killer cell activity, or particular RNase L profiles were a requirement for inclusion in the study. Unpublished comments made during a medical conference (7) exploring hypothetical connections with immune system defects, viral reactivation, and malignancies should not be used to judge the merits of the science in the published paper. "

 

[subtr4ct]

Wildaisy: in my field (in the social sciences), publishing of comments on papers and responses to the comments is sometimes done. It is not terribly common -- usually a sign of a substantial controversy.

 

[Gerwyn]

I think you have to judge who to believe.

One one corner is the tag team of psychiatrists with a track record of dismissing biomedical causation and denigrating patients with retrovirologists whose study failed to pass muster at the lancet and rushed through by the bmj.

On the other side is a group of world respected retrovirologists who passed the most ardous peer review system in the world.

I love the way that they said that Lombardi et all did not give enough information about the patients.

The Science study clearly stated that the Patients fullfilled the Fukuda criteria and the Canadian consensus criterea. IF you think carefully you will realise that if you fulfill the canadian consensus criteria you automatically qualify for Feduka.There is however not one Feduka presentation which would qualify as having ME/cfs diagnosed by the canadian crtterea because neuroendocrine immune symptoms are mandatory.

I would have thought that the fact that they were different patient cohorts would have been obvious even to Wesselly and Co.Perhaps they need it to be stated in simpler terms I would add another comment here which I will leave to the readers imagination

Their idea of complying with the feduka guidelines by the way is;

Fatigue(defined as weariness) sore throat,headache difficulty sleeping, poor concentration----What does that sound like?.It does however comply with FUKUDA.That is from Sharpe et al 1991 should anyone care to look it up.

I also love the ingenious concept of reverse causality.Nothing whatsoever to do with science in any way but an entertaining addition to their long list of metaphors given the status of fact.Talk about erroneous beliefs!(sorry could not resist that one!

Sorry I forgot That sudlow is uniquely placed having no knowledge of virology or neuroimmune endocrine disorders.She is well acquainted with Wesselly i,m told so I guess there is some kind of tenuous connection there

 

[jimbob]

good question wilddaisy, WPI should be able to sue for slander!!!!

 

[Stuart]

Amazingly lame 'technical comments' submitted to the prestigious Science magazine, and referring to self-published two week wonder studies with 'chronic fatigue' psychiatric cohorts as superior? The definition of chutzpah should have links to those 'comments!'

As far as those BMJ, Dutch studies that are used to deflate the "WPI" study (no mentioning of CC/NCI of course!), our own Parvofighter is world famous on her 'technical comment!'