September 18, 2012
Research Finds No Link Between Chronic Fatigue Syndrome And Retroviruses
Lawrence LeBlond for redOrbit.com - Your Universe Online
A Multi-site study confirms that chronic fatigue syndrome (CFS), previously documented in two separate research papers, to be associated with the XMRV and pMLV viruses, respectively, has no connection with either disease-causing virus.
The causes of CFS, also known as myalgic encephalomyelitis (ME), have long puzzled scientists, until a 2009 paper in the journal Science linked it to the mouse retrovirus XMRV (xenotropic murine leukemia virus-related virus). The paper found that affected patients often showed symptoms consistent with chronic infection, and a link was therefore plausible. The findings were applauded as a significant advancement in the causes of CFS.
However, the new study, published today in the American Society for Microbiology´s mBio journal, revealed that previous connections were false and there is still no evidence for an infectious cause behind CFS.
“The bottom line is we found no evidence of infection with XMRV and pMLV. These results refute any correlation between these agents and disease,” said study coauthor Ian Lipkin, of Columbia University, in a public release.
CFS is a disabling condition that produces persistent and unexplained fatigue and contributes to a host of associated health problems, such as muscle weakness, pain, memory loss and restless sleep. CFS treatments cost up to $7 billion annually in the United States alone. Possible causes have been debated for years, but little success has been made.
The 2009 and 2010 studies reported finding the viruses in the blood of patients with CFS, which sparked a ray of hope that the discovery could finally lead to better treatment of the debilitating condition. But other researchers have been unable to replicate the results of either study, raising doubts that these viruses are contributors to CFS.
With the direction of the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), Lipkin and colleagues looked for conclusive answers about a possible link between CFS and XMRV/pMLV.
“We went ahead and set up a study to test this thing once and for all and determine whether we could find footprints of these viruses in people with chronic fatigue syndrome or in healthy controls,” said Lipkin. "Our results confirm there is no link."
For the study, the Columbia University researchers recruited nearly 300 people, 147 with CFS/ME and 146 without. The participants were selected from six sites across the US following extensive clinical assessments and lab screening. These sites included: Brigham and Women's Hospital, the Simmaron Research Institute, Miami Veterans Affairs Medical Center, the Infectious Disease Clinic at Stanford University, the Levine Clinic and the Fatigue Consultation Clinic.
The CFS group had met certain criteria to be included in the study, and participants for the control group were recruited to match the CFS group in a number of areas including sex/gender distribution, race/ethnicity and geographic location. All subjects were also tested for evidence of any other health issue that may cause fatigue before the study began.
The team took blood samples from both groups and analyzed them, checking for the presence of genes specific to XMRV and pMLV, using similar methods implemented in the earlier studies. But in the new study, Lipkin and his team took extra care to eliminate contamination in the enzyme mixtures and chemicals used for testing, which may have been the source of the viruses detected in the previous studies. Both XMRV and pMLV are commonly found in mice but have never been confirmed to infect humans.
In the end, not one of the six laboratories found evidence of XMRV or pMLV in samples from the recruited CFS and control groups.
Dr. Judy Mikovits, ex-researcher of Whittemore Peterson Institute, an author on the 2009 study, celebrated the new findings.
“I greatly appreciated the opportunity to fully participate in this unprecedented study. Unprecedented because of the level of collaboration, the integrity of the investigators, and the commitment of the NIH to provide its considerable resources to the CFS community for this important study,” Mikovits said in a statement. “Although I am disappointed that we found no association of XMRV/pMLV to CFS, the silver lining is that our 2009 Science report resulted in global awareness of this crippling disease and has sparked new interest in CFS research. I am dedicated to continuing to work with leaders in the field of pathogen discovery in the effort to determine the etiologic agent for CFS.”
“Although the once promising XMRV and pMLV hypotheses have been excluded, the consequences of the early reports linking these viruses to disease are that new resources and investigators have been recruited to address the challenge of the CFS/ME,” said Lipkin. “We are confident that these investments will yield insights into the causes, prevention and treatment of CFS/ME.”
The study was funded by the National Institutes of Health and was supported by more than two dozens agencies, organizations and universities, including the Centers for Disease Control and Prevention (CDC), the Food and Drug Administration (FDA), the NIH's National Cancer Institute, Cornell University and Stanford.