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Viral cause for chronic fatigue?

A recently-discovered virus found to be associated with prostate cancer has now been linked to chronic fatigue syndrome (CFS), according to a linkurl:study published;http://www.sciencemag.org/cgi/content/abstract/1179052 online in Science today (8 October). The study, although only correlative, lends a greater immediacy to questions about how the virus is spread and what, if any, other diseases it might cause. XMRVImage: Whittmore Peterson Institute"Either [the virus] is a causative factor or

By | October 8, 2009

A recently-discovered virus found to be associated with prostate cancer has now been linked to chronic fatigue syndrome (CFS), according to a linkurl:study published;http://www.sciencemag.org/cgi/content/abstract/1179052 online in Science today (8 October). The study, although only correlative, lends a greater immediacy to questions about how the virus is spread and what, if any, other diseases it might cause.
XMRV
Image: Whittmore Peterson Institute
"Either [the virus] is a causative factor or it's a marker of patients who cannot clear the virus," linkurl:Eugene Kandel,;http://www.roswellpark.org/Research/Research_Staff/Kandel a molecular biologist at Roswell Park Cancer Center who was not involved in the study, told __The Scientist.__ The study doesn't distinguish between the two possibilities, he said. The virus, awkwardly named xenotropic murine leukemia virus-related virus (XMRV), may simply be a passenger, more prevalent in patients with underlying disease. Doctors and researchers still debate whether CFS is a disorder with physiological causes and what those causes might be. A number of causes have been proposed for CFS, including chronic inflammation, genetic predisposition, and stress. The disease is estimated to affect 1% of the world's population, and a number of viruses, including some herpesviruses and enteroviruses, have been proposed as triggers of the disease. Here, the researchers found XMRV in 67% of samples from patients with chronic fatigue syndrome out of 101 samples analyzed, compared to approximately 4% of 218 control samples. Researchers also found antibodies to XMRV in the serum of the infected patients, suggesting that patients mounted a specific immune response to the virus. XMRV, a retrovirus with close homology to the cancer-causing mouse virus, murine leukemia virus (MLV), was linkurl:first discovered;http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=16609730 in 2006 by researchers tracking down an enzyme that was mutated in prostate cancer patients. The enzyme had both tumor suppressor and antiviral properties, which suggested the possibility that prostate cancer had an infectious cause. When researchers scanned tissue from prostate cancer patients for viral infection using a specially-designed virus chip, they pinpointed XMRV. linkurl:Robert Silverman;http://www.lerner.ccf.org/cancerbio/silverman/ of the Lerner Research Institute at the Cleveland Clinic, a coauthor of the Science paper, said that a larger-scale epidemiological study would have to be done to strengthen the observed correlation. Researchers will also need to explore the basic biology of the virus, such as how it is transmitted, what host factors might restrict its growth, and what other species it might infect, he added. To date, only 12 records appear in a PubMed search under the term XMRV, but that is likely to change. "A lot of people are working on this virus," said Silverman, who was part of the team that first discovered it. "I know, because I've been giving it out to a lot of labs." The researchers also noted that if the study's 4% of control patients infected with XMRV were to be extrapolated to the general population, millions of Americans could be carriers of the virus. This is worrying, said Silverman, because XMRV belongs to a family of viruses that cause neurological disease. It also raises concern in patients undergoing gene therapy, in which MLV is often the viral vector delivering the genes. Kandel and Silverman recently linkurl:published a study;http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=18769545 showing that cells containing non-infectious MLV vectors could regain their ability to replicate and infect other cells when co-infected with XMRV. This could be problematic because "we make vectors that are more aggressive than the natural virus, on the assumption that these viruses can't escape," said Kandel.
**__Related stories:__***linkurl:Viral cause for prostate cancer?;http://www.the-scientist.com/news/display/55966/
[7th September 2009]*linkurl:The virus hunter;http://www.the-scientist.com/article/display/54041/
[January 2008]*linkurl:The infection-chronic disease link strengthens;http://www.the-scientist.com/article/display/12009/
[4th September 2000]
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Comments

Avatar of: MELISSA PETREACA

MELISSA PETREACA

Posts: 7

October 9, 2009

The fact that a virus linked to prostate cancer has also been linked to chronic fatigue syndrome certainly suggests the possibility that this virus, or others like it, could be a critical factor underlying many chronic disease states. That a virus appears associated with an "invisible illness" should cause sufferers to rejoice. With the identification of a potential BIOLOGICAL (as opposed to psychological) cause, this misunderstood condition may finally get the attention and research dollars that it deserves. \n\nIt is my hope that this may also bring new insight into other chronic conditions of unknown cause--fibromyalgia comes to mind.
Avatar of: Keith Loritz

Keith Loritz

Posts: 16

October 10, 2009

When a doctor says, "We do not know what causes this", it simply means, "We do not know which microbe causes this". . . YET.
Avatar of: Anita Allen

Anita Allen

Posts: 11

October 10, 2009

A 67% sensitivity? Homologous with murine leukemia virus? What percent and across what genes of the entire alleged genome?\n\nI hope for light in virology because to me this is another in the road wrong taken and still being followed to its deadend, with Nobel nod.\n\nThey found a highly conserved region in a yet to be defined section of split genes (introns and exons).\n\nThey know a lot about the conserved structural coding region, but not much about the highly mobile, recombinant regulatory stuff. So, they follow highy conserved regions and everytime they find a split gene section, it's a virus.\n\nNever mind about all those retroelements, HERVS,LTRs,LINES,SINES,ALU's and the rest, they're just junk. The fact that they are regulatory is dismissed even though they comprise 75% - 95% of the human genome against the structural region's 2%.\n\nThen the next step will be nuke the highly conserved region along with all the regulatory stuff and bring a new antiretroviral chemo to AIDS and cancer patients - and its never the chemo that kills them it's the virus. When someone dies send in the virologists, not toxicologists!\n\nI would really like to read the definition of virus in virology. When ENCODE came out one conclusion was that the word "gene" had to be redefined. There's been some suggestions but no agreement.\n\nIt seems that the only characteristic needed to be "virus" is the ability to replicate itself. Infectious, the other defining characteristic, is merely inferred on basis of circuituous argument: look how many people have this marker, it must be infectious. - Anita allen, Ekurhuleni, South Africa.
Avatar of: Chris Carter

Chris Carter

Posts: 5

July 17, 2010

Recent research shows that the XMRV virus expresses proteins with short amino acid stretches ("vatches")that exactly match human proteins relevant to fatigue(for example mitochondrial proteins involved in respiration and energy production) and to prostate cancer (proteins involved in cancer pathways and in the control of the expression of the prostate specific antigen). These viral/human protein matches are predicted to be antigenic and antibodies to the virus might also react with their human protein twins, in effect impeding their function.This adds weight to the idea that the XMRV virus causes chronic fatigue and prostate cancer, possibly via autoimmune mechanisms and by interference with the signalling networks of their human counterparts. This phenomenon of viral mimicry of key human proteins is relevant to many other diseases, and is also observed with the HIV-1 virus which expresses proteins that are similar to key components of the human immune system and to autoimmune disorders, such as multiple sclerosis where proteins from the viruses implicated as risk factors (for example the Epstein-Barr virus) are similar to the autoantigens in these disorders. The Herpes simplex virus,implicated as a risk factor in Alzheimer's disease,also expresses vatches that exactly match the beta-amyloid peptide, the cornerstone of Alzheimer's disease pathology. \nThis phenomenon of viral matching appears to be extremely common and probably relates to the idea, formulated by J.B.S.Haldane and F.D'Herelle almost a century ago,that life evolved from viruses. Even after aeons of DNA shuffling,these traces remain in the form of these short peptide matches, peppered throughout our proteome that may be responsible for many human diseases. These papers describing this phenomenon are posted at Nature Precedings http://precedings.nature.com/users/c8e325bfe6bd1d4fc6e006ff204b5f19

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