10/08/2009
Scientists at Cleveland Clinic are part of new research showing a potential retroviral link between XMRV, a virus discovered by Cleveland Clinic and UCSF researchers in 2006 in cancerous prostate tissue, and chronic fatigue syndrome, known as CFS, a debilitating disease that affects millions of people in the United States.
Dr. Robert Silverman, a cancer biologist in the Lerner Research Institute who was part of the team that discovered XMRV, and collaborators at the Whittemore Peterson Institute, located at the University of Nevada, Reno, and the National Cancer Institute, published their findings in the Oct. 8 online issue of Science.
“The discovery of XMRV in two major diseases, prostate cancer and now chronic fatigue syndrome, is very exciting. If cause-and-effect is established, there would be a new opportunity for prevention and treatment of these diseases,” said Silverman.
Related content
Read:
Press release about XMRV from The National Cancer Institute
Learn more about:
Chronic Fatigue Syndrome
Dr. Robert Silverman
Lerner Research Institute
Prostate Cancer
What is XMRV?
- XMRV is a type of virus known as a “retrovirus.” XMRV is a member of the genus, gammaretrovirus, which is closely related to viruses found in mice and other mammalian species. In infected cells, the RNA genome of XMRV is copied into DNA. The viral DNA inserts in the cells’ DNA during replication of XMRV.
How was it discovered?
- In a study of 150 men that examined tissue samples of prostates that had been surgically removed, a team of researchers from Cleveland Clinic and the University of California, San Francisco identified the virus, XMRV, in prostate tumors.
- The researchers first reported their findings on Feb. 24, 2006, at the American Association of Urology meeting in San Francisco. The full report was then published in the March 2006 issue of PLoS Pathogens.
- The same team reported in the January 2007 issue of the Proceedings of the National Academy of Science that XMRV is an infectious virus.
- Prior to these reports, the virus had never been seen before, either in humans or in animals.
What do we know currently about XMRV?
- The initial research determined that XMRV is 25 times more likely to be found in prostate cancer patients with a specific genetic mutation than men without the mutation.
- This finding is consistent with previous epidemiologic and genetic research suggesting that prostate cancer may result from chronic inflammation, perhaps as a response to infection.
- Recent research from the University of Utah has independently confirmed the presence of XMRV in prostate cancer. The findings show that the virus is found in cancer cells and is more frequently associated with more aggressive tumors.
- Now, evidence suggests that XMRV is frequently present in the blood of patients with chronic fatigue syndrome (CFS). This finding shows there is an association between XMRV and CFS but does not prove that XMRV causes CFS. These findings were reported in the journal Science on Oct. 8, 2009, by researchers from Whittemore Peterson Institute (WPI), located at the University of Nevada, Reno, the National Cancer Institute (NCI), part of the National Institutes of Health, and Cleveland Clinic.
What is currently being studied about XMRV?
- Future research will address the critical question of what is the risk to humans of XMRV infections. In particular, is XMRV a cause of human diseases such as prostate cancer and CFS, or is it merely a passenger virus?
- What other diseases might XMRV be involved in?
- If the virus causes disease, how does it do so?
- Development of clinical assays to show who is infected and who is not is essential to linking the virus to human disease.
- How is the virus transmitted from human to human?
- How does our immune system control XMRV infections?
- Does the blood bank need to be screened for XMRV?
- Where did XMRV come from?
What are the future implications and applications for XMRV?
- If XMRV is proven to cause human disease, there would be opportunities for improved diagnosis, treatment (antivirals) and prevention (vaccine).
How could XMRV and HPV be similar?
- We know that HPV causes cervical cancer, and that it is transmitted via sexual intercourse.
- We also know that men with a history of prostatitis and sexually transmitted diseases are at a higher risk for developing prostate cancer.
- These and other findings suggest that there is the potential that XMRV is sexually transmitted.
- In addition to the presence of XMRV in some prostate cancer patients, a disease of men, XMRV has now been found in CFS, which predominantly affects women. Therefore, members of both sexes are at risk of XMRV infection.
How long until XMRV is used as a screening or diagnostic tool or has a vaccine associated with it?
- The best estimates are that we are perhaps two to three years from applying XMRV-based screening and diagnostic measures in the clinical setting. Treatment using an existing, approved antiviral agent could occur in a similar time frame.
- In contrast, a vaccine could take a decade or longer to develop and implement.
