(xenotropic murine leukemia virus-related virus)
What is XMRV?
XMRV retrovirus
- 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 and Emory University has independently confirmed the presence of XMRV in prostate cancer. The findings from the University of Utah show that the virus is found in cancer cells and is more frequently associated with more aggressive tumors.
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, 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.
- Because XMRV has been found in blood there is also a potential for infection from transfusion.
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 one year from applying high-throughput, automated XMRV-based screening and diagnostic measures in the clinical setting.
- In contrast, a vaccine could take a decade or longer to develop and implement.
Related Information
Brian Vastag's article, "Going Viral", recently published in Cleveland Clinic Health magazine provides additional information about connections between viruses and diseases such as prostate cancer. The article is also available online.
XMRV, a novel gammaretrovirus associated with prostate cancer, is found in expressed prostatic secretions and its infectivity is enhanced by prostatic acid phosphatase and semen. These observations suggest that XMRV may be sexually transmitted. Read more on this subject in the Cleveland Clinic publication:
