The researchers discovered the virus in patients with a rare type of prostate cancer. The patients in the study have a genetic mutation that compromised some of their natural defenses against viral infection. Thus, the researchers said their discovery raises the possibility that increased susceptibility to viral infection may play a role in development of some cancers. However, they emphasized that their findings by no means implicate the virus, dubbed XMRV, in causing prostate cancer. The virus may well have flourished as a result of the failure of the defense mechanism; and other factors such as chronic inflammation may play a more direct role in the cancer.
The discovery of the new virus was made by an interdisciplinary research team led by Robert Silverman of Cleveland Clinic and HHMI investigators Joseph DeRisi and Don Ganem, both at the University of California at San Francisco. A paper describing the findings was published on March 31, 2006, in the journal, Public Library of Science Pathogens.
The search for the new virus began when Silverman and his colleagues provided samples of a rare familial prostate cancer in which the viral-defense gene, RNASEL, had been mutated in a specific way. This mutation compromised the function of the enzyme produced by RNASEL, which normally shreds viral genetic material. Infected cells carrying the shredded viral genetic material are usually targeted for destruction by the immune system. While some scientists believe that such vulnerability to viral infection is connected to prostate cancer in these rare cases, others have presented evidence contesting that theory.