The discovery was made with the same DNA-hunting "virus chip" used to confirm the identity of the SARS virus three years ago.
While the genetics of prostate cancer are complex, one of the first genes implicated in the disease was RNASEL, a gene that serves as an important defense against viruses. Given the anti-viral role of this gene, some scientists have speculated that a virus could be involved in some types of prostate cancers in men with mutated RNASEL genes.
In the new study, the researchers discovered the novel virus far more often in human prostate tumors with two copies of the RNASEL gene mutation than in those with at least one normal copy.
"This is a virus that has never been seen in humans before," said Eric Klein, MD, a collaborator in the research and head of urologic oncology at the Glickman Urologic Institute of Cleveland Clinic. "This is consistent with previous epidemiologic and genetic research that has suggested that prostate cancer may result from chronic inflammation, perhaps as a response to infection."
"The power of the virus chip resides in its ability to simultaneously screen for all viruses, without preconceptions or bias," said Joe DeRisi, PhD, a Howard Hughes Medical Institute (HHMI) investigator at UCSF who developed the chip with colleagues in his lab. "In the case of these prostate tissues, no one would have suspected a virus of this class." DeRisi is a UCSF associate professor of biochemistry and co-leader of the study with Don Ganem, MD, also an HHMI investigator at UCSF and a professor of microbiology and immunology.