The endogenous origin and transmission of RNA viral genomes that code for cancer.

In certain experimental animals, type-C virus genomes are universally prevalent. They are mostly but not exclusively transmitted genetically and produce tumors naturally as well as when transmitted experimentally. The spontaneous virus and tumor expressions are regulated and modified by genetic factors; and virus-specific virogenes used as vaccines prior to high-level natural expressions can suppress natural expressions of the virogenes. Application of this significant information to the prevention of cancer in mice now seems quite feasible; however its application to the control of human cancer is still dependent on the isolation of specific human type-C virus(es).