A papovavirus (member of a DNA-containing group of animal viruses) that infects rodents. This virus can induce a wide variety of tumors when inoculated into newborn animals. The simple structure has made the virus a popular model for the study of lytic infection (a viral infection that results in the lysis of the host cell and release of viral progeny) by animal viruses, and viral-induced tumorigenesis (tumor formation). As a result, much is known of the biology of this virus. Discoveries made through studying its action have influenced the work on most other cancers.