ABSTRACT
Viral infections in laboratory mouse colonies are becoming rare as more facilities utilize cesarian-derived mice with maintenance of colonies behind strict biological barriers. The two viruses of greatest importance that induce skin tumors in mice are both members of the family papovaviridae. Polyomavirus has long been a concern as a cause of tumors in many organ systems of mice. Papillomaviruses induce papillomas and squamous cell carcinomas in most mammalian and some avian species. Papillomaviruses infect wild rodents and it is possible, although as yet not convincingly proven, that these viruses infect laboratory mice. Retroviruses have been associated with some skin disorders but are not involved directly in the onset of skin tumors. Papillomaviruses have been considered to be potential cocarcinogens in ultraviolet light or chemical carcinogen-induced cutaneous papillomas or squamous cell carcinomas in inbred and outbred laboratory mice, since the earliest lesions are morphologically similar to those induced by papillomaviruses.
