The primary site of replication alters the eventual site of persistent infection by polyomavirus in mice.

Using DNA blot analysis, we monitored the course of polyomavirus infection in mice receiving an intranasal inoculation and compared this with the course of infection in mice receiving an intraperitoneal inoculation. Intranasal infection was characterized by an initial primary replication phase in the respiratory tract, followed by a systemic infection of the visceral organs. At 12 days postinfection, there was partial clearing of viral DNA in all organs; by 22 days postinfection, viral DNA persisted only in the lungs and kidneys, and the level of DNA slowly decreased during the next 3 months. Lungs have been a previously unrecognized site for polyomavirus persistent infection. In contrast to intranasal infection, intraperitoneal infection of mice was characterized by only three phases: an initial systemic phase in which viral DNA was found in the same respiratory and visceral organs as during intranasal infection, clearing of the virus from the organs, and ultimately, a persistent infection in the kidneys but not in the lungs. Thus, different organs became persistently infected when mice were inoculated via these different routes.