THE PRIMARY SITE OF REPLICATION ALTERS THE EVENTUAL SITE OF PERSISTENT INFECTION BY POLYOMAVIRUS IN MICE

Using DNA blot analysis, the course of polyoma virus infection in mice receiving an intranasal inoculation was monitored, and this was compared with the course of infection in mice receiving an i.p. 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 mo. Lungs were a previously unrecognized site for polyoma virus persistent infection. In contrast to intranasal infection, i.p. infection of mice was characterized by only 3 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.