Interferon induced inhibition of mouse mammary tumor virus production

Treatment of murine cells chronically infected with mouse mammary tumor virus with interferon resulted in a marked inhibition of extracellular virus production. This inhibition occurred despite the lack of effect on the transcription or translation of viral RNA. Interferon treatment did not alter the steady-state level of intracellular viral RNA as determined by hybridization of total cellular and polysomal poly(A) containing RNA with mouse mammary tumor virus complementary DNA. Additionally, analyses by polyacrylamide gel electrophoresis showed no differences in the molecular weights of the major viral proteins in extracts from control and interferon treated cultures. These results are consistent with suggestions that the interferon inhibits production of mouse mammary tumor virus at a late stage of replication.