Enhancement of Transcription of the SV40 Genome in Mouse Embryo Cells by Pretreatment with 5-Iodo-2'-deoxyuridine

Treatment of mouse embryo (ME) cells with 5-iodo-2'-deoxyuridine (IdUrd) before infection with SV40 virus, enhances T-antigen (T-Ag) production as detected by immunofluorescence and complement fixation. Cellular DNA and RNA synthesis are inhibited in both SV40 and mock-infected cells after IdUrd treatment. The analogue pretreatment significantly increases the amount of radiolabelled nuclear and cytoplasmic SV40-specific RNA and the RNA polymerase activity of the viral transcriptional complexes of the Sarkosyl supernatants, suggesting that the enhancement of SV40 T-Ag production in infected pretreated ME cells results from an increased synthesis of early virus RNA.