RNA synthesis in polyoma virus-infected cells. I. Pattern of formation of polyribosome-associated messenger RNA during productive infection

Abstract

Experimental conditions have been established for selective measurement of the synthesis of mRNA in mouse embryo cells. Using such conditions, it was found that productive infection of these cells by polyoma virus resulted in stimulation of mRNA synthesis. The pattern of induction of mRNA synthesis was biphasic, characterized by distinct "early" and "late" periods, as denoted by the time of initiation of progeny viral DNA replication. The formation of "early" mRNA was first detected at 9–11 h postinfection, 6 h prior to the time of onset of virus-induced synthesis of cell DNA and 9 h prior to initiation of polyoma DNA replication. The initiation of synthesis of "late" mRNA was approximately coincident with the onset of formation of viral DNA. Most of the newly synthesized "early" and "late" mRNA was of relatively small size (8–12 S) and was associated with polyribosomes which sedimented at less than 180 S. The proportion of the total "late" mRNA which was virus-specific was three times higher than that of the total "early" mRNA; however, the mRNA synthesized both "early" and "late" was predominantly cell-specific.