Studies on reovirus RNA: II. Characterization of reovirus messenger RNA and of the genome RNA segments from which it is transcribed

Abstract

Data concerning the time-course of reovirus genome RNA replication, reovirus messenger RNA transcription and virion maturation in actinomycin D-treated L cells are presented. Reovirus messenger RNA is transcribed in three size classes, with sedimentation coefficients of approximately 22 to 25, 16 to 18 and 14 s ( l, m and s messenger RNA molecules). These messenger RNA molecules co-sediment exactly with reovirus genome RNA molecules which have been converted to the single-stranded state (molecules L′, M′ and S′). Messenger RNA molecules l, m and s and genome RNA molecules L, M and S are therefore the same length. Messenger RNA molecules l hybridize specifically with genome molecules L and not with molecules M or S; and the same specific hybridization patterns hold for the other pairs of molecules. Messenger RNA molecules l are thus transcribed intracellularly from genome fragments L, etc. Thus the viral genome is transcribed intracellularly in the form of segments which correspond exactly to the genome RNA fragments released from virions by chemical treatment. The significance of these findings is discussed in relation to a model for the reovirus genome and its replication and encapsidation.