Chain initiation by reovirus RNA transcriptase in vitro

THE presence of reovirus RNA transcriptase within the virion has facilitated studies on the mechanism of mRNA synthesis in vitro^1,2. Subviral particles prepared from extracts of reovirus infected L-929 cells have provided stable and highly active RNA transcriptase preparations³. The particulate enzyme efficiently synthesizes in vitro all ten species of the reovirus-specific single-stranded mRNAs that correspond to the ten segments of the double-stranded RNA genome^3,5. The same transcription mechanism seems to apply in vivo and in vitro as suggested by (a) the correlation in size and distribution of the messenger species^3-8 and (b) the complementarity of the corresponding mRNAs to the same template strand (unpublished data of D. Kyner).