The double-stranded RNA genome segments of cytoplasmic polyhedrosis virus are independently transcribed.

The in vitro transcription of the genome segments of insect cytoplasmic polyhedrosis virus was examined for a possible mechanism of coordinate control. Initiation of the first transcription cycle, primed by preincubation in the absence of CTP, was synchronous for all 10 viral genome segments. The time required for the completion of each genome transcript was proportional to the chain length, and all 10 mRNA's were synthesized in molar amounts inversely proportional to their molecular weights. The rate of chain elongation for all mRNA's was approximately 6 nucleotides per s. The combined results indicate that each of the viral genome segments is transcribed independently and suggest that RNA chain elongation, not initiation, is rate limiting for cytoplasmic polyhedrosis virus mRNA synthesis in vitro.