Ribonucleic Acid Synthesis in Cells Infected with Herpes Simplex Virus: Controls of Transcription and of RNA Abundance
Analysis of the kinetics of hybridization in liquid of labeled herpes simplex virus-1 DNA and excess viral RNA revealed the following: (i) Cells infected by herpes simplex virus-1 for 2 hr (before DNA synthesis) contain two classes of RNA molecules differing 140-fold in molar concentrations. The abundant and scarce RNAs are transcribed from 14 and 30% of the DNA, respectively. RNA extracted at 8 hr after infection (late RNA) also contains abundant and scarce classes differing 40-fold in molar concentrations; these are transcribed from 19 and 28% of viral DNA, respectively. Abundance competition hybridization tests indicate that the abundant RNA at 2 hr is a subset of the 8-hr abundant RNA. (ii) The abundant RNAs probably specify structural proteins, as indicated by estimates of DNA template required for structural proteins and by experiments showing that 19 of 24 proteins (corresponding to 68% of genetic information for structural proteins) are already made between 0.5 and 2 hr after infection. We conclude that there are two types of transcriptional controls, i.e., on-off and abundance controls, and that the synthesis of most structural components is an early viral function.