RNA synthesis of vesicular stomatitis virus. X. Transcription and replication by defective interfering particles.

In cells coinfected by standard vesicular stomatitis virus (VSV) and defective interfering (DI) T particles, small RNA consisting of 46 nucleotides was synthesized in molar excess over other VSV-specific RNAs. Although its rate of synthesis increased over time, small RNA accumulated linearly, suggesting that the molecule is unstable. In contrast, replication of the genome RNA of DI T particles was relatively constant after 3 h of infection, resulting in the intracellular accumulation of stable genomic and antigenomic RNA of DI T particles. Coinfection of cells with DI T particles and selected temperature-sensitive mutants from all five complementation groups of VSV indicated that the replication of DI genomes was controlled separately from the synthesis of small RNA. Also, when viral RNA replication was inhibited by cycloheximide, small RNA continued to be synthesized as long as there were enough templates present. These results indicate that small RNA is synthesized by the enzyme(s) involved in VSV transcription and that its dependence on RNA replication is due to the requirement for template amplification.