Synthesis of Viral-Specific RNA in Cells Infected with the Parvovirus, Kilham Rat Virus

Abstract

We have studied the viral-specific RNA synthesized after infection of a permissive cell line with Kilham rat virus (KRV). The RNA was shown to be virus specific by analysis of its nucleotide base ratios and by hybridization with KRV and cellular DNA. Viral RNA is synthesized as early as 2 h after infection. This viral RNA synthesis occurs before viral progeny DNA synthesis which is initiated at 7 to 8 h after infection. The predominant viral RNA synthesized before and after viral progeny DNA synthesis has a sedimentation coefficient of approximately 18 S in dimethylsulfoxide-sucrose gradients and a calculated molecular weight of 6.5 × 10 5 to 7.5 × 10 5 . KRV contains a molecule of single-stranded DNA with a molecular weight of approximately 1.6 × 10 6 . If the viral-specific 18 S RNA is a homogenous species, it would account for 40 to 50% of the viral genome. A small amount of 26 S viral RNA with a molecular weight of 1.6 × 10 6 to 1.7 × 10 6 can also be detected. If this 26 S RNA is a single viral-specific entity, it could represent a transcription of the entire KRV genome.