Synthesis of mRNA by the parvovirus KRV in isolated nuclei.

We have synthesized vial-specific transcripts in nuclei isolated from cells infected with the parvovirus Kilham rat virus. Radioactive vial-specific RNA synthesized in the nuclei was extracted, hybridized to viral DNA, incubated in glyoxal, and electrophoresed in an agarose gel. At least five viral-specific RNAs were detected containing 4.6 Kb (25-26S), 3.2 Kb (major species, 20-22S), 2.9 Kb, 1.3 Kb, and 1.0 Kb pairs. The 4.6 Kb RNA represents a transcript of 95-100% of the viral genome. The major 3.2 and 2.9 Kb RNAs represent a transcript of 50-60% of the viral genome. Over 65% of the viral-specific RNA in the isolated nuclei is polyadenylylated on the 3' terminus. The 5' terminus of the RNA is capped in vitro by the sequence m7G(5')ppp(5')A. Incorporation of [beta-32p]ATP into the 5' cap sequence suggests that initiation of viral RNA synthesis may occur in the infected isolated nuclei.