Vaccinia virus infection of HeLa cells II. Disparity between cytoplasmic and nuclear viral-specific RNA

Abstract

A reassociation kinetic analysis of vaccinia virus DNA and RNA isolated from the nucleus and cytoplasm of infected HeLa cells has been carried out. At 3 hr after infection, the vaccinia-specific RNA found in the cytoplasm represents copies of about 50% of the viral genome. By contrast, the nuclear-associated vaccinia-specific RNA at this time represents only 10% of the vaccinia genome, and is mainly a subset of the RNA found in the cytoplasm. Analysis of the nuclear and cytoplasmic vaccinia-specified mRNA found in cells 8 hr after infection shows that the cytoplasmic vaccinia RNA at this time represents about 90% of the viral genome, whereas the vaccinia RNAs in the nucleus are copies of only 20% of the genome. By contrast, the vaccinia DNA found either in the cytoplasm or associated with the nucleus contains a full range of sequences. The data are consistent with the hypothesis that a unique viral transcriptional or processing step takes place in the nucleus of vaccinia-infected cells.