Nuclear matrices were prepared by DNase and high salt extraction of SV40-infected epithelial monkey cells. The matrices retain the majority of SV40 virions. This conclusion is based on electron microscopic observations of the occurrence of encapsidated viral DNA that is resistant to DNase digestion and on the analysis of viral proteins by gel electrophoresis. Pulse labeled SV40 RNA is also associated with the nuclear matrix (less than 15% of the viral RNA is removed by DNase and high salt). Pulse-chase experiments revealed that processing of SV40 RNA takes place on the nuclear matrix and the processed molecules are directly transported to the cytoplasm where they are associated with the cytoskeleton. These results suggest a central role for the nuclear and cytoplasmic substructures in virus assembly and in the biogenesis of viral RNA.
