Transcriptive functions of Sendai virus nucleocapsid in infected cells

Abstract

The synthesis of virus-specific RNA in the cytoplasm of Ehrlich tumor cells infected with Sendai virus started within parental nucleocapsid structures which had a buoyant density in CsCl gradients of 1.31 g/ml and 1.38 g/ml. Two hours after infection the 1.31 nucleocapsid structure disappeared, and the 1.38 nucleocapsid structure was converted into a complex of density 1.45 g/ml which contained polysomes. The synthesis of virus-specific RNA proceeded within this complex. Cycloheximide did not prevent the formation of the 1.45 complex and the synthesis of virus-specific RNA, suggesting that parental nucleocapsid within the complex contained transcriptase. The 1.45 complex dissociated 3 hr after infection, and nascent RNA separated from the parental RNA. Our findings suggest that the 1.45 complex is a transcriptive complex which contains the parental nucleocapsid, and that genome RNA is transcribed within the nucleocapsid by a virion transcriptase.