[Parent structures of influenza virus in infected cells]

The fate of influenza virus (A/FPV/Weilbridge) parental structures was studied in permissive (chick fibroblasts) and nonpermissive (Ehrlich ascitic carcinoma cells) cell systems. The cells were infected with the virus labeled with 3H-precursors of RNA of the pulse label and by polymerase reaction in vitro. In the cytoplasm, the functionally active parental structures were found in the area of nucleocapsids (40-50 S). Upon recentrifugation in cesium chloride gradient, some of these structures showed nucleocapsid density of 1.34 g/cm3, and some a higher density (1.40-1.41 g/cm3). In the nucleoplasm, the functionally active structures 2 hours after infection sedimented in the zones of 20-35 S and 3 hours postinfection in the zone of 70-90 S. Both in the cytoplasm and nucleoplasm the parental structures were unstable, undergoing rapid deproteinization. Similar parental structures were found in permissive and nonpermissive cell systems.