2 STAGES OF INFLUENZA-VIRUS DEPROTEINIZATION IN INFECTED-CELLS

  • 1 January 1980
    • journal article
    • research article
    • No. 5,p. 624-629
Abstract
MDCK cells (a continuous line of dog kidney) were infected with 3H-urindine- or 14C-aminoacid-labeled WSN strain influenza virus. The cells were fractionated 30 min and 2 h postinfection and viral structures in subcellular structures were identified by sedimentation, density centrifugation and protein analysis in polyacrylamide gel. At 30 min postinoculation, the perinuclear cytoplasm was shown to contain structures with the properties of viral nucleoids [ribonucleoproteins (RNA) surrounded with a layer of M protein] . The sedimentation rate in glycerol gradients was 70-90 S and the buoyant density in CsCl 1.30 g/ml. The nuclei were found to contain viral RNP with a buoyant density of 1.39-1.41 g/ml. By 2 h after inoculation the amount of RNP decreased in the nuclei and increased in the cytoplasm, indicating RNP transport from the nucleus into the cytoplasm. Treatment of the cells with cytochalasin B (a substance breaking nucleus-cytoplasm bonds) resulted in redistribution of radioactivity in subcellular fractions: an increase of radioactivity in the nuclear extract and a decrease in the nuclear sediment. Autoradiography of cytochalasin-treated cells revealed accumulations of viral structures around nucleoli. Participation of the nucleoli suggests transportation of viral structures into the cytoplasm. A hypothetical scheme of the processes of deproteinization and transport of viral structures in an infected cell was proposed.