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[2 stages of influenza virus deproteinization in infected cells]
Abstract:
MDCK cells (a continuous cell line of dog kidney) were infected with 3H-uridine- or 14C-aminoacide-labeled influenza virus, the WSN strain. The cells were fractionated 30 min and 2 hours postinfection, and viral structures in subcellular structures were identified by sedimentation and density centrifugation and protein analysis in polyacrylamide gel. At 30 min after inoculation the perinuclear cytoplasm was shown to contain structures with the properties of viral nucleoids (ribonucleoproteins--RNP--surrounded with a layer of M protein). Their sedementation rate in glycerol gradients was 70--90 S, and the buoyant density in cesium chloride 1.30 g/ml. The nuclei were found to contain viral RNP with a buoyant density of 1.39--1.41 g/ml. Two hours after inoculation the amount of RNP in the nuclei decreased and in the cytoplasm increased indicating RNP transport from the nucleus into the cytoplasm. Treatment of the cells with cytochalasine 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 cytochalasine-treated cells revealed accumulations of viral structures around nucleoli. These data suggest participation of the nucleoli in transportation of viral structures into the cytoplasm. Based on the foregoing data, a hypothetical scheme of the processes of deproteinization and transport of viral structures in an infected cell has been proposed.
Insights
Influenza virus infection in MDCK cells reveals viral nucleoproteins (RNP) move from the nucleus to the cytoplasm, potentially involving nucleoli in transport. This study proposes a model for viral structure deproteinization and movement within infected cells.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Context:
- Investigating the intracellular trafficking of influenza virus components is crucial for understanding viral replication.
- MDCK cells provide a model system for studying host-pathogen interactions at the cellular level.
Purpose:
- To elucidate the subcellular localization and transport dynamics of influenza virus ribonucleoproteins (RNP) in infected MDCK cells.
- To identify the role of cellular structures, such as nuclei and nucleoli, in the influenza virus life cycle.
Summary:
- MDCK cells infected with influenza virus showed viral nucleoids (RNP) in the perinuclear cytoplasm and nuclei at 30 minutes post-infection.
- By 2 hours post-infection, RNP decreased in nuclei and increased in cytoplasm, indicating nuclear-to-cytoplasmic transport.
- Cytochalasin B treatment caused RNP accumulation around nucleoli, suggesting nucleolar involvement in viral structure transport to the cytoplasm.
- Data supports a hypothetical model for viral deproteinization and transport within infected cells.
Impact:
- Provides insights into the mechanisms of viral RNA transport and assembly.
- Highlights potential roles of cellular organelles in supporting viral replication.
- Contributes to the understanding of influenza virus pathogenesis and informs antiviral strategies.