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[Influenza virus penetration into the cells of a continuous dog-kidney line]
Abstract:
The penetration of the influenza virus (WSN) into MDCK cells and its intracellular fate was studied using electron microscopy of ultrathin sections of infected cells at early steps of infection, and biochemical analysis of intracellular subviral components. In electron micrographs, the virus particles absorbed on the cells and located inside phagosomes were detected. In both the cases, the fusion of the virus with cell envelopes was distinctly seen. The fusion took place with incubation at 37 degrees C and 4 degrees C, thus suggesting a non-enzymatic mechanism. The inner virus component released into the cytosol after fusion represented virus cores, i. e. ribonucleoproteins (the final products of uncoating) surrounded by the inner protein membrane consisting of matrix (M) protein. The cores were accumulated in perinuclear cytoplasm of infected cells and were most probably intermediates in virus uncoating.
Insights
Influenza virus enters cells via fusion with cell envelopes at both 37°C and 4°C, suggesting a non-enzymatic mechanism. Released virus cores accumulate near the nucleus, indicating they are intermediates in the uncoating process.
Area of Science:
- Virology
- Cell Biology
- Microscopy
Context:
- Investigating early stages of influenza virus (WSN strain) infection in Madin-Darby Canine Kidney (MDCK) cells.
- Utilizing electron microscopy and biochemical analysis to track virus entry and intracellular fate.
Purpose:
- To elucidate the mechanism of influenza virus penetration into host cells.
- To identify the structures involved in early viral uncoating and their cellular localization.
Summary:
- Electron microscopy revealed virus particles attached to and internalized within MDCK cells via phagosomes.
- Virus-host cell membrane fusion was observed at both physiological (37°C) and reduced (4°C) temperatures, indicating a non-enzymatic fusion process.
- Post-fusion, virus cores (ribonucleoproteins and matrix M protein) were released into the cytosol and accumulated in the perinuclear region, suggesting their role as uncoating intermediates.
Impact:
- Provides detailed insights into the initial steps of influenza virus infection at the cellular level.
- Identifies key viral components and their localization during early infection.
- Contributes to understanding virus-host interactions and potential targets for antiviral strategies.