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Mechanism of astrovirus entry into Graham 293 cells
G Donelli1, F Superti, A Tinari
1Department of Ultrastructures, Istituto Superiore di Sanità, Rome, Italy.
Abstract:
Astroviruses are intestinal pathogens associated with gastroenteritis in man and animals. The mechanism of internalization into host cells has not been reported previously. The cell entry pathway of serotype 1 human astrovirus into 293 cell line was studied biochemically and morphologically. Viral infection was monitored by indirect immunofluorescence. Infected cells were treated with the lysosomotropic agents ammonium chloride, methylamine, and dansylcadaverine or the ionophore monensin to raise the intraendosomal and intralysosomal pH. All drugs tested inhibited the early stages of infection whereas they did not interfere with the viral binding to the plasma membrane. The presence of astrovirus particles was detected by electron microscopy in coated pits and later in coated vesicles. The data indicate adsorptive endocytosis as the most probable mechanism by which astroviruses enter susceptible cells.
Insights
Human astrovirus, a cause of gastroenteritis, enters host cells via adsorptive endocytosis. This process involves the virus binding to the cell surface and being engulfed into vesicles.
Area of Science:
- Virology
- Cell Biology
- Pathogen Research
Background:
- Astroviruses are significant intestinal pathogens responsible for gastroenteritis in humans and animals.
- The precise mechanism of astrovirus entry into host cells remained uncharacterized prior to this study.
Purpose of the Study:
- To elucidate the cell entry pathway of serotype 1 human astrovirus into the 293 cell line.
- To investigate the biochemical and morphological aspects of astrovirus internalization.
Main Methods:
- Biochemical assays using lysosomotropic agents (ammonium chloride, methylamine, dansylcadaverine) and an ionophore (monensin) to alter intraendosomal/intralysosomal pH.
- Morphological analysis using electron microscopy to visualize viral particle localization.
- Monitoring viral infection via indirect immunofluorescence.
Main Results:
- Lysosomotropic agents and monensin inhibited early infection stages without affecting viral binding to the plasma membrane.
- Electron microscopy revealed astrovirus particles within coated pits and coated vesicles.
- Data strongly suggest adsorptive endocytosis as the primary entry mechanism.
Conclusions:
- Human astrovirus utilizes adsorptive endocytosis for entry into susceptible host cells.
- This mechanism is crucial for understanding astrovirus pathogenesis and developing antiviral strategies.