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Cell attachment and penetration by influenza virus
Abstract:
Attachment and penetration of influenza virus into clone 1-5C-4 cells were quantitatively determined by the immunofluorescent cell-counting assay. Aided by centrifugal force, more than 95% of virus inocula of five representative influenza virus strains (A(0)/PR8, A(1)/Ann Arbor, A(2)/Japan, B/Lee, B/Great Lakes) were attached to cells at a linear rate within 10 min, in contrast to approximately 35% after stationary incubation at 35 C for 2 h. By the former procedure, a proportionality between the number of infected cells and volume of inoculum was revealed which was not evident when stationary incubation was employed. Maximal binding of virus to cells occurred at 0.2 M NaCl. The salt requirement, added to evidence of pH dependence and temperature independence, indicated that the initial virus-cell union involved electrostatic forces. Virus penetration into cells, measured by the insensitivity of virus-cell complexes to antiviral serum, was linear and complete within 15 min at 35 C for all five virus strains tested. Maximal virus penetration occurred at 0.1 to 0.2 M NaCl; the process was pH- and temperature-dependent. Both virus attachment and penetration processes were partially inhibited in the presence of diethylaminoethyl-dextran.
Insights
Centrifugal force significantly enhances influenza virus attachment and penetration into host cells. This method reveals a direct relationship between inoculum volume and infection rates, unlike stationary incubation.
Area of Science:
- Virology
- Cell Biology
- Immunology
Background:
- Influenza virus infection relies on efficient attachment and entry into host cells.
- Understanding these initial steps is crucial for developing antiviral strategies.
Purpose of the Study:
- To quantitatively assess the impact of centrifugal force on influenza virus attachment and penetration.
- To elucidate the physical and chemical factors influencing these processes.
Main Methods:
- Immunofluorescent cell-counting assay used to quantify virus attachment and penetration.
- Comparison of centrifugal force-aided methods versus stationary incubation.
- Analysis of salt concentration, pH, and temperature effects on virus-cell interactions.
Main Results:
- Centrifugal force increased virus attachment to over 95% within 10 minutes, compared to 35% with stationary incubation.
- Electrostatic forces were indicated to mediate initial virus-cell attachment, with optimal binding at 0.2 M NaCl.
- Virus penetration was linear, complete within 15 minutes at 35°C, and dependent on pH and temperature, with optimal NaCl at 0.1-0.2 M.
- Diethylaminoethyl-dextran partially inhibited both attachment and penetration.
Conclusions:
- Centrifugal force is a highly effective method for enhancing influenza virus attachment and penetration.
- Initial virus-cell interactions are governed by electrostatic forces, influenced by salt concentration, pH, and temperature.
- These findings provide insights into the biophysical mechanisms of influenza virus entry.