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Abstract:
Plaque production by 55 rhinoviruses in several lines of HeLa cells is reported. Forty-nine types produced macroscopic plaques under the conditions described previously employing 30 mM MgCl(2) and 30 mug/ml of DEAE-dextran in overlay and M HeLa cells. Basically three kinds of plaques were observed: clear large and intermediate sized plaques and small turbid plaques. Five rhinoviruses produced plaques only in a sensitive clonal line isolated from the M HeLa line. Rhinovirus type 4 produced plaques after the pretreatment of cells with actinomycin D. Enhancement of plaque formation by MgCl(2) has been demonstrated to date with 17 rhinoviruses. Some rhinoviruses were enhanced either by DEAE-dextran or by dextran sulfate in the overlay. No inhibitors were found in any of 10 bovine sera tested. Rhinovirus type 2 was visualized inside HeLa cells by electron microscopy and there appeared to be a very high ratio of physical particles per infectious unit of virus.
Insights
This study details rhinovirus plaque formation in HeLa cells, finding that MgCl(2) enhances plaque development for many types. Different plaque morphologies were observed, with some rhinoviruses requiring specific cell lines or treatments for growth.
Area of Science:
- Virology
- Cell Biology
Background:
- Rhinoviruses are a common cause of human respiratory illness.
- Understanding rhinovirus replication is crucial for developing antiviral strategies.
Purpose of the Study:
- To investigate plaque production of 55 rhinovirus types in various HeLa cell lines.
- To identify factors influencing rhinovirus plaque formation and morphology.
Main Methods:
- Culturing 55 rhinovirus types in different HeLa cell lines.
- Utilizing magnesium chloride (MgCl(2)) and DEAE-dextran in cell culture overlays.
- Observing and categorizing plaque morphologies.
- Employing electron microscopy to visualize rhinovirus particles within cells.
Main Results:
- Forty-nine rhinovirus types produced macroscopic plaques under specific conditions (30 mM MgCl(2), 30 µg/ml DEAE-dextran).
- Three distinct plaque types were observed: clear large, intermediate, and small turbid plaques.
- Five rhinoviruses required a specific clonal HeLa cell line for plaque formation.
- Rhinovirus type 4 plaque formation was induced by actinomycin D pretreatment.
- Magnesium chloride enhanced plaque formation in 17 rhinovirus types.
- DEAE-dextran or dextran sulfate enhanced plaque formation in some rhinoviruses.
- No inhibitors were detected in tested bovine sera.
- Electron microscopy revealed a high ratio of physical rhinovirus particles to infectious units.
Conclusions:
- Plaque production assays are effective for characterizing rhinovirus behavior in cell culture.
- Specific cellular and chemical conditions significantly impact rhinovirus plaque formation.
- Further research into the particle-to-infectivity ratio may offer insights into rhinovirus replication efficiency.