Integrating replication kinetics and ultrastructural analysis to identify targets for optimizing rVSV bioproduction.

Area of Science:

• Biopharmaceutical industry
• Virology
• Cell biology

Background:

• Viral products are increasingly important for gene therapy and oncolytic agents.
• Optimizing virus production is crucial for the biopharmaceutical industry.
• Established bioprocess parameters need to be supplemented with advanced analytical methods.

Purpose of the Study:

• To identify bioprocess optimization targets for therapeutic virus production.
• To combine ultrastructural analysis of infected cells with virus replication kinetics.
• To explore the utility of electron microscopy in bioprocess design.

Main Methods:

• Used oncolytic recombinant vesicular stomatitis virus (rVSV) as a model system.
• Assessed replication kinetics using TCID50, qPCR, and optical cytometry.
• Analyzed cell ultrastructure via transmission electron microscopy of high-pressure frozen, freeze-substituted samples.

Main Results:

• Observed a decrease in producer cell diameter during rVSV infection, indicating potential for online monitoring.
• Identified clusters of virions attached to cell membranes, suggesting a target for enhancing virus release.
• Detected inclusion bodies surrounded by endoplasmic reticulum, indicating surplus genomic copies and a bottleneck for particle assembly.

Conclusions:

• Electron microscopy provides valuable insights for optimizing oncolytic virus bioproduction.
• Identified specific ultrastructural changes and cellular events as targets for process improvement.
• Demonstrated the potential of advanced microscopy techniques in biopharmaceutical development.