Bionnova, Processing Focus China 2021

High yield mRNA production process from E.Coli to highly pure mRNA

Speaker: Ales Strancar, Managing Director

Key points:

Established processes for pDNA manufacturing include purification steps designed to enrich the supercoiled (sc) isoform. Homogeneous supercoiled isoform improves cell transfection efficiency in fermentation processes and is favoured in cell culture production systems. In vitro transcription (IVT), the enzymatic process used for production of mRNA vaccines differentiates itself from biological fermentation processes by the need for linearised plasmid DNA. The linear isoform is produced with restriction enzymes from open circular and supercoiled plasmid DNA. Employing a traditional pDNA manufacturing process, which removes linear and open-circular isoforms, will therefore reduce the production yield. When plasmid DNA and mRNA are treated as a single production process, the purification steps can be optimised, yields improved, and the overall production cost reduced.
A new purification approach starting from E.Coli all through to mRNA production is presented here. This new approach integrates a pDNA linearisation step before polishing (removal of linear and open circular isoforms) of plasmid DNA. The polishing step, placed after enzymatic linearisation, purifies linear pDNA from enzyme and other unwanted process impurities. The linearised plasmid DNA is then used in IVT for production of mRNA. This approach further introduces mRNA purification tools for improved contaminant removal. The altered sequence of purification and linearisation reduces the overall number of purification steps required, improves recoveries, while the complete process results in extra low protein impurity and very efficient dsRNA removal.

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