Production of influenza virus in serum-free mammalian cell cultures

Human influenza viruses are routinely isolated and grown in a variety of mammalian cell substrates. However, influenza viruses for use as inactivated vaccine are still produced in embryonated eggs. Using a perfusion culture-based bioreactor process using serum-free medium, both human and equine influenza viruses of different types and subtypes could be produced to high titres. Classical DEAE-dextran microcarriers were found to be more suitable than polyester sponge carriers for virus production. In addition, MDCK cells grown in serum-free medium were further validated as the most suitable cell substrate compared to Vero and BHK-21 C13 cells for large scale virus production of influenza virus. Finally, to minimize potential contamination by adventitious agents, it was demonstrated that a new serum-free medium in which all animal-derived products are replaced by a plant extract, efficiently supports the growth of MDCK cells as well as the production of influenza virus in the presence of trypsin when using the perfusion bioreactor process.