Experimental studies from shake flasks to 3 L stirred tank bioreactor of nutrients and oxygen supply conditions to improve the growth of the avian cell line DuckCelt®-T17

To produce viral vaccines, avian cell lines are interesting alternatives to replace the egg-derived processes for viruses that do not grow well on mammalian cells. The avian suspension cell line DuckCelt -T17 was previously studied and investigated to produce a live attenuated metapneumovirus (hMPV)/respiratory syncytial virus (RSV) and influenza virus vaccines. However, a better understanding of its culture process is necessary for an efficient production of viral particles in bioreactors. The growth and metabolic requirements of the avian cell line DuckCelt -T17 were investigated to improve its cultivation parameters. Several nutrient supplementation strategies were studied in shake flasks highlighting the interest of (i) replacing L-glutamine by glutamax as main nutrient or (ii) adding these two nutrients in the serum-free growth medium in a fed-batch strategy. The scale-up in a 3 L bioreactor was successful for these types of strategies confirming their efficiencies in improving the cells' growth and viability. Moreover, a perfusion feasibility test allowed to achieve up to ~ 3 times the maximum number of viable cells obtained with the batch or fed-batch strategies. Finally, a strong oxygen supply - 50% dO - had a deleterious effect on DuckCelt -T17 viability, certainly because of the greater hydrodynamic stress imposed. The culture process using glutamax supplementation with a batch or a fed-batch strategy was successfully scaled-up to 3 L bioreactor. In addition, perfusion appeared as a very promising culture process for subsequent continuous virus harvesting.