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Abstract:
Disposable bioprocessing systems for media preparation as well as cell cultivation that can be easily brought to production scale have seen a fast evolution in the last few years in bioprocess engineering. Especially, the wave bioreactor with a maximum working volume of 500 L has seen a strong demand for different applications, e.g. plant cells, insect cells with baculovirus as well as different animal cells. The cultivation is performed in disposable cellbags, allowing faster set-up of upstream processing, leading to less requirements for process validation and low investment costs.
The use of a 2L-Wave bioreactor is described for the production of influenza A virus (equine and human) with MDCK cells growing on microcarriers (Cytodex 1). Cultivations with microcarrier concentrations of 2 g/L and 4 g/L in serum containing GMEM medium (SC) are compared to cultivations in serum-free Ex-Cell MDCK medium (SF). Under completely serum-free conditions washing steps and medium exchange was not needed before infection, but difficulties in cell attachment had to be overcome. Discussion of the metabolic data (glucose, lactate, glutamine, ammonia, glutamate, amino acids) from carbon and amino acid metabolism together with cell numbers and virus titers during cell growth and virus replication phase will allow the analysis of advantages and disadvantages of the presented cultivation conditions. The cell physiology is further characterized via the cell cycle distributions during cultivation and infection.
For the wave cultivation maximum virus titers of 2.3-2.6 log HA units/ 100 µL were reached from infection with a moi of 0.05, comparable to a stirred tank bioreactor process. However, in SF medium pH dropped to less than pH 6.8 which resulted in lower HA-titers of 1.7 log HA units/ 100 µL. For the higher microcarrier concentration medium exchange steps (500 mL) were needed for both media. High cell densities (2.8 x 106 cells/mL for 2 g/L microcarrier and 4.7 x 106 cells/mL for 4 g/L microcarrier) in SC medium showed, that the wave bioreactor is a good alternative to stirred tank processes and might be a good and simple production method in case of a pandemic.
