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Zusammenfassung:
Introduction
The replication of viruses using cell culture processes can help to increase productivity as well as applicability of viral vaccines. The viral yield depends on the reached cell density and specific viral replication rate. For a better understanding of the metabolic interactions, a metabolic flux model was applied to different cultivation conditions. Serum containing GMEM medium with glutamine was compared to medium with pyruvate as well as serum-free medium. The effect of viral infection was analyzed by simultaneous infection of the cells using a high MOI (20).
Results
For anchorage-dependent cell growth characteristic phases could be detected that show quasi stationary state behaviour (Wahl et al., 2008). Stationary metabolic flux analysis was applied to these phases and compared; Significant differences were found especially regarding the glycolytic activity as well as oxidative phosphorylation. Comparing glutamine containing with pyruvate containing medium a decrease of more than 50% in glycolytic fluxes was observed while respiration increased by about 100%. Rates in serum-free cultivations are in between these values. Less pronounced changes were found for amino acid metabolism. Influenza virus infection leads to an increase in glucose catabolism and lactate excretion. At the same time intracellular concentrations were monitored. A high correlation between flux rates and intracellular metabolite levels was observed during infection.
Conclusions
High cell densities will only be reached in media providing sufficient nutrients and low accumulation of toxic waste products like lactate and ammonia. First high cell density experiments using a medium with pyruvate addition worked out well using a perfusion strategy.
