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Abstract

For more than half a century influenza vaccines have been produced in embryonated hen’s eggs. While this is still a widely used technique today, there are several drawbacks of this method. These include difficult standardization, chicken protein intolerance, and a fragile supply chain. Therefore, animal cell cultures are becoming increasingly important in influenza vaccine manufacturing. Fast, reliable and robust production processes are essential to manufacturers, as sufficient amounts of vaccine have to be provided within limited time frames. In spite of considerable progress in basic virology over the past decade, there have been only few efforts to characterize cell culture-based influenza vaccine production regarding virus-host cell interaction. For instance, it is largely unknown what role the activation of innate immunity of host cells plays in influenza vaccine production and what impact activation of signaling pathways has on virus yields. In this project, the activation of a number of signaling cascades crucial for influenza A virus replication (NF-κB, IRF-3, PI3K-Akt, Jak-Stat, Raf/MEK/ERK, PKR/eIF2α) was monitored in Madin-Darby Canine Kidney (MDCK) cells using phospho-specific antibodies. Two variants of influenza virus A/PuertoRico/8/34 H1N1 were investigated that replicate to different final titers in cell culture. It could be shown that signaling pathways are induced stronger by the variant that replicates less well. In addition, these results obtained in high multiplicity of infection experiments were confirmed under bioprocess conditions. Current efforts are aimed at clarifying the actual significance of the monitored pathways for virus replication by RNAi technology and by the use of small molecule inhibitors. In the long run, these efforts will facilitate understanding of virus replication in cell culture-based vaccine production and contribute to the design of production cell lines. [1, 2] [1] Heynisch B, Frensing T, Heinze K, Seitz C, Genzel Y, Reichl U. Differential activation of host cell signalling pathways through infection with two variants of influenza A/Puerto Rico/8/34 (H1N1) in MDCK cells. Vaccine 2010 Nov 29;28(51):8210-8. [2] Seitz C, Frensing T, Hoper D, Kochs G, Reichl U. High yields of influenza A virus in Madin-Darby canine kidney cells are promoted by an insufficient interferon-induced antiviral state. J Gen Virol Jul;91(Pt 7):1754-63.