Differential activation of host cell signalling pathways through infection with two variants of influenza A/Puerto Rico/8/34 (H1N1) in MDCK cells.

In cell culture-based influenza vaccine production, few efforts have been undertaken to characterise virus-host cell interactions in detail. Two influenza virus strains that grew to different virus titres, and differed in virus dynamics, apoptosis induction and proteome changes were observed. In order to elucidate biological mechanisms related to these differences, the induction of signalling cascades in adherent MDCK cells infected with two variants of influenza A/PuertoRico/8/34 (H1N1) was analysed. The pathways chosen for analysis are key components of the innate immune response and crucial for influenza A virus replication (NF-κB, IRF-3, PI3K-Akt, Jak-Stat, Raf/MEK/ERK, PKR/eIF2α). Interestingly, all investigated pathways were induced stronger by PR8-NIBSC than by PR8-RKI, the virus variant which results in higher virus titres. In particular, PR8-NIBSC infection lead to a higher induction of IFN-beta as well as IFN-stimulated gene expression, which was confirmed by Western blot as well as real-time PCR. Overall, results obtained clearly facilitate interpretation of observations regarding proteome changes and virus-induced apoptosis in cell culture-based vaccine manufacturing processes and support efforts towards design of improved host cell lines.