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Abstract

IMPACT OF INTERFERON SIGNALLING ON VIRUS YIELD IN MAMMALIAN CELL CULTURE-BASED INFLUENZA VACCINE PRODUCTION Background. A well characterized factor limiting Influenza replication in vivo is the type I interferon (IFN) response. We want to analyse whether induction of type I IFN is also a yield limiting factor in a Madin-Darby canine kidney (MDCK) based Influenza production process. Methods. Adherent MDCK cells were transiently electroporated with plasmids coding for several viral IFN antagonists or treated with IFN containing medium and subsequently infected with different influenza strains. Expression of IFN-β and Mx1 was monitored by qRT-PCR,.and the impact on virus yields was analysed (qRT-PCR, HA activity). Results. In cells transfected with viral IFN antagonists, significant reduction of IFN signalling (up to 90 %) during Influenza replication was achieved compared to control cells. Cells treated with IFN prior to infection expressed higher levels of IFN-β and Mx1 during the whole course of virus infection. Concerning virus yield, results indicate that for influenza strains lacking functional NS1, IFN signalling and resulting expression of antiviral genes is a limiting factor for cell specific virus production. For delNS1, an 8-fold increase in virus yield was observed in cells transfected with Influenza NS1 and in cells pre-treated with IFN growth was significantly reduced. However, for virus strains with functional NS1 neither reduction of yield was found in IFN-treated cells nor an increase of yield was seen in cells transfected with IFN antagonists. Conclusions. Experimental data clearly indicate that Interferon expression during Influenza replication is not a yield limiting factor In a MDCK cell culture-based vaccine production processes.