Production and antigenic properties of influenza virus from suspension MDCK-siat7e cells in a bench-scale bioreactor

In efforts to overcome limitations associated with egg-based influenza vaccines, mammalian cell substrates have gradually emerged as potential production platforms. Recently, a suspension Madin Darby canine kidney (MDCK) cell line for influenza virus production was created by expressing the human siat7e gene. To examine the broad susceptibility of this novel cell line, the scalability of the production process, and the antigenic stability of cell-derived progeny viruses, infection experiments using four current influenza vaccine strains (A/California/07/2009 X-179A H1N1, A/Brisbane/59/2007 IVR-148 H1N1, A/Uruguay/716/2007 X-175C H3N2, and B/Brisbane/60/2008) were performed. In small-scale experiments, this cell line was found to support high-titer replication of all four virus strains. Subsequently, production in a bench-scale bioreactor and the antigenic characteristics of progeny viruses were assessed. High titers of hemagglutinin (at least 1:512) were produced in a 2-L bench-scale bioreactor with all four strains. Immunoblot results demonstrated higher yields in the cells than those obtained in chicken embryonated eggs with three of the four tested strains. Progeny viruses collected after serial passages in this cell line exhibited minimal mutations in the HA-encoding gene. Hemagglutination inhibition (HAI) assays using ferret antiserum confirmed the antigenic stability. As a proof-of-concept this work demonstrates that by using a proper strategy, high yields of biologically active hemagglutinin can be produced from scalable cultures of suspension MDCK-siat7e cells.