Unveiling the multi-characteristic potential of hyper-productive suspension MDCK cells for advanced influenza A virus...

The global population faces persistent threats from influenza viruses, with vaccination remaining the most cost-effective preventive measure against influenza. Mammalian cell-based influenza vaccine production has garnered significant attention due to its enhanced safety profile, process controllability, and ability to circumvent adaptive mutations commonly associated with traditional egg-based vaccines, and the particular promise of suspension cell-based production systems for their convenience, economic viability, and scalability potential. Despite years of development and an increasing number of approved animal substrate-based vaccines, numerous challenges persist, especially the incomplete understanding of influenza virus amplification features in the producing cell lines. In previous research, we developed a high-titer suspension MDCK cell-based influenza virus production process and established a high-generation MDCK cell line (MDCK-HG). This study demonstrated enhanced productive capacity of MDCK-HG cells across diverse operational conditions. The maximum hemagglutination titer achieved 15.02 Log₂HAU/100 μL for H9N2 strain and 12.55 Log₂HAU/100 μL for H1N1 strain, which evidenced by a 56.95 % and a 189.79 % increase compared to the original suspension MDCK cells. Through kinetics analyses, transcriptomic profiling, and metabolic characterization, we identified the kinetic features of high-generation cell lines for efficient influenza virus production and discovered that the redistribution of cell cycles, enhanced anti-apoptotic capabilities, elevated membrane synthesis rates, and efficient energy metabolism likely contribute to their increased viral production capacity. These findings not only deepen our understanding of the influenza vaccine production process but also provide valuable guidance for future systematic metabolic engineering efforts aimed at establishing more robust vaccine production processes.