From single-cell cloning to high-yield influenza virus production - implementing advanced technologies in vaccine process development.

Innovations in viral vaccine manufacturing are crucial for pandemic preparedness and to meet ever-rising global demands. For influenza, however, production still mainly relies on technologies established decades ago. Although modern production shifts from egg-based towards cell culture technologies, the full potential has not yet been fully exploited. Here, we evaluate whether implementation of state-of-the-art technologies for cell culture-based recombinant protein production are capable to challenge outdated approaches in viral vaccine process development. For this, a fully automated single-cell cloning strategy was established to generate monoclonal suspension Madin-Darby canine kidney (MDCK) cells. Among selected cell clones, we could observe distinct metabolic and growth characteristics, with C59 reaching a maximum viable cell concentration of 17.3 × 106 cells/mL and low doubling times in batch mode. Screening for virus production using a panel of human vaccine-relevant influenza A and B viruses in an ambr15 system revealed high titers with yields competing or even outperforming available MDCK cell lines. With C113, we achieved cell-specific virus yields of up to 25,000 virions/cell, making this cell clone highly attractive for vaccine production. Finally, we confirmed process performance at a 50-fold higher working volume. In summary, we present a scalable and powerful approach for accelerated development of high-yield influenza virus production in chemically defined medium starting from a single cell.