Characterization of a suspension Vero cell line for viral vaccine production.

Vero cells, as approved by the World Health Organization, have been the most commonly used continuous cell line for viral vaccine production over the last 25 years, but their adherent phenotype continues to limit productivity. Adapting to a suspension culture would overcome this restriction and reduce production costs. First, a Vero suspension isolate was obtained and metabolically characterized. Second, RNA sequencing analysis was used to identify differentially expressed genes between adherent and suspension cells, which revealed complete downregulation of adhesion and matrix-associated genes. Additionally, signaling pathways involving Wnt and other tyrosine kinase receptors were identified as potential leads for growth optimization. In particular, supplementation with fibroblast growth factor 2 allowed for a 20% increase in cell density. Finally, a comparative viral productivity assay revealed a 30% increase in poliovirus production in suspension Vero cells compared to adherent cells depending on the serotype, as well as a 140% increase in respiratory syncytial virus production and a 150% increase in yellow fever virus production. This work establishes the potential of the suspension Vero cell line as a new cell platform for viral vaccine production.