Effects of antifoam agents on Spodoptera frugiperda 9 cell growth and baculovirus infection dynamics

The baculovirus expression system is widely used for recombinant protein production. However, its scalability under shaking or stirring cultivation conditions remains a challenge due to foam formation which can negatively affect cell metabolism and viability, complicate process control, and ultimately lower productivity. Compared to other protein expression platforms, the effect of antifoam agents on insect cell culture has been rarely investigated. This study examines the influence of three antifoam agents-Antifoam 204 (AF204), polypropylene glycol (PPG), and a silicone-based compound (SAG471)-on Spodoptera frugiperda (Sf) 9 cell growth, viability, baculovirus infectivity, and infection dynamics. Dose-response experiments in adherent culture showed that high antifoam concentrations inhibited metabolic activity. In suspension culture, low concentrations of AF204 and PPG enhanced cell growth by reducing lag phase and population doubling time, while growth with SAG471 remained comparable to a no-antifoam control. In virus titer experiments, no effects on the plaque-forming ability of baculovirus particles could be observed. However, infection dynamics monitored in suspension cultures improved in the presence of all three antifoam agents, as shown by cell size increase, living cell stagnation, and enhanced single-cell fluorescence. Foam reduction experiments demonstrated that only SAG471 contributed to foam removal within a non-toxic concentration range. The results indicate that antifoam agents, depending on their concentration and composition, can enhance Sf9 cell growth and viability while potentially modulating cell membrane properties that could improve viral infection efficiency and transfection efficiency of exogenous material. This highlights the potential of antifoam agents for optimizing other virus-based expression systems in higher eukaryotic cells.