Metabolic modulation through amino acid supplementation enhances foot-and-mouth disease replication in BHK-21 cell culture

Foot-and-mouth disease virus (FMDV) remains one of the most contagious and economically damaging pathogens affecting cloven-hoofed livestock worldwide. Despite the availability of inactivated vaccines, large-scale production continues to face bottlenecks due to suboptimal virus yields in cell culture. Viral replication depends heavily on host cell metabolism, particularly amino acid supply. This study aimed to optimize FMDV growth by supplementing synthetic culture media with selected amino acid and those that could enhance FMDV yield in BHK-21 cells. Five amino acids, arginine, lysine, serine, threonine, and valine, were individually added to Dulbecco’s Modified Eagle Medium (DMEM) at elevated concentrations, and their influence on virus production was quantified using an ELISA-based antigen assay. All experiments were performed in three biological replicates. Among them, valine and lysine significantly boosted viral titers relative to the control, with valine yielding the highest increase (OD 2.92±0.19). These differences are statistically significant (p<0.05) and OD value represents relative absorbance measurements. Further optimization showed that a two-fold valine concentration produced the maximum output, whereas higher concentrations suppressed replication, indicating a concentration-dependent metabolic threshold. The enhancement observed with valine may reflect broader metabolic interactions described in prior studies, but the underlying mechanism remains to be determined. Lysine’s influence may align with known biochemical properties of positively charged amino acids, though no mechanistic analysis was performed. Overall, these findings demonstrate that fine-tuning amino acid composition, particularly moderate valine enrichment, can substantially increase FMDV yield without altering the viral genome or culture process. This simple yet effective metabolic adjustment offers a practical route to improving antigen output and reducing manufacturing costs in FMD vaccine production systems.