Evaluation of an In-House Developed Foot-and-Mouth Disease Virus SAT 3 Vaccine Strain Based on Antigen Productivity and Inactivation Kinetics for Commercial Feasibility.

BACKGROUND

In the Republic of Korea, a bivalent foot-and-mouth disease (FMD) vaccine covering serotypes O and A is administered to livestock, while antigens for the other serotypes are stockpiled in overseas antigen banks. To achieve self-reliance in FMD vaccine production, various vaccine strains have been developed using in-house technology. Although SAT 3 has historically been confined largely to Africa, preparedness against this serotype remains necessary, as the possibility of its introduction into Korea cannot be completely excluded.

METHODS

In this regard, we evaluated the commercial potential of the SAT 3 ZIM-R vaccine strain by assessing antigen productivity, scalability, inactivation kinetics, and immunogenicity.

RESULTS

Supplementation with 3 mM Ca2+ markedly increased antigen yield compared with that obtained in the absence of calcium. Further optimization showed that antigen yield was highest at pH 8.0-8.5. During scale-up, antigen yield was maintained at 9.2-9.8 μg/mL in flask cultures and remained high at approximately 7.8 μg/mL in a bioreactor, demonstrating robust scalability. Treatment with 2 mM binary ethylenimine at 26 °C achieved complete inactivation within 24 h. Vaccines formulated with the SAT 3 ZIM-R antigen produced either in flasks or in a bioreactor induced comparable neutralizing antibody responses in pigs following both the primary and booster immunizations.

CONCLUSIONS

Collectively, these findings indicate that SAT 3 ZIM-R is a promising vaccine candidate for large-scale vaccine antigen production and the future establishment of a domestic FMD antigen bank in Korea.