Efficacy of Binary Ethylenimine in the Inactivation of Foot-and-Mouth Disease Virus for Vaccine Production in South Korea

Foot-and-mouth disease (FMD) vaccines must be produced in a biosafety level 3 facility, so the FMD virus (FMDV) must be completely inactivated after amplification. The inactivation kinetics of FMDV during vaccine antigen production were assessed by evaluating whether the viral titer dropped below 10(−7) TCID(50)/mL within 24 h of binary ethyleneimine (BEI) treatment. This study dealt with four FMD vaccine candidate strains for the efficacy of BEI treatment at different concentrations and temperatures to determine the optimal inactivation condition of each virus. Two domestic isolates, O/SKR/Boeun/2017 (O BE) and A/SKR/Yeoncheon/2017 (A YC), and two recombinant viruses, PAK/44/2008 (O PA-2) and A22/Iraq/24/64 (A22 IRQ), were investigated. The O BE and A22 IRQ required 2 mM BEI at 26 °C and 0.5 mM BEI at 37 °C for complete inactivation. The O PA-2 and A YC required 2 mM BEI at 26 °C and 1 mM BEI at 37 °C. Crucially, the yield of FMD virus particles (146S) in the viral infection supernatant was higher (>4.0 µg/mL) than those previously reported; additionally, there was little antigen loss, even after 24 h of treatment with 3 mM BEI. Overall, it is considered economical to produce FMD vaccines using these four kinds of viruses; therefore, these candidate strains will be prioritized for the manufacture of FMD vaccines in South Korea.