Evaluation of protective efficacy of an inactivated Japanese encephalitis virus genotype Ⅴ strain in mice

The detection of Japanese encephalitis virus (JEV) genotype V (GV) in humans in Korea in 2015 has raised concerns regarding its potential public health impact. Current JEV vaccines, based on genotype Ⅲ (GⅢ) strains, exhibit suboptimal neutralizing activity against JEV GV, thereby underscoring the need for genotype-specific vaccines. To address this, we developed the KNIH (GV) vaccine strain optimized for enhanced production efficiency. We evaluated its neutralizing activity and protective efficacy in a murine model. The currently available GⅢ-based vaccine (Beijing-1 strain) exhibited limited neutralizing efficacy against JEV GV. Conversely, the KNIH-based vaccine elicited strong neutralizing responses against JEV GV but exhibited reduced cross-neutralization against JEV GⅢ. In conclusion, the K15P38-KNIH strain represents a promising vaccine candidate for mitigating the risk associated with JEV GV reemergence. Future studies will focus on evaluating the efficacy of bivalent vaccination strategies against other circulating JEV genotypes in Korea.