Archives

Page No. : 1-7

ABSTRACT

Japanese encephalitis virus (JEV), a member of the genus Orthoflavivirus, is a leading cause of epidemic encephalitis in Asia, transmitted by Culex mosquitoes with pigs and wading birds acting as amplifying and reservoir hosts, respectively. The virus exhibits genetic variability and has five genotypes I to V (GI–GV). Historically, genotype III (GIII) was the most widespread, but over recent decades genotype I (GI) has largely replaced it across Asia. This genotype shift is attributed to genetic adaptability, increased replication efficiency in mosquito and avian hosts, and better transmission in enzootic cycles by GI. Genotype V (GV), once considered geographically restricted and of low epidemiological importance, has recently re-emerged in countries like China and South Korea, posing new challenges. Vaccine efficacy is closely tied to these genetic shifts; as most current vaccines are based on GIII strains. Studies indicate reduced cross-neutralization and protective immunity by GIII based vaccines against GV and certain GI strains, highlighting gaps in existing vaccination strategies. Understanding JEV s genotype evolution, the factors driving these shifts, and their implications for host adptation and vaccine efficacy is crucial to address the ongoing public health challenge posed by this emerging arbovirus.

Keywords: Japanese encephalitis virus, Genotypes, Distribution, Evolution, Vectors, Humans, Pigs