Analysis of Japanese Encephalitis Vector Ecology, Host Serology, and Viral Genetic Characteristics in Hunan Province, China

OBJECTIVE: This study aims to investigate the epidemiological characteristics and transmission risk of Japanese encephalitis virus (JEV) in Hunan Province by analyzing mosquito population distribution, piglet serological profiles, and the phylogenetic features of circulating JEV strains. METHODS: Mosquito and piglet serum samples were collected from five prefecture-level cities in Hunan Province. Mosquito species were identified and their densities were measured. Piglet serum samples were tested for JEV antibodies. Detected JEV strains from mosquitoes were sequenced, and phylogenetic analysis was performed. RESULTS: Culex pipiens pallens/quinquefasciatus (65.65%) and Culex tritaeniorhynchus(12.93%) were the dominant mosquito species. The highest mosquito density was observed in pigpens (26.0 mosquitoes/light trap-night). The JEV antibody positivity rate in piglets began to rise in June, peaked in September (83.33%), and lagged two months behind the peak mosquito density (June-July). A significant temporal correlation was found between piglet antibody positivity and mosquito density (*p* < 0.05). Phylogenetic analysis showed that all mosquito-derived JEV strains belonged to genotype I (GI), with 15-17 amino acid mutations in the E gene compared to the vaccine strain SA14-14-2. CONCLUSION: There is a persistent JEV transmission risk in Hunan Province. These findings provide critical insights for local vector control, vaccine optimization, and piglet immunization strategies.