Sero-Molecular Epidemiology of Japanese Encephalitis in Zhejiang, an Eastern Province of China.

• Published in: PLOS Neglected Tropical Diseases
• Main Authors: Jin-Ren Pan, Ju-Ying Yan, Jia-Yue Zhou, Xue-Wen Tang, Han-Qing He, Rong-Hui Xie, Hai-Yan Mao, Yan-Jun Zhang, Shu-Yun Xie
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science (PLoS) 2016
• Subjects: Arctic medicine. Tropical medicine; RC955-962; Public aspects of medicine; RA1-1270; Arctic
• Online Access: https://doi.org/10.1371/journal.pntd.0004936; https://doaj.org/article/c1aaa6e6356e456187f75f15921210f5

BACKGROUND:Sporadic Japanese encephalitis (JE) cases still have been reported in Zhejiang Province in recent years, and concerns about vaccine cross-protection and population-level immunity have been raised off and on within the public health sphere. Genotype I (GI) has replaced GIII as the dominant genotype in Asian countries during the past few decades, which caused considerable concerns about the potential change of epidemiology characteristics and the vaccine effectiveness. The aim of this study was to investigate the prevalence of JE neutralizing antibody and its waning antibody trend after live attenuated JE vaccine immunization. Additionally, this study analyzed the molecular characteristics of the E gene of Zhejiang Japanese encephalitis virus (JEV) strains, and established genetic relationships with other JEV strains. METHODOLOGY/PRINCIPAL FINDINGS:A total of 570 serum specimens were sampled from community population aged from 0 to 92 years old in Xianju county of Zhejiang Province in 2013-2014. Microseroneutralization test results were analyzed to estimate the population immunity and to observe antibody dynamics in vaccinated children. E genes of 28 JEV strains isolated in Zhejiang Province were sequenced for phylogenetic tree construction and molecular characteristics analysis with other selected strains. Positive JE neutralizing antibody rates were higher in residents ≥35 years old (81%~98%) and lower in residents <35 years old (0~57%). 7 or 8 years after the 2nd live attenuated vaccine dose, the antibodies against for 4 different strains with microseroneutralization test were decreased by 55%~73% on seropositive rates and by 25%~38% on GMTs respectively. JEV strains isolated in recent years were all grouped into GI, while those isolated in the 1980s belonged to GIII. On important amino acid sites related to antigenicity, there was no divergence between the Zhejiang JE virus strains and the vaccine strain (SA14-14-2). CONCLUSION/SIGNIFICANCES:JE neutralizing antibody positive rates increase in age ...