山东省蚊虫乙脑病毒携带状况及分子流行病学研究

Prevalence and Molecular Epidemiology of Japanese Encephalitis Virus in Mosquitoes in Shandong Province,China

为探索中国山东省蚊虫中流行性乙型脑炎(简称乙脑)病毒的携带状况,研究其分子流行病学特征,本研究于2017年和2019年夏季,在济宁微山县、临沂莒南县、东营垦利区、淄博淄川区、烟台龙口市、济南历城区(2017年)和济阳县(2019年)等6个监测点采集蚊虫,分拣分装研磨后,提取上清RNA,使用荧光定量PCR实验检测乙脑病毒核酸,采用最大似然法估算蚊虫中乙脑病毒的携带率,并对阳性标本进行乙脑病毒PrM基因的扩增测序和系统发生学分析。共采集蚊虫标本36015只,其中三带喙库蚊26969只,为优势蚊种。所有蚊虫分为605份标本进行检测,共检出乙脑病毒核酸阳性标本100份,分别来自三带喙库蚊(95)、骚扰阿蚊(2)、中华按蚊(2)和淡色库蚊(1)。2017年和2019年山东省监测点蚊虫JEV总体感染率分别为4.03‰和1.98‰,不同年份不同监测点的蚊虫中乙脑病毒感染率有较大差异。基于PrM基因的系统发生学分析显示本研究的阳性标本均为基因1型乙脑病毒。本研究证明了山东省蚊虫中存在持续性的基因1型乙脑病毒循环,其感染率随时间和地区的不同而呈现动态变化,加强人群中乙脑疫苗的接种是保持全省乙脑发病处于较低状态的重要保证。

We wished to investigate the prevalence and molecular epidemiology of the Japanese encephalitis virus(JEV)in mosquitoes in Shandong Province(China).In 2017 and 2019,mosquitoes were collected in six counties:Weishan,Jvnan,Kenli,Zichuan,Longkou,and Licheng(2017)/Jiyang(2019).Then,mosquitoes were identified according to morphologic characteristics,pooled by species,and homogenized.Total RNA was extracted and real-time reverse transcription-quantitative polymerase chain reaction was conducted to examine JEV RNA.The number of JEV-positive mosquitoes per 1,000 individuals was estimated by the maximum-likelihood method.The PrM coding region of the JEV was amplified,sequenced,and analyzed phylogenetically.A total of 36,015 mosquitoes were collected,26,969 of which belonged to a predominant species:Culex tritaeniorhynchus.Of the 605 pools of mosquitoes,100 pools were positive for the JEV:95 pools of Culex tritaeniorhynchus,two pools of Armigeres obturbans,two pools of Anopheles sinensis,and one pool of Culex pipiens pallens.The overall prevalence of JEV infection was 4.03 and 1.98 per 1000mosquitoes for 2017 and 2019,respectively,and varied in different sites and different years.Phylogenetic analysis based on the nucleotide sequences of the PrM showed that all JEV sequences belonged to genotype 1.Our study demonstrates persistent circulation of genotype 1 of the JEV in mosquitoes in Shandong Province and reveals that the prevalence of infection in mosquitoes varies dynamically.A high inoculation rate of JE vaccine is crucial to keep the prevalence of JE at a low level.