浙江省猪血清中乙脑病毒的分离鉴定及抗体的测定

目的对浙江嘉兴地区采集的猪血清进行乙型脑炎病毒分离鉴定以及了解该地区猪感染乙型脑炎病毒的状况。方法在浙江省嘉兴地区采集猪血清标本，利用病毒分离方法检测猪血清是否携带乙脑病毒，利用间接免疫荧光法对猪血清进行抗体检测。应用荧光定量RT PCR方法对新分离病毒进行鉴定；设计特异性引物，利用RT PCR方法扩增新分离乙脑病毒PrM-E基因，并对新分离病毒进行基因分型和E基因的分析。结果共采集240份猪血清标本，抗体检测阳性率为61.6%。其中6月中旬50%以上的猪乙脑病毒抗体呈阳性。分离出3株病毒。经荧光定量RT PCR鉴定3株病毒均为乙脑病毒，基因分析表明3株病毒均属于基因I型乙脑病毒。对这2株乙脑病毒的E基因区段进行分析，它们之间核苷酸和氨基酸的同源性均为100%。与疫苗株SA14 14 2相比，核苷酸同源性在87.7%，氨基酸同源在97.0%以上。结论浙江省嘉兴地区猪群中存着乙脑病毒的隐性感染或曾经感染过，提示在该地区自然界中存在着乙脑病毒。

Isolation of Japanese encephalitis virus and detection of antibody against Japanese encephalitis virus in serum of swine from Zhejiang

In order to study Japanese encephalitis virus carried by swine and investigate serum from Jixin region in Zhejinag province antibodies against JEV were tested by IFA.Japanese encephalitis virus in sera were detected by virus isolation.The isolated strains were identified by real time RT-PCR.The Prm-E gene of the isolated virus was amplified by RT-PCR.The result showed that antibodies against JEV were found in 148 out of 240 serum samples and the total positive rate was 61.6%.Three strains were isolated with cytopathogenic effect（CPE）in BHK-21.The phylogenetic analysis showed that the new isolates belonged to genotype I of JEV.Sequence analysis showed that the homology of nucleotide sequences and amino acid sequences among three strains were 100%.Compared with the nucleotide sequences between two strains and the JEV vaccine strain SA14-14-2,the homology was up to 87.7%,and homology of amino acid sequences were up to 97.0%.Compared with the vaccine strain,there were 15 common amino acid sequences in all the three strains.