猪源性乙型脑炎病毒分离株全基因序列测定和分析

[摘要] 目的 了解猪源性乙型脑炎病毒（乙脑病毒）的基因特征。方法 对猪源性乙脑病毒株（JX61）进行全基因组序列测定和基因进化特性的分析。结果 猪源性乙脑病毒JX61株全基因组全长均为10964个核苷酸,含有一个开放阅读框架,编码3432个氨基酸。与GenBank中选择的41株乙脑病毒全基因序列比较发现,其核苷酸同源为83.6-99.3%,氨基酸总体同源性为94.9%-99.6%。通过全基因序列进行系统进化分析均显示该毒株属于基因I型乙脑病毒。结论 猪源性乙脑病毒JX61株属于基因I型,与国内分离株XJP613关系最为接近。提示猪体内的乙脑病毒基因型别有了新的变化,这也是浙江省在猪机体第一次分离基因I型乙脑病毒。     

云南省通海县蚊虫2株乙型脑炎病毒的分离鉴定

目的了解云南省通海县蚊虫携带的乙型脑炎病毒(JEV)情况、分子特征及基因分型。方法 2015年7月在云南省玉溪市通海县采用诱蚊灯在调查点通宵捕捉蚊虫,蚊虫研磨后分别接种BHK-21和C6/36细胞进行病毒分离,使用黄病毒属特异引物进行初步鉴定,使用乙型脑炎病毒E基因特异引物进行RT-PCR扩增及测序,使用Megalign、Genedoc、Mega7等软件进行序列分析。结果共捕获三带喙库蚊、中华按蚊、致倦库蚊和骚扰阿蚊2 300只,其中三带喙库蚊为优势蚊种(78%)。分46批进行病毒分离,获得2株阳性分离物,接种BHK-21细胞96 h,引起细胞病变。使用黄病毒属特异引物和乙型脑炎病毒E基因特异引物扩增均为阳性。序列分析结果显示,2株新分离乙型脑炎病毒与疫苗株SA14-14-2在E基因存在12个氨基酸差异位点,在8个与乙脑病毒毒力相关的位点上存在6个差异位点。E基因遗传进化分析显示,2株新分离病毒与基因Ⅰ型乙型脑炎病毒位于同一进化分支,核苷酸和氨基酸同源性分别为91.8%～99.1%和98.0%～100%。遗传进化分析显示,其与云南2016年蚊虫中分离的乙脑病毒株JEV/mosq/YN/2016亲缘关系较近,核苷酸和氨基酸同源性分别为99.1%和99.8%。结论云南省通海县分离的2株病毒鉴定为基因Ⅰ型乙型脑炎病毒,其与云南省近年来流行的毒株遗传进化关系较近。2毒株的E基因上与毒力相关的关键位点中有2个位点发生突变,结构域Ⅲ的关键抗原未发生改变,因此SA14-14-2减毒疫苗株仍可用于该地区人群的免疫接种,以预防乙型脑炎的发生和流行。     

云南省通海县蚊虫2株乙型脑炎病毒的分离鉴定北大核心CSCD

目的了解云南省通海县蚊虫携带的乙型脑炎病毒(JEV)情况、分子特征及基因分型。方法2015年7月在云南省玉溪市通海县采用诱蚊灯在调查点通宵捕捉蚊虫,蚊虫研磨后分别接种BHK-21和C6/36细胞进行病毒分离,使用黄病毒属特异引物进行初步鉴定,使用乙型脑炎病毒E基因特异引物进行RT-PCR扩增及测序,使用Megalign、Genedoc、Mega7等软件进行序列分析。结果共捕获三带喙库蚊、中华按蚊、致倦库蚊和骚扰阿蚊2300只,其中三带喙库蚊为优势蚊种(78%)。分46批进行病毒分离,获得2株阳性分离物,接种BHK-21细胞96h,引起细胞病变。使用黄病毒属特异引物和乙型脑炎病毒E基因特异引物扩增均为阳性。序列分析结果显示,2株新分离乙型脑炎病毒与疫苗株SA14-14-2在E基因存在12个氨基酸差异位点,在8个与乙脑病毒毒力相关的位点上存在6个差异位点。E基因遗传进化分析显示,2株新分离病毒与基因Ⅰ型乙型脑炎病毒位于同一进化分支,核苷酸和氨基酸同源性分别为91.8%~99.1%和98.0%~100%。遗传进化分析显示,其与云南2016年蚊虫中分离的乙脑病毒株JEV/mosq/YN/2016亲缘关系较近,核苷酸和氨基酸同源性分别为99.1%和99.8%。结论云南省通海县分离的2株病毒鉴定为基因Ⅰ型乙型脑炎病毒,其与云南省近年来流行的毒株遗传进化关系较近。2毒株的E基因上与毒力相关的关键位点中有2个位点发生突变,结构域Ⅲ的关键抗原未发生改变,因此SA14-14-2减毒疫苗株仍可用于该地区人群的免疫接种,以预防乙型脑炎的发生和流行。     

重庆三峡库区2012年乙脑病毒分离株基因序列分析

目的 通过分析2012年重庆三峡库区蚊虫中分离乙脑病毒株PrM及E基因序列,揭示毒株的遗传特性。方法 对新分离乙脑病毒的PrM及E基因进行PCR扩增,将扩增产物测序。用分子生物学软件进行核苷酸及氨基酸序列分析,并绘制系统进化树。结果 新分离的8株乙脑病毒株均为基因I型,与我国其他省市的既往分离株进化关系较近;分离株与减毒活疫苗株SA14-14-2相比较,PrM区核苷酸同源性在85.1%～86.7%之间,氨基酸同源性在95.1%～96.3%之间;E基因区核苷酸同源性在87.6%～87.8%之间,氨基酸同源性在96.9%～97.1%之间。所有新分离株与疫苗株在E基因存在14个氨基酸差异位点。结论 2012年8株重庆乙脑分离株为基因I型,在E基因区域与疫苗株相比有部分差异。     

广西新分离流行性乙型脑炎病毒GP0722株全基因组分子特性研究

目的 对广西新分离乙脑病毒GP0722株进行全基因序列测定和分析,了解其基因组结构及毒力特征。方法 应用乙脑病毒全基因组扩增引物进行RT-PCR扩增,PCR产物直接测序,拼接后得到全基因序列。应用Clustal X(1.8)、DNASTAR、Mega 4. 1等生物软件进行核苷酸序列及氨基酸序列分析和病毒的系统进化分析。结果 广西新分离乙脑病毒GP0722全基因长10 965个核苷酸,从97到10 395位编码一个开放阅读框,编码3 432个氨基酸,与目前使用的减毒活疫苗株SA-14-14-2株比较,只有88.9%的核苷酸同源性,97.6%的氨基酸同源性,全基因组共存在1 222个核苷酸差异,83个氨基酸差异。与GenBank中选择的21株乙脑病毒全基因序列比较发现,其核苷酸总体差异率为0.9%~18.8%,氨基酸总体差异率为0.1%~5.2%。通过PrM/C区段、E区段、3′NTR区段和全基因序列进行系统进化分析显示该毒株属于基因1型乙脑病毒。结论 新分离的乙脑病毒GP0722株属于基因1型,与JEV/sw/Mie/40/2004进化关系最近,与疫苗株SA-14-14-2相比关键位点氨基酸未见变异,现行使用的疫苗仍能保护GP0722引起的感染。     

猪乙脑病毒IgG抗体间接免疫荧光检测方法的建立与初步应用

目的建立检测猪血清中流行性乙型脑炎病毒(JEV)IgG抗体的间接免疫荧光试验(IFA)。方法用乙脑病毒感染C6/36白蚊伊蚊细胞制备抗原片,建立检测猪血清中JEV-IgG抗体的IFA方法,并用于猪乙脑血清流行病学调查。结果成功建立特异的猪JEV-IgG的IFA检测方法,并对50份母猪、55份仔猪和65份屠宰猪的血清进行检测。乙脑血清抗体效价≥1:200的分别为88.00%,10.91%和24.62%。结论建立的IFA方法能较好的用于猪血清乙脑流行病学调查。     

3批乙型脑炎减毒活疫苗病毒全基因序列测定和分析

目的对3批乙型脑炎减毒活疫苗病毒进行全基因测序,并与疫苗原始种子序列进行比较。方法随机选取某厂家生产的3批乙脑减毒活疫苗,提取病毒全基因组RNA,逆转录为cDNA后分段PCR扩增并测序。序列拼接后利用MegAlign软件与GenBank中乙脑减毒活疫苗原始种子全基因序列进行同源性比较。结果 3批乙型脑炎减毒活疫苗病毒基因组全长10 977个核苷酸,与乙脑减毒活疫苗原始种子序列同源性为100%。结论三批次乙型脑炎减毒活疫苗遗传特性高度稳定。     

一株神经外低毒力乙型脑炎病毒株的全基因序列分析

目的探究1株新分离的基因Ⅰ型乙脑病毒株的分子生物学特征及其低毒力的分子基础。方法对病毒株扩增,提取其RNA,逆转录PCR后测序,序列与来自世界不同地区不同基因型的野毒株进行同源性比较,并与强毒P3株进行氨基酸位点比对。结果SC04-17在核苷酸和氨基酸序列上,存在与其他基因型毒株不同的特点,与世界各地毒株核苷酸差异率为1.8%～16.5%,氨基酸差异率为0.8%～5.0%;与减毒活疫苗株SA14-14-2的核苷酸、氨基酸同源性分别为88.5%和97.6%,与灭活疫苗株P3核苷酸、氨基酸同源性分别为88.8%和97.9%;与P3强毒株比对,发现72个氨基酸位点差异,分布在全基因的各个区域（E、NS5、NS1和NS3区）。结论SC04-17株的基因序列存在一些独特位点,这些位点的氨基酸变化可能与其低毒力特征有关。     

基因Ⅲ型乙型脑炎病毒Real-time PCR检测方法的建立及应用

目的建立针对云南地区流行的基因Ⅲ型乙型脑炎病毒株Real-time PCR检测方法。方法根据云南地区分离株乙型脑炎病毒株(Yunnan0901)基因组核苷酸序列设计特异性引物,构建pMD18-T-JEV-E质粒,以此为模板进行SYBR GreenⅠReal-time PCR扩增并制作标准曲线,摸索最佳反应体系条件,建立乙型脑炎病毒荧光定量PCR检测方法,并与普通RT-PCR方法相比较。结果建立的SYBR GreenⅠReal-time PCR标准曲线呈现良好的重复性和特异性,与模板浓度呈现良好的线性关系。与RT-PCR方法相比,SYBR GreenⅠReal-time PCR的灵敏度高10倍,而且不与猪瘟病毒、猪蓝耳病毒、猪圆环病毒、基孔肯雅病毒、辛德毕斯病毒核酸发生非特异性扩增,具有良好的特异性。用该方法检测云南部分地区的蚊虫样品,其中库蚊、按蚊乙型脑炎病毒阳性率分别为17.4%和30.7%,且主要为基因型Ⅲ型。结论本实验建立的检测基因Ⅲ型乙型脑炎病毒的SYBR GreenⅠReal-time PCR方法具有特异、敏感、快速、定量、重复性好等特点,可应用于乙型脑炎疫情的监测。     

基因Ⅲ型乙型脑炎病毒Real-time PCR检测方法的建立及应用北大核心CSCD

目的建立针对云南地区流行的基因Ⅲ型乙型脑炎病毒株Real-time PCR检测方法。方法根据云南地区分离株乙型脑炎病毒株(Yunnan0901)基因组核苷酸序列设计特异性引物,构建pMD18-T-JEV-E质粒,以此为模板进行SYBR GreenⅠReal-time PCR扩增并制作标准曲线,摸索最佳反应体系条件,建立乙型脑炎病毒荧光定量PCR检测方法,并与普通RT-PCR方法相比较。结果建立的SYBR GreenⅠReal-time PCR标准曲线呈现良好的重复性和特异性,与模板浓度呈现良好的线性关系。与RT-PCR方法相比,SYBR GreenⅠReal-time PCR的灵敏度高10倍,而且不与猪瘟病毒、猪蓝耳病毒、猪圆环病毒、基孔肯雅病毒、辛德毕斯病毒核酸发生非特异性扩增,具有良好的特异性。用该方法检测云南部分地区的蚊虫样品,其中库蚊、按蚊乙型脑炎病毒阳性率分别为17.4%和30.7%,且主要为基因型Ⅲ型。结论本实验建立的检测基因Ⅲ型乙型脑炎病毒的SYBR GreenⅠReal-time PCR方法具有特异、敏感、快速、定量、重复性好等特点,可应用于乙型脑炎疫情的监测。     

中国首次分离的二株基因Ⅰ型流行性乙型脑炎病毒全基因组序列分析

目的 分析中国首次分离的基因Ⅰ型流行性乙型脑炎病毒(JEV)全基因组的基因组特征。方法 设计JEV全基因组扩增引物,RT-PCR扩增片断,PCR产物直接测序,拼接后获得全基因组序列。采用生物学软件进行同源性和系统进化分析。结果 1977和1982年分离自云南蚊虫的M28和BN82215病毒株基因组全长分别为10 969 bp和10 970 bp,5′非编码区均含有96个核苷酸,3′非编码区含有573和574个核苷酸。它们的开放阅读框(ORF)都从97到10 396位,共10 299个核苷酸,编码3 433个氨基酸。M28和BN82215株与来自GenBank的5个基因型JEV株的全基因组核苷酸和氨基酸同源性分别为78.4％～96.3％和91.4％～99.6％,与近几年国内外基因Ⅰ型流行株的同源性最高,进化关系最接近,都属于基因Ⅰ型。这两株病毒与JEV疫苗株SA14-14-2相比,有56个氨基酸差异,其中E基因有11个氨基酸差异,但都不属抗原关键位点。结论 本研究阐明了中国首次分离的基因Ⅰ型JEV的全基因组分子特征,决定病毒抗原和毒力的E蛋白关键位点无明显变化。证实20世纪70和80年代云南省就有基因Ⅰ型JEV流行。     

Short report: genetic heterogeneity of Japanese encephalitis virus assessed via analysis of the full-length genome sequence of a Korean isolate.

We determined the full-length genome sequence of Japanese encephalitis virus (JEV) K94P05 isolated in Korea. Sequence analysis showed that the 10,963-nucleotide-long RNA genome of K94P05 was 13 or 14 nucleotides shorter than the genome of other JEV isolates because of a deletion in the 3' noncoding region of K94P05. Compared with sequences of other JEV isolates, the full-length nucleotide sequence showed 89.0-89.6% homology, and the deduced amino acid sequence showed between 96.4-97.3% homology. A region of approximately 60 nucleotides immediately downstream of the open reading frame stop codon of K94P05 showed high sequence variability as compared with other JEV isolates. K94P05 formed a distinct group within a phylogenetic tree established with the full-length genome sequences. Cross-neutralization studies showed that polyclonal antibodies to Korean isolates were 3 times better at neutralizing the Korean isolates than antibodies to Nakayama-NIH. These findings suggest that Korean JEV K94P05 is genetically and antigenically distinct from other Asian JEV isolates.     

Complete nucleotide sequence of an Indian strain of Japanese encephalitis virus: sequence comparison with other strains and phylogenetic analysis.

The RNA genome of an Indian strain of Japanese encephalitis virus (JEV), GP78, was reverse transcribed and the cDNA fragments were cloned in bacterial plasmids. Nucleotide sequencing of the cDNA clones covering the entire genome of the virus established that the GP78 genome was 10,976 nucleotides long. An open reading frame of 10,296 bases, capable of coding for a 3,432 amino acid polyprotein, was flanked by 95- and 585-base long 5'- and 3'-non-coding regions, respectively. When compared with the nucleotide sequence of the JaOArS982 strain, the JEV GP78 genome had a number of nucleotide substitutions that were scattered throughout the genome except for the 5'-noncoding region, the sequence of which was fully conserved. Comparison of the complete genome sequences of different JEV isolates showed a 1.3-4.1% nucleotide sequence divergence among them, which resulted in 0.6-1.8% amino acid sequence divergence. Analysis based on the complete genome sequences of different JEV isolates showed that the GP78 isolate from India was phylogenetically closer to the Chinese SA14 isolate.     

Failure of Japanese encephalitis vaccine and infection in inducing neutralizing antibodies against West Nile virus, People's Republic of China

We examined whether live attenuated Japanese encephalitis (JE) vaccine is effective in preventing West Nile virus (WNV) infection in the People's Republic of China. Three groups were recruited into the study: patients with Japanese encephalitis (JE), healthy controls vaccinated with live attenuated 2 SA14-14-vaccine against JE virus (JEV), and unvaccinated healthy controls. Serum samples were collected and screened for IgG antibodies against JEV by an indirect immunofluorescence assay. Positive samples were then analyzed for levels of antibodies against JEV and neutralizing antibodies against West Nile virus (WNV) by a plaque-reduction neutralization test (PRNT). Although most persons had medium to high levels of JEV-reactive IgG and neutralizing antibodies, only 2 of the 82 unvaccinated control samples were positive for the WNV-reactive antibodies. These findings suggest that previous JEV infection or vaccination did not induce adequate levels of WNV-reactive antibodies in the population studied. However, how these persons would respond to a secondary flavivirus infection and whether their prior experience with wild-type or attenuated JE vaccine will provide some cross-protection against WNV disease still warrants further investigation.     

Surveillance of Japanese Encephalitis Virus Infection in Mosquitoes in Vietnam from 2006 to 2008

Japanese encephalitis virus (JEV) infection in mosquitoes was monitored in Vietnam from 2006 to 2008. A total of 15,225 mosquitoes, identified as 26 species in five genera were collected and 12,621 were grouped into 447 pools for examination of JEV infection by assays for cytopathic effects in C6/36 cells and by RT-PCR to detect flavivirus RNA. Three JEV strains were isolated from Culex tritaeniorhynchus Giles collected in northern and southern Vietnam and two JEV strains were isolated from Culex vishnui Theobald collected in the highlands of Vietnam. Genetic and phylogenetic analyses, based on complete E gene nucleotide sequences, revealed that the five JEV strains were classified into the genotype I group and six amino acid differences were found in these five strains. These results indicated that multiple JEV genotype I populations are circulating countrywide in Vietnam, transmitted by bites of their Cx. tritaeniorhynchus and Cx. vishnui.