西方马脑炎病毒TaqMan MGB荧光定量RT-PCR检测方法的建立

通过RT-PCR从西方马脑炎病毒(WEEV)中扩增得到1 317bp特异的保守序列,将其克隆到pMD-20T载体中,进行体外转录,制备标准品cRNA。以10倍比稀释的cRNA为模板,进行TaqMan MGB荧光定量RT-PCR扩增并制作标准曲线,建立了WEEV荧光定量RT-PCR检测方法。对建立的方法进行了特异性和敏感性试验。结果表明,建立的荧光定量RT-PCR方法最低可检测10拷贝的cRNA;且与马鼻肺炎病毒(EHV-1)、马动脉炎病毒(EAV)、马流感病毒(EIV,H3N8)、西尼罗病毒(WNV)、东方马脑炎病毒(EEEV)和日本脑炎病毒(JEV)不发生交叉反应。与常规RT-PCR相比,该方法更加快速,特异性和敏感性更高,灵敏度为常规RT-PCR方法的100倍。     

5种人兽共患病病毒多重RT-PCR检测方法的初步建立

为建立可同时检测裂谷热病毒(RVFV)、戊型肝炎病毒(HEV)、狂犬病毒(RV)、水泡性口炎病毒(VSV)及口蹄疫病毒(FMOV)5种人兽共患病病毒的多重RT-PCR快速检测方法,本研究根据GenBank登录的上述5种病毒的全基因组序列,设计了5对多重PCR引物,通过优化反应条件,建立检测以上5种病毒的多重RT-PCR方法.通过对同一种属的其他病毒及相关病毒的检测,确定方法的特异性;通过对体外转录合成的RNA进行定量检测的方法,确定方法的敏感度.实验结果表明:在同一RT-PCR反应体系中可同时检测以上5种病毒,扩增片段长度分别为499 bp、137 bp、274 bp、224 bp、389 bp;而对新城疫病毒(NDV)、赤羽病病毒(AKAV)、牛流行热病毒(BEFV)和乙型脑炎病毒(JBEV)的检测均为阴性;5种病毒RNA的最低检测拷贝数分别为2.91×104、3.14×1 03、1.25×103、6.65×103和2.38×104.利用该方法对11份RV已知阳性样本和7份HEV已知阳性样本检测结果均呈阳性.本研究建立了一种快速、可同时检测5种人兽共患病病毒的多重RT-PCR检测方法,该方法具有良好的特异性和较高的敏感性.     

东方马脑脊髓炎病毒TaqMan MGB荧光定量RT-PCR检测方法的建立

本试验通过RT-PCR从东方马脑脊髓炎病毒(EEEV)中扩增得到128bp的特异性保守序列,将其克隆到pMD20-T载体中,并进行体外转录,制备标准品cRNA。以10倍系列稀释的cRNA为模板,进行TaqMan MGB荧光定量RT-PCR扩增并制作标准曲线,建立了EEEV TaqMan MGB荧光定量RT-PCR的检测方法。进一步对建立的方法进行了特异性和敏感性试验。结果表明,建立的TaqMan MGB荧光定量RT-PCR最低可检测10拷贝/μL的cRNA;且与阴性对照及马鼻肺炎病毒(EHV-1)、马动脉炎病毒(EAV)、马流感病毒(EIV,H3N8)、西尼罗病毒(WNV)、西方马脑脊髓炎病毒(WEEV)和日本马脑炎病毒(JEV)均不发生交叉反应。所制作的标准曲线在1.0×101~1.0×106拷贝/μL浓度范围内有极好的线性关系,相关系数为0.998,标准曲线方程式为y=40-3.35logx;与常规RT-PCR相比,该方法更加快速,特异性和敏感性更高,灵敏度为常规RT-PCR方法的100倍。试验结果表明,建立了一种快速、高效、特异、敏感的EEEV TaqMan MGB荧光定量RT-PCR检测方法。     

流行性乙型脑炎病毒一步法RT-LAMP检测方法的建立

为建立一种简便、快速、灵敏、特异的乙型脑炎病毒(JEV)检测方法,本研究根据GenBank中登录的25株流行性JEV基因组序列,设计3对特异性的环介导等温扩增(LAMP)引物,优化反应体系,建立了一步法反转录-LAMP(RT-LAMP)检测方法。该方法检测时间短,灵敏度比常规RT-PCR方法高,可检测出103TCID50/0.2mL JEV;特异性强,对猪细小病毒、猪圆环病毒、伪狂犬病毒、猪瘟病毒等常见猪病毒均无交叉反应。结果判定时只需要在扩增产物中加入SYBR GreenⅠ染料,就可以直接在可见光或紫外光下观察颜色变化。该方法简便快捷,省时省力,是一种适用于基层实验室快速、准确检测流行性JEV的方法。     

日本脑炎病毒套式RT-PCR方法的建立与初步应用

根据GenBank上登录的日本脑炎病毒(JEV)E基因序列,设计内外2对引物.以JEV疫苗株为模板,建立了检测猪JEV的套式RT-PCR方法.应用该方法对JEV疫苗株RNA进行扩增,获得与预期大小相符,长度为228 bp的目的片段;检出JEV-RNA的灵敏度约为0.3 pg.表明所建立的套式RT-PCR方法对JEV的检测敏感性高、特异性强.     

基于E基因的猪乙型脑炎病毒一步法RT-PCR快速检测方法的建立和应用

根据猪乙型脑炎病毒(JEV)E基因保守序列设计了1对引物,建立了检测猪乙型脑炎病毒一步法反转录-聚合酶链(RT-PCR)方法,并对其特异性、敏感性进行了研究。该一步法RT-PCR对JEV扩增结果为阳性,对照毒株扩增结果均为阴性,对JEV检测的灵敏性为10 pg总RNA量。以上结果表明该一步法RT-PCR特异性强、敏感性高、简便、快速,可用于猪乙型脑炎的早期确诊和病毒鉴定。     

家畜传染病学分会第十三次学术研讨会学术报告之四 近年来我国流行性乙型脑炎研究进展

流行性乙型脑炎又称日本乙型脑炎,简称乙脑,是由日本乙型脑炎病毒(Japanese encephalitis Virus,JEV)引起的一种蚊媒性人兽共患传染病。多种动物易感,蚊是JEV的主要传播媒介,猪是该病毒在自然界最重要的贮存和增殖宿主,且可引起仔猪脑炎和种猪繁殖障碍,给养猪业造成巨大经济损失。人对JEV普遍易感,但大多数为隐性感染,少数青少年及儿童感染后发生病毒性脑炎,病死率高。     

检测CSFV、JEV、PRRSV三种RNA病毒多重RT-PCR方法的建立

猪瘟病毒(CSFV)、流行性乙型脑炎病毒(JEV)和猪繁殖与呼吸综合征病毒(PRRSV)是引起严重的种猪繁殖障碍的病原,而且经常混合感染,及时准确诊断是防治的前提。根据GenBank发表序列选取3对引物建立检测CSFV、JEV和PRRSV病毒的多重RT-PCR方法,扩增产物分别为508 bp、380 bp、263 bp。经与IDEXX商品化的检测CSW抗原试剂盒比较,二者的符合率为96.7%;扩增JEV和PRRSV PCR产物分别经EcoR V和Sau3A I酶切得到预期的片段。建立的多重RT-PCR检测JEV、PRRSV和CSFV敏感度分别为12.5个TCID_(50)、10个TCID_(50)和10~(-3)ng总RNA。结果表明该多重RT-PCR方法具有很好的特异性和敏感性,可用于临床三种病毒核酸的检测。     

乙型脑炎病毒套式RT-PCR检测方法的建立及应用

为了建立一种快速的乙型脑炎病毒(JEV)病原检测方法,根据GenBank上登录的JEV基因组序列,设计合成内外2对引物,优化PCR反应条件,建立了检测JEV的套式RT-PCR方法。结果:该方法对猪繁殖与呼吸综合征病毒、猪瘟病毒、猪细小病毒、猪圆环病毒2型、猪伪狂犬病毒的扩增结果均为阴性;该方法第1次扩增的敏感性是100 pg,第2次扩增的敏感性是1 pg,第2次比第1次扩增的敏感性高100倍。研究表明建立的套式RT-PCR方法具有良好的特异性、敏感性,可以准确快速检测出极低含量的JEV,将为JEV感染的临床诊断、病料检测和分子流行病学调查等提供一种高效、快速、特异、灵敏的检测方法。     

我国流行性乙型脑炎研究近况

流行性乙型脑炎又称日本乙型脑炎(简称乙脑),是一种由日本脑炎病毒(JEV)引起的人兽共患传染病。近两年来我国学者对该病进行了不少研究,获得显著进展。本文从流行性乙型脑炎的病原学、流行病学、检测技术、免疫预防和疫苗研制等方面在我国的研究现状进行综述。     

Identification of equine herpesvirus 3 (equine coital exanthema virus), equine gammaherpesviruses 2 and 5, equine adenoviruses 1 and 2, equine arteritis virus and equine rhinitis A virus by polymerase chain reaction

OBJECTIVE: To develop rapid (< 8 hour) tests using polymerase chain reaction (PCR) for the diagnosis of equine herpesvirus 3 (EHV3; equine coital exanthema virus), equine gammaherpesviruses 2 (EHV2) and EHV5, equine adenovirus 1 (EAdV1), EAdV2, equine arteritis virus (EAV), equine rhinitis A virus (ERAV; formerly equine rhinovirus 1) DESIGN: Either single round or second round (seminested) PCRs were developed and validated. METHODS: Oligonucleotide primers were designed that were specific for each virus, PCR conditions were defined and the specificity and sensitivity of the assays were determined. The application of the tests was validated using a number of independent virus isolates for most of the viruses studied. The PCRs were applied directly to clinical samples where samples were available. RESULTS: We developed a single round PCR for the diagnosis of EHV3, a seminested PCR for EHV2 and single round PCRs for EHV5, EAdV1, EAdV2 and RT-PCRs for EAV and ERAV. The PCR primer sets for each virus were designed and shown to be highly specific (did not amplify any recognised non-target template) and sensitive (detection of minimal amounts of virus) and, where multiple virus isolates were available all isolates were detected. CONCLUSION: The development and validation of a comprehensive panel of PCR diagnostic tests, predominantly for viruses causing equine respiratory disease, that can be completed within 8 hours from receipt of clinical samples, provides a major advance in the rapid diagnosis or exclusion diagnosis of these endemic equine virus diseases in Australia.     

马疱疹病毒1型SYBR Green Ⅰ荧光定量PCR检测方法的建立

为建立马疱疹病毒Ⅰ型(EHV-1)的检测方法,本研究以EHV-1 gB基因的一段保守区域(1207 bp～1509 bp)作为检测的目的片段设计引物,通过对其反应条件的优化,建立了特异性检测EHV-1的SYBR Green I 荧光定量PCR方法.实验结果表明:该方法检测目的基因的灵敏度下限为10拷贝/μL,比常规PCR方法高100倍;与马疱疹病毒4型(EHV-4)及其他马传染病病原体无交叉反应;组内及组间的变异系数均小于2％.该方法检测速度快及高敏感性的特点为马鼻肺炎的防制提供了有力保障,同时也为进一步开展马鼻肺炎相关的研究提供了有效的辅助检测方法技术.     

H3N8亚型马流感病毒单克隆抗体的制备及鉴定

以灭活马流感病毒(EIV)A/Equine/Jilin/1/1989(H3N8)为免疫原,免疫Balb/c小鼠,经常规细胞融合后,用血凝抑制试验(H1)和间接ELISA方法筛选获得3株(3C2、5G10和5A10)能稳定分泌H3N8亚型马流感病毒单克隆抗体(mAb)的杂交瘤细胞株.其中3C2和5G10为IgG2α,5A...     

应用多重PCR检测和区分3个型的马疱疹病毒

针对马疱疹病毒（EHV）的EHV-1、EHV-2和EHV-4糖蛋白B基因序列，设计、合成了3对特异性引物进行多重PCR，不仅可以在数小时内分别检测这3个型的EHV，而且在同一反应系统内可以清晰地区分EHV-1、EHV-2和EHV-4，其PCR产物大小分别为226、333、570bp，符合预期的片段大小，序列分析证实与已发表的序列一致；该检测方法的灵敏度达到10^3 TCID50；分别从血清学阳性但病毒分离为阴性的1匹进口马组织样品和一些出口前检疫马的鼻咽样品检测到EHV-1和EHV-4特异性核酸。     

抗东方马脑炎病毒结构蛋白E2单克隆抗体的制备及其抗原表位的鉴定

为制备抗东方马脑炎病毒(EEEV)结构蛋白E2的单克隆抗体(MAb)并鉴定其抗原表位,本研究以Bac-to-Bac真核表达系统表达EEEV E2蛋白,纯化后作为免疫原免疫BALB/c小鼠,取其脾淋巴细胞与小鼠骨髓瘤细胞SP2/0进行融合.以原核表达载体pET-30a表达并纯化的EEEV E2蛋白作为包被抗原建立间接ELISA方法筛选杂交瘤细胞,获得4株稳定分泌抗EEEV E2蛋白MAbs的杂交瘤细胞株,分别命名为6F3、6F11、7C11、8B11.Western blot与间接免疫荧光试验结果表明,获得的4株MAbs均与EEEV呈阳性反应,而与西方马脑炎病毒、乙型脑炎病毒以及登革热病毒1型～4型呈阴性反应.利用部分重叠的原核表达的短肽对E2蛋白抗原表位进行鉴定,初步确定MAb 6F11、7C11和8B11识别的抗原表位均为E-33 (321EGLEYTWGNHPPKRVW336),而MAb 6F3无短肽与其反应,推测可能为构象表位.本研究结果为建立EEEV型特异性检测方法、研究E2蛋白结构功能及该病的进一步防制奠定了基础.     

Identification of equine herpesviruses 1 and 4 by polymerase chain reaction

OBJECTIVE: To develop and validate specific, sensitive and rapid (< 8 hour) diagnostic tests using polymerase chain reaction (PCR) for the diagnosis of abortion and respiratory disease caused by equine herpesvirus 1 (EHV1; equine abortion virus) and EHV4 (equine rhinopneumonitis virus). DESIGN: Primer sets based on nucleotide sequences encoding glycoprotein H (gH) of EHV1 and gB of EHV4 were designed and used in single round and second round (seminested) PCRs, and in a multiplex PCR for the diagnosis of EHV1 and EHV4 infections. METHODS: Oligonucleotide primers were designed for each virus, PCR conditions were defined and the specificity and sensitivity of the assays were determined. The tests were applied to tissue samples from aborted equine foetuses and to nasopharyngeal swabs from horses with acute febrile respiratory disease. RESULTS: Individual single round and a second round (seminested) EHV1 and EHV4 PCRs were specific in that EHV1 primers amplified all (n = 30) EHV1 isolates and did not amplify EHV4. Similarly EHV4 primers amplified all (n = 6) EHV4 isolates and did not amplify EHV1. Both PCRs were sensitive in that the first round EHV1 PCR detected 1220 molecules of EHV1 plasmid DNA and the first round EHV4 PCR detected 7280 molecules of EHV4 plasmid DNA. The EHV1 second round PCR was 100 times more sensitive in that it detected 12 molecules of EHV1 DNA and the EHV4 second round PCR was 1000 times more sensitive in that it detected 8 molecules of EHV4 DNA. There was a high correlation between detection of EHV1 by virus isolation and PCR when tissue samples from 71 aborted foetuses were examined; all samples positive by virus isolation were positive by PCR. Similarly the EHV4 PCR was at least as sensitive as virus isolation when applied to nasaopharyngeal swabs from horses with respiratory disease in that all samples positive by virus isolation were also positive by PCR. CONCLUSION: Individual single round and second round (seminested) PCRs and a seminested multiplex PCR were developed that enabled reliable, rapid detection of EHV1 and EHV4 in aborted foetal tissues and nasopharyngeal swab samples.     

A survey of respiratory viruses in New Zealand horses

AIMS: To determine which viruses circulate among selected populations of New Zealand horses and whether or not viral infections were associated with development of respiratory disease.

METHODS: Nasal swabs were collected from 33 healthy horses and 52 horses with respiratory disease and tested by virus isolation and/or PCR for the presence of equine herpesviruses (EHV) and equine rhinitis viruses.

RESULTS: Herpesviruses were the only viruses detected in nasal swab samples. When both the results of nasal swab PCR and virus isolation were considered together, a total of 41/52 (79%) horses with respiratory disease and 2/32 (6%) healthy horses were positive for at least one virus. As such, rates of virus detection were significantly higher (p<0.001) in samples from horses with respiratory disease than from healthy horses. More than half of the virus-positive horses were infected with multiple viruses. Infection with EHV-5 was most common (28 horses), followed by EHV-2 (27 horses), EHV-4 (21 horses) and EHV-1 (3 horses).

CONCLUSIONS: Herpesviruses were more commonly detected in nasal swabs from horses with respiratory disease than from healthy horses suggesting their aetiological involvement in the development of clinical signs among sampled horses. Further investigation to elucidate the exact relationships between these viruses and respiratory disease in horses is warranted.

CLINICAL RELEVANCE: Equine respiratory disease has been recognised as an important cause of wastage for the equine industry worldwide. It is likely multifactorial, involving complex interactions between different microorganisms, the environment and the host. Ability to control, or minimise, the adverse effects of equine respiratory disease is critically dependent on our understanding of microbial agents involved in these interactions. The results of the present study update our knowledge on the equine respiratory viruses currently circulating among selected populations of horses in New Zealand.