Real-time PCR for detection and differentiation of Streptococcus equi subsp. equi and Streptococcus equi subsp. zooepidemicus

Strangles is a contagious equine disease caused by Streptococcus equi subsp. equi. In this study, clinical strains of S. equi (n=24) and Streptococcus equi subsp. zooepidemicus (n=24) were genetically characterized by sequencing of the 16S rRNA and sodA genes in order to devise a real-time PCR system that can detect S. equi and S. zooepidemicus and distinguish between them. Sequencing demonstrated that all S. equi strains had the same 16S rRNA sequence, whereas S. zooepidemicus strains could be divided into subgroups. One of these (n=12 strains) had 16S rRNA sequences almost identical with the S. equi strains. Interestingly, four of the strains biochemically identified as S. zooepidemicus were found by sequencing of the 16S rRNA gene to have a sequence homologous with Streptococcus equi subsp. ruminatorum. However, they did not have the colony appearance or the biochemical characteristics of the type strain of S. ruminatorum. Classification of S. ruminatorum may thus not be determined solely by 16S rRNA sequencing. Sequencing of the sodA gene demonstrated that all S. equi strains had an identical sequence. For the S. zooepidemicus strains minor differences were found between the sodA sequences. The developed real-time PCR, based on the sodA and seeI genes was compared with conventional culturing on 103 cultured samples from horses with suspected strangles or other upper respiratory disease. The real-time PCR system was found to be more sensitive than conventional cultivation as two additional field isolates of S. equi and four of S. zooepidemicus were detected.     

Development of loop-mediated isothermal amplification (LAMP) targeting the GroEL gene for rapid detection of Riemerella anatipestifer

Riemerella anatipestifer (RA) infections cause major economic losses in the duck industry. Detection of RA using conventional assays is time-consuming and laborious. In this study, a simple and rapid assay for the detection of RA was established based on the GroEL gene sequence of RA using loop-mediated isothermal amplification (LAMP) with a set of six primers (two outer primers, two inner primers, and two loop primers). This assay was able to detect all the tested RA strains with different serotypes. A minimum of 10 colony-forming units (CFU) of RA was detected, which represents 50-fold higher sensitivity than that of the standard polymerase chain reaction (PCR) method. This assay showed good specificity to RA strains and did not react with any other species of bacteria. The assay is rapidly completed and the amplification is achieved at a minimum of 20 min at 65 C. Furthermore, the assay successfully detected RA in the liver samples of ducklings infected with RA, suggesting that the assay could be used for the clinical diagnosis of RA infection.     

绵羊肺炎支原体LAMP检测方法的建立及初步应用

针对绵羊肺炎支原体(Mo) 16S rRNA基因设计4条环介导等温扩增(LAMP)引物,通过优化反应条件与体系,建立了Mo检测LAMP方法,并对其进行特异性、敏感性及临床应用性检测.结果显示,于60℃保温60 min即可最优化检测Mo,且所建方法仅能特异扩增Mo,最低检出分子拷贝数为1.0×102copies/μL,具有良好的特异性和敏感性.对4份已知阳性病料进行LAMP检测均为阳性,表明所建LAMP可初步应用于临床检测,为羊Mo感染病例诊断提供了新方法.     

嗜水气单胞菌Lamp检测方法的建立及应用

基于嗜水气单胞菌气溶素（aerolysin）基因的序列，设计了1套引物，通过条件优化，成功建立了针对致病性嗜水气单胞菌的环媒恒温基因扩增（Lamp）检测法。采用Lamp法对病原菌进行了扩增，并对病鱼血样进行了检测。结果表明，该法只检出致病性嗜水气单胞菌。对不同浓度的细菌悬液扩增结果表明，Lamp检测嗜水气单胞菌的最低菌液浓度为1．4～14／μL。     

犬细小病毒LAMP检测方法的建立

为提高犬细小病毒(CPV)的检出率,降低检测成本,本研究采用环介导等温扩增(LAMP)技术,建立了一种新型敏感、特异、快速、简便、实用的检测CPV的技术。针对CPVVP2基因保守区设计6条引物,进行LAMP扩增,对扩增反应进行优化,并检测其敏感性、特异性。所建立的方法最佳反应时间为60min,具有良好的特异性,与同属的其它病毒无交叉反应。该方法对CPV的最低检出量为9.3×10-5ng/μL,其敏感性是PCR的100倍。结果表明,该方法特异性强、敏感性高,并且操作简便、检测成本低,检测时间短,在CPV的综合防治和早期诊断方面具有很高的实用价值。     

环介导等温扩增(LAMP)检测禽脑脊髓炎病毒方法的建立

根据已发表的禽脑脊髓炎病毒的VP2基因序列,设计并合成了6对特异扩增禽脑脊髓炎病毒VP2基因片段的引物,通过条件优化,成功建立了针对禽脑脊髓炎病毒的环介导等温扩增(LAMP)检测法,并测定其特异性和敏感性,对采集的禽临床样品的核酸分别进行了检测.结果表明,该法只检出禽脑脊髓炎病毒.敏感性扩增结果表明,Lamp检测禽脑脊髓炎病毒为100fg的RNA模板.该LAMP方法有简便、快速和特异性高的优点,可用于临床上对禽脑脊髓炎病毒的快速检测.     

Development of a loop-mediated isothermal amplification assay for the detection of Mycobacterium bovis

Bovine tuberculosis caused by Mycobacterium bovis is an important zoonosis. In this study, a simple, rapid method for detecting this organism was developed based on loop-mediated isothermal amplification of the mpt83 gene. The technique will be of value in the clinical and field-based diagnosis of M. bovis and can differentiate it from other bacteria such as Corynebacterium diphtheriae, Streptococcus pneumoniae, β-haemolytic streptococci, Pseudomonas aeruginosa, Yersinia pseudotuberculosis, Staphylococcus aureus, and Klebsiella pneumoniae. The limit of detection was 10 copies/μL and the results were corroborated by PCR. The method was highly specific and more sensitive than PCR.     

猪细环病毒LAMP检测方法的建立

为建立一种特异和快速的猪细环病毒(TTSuV)检测方法,本研究通过比对TTSuV的全基因序列,选择其保守区域,设计了针对TTSuV检测的LAMP引物,利用LAMP Real Time Turbidimeter LA-320仪对反应体系及条件进行了优化,建立TTSuV环介导等温扩增的检测方法.结果表明:该方法最佳反应条件为64℃恒温50 min,病毒的最低检出限为5.5拷贝/μL,并且与其他相关传染病无交叉反应.临床样品检测结果显示,猪繁殖与呼吸综合征病毒-(PRRSV)和2型猪圆环病毒(PCV2)阳性的样品中TTSuV呈高阳性率,分别为92％和87.3％,显著高于非PRRSV和PCV2阳性的猪群.该方法的建立为快速及特异性的检测猪TTSuV提供了有效的方法.     

Multiplex polymerase chain reaction for identification and differentiation of Streptococcus equi subsp. zooepidemicus and Streptococcus equi subsp. equi

The closely related streptococcal species Streptococcus equi subsp. zooepidemicus and S. equi subsp. equi were identified by polymerase chain reaction using oligonucleotide primers designed according to species-specific parts of the superoxide dismutase A encoding gene sodA. A further differentiation of both subspecies could be performed by amplification of the genes seeH and seeI encoding the exotoxins SeeH and SeeI, respectively, which could be detected for S. equi subsp. equi but not for S. equi subsp. zooepidemicus. A further simplification of the identification and differentiation of both subspecies was conducted by sodA-seeI multiplex polymerase chain reaction.     

环介导等温扩增技术的改进和发展

环介导等温扩增技术(LAMP)是一种新兴的快速扩增技术,非常适合于现场检测。自建立以来,其在反应速度、产物检测和引物设计等许多方面又得到了进一步的改进和发展,使其性能更优异,用途更广泛。     

副猪嗜血杆菌环介导等温扩增快速检测方法的建立

采用环介导等温扩增技术(loop-mediated isothermal amplification,LAMP)建立了一种快速、灵敏、高度特异的副猪嗜血杆菌(Hps)检测方法。针对Hps16S rRNA基因保守区域设计6条引物,在Bst大片段聚合酶的作用下,对模板DNA进行梯状等温扩增,并且优化LAMP的反应体系,检验其灵敏性与特异性。结果表明:该方法对Hps的最小检测限为0.2pg/μL,灵敏性高于常规PCR方法103倍;完成反应仅需65min。该方法灵敏度高、特异性好,能够作为Hps的快速诊断方法,对于基层和实验室应用均具有良好前景。     

狂犬病病毒LAMP检测方法的建立及初步应用

针对狂犬病病毒基因Ⅰ型核蛋白保守区设计4条识别靶序列上6个位点的特异性引物,在链置换聚合酶(Bst酶)作用下,60℃恒温1 h内完成扩增。反应特异性强、灵敏度高。扩增产物可通过琼脂糖凝胶电泳、显色反应或浊度比较进行判定。通过对反应条件的优化,病毒基因的的最低检出量可达到101拷贝数。该方法可用于狂犬病病毒的实验室检测和临床初步诊断。     

志贺氏菌属环介导恒温扩增快速检测方法的建立及初步应用

为建立快速检测志贺氏菌属的方法,本研究针对其ipaH基因,建立了志贺氏菌属环介导恒温护增(LAMP)快速检测方法。利用该方法对50株细菌进行检测,结果显示7株志贺氏菌均为阳性,其它菌均为阴性,表明该方法具有高度特异性。灵敏度试验显示,对志贺氏菌纯培养菌的检测灵敏度为28cfu/mL,对污染食品中志贺氏菌的检测灵敏度为35cfu/mL。利用该方法对195份涉及肉类、奶类、豆制品及人工污染样品进行检测,共检出29份阳性样品,与细菌分离鉴定检测结果一致。该LAMP方法操作简便、特异性强、灵敏度高且成本低廉,具有良好的应用前景。     

环介导等温扩增技术快速检测猪流行性腹泻病毒

为建立一种快速、灵敏的检测猪流行性腹泻病毒(PEDV)的环介导等温扩增(LAMP)检测方法,本研究针对PEDV的NP基因设计LAMP引物,对反应体系优化并进行特异性及敏感性等试验.结果表明,该方法在65℃下恒温扩增60 min,经SYBR Green Ⅰ染色后仅肉眼观察即可判定结果.该方法特异性好,与传染性胃肠炎病毒、猪轮状病毒、猪瘟病毒及大肠杆菌等无交叉反应,对重组质粒最低检测限度为16拷贝/μL,灵敏度高于普通PCR.该LAMP检测方法特异性强,灵敏度高,操作方便,适于临床检测PEDV.     

弓形虫环介导等温扩增快速检测方法的建立

为了建立弓形虫的快速检测方法,本研究建立了一种灵敏、特异、快速的分子生物学检测方法——环介导等温扩增技术(LAMP)。用10倍系列稀释的DNA样品对该检测方法的灵敏度进行了测试,同时通过对扩增产物做内切酶验证;为证明LAMP技术的特异性,对新孢子虫、附红细胞体、瑟氏泰勒虫等病原体进行检测。结果显示:利用LAMP技术成功检测到弓形虫基因区,此方法的灵敏度可达到能检测5个拷贝DNA分子水平,酶切分析结果正确,并且特异性强,对新孢子虫、附红细胞体、瑟氏泰勒虫等病原体检测均为阴性。说明LAMP技术可应用于弓形虫的快速检测。     

新城疫病毒逆转录环介导等温扩增检测方法的建立

为建立一种新城疫病毒(NDV)的简便、快速、高灵敏度的检测方法,本研究根据NDV融合蛋白基因(F基因)设计合成6条特异性引物,在恒温水浴中进行核酸扩增反应,对反应温度、反应时间以及反应液中Mg2+浓度进行优化,获得最佳反应条件,结果经凝胶电泳分析并在可见光下直接观察.整个RT-LAMP检测用时0.5 h,检测敏感度比RT-PCR高100倍,对禽流感病毒、鸡传染性支气管炎病毒和鸡传染性喉气管炎病毒无交叉反应.本研究建立的NDV RT-LAMP检测方法速度快、不需要高精密的仪器,而且具有灵敏度高、特异性强,操作简单等特点,有望在核酸扩增检测方法中取代RT-PCR技术.     

鸭瘟病毒环介导等温扩增(LAMP)快速检测方法的建立与应用

为建立一种简便、快速、灵敏、特异的鸭瘟病毒(DPV)检测方法,本研究根据GenBank中登录的DPV基因组序列,设计3对特异性的环介导等温扩增(LAMP)引物,经优化反应体系,建立了LAMP快速检测方法.结果表明,LAMP方法能够在63℃恒温下,1h内实现目的核酸的大量扩增.结果判定时只需要在扩增产物中加入SYBRGreen Ⅰ染料,就可以直接在可见光或紫外光下观察颜色变化.该方法敏感性可达0.245 μg/L,比普通PCR灵敏性高10倍;对鸭病毒性肝炎病毒、H9N2亚型禽流感病毒、鸭副黏病毒、鸭源偏肺病毒等的核酸无交叉反应;利用建立的LAMP检测方法对40份临床样品的阳性检出率为30％.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DPV的方法.     

刺激隐核虫LAMP检测方法的建立

为提高大黄鱼刺激隐核虫病的病原体检出率,本研究针对刺激隐核虫(Cryptocaryon irritans) 18S-ITS2基因序列设计4条LAMP引物,在内外引物浓度比2∶1～6∶1、Mg2+浓度2 mmol/L、反应温度61℃～66℃、反应时间60 min的优化条件下,扩增产物经电泳后呈现特异性的LAMP梯形条带.本研究建立的LAMP方法具有高灵敏度(10-7 ng/μL DNA浓度),比常规PCR方法高100倍.将该方法应用于采集自不同地域的虫体样本、病鱼和水样以及不同组织样品的检测,结果在13份样品中有10份检出阳性,并显示该方法既能够检测发病鱼,也能够检出已感染但未发病的鱼.实验表明,该方法是一种能够快速、简易、特异、敏感地检测海水鱼类刺激隐核虫病的病原学检测方法.     

猪多杀性巴氏杆菌环介导等温扩增检测方法的建立

为建立猪多杀性巴氏杆菌(Pm)的快速检测方法,本研究以Pm的PlpB基因序列为靶基因设计特异性引物,建立了Pm特异性的环介导等温扩增(LAMP)快速检测方法.经反应条件优化,确定反应条件为63℃,20 min.检测结果显示,建立的LAMP检测方法具有良好的特异性,灵敏度为25 cfu/mL;与大肠杆菌、副猪嗜血杆菌、胸膜肺炎放线杆菌、沙门氏菌无任何交叉反应.采用建立的LAMP方法与常规PCR方法对临床54份分离样品进行检测,检测结果为31份为阳性,23份为阴性,二者符合率为100％.该方法的建立为Pm在临床上的快速检测提供了一种新的技术手段.