Detection of canine parvovirus in fecal samples using loop-mediated isothermal amplification.

Loop-mediated isothermal amplification (LAMP) is a novel, sensitive, and rapid technique for detection of genomic DNA. The end-product of the technique is a white precipitate of magnesium pyrophosphate that is visible without the use of gel electrophoresis. The LAMP method was applied to the detection of canine parvovirus (CPV) genomic DNA. A set of 4 primers, 2 outer and 2 inner, were designed from CPV genomic DNA targeting the VP2 gene. The optimal reaction time and temperature for LAMP were determined to be 60 minutes and 63 degrees C. On the basis of results for 50 canine fecal samples using polymerase chain reaction (PCR) analysis as the gold standard, the relative sensitivity of LAMP was 100% and the relative specificity was 76.9%. The detection limit of the LAMP method was 10(-1) median tissue culture infective doses (TCID50)/ml, compared with 10 TCID50/ml for PCR analysis. In addition to the advantage resulting from visual detection of the end product, the LAMP method is very rapid, requiring only 1 hour to complete. This assay would be a viable alterative to PCR analysis for diagnosis of CPV infection in dogs. The LAMP method holds promise for use as a diagnostic assay for CPV detection in a clinical setting.     

Comparison of the Immunofluorescence Assay with RT-PCR and Nested PCR in the Diagnosis of Canine Distemper

Two pairs of primers were prepared, both localized within the sequences of the nucleoprotein gene (NP) of canine distemper virus (CDV). A number of experiments were done to optimize the conditions of RT-PCR and nested PCR methods. The nucleic acids of the Onderstepoort, Rockborn, Snyder Hill and Lederle strains of CDV could be detected with these primers. However, they did not react with the sequences of the Edmonston strain of the measles virus. The detection limit for RT-PCR was 10 TCID50 and for nested PCR 0.1 TCID50 of CDV. The RT-PCR was able to demonstrate the nucleic acid of CDV in the blood of all seven puppies vaccinated with a modified live virus. Blood samples of 23 dogs clinically suspected of distemper were examined by RT-PCR combined with nested PCR, and the results were compared with the detection of the CDV antigen in the smears from the mucous membranes by the direct immunofluorescence (IF) test. Of the 23 dogs, 12 were positive in nested PCR, six in the IF assay, and only two in single RT-PCR. It is concluded that nested PCR seems to be the most sensitive method for ante-mortem diagnosis of canine distemper, especially in its subacute or chronic forms.     

LAMP快速检测犬传染性肝炎方法的建立及应用

根据GenBank上公布的犬腺病毒I型（CAV-I）E3基因序列,设计了3对特异性环介导等温扩增（LAMP）引物,以CAV-I DNA为模板,通过条件优化建立了犬传染性肝炎LAMP快速检测方法,该方法能够在63℃恒温下30min内实现目的核酸的大量扩增,在可见光下即可直接观察扩增产物荧光颜色变化来判定结果。特异性和灵敏度试验表明,该LAMP检测方法只对CAV-I有特异性扩增,对其他无关核酸无扩增。与常规PCR检测相比,LAMP的检测灵敏度较好,最低检出限为10-7TCID50,是PCR检测方法的100倍。临床样品检测结果表明, LAMP阳性检出率为36%,与病毒分离鉴定的结果符合率达96.8%,与PCR检测的结果符合率达100%,且快速简便,成本低,适用于基层实验室的快速疾病诊断。     

犬瘟热病毒野毒株与疫苗株鉴别检测RT-LAMP方法的建立

为建立一种鉴别犬瘟热病毒(CDV)野毒株与疫苗株的反转录-环介导等温扩增方法(RT-LAMP),本研究通过比对野毒株与疫苗株H基因设计特异性引物,对反应体系中的Mg2+、Betaine、Bst DNA Polymerase、dNTP和反应温度等条件分别进行优化,建立用于鉴别检测CDV野毒株与疫苗株的RT-LAMP。建立的RT-LAMP方法检测CDV野毒株时,在65℃水浴锅中反应40 min即可完成。该方法具有高度特异性,对犬细小病毒、犬腺病毒、狂犬病毒、犬冠状病毒无交叉反应,敏感度可达40 copies/μL,是常规RT-PCR方法的100倍。     

大熊猫犬瘟热病毒LG株的分离鉴定

为获得大熊猫犬瘟热病毒株,采集死亡大熊猫的心脏、肺、肝病料,研磨并反复冻融后收集上清液接种Vero细胞,待出现细胞病变(CPE)后,收集病毒液。用逆转录-聚合酶链反应(RT-PCR)鉴定病毒分离株,测定病毒TCID_(50),动物回归试验测定其毒力。结果显示,盲传到第5代时,Vero细胞出现圆缩、聚集、脱落等病变;PCR扩增出287bp片段,与预期相符;测序结果显示,该毒株与已发表的CDV SD(14)11毒株(亚洲-Ⅰ型)的同源性为98%;毒株的TCID_(50)为10~(-5.2)/mL;幼犬感染分离毒株后出现体温升高、鼻头发干、拉稀、眼鼻分泌出水样分泌物等症状。本研究成功分离出大熊猫源犬瘟热病毒株。     

小反刍兽疫病毒RT-LAMP检测方法的建立

利用逆转录环介导等温核酸扩增技术(RT-LAMP)建立了小反刍兽疫病毒快速检测方法,同时评价了该方法的灵敏性和特异性。结果表明,根据小反刍兽疫病毒N基因保守区域设计的LAMP引物能够在63℃恒温下,1小时内实现目的核酸的大量扩增,由于在检测前加入荧光指示试剂,检测结果可以直接用肉眼判断,避免了由于开盖检验带来的扩增产物污染导致的假阳性。该检测体系具有较高的特异性,只能特异性地检测目的病毒,与其他同属的病毒或类似病毒等无交叉反应;具有较高的检测灵敏度,比普通RT-PCR灵敏性高10倍,与荧光RT-PCR的灵敏度相当。     

猪脑心肌炎病毒RT—LAMP检测方法的建立

针对猪脑心炎病毒（Encephalomyocarditis virus,EMCV）3D基因保守序列的6个特异性部位设计了2对引物,利用BstDNA聚合酶,63℃恒温保持50min即可完成反转录与扩增反应,产物中加入SYBR GreenI染料,在紫外光下可直接观察判定扩增结果,试验成功建立了猪EMCV的RT-LAMP检测方法。结果表明：该方法灵敏度比RT-PCR高100倍,具有良好的重复性和稳定性,而且对其他病毒均无扩增结果,可作为猪EMCV的快速诊断方法。     

同时检测犬瘟热病毒和犬细小病毒双重PCR方法的建立

为建立可以同时检测犬瘟热病毒(CDV)和犬细小病毒(CPV)的双重PCR方法,本研究根据GenBank登录的CDV N蛋白序列和CPV NS基因保守序列,设计合成2对特异性引物。通过优化反应条件,对CDV阳性病毒株反转录后的cDNA模板和CPV的DNA模板进行双重PCR扩增,同时得到2条与试验设计相符的669 bp(CDV)和392 bp(CPV)特异性条带,建立了同时检测CDV和CPV的双重PCR方法。实验结果表明:在同一PCR反应体系中可以同时检测这2种病毒,而对犬腺病毒Ⅰ型、犬腺病毒Ⅱ型、狂犬病毒检测均为阴性;CDV和CPV的最低检出限分别为101.8TCID50和101.4TCID50。采用该方法对在黑龙江省不同地区所采集的30份犬病料样品进行检测,CDV阳性率为30%;CPV阳性率为23.33%,表明建立的PCR方法可以用于临床诊断。     

环介导等温扩增技术快速检测犬细小病毒方法的建立

旨在建立一种利用环介导等温扩增技术(LAMP)检测犬细小病毒感染的新方法。根据Gen-Bank中犬细小病毒(CPV)VP2基因序列,设计4条LAMP特异性引物,对反应条件、特异性、敏感性、可视化效果和应用效果进行研究。结果显示,在65℃等温条件下、1h内可完成LAMP扩增过程;病毒的最低检出限量为10-2个TCID50/mL;特异性和可视效果良好;对36份临床标本进行检测,阳性检出率为80.5%(29/36),检出率高于普通PCR 72.2%(26/36)。建立的LAMP检测方法,显示了较高的特异性和敏感性,而且兼具高效、快捷、可视化的优势,为临床检测犬细小病毒感染提供了一种快速简便的新方法。     

犬瘟热病毒单克隆抗体的研制及胶体金试纸条检测方法的建立

本研究利用原核表达、纯化的犬瘟热病毒(Canine distemper virus,CDV)N 蛋白免疫BALB/C小鼠,成功筛选到两株分泌CDV N 蛋白单克隆抗体的杂交瘤细胞株,分别命名为D3、D6。2株杂交瘤细胞分泌单克隆抗体敏感性、特异性良好,能识别不同来源的犬瘟热病毒株,单抗亚类均为IgG1。以D3作为金标抗体,D6作为检测抗体,兔抗鼠IgG作为质控线抗体,制备犬瘟热病毒胶体金检测试纸条,检测犬瘟热病毒敏感性为1000TCID50,能有效检测区分犬瘟热病毒、犬细小病毒(Canine parvovirus,CPV)、犬腺病毒2型(Canine adenovirus type 2,CAV2)、狂犬病病毒(Rabies virus,RV)。综上,本研究建立的胶体金试纸条检测方法,灵敏度高、特异性强,适用于犬瘟热病毒临床快速诊断。     

水疱性口炎病毒RT-LAMP快速检测方法的研究

根据逆转录环介导等温扩增(RT-LAMP)原理,针对水疱性口炎病毒(VSV)糖蛋白G基因序列中的6个区域设计内外各1对特异引物,建立扩增VSV糖蛋白(G)基因的RT-LAMP方法。扩增产物电泳呈特异的阶梯状条带分布,扩增产物加SYBR GREEN I染色呈特征性的黄绿色,肉眼可直接观察判定。同时,还建立了可以进行定量检测的实时RT-LAMP方法。特异性试验显示,本方法可快速检验鉴别VSV与口蹄疫病毒(FMDV)和猪水泡病病毒(SVDV)。敏感性试验显示,建立的实时RT-LAMP方法检测VSVRNA的最低检测量为0.01 PFU,比实时荧光RT-PCR显著提高。建立的LAMP方法可检测p-VSVNJ质粒DNA的最低量为6.36×10-3pg/μL(1.4×103copies/μL),比PCR也显著提高。综合表明,本研究建立RT-LAMP检测VSV的方法具有特异、敏感、快速、简便的特点,具有开发应用前景。     

Development of a triplex TaqMan real-time RT-PCR assay for differential detection of wild-type and HCLV vaccine strains of classical swine fever virus and bovine viral diarrhea virus 1

In this study, genomic sequences of pestiviruses available in GenBank were aligned to design three primer pairs and TaqMan probes: two targeting the NS5A region of the viral genome of classical swine fever virus (CSFV) for the differentiation of wild-type CSFV and hog cholera lapinized vaccine (HCLV) vaccine, and one targeting the 5'-untranslated region of bovine viral diarrhea virus 1 (BVDV-1). With these primers and probes, a triplex TaqMan real-time RT-PCR assay was developed for differentiating wild-type CSFV, the HCLV strain, and BVDV-1. The detection limit of the assay was 4.5 TCID(50) for wild-type CSFV, 10 TCID(50) for HCLV-strain CSFV, and 3.2 TCID(50) for BVDV-1. The triplex real-time RT-PCR had at least 98% (248 samples) agreement with other RT-PCR methods. The assay provides a sensitive tool for simultaneous detection and differentiation of wild-type CSFV and HCLV from BVDV-1.     

犬流感病毒RT-LAMP快速检测方法的建立

为了建立一种便捷、灵敏的犬流感病毒(CIV)检测技术,本研究根据CIV相对保守的M片段设计3对特异性引物,建立CIV的RT-LAMP检测方法,对反应体系中的MgSO4、Betaine、Bst DNA PoLymerase、dNTP、引物浓度等分别进行了优化,并进行敏感性和特异性试验。结果表明:所建立的反应体系在恒温水浴锅中作用45min即可得到其特有的阶梯状条带,而且对犬细小病毒、犬瘟病毒和犬副流感病毒的扩增结果均为阴性。该方法对CIV RNA的最小检测限为0.1pg,灵敏性高于一步RT-PCR方法。RT-LAMP和普通RT-PCR方法检测临床样品的符合率为93.02%。该方法为犬流感病毒的临床检测提供了一种简便、实用的方法,为基层检疫提供了方便。     

犬瘟热病毒RT-LAMP检测方法的建立及初步应用

环介导等温基因扩增技术(loop-mediated isothermal amplification,LAMP)是一种特异、灵敏、快速的检测方法。为提高犬瘟热病毒(CDV)检测效率、降低检测成本,针对犬瘟热病毒N基因保守区的8个位点设计了6条引物进行RT-LAMP一步法扩增。对反应体系及条件优化,检测特异性、敏感性,扩增产物通过凝胶电泳、显色反应和浑浊度比较进行判定。试验结果表明,该方法特异性强、敏感度高,操作简便、快速、便于观察,适用于门诊和现场检测。     

猪瘟病毒野毒株RT-LAMP可视化检测方法的建立

本研究旨在建立一种可视化检测猪瘟病毒(CSFV)野毒株的反转录.环介导等温扩增方法(RT-LAMP).根据CSFV的NS5B基因序列设计一套RT-LAMP引物,以样品的cDNA为模板,利用Bsf DNA聚合酶,在62℃恒温条件下进行扩增,扩增产物中加入sYBR Green I染料直接或在紫外光下观察判定扩增结果.该方法可检测出不同基因型的CSFV厂野毒株,其检出极限为2.5 TCID_(50)的CSFV,与实时荧光定量RT.PCR方法的敏感性相当;特异性试验表明,该方法对猪瘟免化弱毒疫苗株(HCLV)、牛病毒性腹泻病毒以及其它常见猪源病毒均无扩增反应;通过对126份不同样品进行检测比较,该方法与实时荧光定量RT-LAMP检测方法的符合率达100%.与引物.探针能量转移PCR方法的符合率为98.4%.该方法无需特殊仪器,是一种适用于基层的快速、简便的CSFV野毒鉴别检测方法.