免疫磁分离-荧光PCR应用在肉类单增李斯特氏菌的检测

目的建立适用于肉类产品中单核增生李斯特氏菌的荧光PCR检测方法。方法根据单增李斯特氏菌溶血素基因hlyA,设计合成引物和荧光探针,结合免疫磁珠筛选,选择简便的DNA提取方法,建立适用于检测肉类制品中单增李斯特氏菌的荧光PCR方法。对该方法进行特异性、灵敏度及模拟样品检测效果的研究。结果对20株不同菌属的标准菌株和30株野生李斯特氏菌菌株,及混合菌液的检测,结果显示该方法具有良好的特异性。对染菌模拟样本的检测结果表明,经过24h增菌,该方法的检测低限为1cfu/g,整个流程只需27h。结论免疫磁分离荧光PCR方法为快速、简便和准确检测肉类制品中单增李斯氏菌提供了一个新的途径。     

空肠弯曲菌实时荧光定量PCR检测方法的研究

目的建立一种快速廉价的检测空肠弯曲菌的实时荧光定量PCR方法。方法根据空肠弯曲菌flaA、gyrA基因设计引物,建立空肠弯曲菌实时荧光定量PCR检测方法。结果以flaA基因引物对空肠弯曲菌DNA进行实时荧光定量PCR,扩增曲线呈S形指数增长,大肠埃希菌等对照菌扩增阴性。方法的灵敏度为10CFU/ml菌悬液。结论建立的空肠弯曲菌荧光定量PCR检测方法具有快速、简便、准确等特点,具有一定的使用价值。     

TaqMan MGB探针实时荧光定量PCR快速检测布鲁氏菌

目的利用新一代TaqMan MGB探针技术,建立特异敏感的实时荧光定量PCR方法,用于布鲁氏菌的快速检测。方法针对布鲁氏菌基因组中16SrRNA序列设计特异性引物和探针,建立一套基于TaqMan MGB探针技术的实时荧光定量PCR方法,验证方法的特异性、敏感性和稳定性,对2008-2010年期间采集的773份动物样本中的布鲁氏菌进行检测,并与普通PCR方法进行比较分析。结果建立的TaqMan MGB探针实时荧光定量PCR方法对布鲁氏菌的检测具有高度的特异性,对小肠结肠耶尔森菌、假结核耶尔森菌、肠炎沙门氏菌、大肠埃希菌、铜绿假单胞菌、空肠弯曲菌、泰泽氏菌均无交叉反应。生成的标准曲线的相关系数为0.999,斜率为-3.301,TaqMan MGB探针实时荧光定量PCR效率为100.872%。TaqMan MGB探针实时荧光定量PCR能够准确地从布鲁氏菌阳性样本中检测到布鲁氏菌DNA,最低能够检测到的布鲁氏菌数量为9.3拷贝,比常规PCR方法的灵敏度高100倍。对773份动物样本进行检测,结果TaqMan MGB探针实时荧光定量PCR能检出53份布鲁氏菌阳性样本,而常规PCR只检出37份阳性。结果显示,TaqMan MGB探针实时荧光定量PCR方法比常规PCR方法更敏感,能够直接从动物样本中检出布鲁氏菌DNA,检测时间仅为2h。结论本研究首次建立了直接用于检测动物样本中布鲁氏菌的TaqMan MGB探针实时荧光定量PCR方法,该技术适用于传染性病原体的快速检测与鉴定。     

基于核酸预混室温储运技术的荧光定量PCR快速检测鼠疫耶尔森氏菌

目的 实现荧光定量PCR技术在鼠疫现场和基层的应用。方法 本试验将已建立的基于核酸预混室温储运技术的荧光定量PCR方法应用于我国各鼠疫疫源地野生菌株的检测,进行特异性评价。选取分布于我国境内不同鼠疫疫源地野生鼠疫耶尔森氏菌株、鼠疫减毒菌株、耶尔森菌属近缘菌株假结核菌及小肠结肠炎菌进行荧光定量PCR检测。结果 55株鼠疫耶尔森氏菌及鼠疫减毒菌株扩增阳性,假结核耶尔森氏菌、小肠结肠炎耶尔森氏菌无阳性扩增,冻干试剂在室温25 ℃和37 ℃条件下可保存6个月,敏感性与冷冻保存无差异,核酸扩增诊断可在1 h内完成。结论 应用基于核酸预混室温储运技术的荧光定量PCR方法对我国各鼠疫疫源地55株鼠疫耶尔森氏菌检测呈现高度特异性,本试验冻干试剂具有可室温保存、便于运输、检测结果精准、快速等特点,具有较好的鼠疫现场应用前景。     

荧光定量PCR快速检测鼠疫耶尔森氏菌的实验研究

目的　利用LightCycler建立一种简便、特异的荧光定量PCR检测方法 ,用于鼠疫耶尔森氏菌的快速检测。 方法　采用SYBRGreenI随机掺入法 ,以Roche试剂盒为标准 ,比较两公司的DNA聚合酶 ,用鼠疫菌 310 0 4建立荧光PCR反应体系 ;针对鼠疫耶尔森氏菌特异的染色体标识序列和质粒上F1抗原基因设计引物 ,检测其灵敏度和特异性 ,以盲测试验进行验证 ;在此基础上鉴定 2 75株鼠疫耶尔森氏菌 ,并测试该法检测脏器污染模拟标本的灵敏度。结果　建立以一个公司试剂为主较低成本的PCR反应体系 ;EV76的检测灵敏度可达每反应体系 1.6个菌 ;检测我国 18个生态型共计 2 75株鼠疫耶尔森氏菌及 2 8株非鼠疫菌株的PCR扩增结果表明 ,鼠疫菌株均出现特异的扩增结果 ,2 8株对照菌株均为阴性 ;肝、脾、肺模拟标本检测灵敏度可达每反应体系 4 0 0 0个菌。结论　该方法对于检测鼠疫耶尔森氏菌具有简便、快捷、高敏感性和特异性的特点 ,适用于鼠疫紧急疫情时的快速诊断和疫源地监测     

基于TaqMan探针的双重荧光定量PCR方法检测海产品中的副溶血弧菌

目的建立海产品中副溶血弧菌检测的双重荧光定量PCR体系。方法针对副溶血弧菌种特异性基因tlh和tdh设计引物和TaqMan探针,建立双重荧光定量PCR体系,进行特异性与敏感性研究;利用该体系检测海产品中的副溶血弧菌。结果副溶血弧菌可得到特异性扩增,而其它与副溶血弧菌共存于海产品中的细菌均未见扩增曲线。副溶血弧菌与其它细菌的混合DNA检测表明,其它细菌基因组的存在时并不干扰副溶血弧菌检测。副溶血弧菌典型菌株FJ14和BJ97的敏感性试验显示,该体系的最低检测DNA浓度分别为49.8pg与77.8pg,最低检测细菌浓度为56CFU/mL和371CFU/mL。对舟山菜市场采集的50份样本检测表明,32份为tlh基因阳性,3份为tdh基因阳性,与传统方法的检测结果相同。结论与传统检测方法相比,副溶血弧菌的双重荧光定量PCR检测方法快速准确,结果直观。     

应用荧光定量PCR检测细菌性脑膜炎病原体DNA的研究

目的应用荧光定量PCR检测细菌性脑膜炎病原体DNA,并对脑膜炎奈瑟菌进行基因分群。方法提取脑膜炎患者脑脊液和血标本中待检菌DNA,采用荧光定量PCR扩增ctrA、bexA、lytA基因,对ctrA扩增阳性标本及部分流脑菌株进行基因分群。结果 685份脑脊液标本中19份检出脑膜炎奈瑟菌、8份检出肺炎链球菌、2份检出b型流感嗜血杆菌DNA基因片段;2份血清标本脑膜炎奈瑟菌DNA基因检测均为阳性。对ctrA基因扩增阳性标本进行A、B、C、W135、X及Y分群,有18份为C群,3份为B群;部分健康人群携带的流脑菌株有14份为B群,2份为C群,1份为X群。结论荧光定量PCR灵敏性高,检测快速,可用于细菌性脑膜炎病原体的检测、鉴别及对脑膜炎奈瑟菌的分群。     

基于样品检测的布鲁氏菌荧光定量PCR方法的建立

目的 本文建立一种基于样品检测的特异性好、灵敏性高的布鲁氏菌荧光定量PCR检测方法。方法 以哺乳动物beta-actin基因和外源重组质粒为内参,针对布鲁氏菌属特异性基因IS711,建立用于样品检测的布鲁氏菌荧光定量PCR方法,并验证其敏感性、特异性及稳定性,绘制标准曲线。将该方法用于哺乳动物样品检测,并与细菌分离培养检测结果比较。结果 荧光定量PCR方法对布鲁氏菌检测有良好的特异性,3对引物对阴性对照菌均无非特异性扩增;该方法用于样品检测的最低检测限为17拷贝;内外源内参同时存在条件下,布鲁氏菌荧光定量PCR的标准曲线相关系数为R²=0.997(Y=-3.12X+40.9)。将该方法直接用于181份动物样本的检测,并与分离培养结果相比,荧光定量PCR检测阳性率为11.4%,细菌分离培养检测阳性率为9.9%,且细菌分离培养阳性样品与荧光定量PCR阳性样品中编号基本一致。结论 本文建立的荧光定量PCR检测方法灵敏性高、特异性及稳定性好,可直接应用于样品的检测,检测结果受内参基因质控。     

实时PCR在大肠杆菌O157∶H7快速检测中的应用

目的建立一种快速、敏感、特异的大肠杆菌O157∶H7的定量检测方法。方法根据GenBank公布的O157∶H7大肠杆菌rfbE基因序列,应用分子生物学软件进行序列比对,在该基因的保守区设计引物和TaqMan探针,对荧光定量PCR反应条件进行优化,建立实时荧光定量PCR检测大肠杆菌O157∶H7的反应体系,并对该法的特异性、敏感性和重复性进行了评价。结果所有大肠杆菌O157∶H7菌株的检测结果均为阳性,而所有其它菌株检测结果均为阴性;该方法检测的灵敏度可达1cfu/μL,重复性检测的变异系数均小于5%。在模拟污染牛奶中,可检出1×102cfu/μL的细菌。从细菌核酸提取至完成检测约需3h。结论本研究建立的基于Taqman探针技术的实时PCR检测体系具有快速、灵敏度高、特异性强等优点,可用于大肠杆菌O157∶H7食物中毒的快速诊断和食品微生物检测,为食源性疾病的分子流行病学调查提供新的检测手段。     

利用基因芯片快速检测多种临床常见致病菌及其耐药性基因

目的快速、准确、灵敏地检测临床常见的致病菌及其耐药基因。方法采用基因芯片技术，利用细菌23S rRNA基因序列信息和某些耐药基因作为检测靶基因，设计针对不同菌属的寡核苷酸探针和耐药基因探针的基因芯片，聚合酶链反应（PCR）扩增并荧光标记目的DNA片段，通过杂交反应检测致病菌及其耐药基因。结果在理想状态下（检测试剂盒抽提的细菌基因组DNA）检测的结果与国内外文献报道的灵敏度相当（10^3～10^6细菌／ml），并在部分临床分离株、耐药标准菌株中进行验证，显示该方法有良好的特异性及可重复性。细菌种类能鉴别到种水平的有16种，能鉴别到属水平的有7类。覆盖了临床常见的多种病原菌，并且还可同期检测超广谱β内酰胺酶（ESBLs）基因耐药。结论DNA芯片检测具有快速、高特异性和高灵敏度的特点，是常规鉴定方法的一种有益补充。     

The use of fluorescent molecular beacons in real time PCR of IgH gene rearrangements for quantitative evaluation of multiple myeloma

BACKGROUND AND OBJECTIVES Fluorescent molecular beacons have been employed as hybridization probes in real time quantitative PCR to quantify residual disease in multiple myeloma (MM). DESIGN AND METHODS: After clinical diagnosis of MM, the CDR1, CDR2 and CDR3 regions of the IgH gene were analysed and sequenced to identify its clonal nature. Unique sequences of the clonal IgH rearrangement were used to design specific molecular beacon probes for each MM patient. A molecular beacon probe for the beta-globin gene was used as a reference control to calculate relative amounts of the clonal B-cell population. RESULTS: Optimization of probe design resulted in the use of a competitive sequence at the IgH area target between the loop and part of the stem of the molecular beacon. Cycling conditions and fluorescence temperature acquisition were optimized for a Light Cycler. To validate this method for the follow-up of treated MM patients, we investigated accuracy, as well as interassay and intrassay reproducibility. CONCLUSIONS: Our results indicated that real time PCR with specific molecular beacons provides a feasible, accurate and reproducible method for the determination of minimal residual disease in MM.     

Flanders病毒TaqMan RT-PCR检测方法的建立

目的 应用TaqMan PCR技术建立针对Flanders病毒(Flanders virus, FLAV)的实时荧光定量PCR检测方法。方法 下载GenBank中FLAV基因序列资料并进行多序列比对分析,选择其L基因中的高保守序列片段进行FLAV特异引物与探针的设计,使用来自于不同科属的15株病毒验证方法特异性,通过重复/平行实验验证方法稳定性,并利用体外转录的L基因RNA标准品建立基因拷贝数绝对定量分析模型。结果 引物与探针工作特异性良好,同一样品重复检测Ct值的变异系数均小于1.7%,定量分析模型灵敏度达到100 copies/PCR。结论 建立完成针对FLAV的TaqMan PCR检测方法。实验结果显示,本方法具有高特异性、高敏感性、高稳定性、简便、易操作的特点,为今后对FLAV的检测、监测及相关研究提供技术手段。     

Identification of mycobacteria by sequencing of rpoB gene and 16S rRNA

PURPOSE: To classify a specific Mycobacterium among various mycobacteria utilizing sequencing of rpoB gene. To classify mycobacteria not identified by DNA-DNA hybridization (DDH) using sequencing of rpoB and 16S rRNA gene. OBJECTS AND METHODS: Classification of 106 Mycobacteria strains, one Nocardia strain, one Rhodococcus strain, four Gordona strains was made by using partial sequencing of rpoB and 16S rRNA (RIDOM). Thereafter, 38 mycobacteria clinical strains not identified by DDH were classified utilizing the DNA sequencing data. RESULTS: Pairs of M. kansasii and M. gastri, M. abscessus and M. chelonae, M.fortuitum (ATCC49404) and M. polcinum, M. peregrinum and M. septicum, M. farucinogense and M. senegalense and M. fortuitum (ATCC49403), Rhodococcus, Nocardia and Gordona strains were classified using sequencing of rpoB gene. Even though sequencing of rpoB and 16S rRNA gene was utilized, it was impossible to classify M. tuberculosis complex, M. avium family, M. marinum and M. ulcerans, and M. fortitum subsp. fortuitum and M. fortuitum subsp. acetamidolyticus. The 38 mycobacteria clinical strains not identified by DDH were successfully classified using sequencing of both rpoB and 16S rRNA. These sequencing analyses showed that M. heckeshornense, M. branderi, M. intermedium, M. shimoidei, M. wolinskyi, M. malmoense and M. lentiflavum could be identified. Thirty six clinical isolates (94.7%) and 32 clinical isolates (84.2%) were identified by rpoB sequencing and 16S rRNA sequencing (RIDOM), respectively. CONCLUSION: The classification ratio of mycobacteria including Nocardia, Rhodococcus and Gordona is 69.6% for sequencing of 16S rRNA and 89.3% for sequencing of rpoB gene. Sequencing of rpoB is useful for classification of mycobacteria due to its genetic diversity, but has some limitation in its application. In order to classify mycobacteria more accurately, it is important to combine sequencing of rpoB and 16S rRNA and biochemical/biological tests.     

16S-23SrDNA间隔区序列PCR扩增及探针杂交用于偶然分支杆菌暴发感染的研究

目的　从基因水平上确认福建省南平市注射后偶然分支杆菌暴发感染的致病菌,并建立PCR结合DNA探针杂交快速鉴定偶然分支杆菌的方案。方法 根据偶然分支杆菌16S-23S rDNA间隔区序列,设计合成一段寡核苷酸探针,采用PCR扩增、RFLP和DNA斑点杂交技术,对29株偶然分支杆菌临床分离株进行鉴定。结果 29株偶然分支杆菌临床分离株均被PCR扩增出一条约470bp的DNA条带,DNA探针杂交也出现特异的杂交斑点。结论 16S23SrDNA间隔区序列PCR扩增及DNA探针杂交在基因水平上确认引起此次注射后暴发感染的致病菌为偶然分支杆菌,该方法具有灵敏、特异的特点。     

KOD DNA聚合酶荧光PCR技术在肺结核诊断中的应用评价

目的 评估基于KOD DNA聚合酶的荧光PCR技术在肺结核诊断中的临床应用价值。方法 采集2019年10月至2020年4月疑似肺结核的住院患者痰标本,进行涂片抗酸染色、MGIT960液体培养、KOD DNA聚合酶荧光PCR和Taq DNA聚合酶荧光PCR检测。以临床诊断结果为参照,MGIT960液体培养法为金标准,荧光PCR与Taq DNA聚合酶荧光PCR法比较,评价KOD DNA聚合酶荧光PCR法检测MTB的效能。结果 共对337例临床样本进行检测,MGIT960液体培养法、Taq DNA聚合酶荧光PCR和KOD DNA聚合酶荧光PCR检测MTB的敏感度分别为71.56% (156/218)、76.15% (166/218) 和76.61% (167/218)。KOD DNA聚合酶荧光PCR与MGIT960液体培养检测敏感度差异无统计学意义 (χ²=1.445,P=0.229>0.05)。KOD DNA聚合酶荧光PCR检测MTB的敏感度和特异度分别为92.31% (144/156)和86.39% (146/169),涂阴患者中检测敏感度和特异度分别84.21% (64/76)和88.48% (146/165)。结论 KOD DNA聚合酶荧光PCR检测MTB敏感度和特异度较高,能够为临床诊断肺结核提供依据,操作简便、快速,适合在我国各级结核病实验室推广。     

The chicken leptin gene: has it been cloned?

The DNA sequence of a chicken leptin gene that shares 95% nucleotide similarity with the mouse leptin sequence has been recently reported (Taouis et al., 1998, Gene 208, 239-242). Experiments have been performed independently in two laboratories to try to confirm this finding. Fourteen PCR primers based on the mouse leptin sequence were designed to amplify the avian leptin gene. Four of the primers were identical to the mouse and published chicken leptin sequences. PCR amplification was carried out on genomic DNA and reverse-transcribed mRNA from the fat, liver, and pancreas of several chicken strains and from the domestic turkey, goose, and Japanese quail. No PCR products sharing close similarity to the mouse leptin sequence were generated from any avian templates. Amplification of mouse leptin sequence was consistently obtained when control mouse templates were used. Northern hybridization using a mouse leptin probe failed to produce a signal with poly(A)+ RNA from chicken fat and liver and from the fat and liver of force-fed geese but a strong signal was obtained from control mouse fat total RNA. Southern hybridization under low stringency washing conditions revealed hybridization of a mouse leptin probe to chicken genomic DNA. Under higher stringency washing conditions, the chicken signal disappeared, while those from control mouse and sheep genomic DNA remained. This suggests that the putative chicken leptin sequence shares less than the 83% nucleotide sequence identity between the mouse and sheep genes. It is concluded that a chicken leptin gene sequence with close sequence similarity to mouse leptin is not present in the chicken genome. Furthermore, mRNA sharing high sequence identity with mouse leptin is not present in the fat or liver of the domestic chicken, turkey, goose, or Japanese quail.     

套式PCR和DNA探针技术检测Q热立克次体

目的 建立套式PCR（NPCR）和DNA探针技术用于检测Q热立克次体。方法 依据已知的Cb 23s rRNA基因序列,设计两对引物用于建立套式PCR技术,并将扩增片段制成探针进行斑点杂交。结果 9株Cb分离株均可扩增出阳性产物带,而对照菌均为阴性,扩增灵敏度可达0.1pg Cb DNA,实验感染第6天的豚鼠血、小鼠血、小鼠脾脏均可扩增出阳性带;用七医株扩增片段制成的探针与9株Cb分离株的全DNA呈阳性杂交,对照菌为阴性,探针杂交灵敏度为0.5ng Cb DNA,感染的豚鼠血、小鼠血、小鼠脾脏均可呈阳性反应。结论 我们的NPCR和DNA探针技术具有很好的特异性和灵敏度,可将二者联合用于Q热的病原学诊断。     

16SrRNA基因PCR加反相杂交技术检测细菌DNA

目的探讨聚合酶链反应（ＰＣＲ）加反相杂交技术在细菌ＤＮＡ检测中的应用。方法以１６ＳｒＲＮＡ基因为靶序列，设计引物及寡核苷酸探针，采用ＰＣＲ法加反相杂交检测标准菌株及临床标本细菌ＤＮＡ。结果对２０株不同标准菌株进行ＰＣＲ扩增，均出现３７１ｂｐ长度的ＤＮＡ片段，敏感性试验可检测出１０－１２ｇ的细菌ＤＮＡ，与人基因组及病毒无交叉反应；２２份血培养阳性标本及４份脑脊液培养阳性标本均扩增出３７１ｂｐ长度ＤＮＡ条带，反相杂交区分革兰阳性／阴性细菌与培养结果相符。结论１６ＳｒＲＮＡ基因ＰＣＲ加反相杂交技术检测细菌ＤＮＡ，具有敏感、快速、准确的特点，为细菌感染的临床诊断提供了科学的依据。     

分子信标实时荧光定量PCR构绵羊PrP基因质粒和标准曲线

目的为能够用实时荧光定量PCR研究消化系统PrPmRNA的表达水平,构建目的基因PrP的标准品质粒和标准曲线。方法根据GenBank中绵羊基因编码区保守序列,设计特异性引物和分子信标探针;提取总RNA,经反转录、RT—PCR后,提取质粒,PCR-SSCP及测序鉴定,获得ARQ质粒;将质粒梯度稀释,进行荧光定量PCR,获得标准曲线及回归方程。结果结果显示,本实验设计的分子信标具有特异性强、灵敏度高和结果准确的特性;标准曲线相关系数r。=0．999,表明线性关系好,成功构建了目的基因的标准品质粒和标准曲线。     

Development and comparison of the real-time amplification based methods--NASBA-Beacon, RT-PCR taqman and RT-PCR hybridization probe assays--for the qualitative detection of sars coronavirus

The aim of this study was to develop a rapid, sensitive and robust procedure for the qualitative detection of SARS coronavirus RNA. Three unique detection formats were developed for real-time RNA amplification assays: a post amplification detection step with a virus-specific internal capture probe based on Taqman (RT-PCR TaqMan assay), hybridization probe (RT-PCR hybridization probe assay) and a real-time assay with virus-specific molecular beacon probes (NASBA-Beacon assay). The analytical sensitivity or reproducibility of the test results among those three assays was compared. All assays yielded results by detecting SARS coronavirus targeting the BNI-1 region in less than 2 hours. RNA detection by all the formats was unaffected by the presence of human sputum. The limits of detection were at least 10 copies of input RNA for both RT-PCR formats (RT-PCR TaqMan and RT-PCR hybridization probe assays), while the NASBA-Beacon assay could detect as little as 1 copy per reaction, with high reproducibility of the coefficient of variation (CV) of <10. These results demonstrate that real-time NASBA provides a rapid and sensitive alternative to RT-PCR for the routine qualitative assay of sputum for SARS corona viral RNA detection.