用PCR技术检测13株霍乱弧菌毒素基因

根据霍乱弧菌肠毒素（ＣＴ）产生的特性，可以区分出产毒性的霍乱弧菌（流行株）和非产毒性霍乱弧菌（非流行株）。本文利用ＰＣＲ试剂盒于１９９７年６月对１３株不同来源的霍乱弧菌进行ＣＴ基因的检测。结果报道如下。材料与方法（１）ＰＣＲＤＮＡ扩增仪：珠海市黑马公...     

3组套式PCR用于检测及区分霍乱弧菌O1群古典型,埃尔托型和O139群

针对霍乱弧菌肠毒素Ａ亚单位（ｃｔｘＡ）基因设计两对引物,建立套式ＰＣＲ,可特异扩增霍乱弧菌Ｏ１群古典型、埃尔托型和Ｏ１３９群;针对霍乱弧菌毒力协调菌毛Ａ亚单位（ＴｃｐＡ）基因设计两对引物,外引物可特异扩增霍乱弧菌Ｏ１群古典型、埃尔托型和Ｏ１３９群,内引物只能特异扩增霍乱弧菌Ｏ１群埃尔托型和Ｏ１３９群;针对Ｏ１３９群特异基因设计两对引物,建立套式ＰＣＲ,可特异扩增Ｏ１３９群。先利用针对ｃｔｘＡ基因设计的套式ＰＣＲ进行初筛,再进一步用另外两组套式ＰＣＲ,可检测及区分霍乱弧菌Ｏ１群古典型、埃尔托型和Ｏ１３９群。对４８株ＥＶＣ,２株ＣＶＣ,６株Ｏ１３９群和３３株非Ｏ１非Ｏ１３９群进行检测,扩增结果与设计均一致。套式ＰＣＲ检测的敏感性可达到１～１０ＣＦＵ。本文建立的方法简单、快速、特异和敏感,有较大的应用价值。     

多重PCR检测霍乱弧菌RTX毒力基因

目的：探索建立一种快速、敏感的诊断方法，用于检测霍乱弧菌RTX毒力基因。方法：针对霍乱弧菌霍乱肠毒素A亚单位基因（ctxA）、RTX毒素家族的细胞毒素基因（rtxA）和毒素激活子基因（rtxC）分别设计3对引物，建立多重PCR方法；用Hep-2细胞测毒方法检测rtxA、rtxC阳性菌株毒素的表达。结果：所有183株临床和环境中分离的霍乱弧菌中，PCR和Hep-2细胞测毒法RTX毒素均为阳性，而古典生物型标准株（569B）二者均为阴性。结论：该方法快速、特异、敏感，具有较大的应用价值。     

应用PCR技术检测霍乱肠毒素

聚合酶链反应(PCR)是一种快速检测霍乱弧菌肠毒素(CT)的方法。用PCR法检测从水和水产品分离的8株O1群霍乱弧菌CT，结果均为阴性。CT的检测对了解水和水产品中分离株是否对公共卫生构成威胁有重要意义。O1群霍乱弧菌的霍乱肠毒素A亚单位(ctxA)基因引物也能扩增0139。     

实时聚合酶链反应检测O1群和O139群霍乱弧菌方法的建立及应用

目的建立检测O1群和O139群霍乱弧菌的实时荧光聚合酶链反应（RT—PCR）方法并进行水体标本的检测评价。方法根据O1群和O139群霍乱弧菌O抗原编码基因rfb序列设计引物，利用SYBRGreen染料，建立同时检测霍乱弧菌O1群和O139群的RT—PCR方法，对所建立的方法分别进行实验室内的灵敏度、特异性及重复性评价。采集河口水标本增菌后进行RT—PCR检测，与分离培养方法比较评价实际应用价值。结果建立了检测O1群和O139群霍乱弧菌的双重RT—PCR方法，根据扩增产物的溶解温度能有效区分O1群和O139群霍乱弧菌两种目标片段的扩增；对其他10种弧菌染色体DNA没有扩增；RT—PCR检测524份河口水体标本的增菌液，与常规分离方法相比显示了明显的灵敏性，并且所有常规分离方法阳性标本其荧光PCR检测亦为阳性。结论以O1群和O139群rfb基因为目标检测片段建立的霍乱弧菌RT—PCR方法可用于环境水体样本中霍乱弧菌常规分离前的快速筛查。     

多基因PCR技术及其应用

多基因ＰＣＲ作为一个常规的技术，广泛应用在病原体鉴别、性别鉴定、连锁分析、法医研究、模板检测和基因的疾病诊断等方面，它是测和杂交分析之前的最终定论。本文就多基因ＰＣＲ的优点、反应环境的优化和应用等作一综述。     

广东省外环境O1/O139群霍乱弧菌毒力基因分型

目的 分析广东省外环境来源O1/O139群霍乱弧菌毒力基因的携带及基因分型特征,为霍乱防控提供依据.方法 选取2008—2009年广东省O1/O139群霍乱弧菌水体分离株69株,水产品分离株16株和同期病例分离株5株,应用多重聚合酶链反应对ctxA、ace、zot、tcpA、tcpI、hlyA、ompU、toxR等8种毒力基因进行检测和分型分析.结果 90株O1/O139群霍乱弧菌均携带hlyA和toxR基因;5株病例菌株中有3株携带8种毒力基因,另外2株小川型菌株为非产毒株,基因型为hlyA⁺toxR⁺ompU⁺zot⁺tcpA⁺tcpI⁺型和hlyA⁺toxR⁺tcpA⁺型;水体菌株中,稻叶型菌株以hlyA⁺toxR⁺ompU⁺ace+zot⁺tcpI⁺型(34.15%)为主,小川型(66.67%)和O139群(70%)以hlyA⁺toxR⁺型为主;水产品菌株中,稻叶型菌株以hlyA⁺toxR⁺ompU⁺tcpI⁺型(75.00%)为主,小川型菌株各种基因型别均有分布,无明显优势基因型别.结论 广东省外环境来源O1/O139群霍乱弧菌以非产毒株广泛存在,毒力基因型别多样.     

不同人群TTV DNA的检测及基因分型研究

目的检测健康人群及肝病患者TTV感染状况及基因分型。方法采用TTV（N22）区核苷酸序列设计引物,建立半巢式PCR（nPCR）方法,对314例7种不同人群血清检测TTV DNA,限制性内切酶Pstl、Ndel进行酶切分型。结果TTV在肝硬化患者、丙型肝炎、急性甲型肝炎、慢性乙型肝炎、急性乙型肝炎、健康人群和乙肝疫苗接种者中感染率分别为72.72%、60.71%、56.52%、48.00%、46.15%、44.21%和34.78%。肝硬化患者感染率明显高于正常人群和乙肝疫苗接种者（P〈0.01）,也显著高于急性乙型肝炎及慢性乙型肝炎（P〈0.05）。基因分型以G1型为主占（75.32%）,G2型占（9.09%）,（G1＋G2）混合型占（15.58%）。慢性乙型肝炎和丙型肝炎G1型阳性率最高,分别为83.33%和82.35%,但与其它组无差异（P〉0.05）。G1型男性感染率为73.33%,女性感染率为79.59%,不同年龄组G1型感染率最高为1-10岁年龄组（83.33%）最低是11-20岁年龄组（70.83%）。但年龄性别间无统计学意义（P〉0.05）。结论TTV在健康人群及肝病患者中有较高的感染率。基因型以G1型为主,提示G1型对肝脏的致病性较微弱,对乙型肝炎,丙型肝炎的病程及愈后无影响。     

霍乱弧菌NhaA基因的扩增、克隆和初步鉴定

目的 体外扩增、克隆霍乱弧菌O1群和O139群1149bp的NhaA基因片段。方法 采用PCR方法扩增NhaA基因,经限制性内切酶BamHI和EcoRI酶切的用低熔点琼脂糖法回收纯化,插入pcDNA3载体的多克隆位点,构建重组体,转化大肠杆菌,并对克隆基因进行酶切鉴定。结果 分别从霍乱弧菌O1群和O139群扩增出1149bp的NhaA基因片段,所构建的重组体经酶切分析和预期结果一致。结论 成功扩增并克隆我国散发霍乱O1群和O139群NhaA基因,为研究霍乱流行规律和基因疫苗提供了重要的实验依据。     

中国O139群霍乱弧菌核糖体基因多态性的研究

目的：分析国内O139群霍乱弧菌分离株的遗传多态生，方法：以16s rRNA和23s rRNA核糖体基因作探针，对内切酶消化的菌株染色体DNA进行Bouthern杂交，分析杂交图谱。结果：选择的122株O139群霍乱弧菌得到10种核糖体基因型。9株ctxAB,zot和RS均为阴性的无菌菌株，分离于4种独特的核糖体基因型。结论：O139群霍乱弧菌在遗传分化及克隆群的地区分布上存在多态性，提示国内O139霍乱流行的复杂性。     

Taq-Man实时荧光定量PCR同时检测O1和O139群霍乱弧菌

目的针对霍乱弧菌血清群各自编码O抗原的特异性基因建立能够快速、准确地同时检测O1和O139群霍乱弧菌的荧光PCR检测方法,并克服常用PCR检测方法中经常出现的假阳性现象。方法分别以rfbM和wbfR基因作为O1和O139群霍乱弧菌的模板设计引物和探针,通过优化反应条件建立了能够同时检测O1群和O139群霍乱弧菌的二联实时荧光定量PCR方法(FQ-PCR)。对该方法的特异性、灵敏度进行评估,并对10份模拟食品样品和133份临床样品进行了检测。结果特异性试验表明,该方法能选择性检测O1和O139群霍乱弧菌,能有效地避免O141群霍乱弧菌和拟态弧菌的假阳性,特异性为100%;灵敏度试验表明,O1群霍乱弧菌和O139群霍乱弧菌检出限分别为92cfu/ml和116cfu/ml;另外,试验建立的检测方法对模拟样品和临床样品检测结果与国标法的检测结果完全一致,符合率为100%。结论该实时荧光PCR检测方法能够同时检测O1和O139群霍乱弧菌,而且特异性好、灵敏度高,能有效克服假阳性,适用于基层疾病控制、口岸检疫单位日常疫情监测和临床诊断。     

Emergence of classical ctxB genotype 1 and tetracycline resistant strains of Vibrio cholerae O1 El Tor in Assam, India

Cholera epidemics with moderately high case fatality rates in Assam, northeast India were investigated in 2007, 2008 and 2010. Based on mismatch amplification mutation assay PCR for detection of ctxB allele, 40 isolates of Vibrio cholerae O1 El Tor collected from the epidemics were found to harbour the classical ctxB gene allele of cholera toxin (CT). DNA sequencing of ctxB gene confirmed the isolates to be genotype 1 of ctxB. Antimicrobial susceptibility tests reveal that 100% of the isolates were resistant to trimethoprim and 40% were resistant to tetracycline. The recent V. cholerae O1 strains circulating in Assam, India are due to the El Tor variant carrying classical type CT. Emergence of tetracycline and trimethoprim resistant strains necessitates the review of antibiotic use for severe cholera.     

Enzyme markers for Vibrio cholerae: identification of classical, El Tor and environmental strains

Enzyme electrophoretic variants were studied in 49 strains of Vibrio cholerae using zymovar analysis. The following seven enzymes were selected for use: alanine dehydrogenase (ADH), isocitrate dehydrogenase (IDH), malate dehydrogenase (MDH), phosphoglucomutase (PGM), glucosephosphate isomerase (GPI), 6-phosphogluconate dehydrogenase (6PGDH) and glucose-6-phosphate dehydrogenase (G6PDH). The results indicated the presence of three main groups defined chiefly by their GPI and 6PGDH variants. The first group, defined by possessing the variants GPI-2 and 6PGDH-3, contained all the 01 serovar and E1T or biovar isolates from cholera cases. The second group, defined by possessing the variants GPI-3 and 6PGDH-2, contained all the 01 serovar and classical biovar isolates; the third group was heterogeneous and included the 01 serovar isolates from environmental sources as well as isolates of other serovars (the so called NAGs, non-agglutinable with 01 antisera or NCVs). It is thus now possible to separate the epidemic strains of 01 serovar from other members of this serovar isolated from the environment. Zymovar analysis deals with differences which are a direct expression of the genome and seems to be unaffected by gross phenotypic changes such as smooth-rough variation and phage resistance. It is a promising tool for investigating bacteriological and epidemiological questions, in particular the significance of an environmental reservoir of cholera.     

中国O1群El Tor霍乱弧菌产毒株表型多态性研究

目的 了解近50年中国不同地区分离的O1群El Tor型霍乱弧菌产毒株的生物表型特征变化。方法 采用多粘菌素B敏感试验、第Ⅳ组霍乱噬菌体裂解试验、VP试验和溶血实验进行表型特征分析。结果 生物型表型特征分析表明133株菌具有典型的El Tor生物型表型特征,其余251株菌呈现不典型的El Tor生物型表型特征;综合ctxB、rstR基因型和生物型表型特征分析,385 株检测菌株中 64 株为典型 El Tor 生物型菌株,21 株菌有典型的 El Tor 生物型表型特征但携带古典型ctxB基因,杂合型特征菌有280株,根据ctxB、rstR和表型特征的不同组合可再分为45个杂合型。结论 中国O1群El Tor霍乱弧菌菌株呈现明显的表型多态性,传统的表型分型特征不能有效区分古典生物型和El Tor生物型菌株。     

Amino-terminal domain of the El Tor haemolysin of Vibrio cholerae O1 is expressed in classical strains and is cytotoxic.

Previous studies have shown that the classical isolates of Vibrio cholerae possess an 11 bp deletion in the structural gene for the El Tor haemolysin leading to the production of a 27 kDa non-haemolytic truncated product HlyA* compared to the 82 kDa haemolysin, HlyA. These studies were designed to assess whether this truncated product had any biological activity. A KmR cartridge was introduced into the hlyA gene effectively eliminating the haemolysin. This was recombined into the chromosome of a variety of strains and isogenic pairs were examined in a number of systems. These studies suggest that the haemolytic (cytolytic) domain of HlyA resides at the C-terminus and that the N-terminus, which is conserved as HlyA* in classical strains, possesses enterotoxic (cytotoxic) activity. Experiments with the cholera-toxinless vaccine candidate JBK70 and its hlyA::KmR mutant suggest that HlyA* may be responsible for the residual diarrhoea observed in cholera-toxinless vaccine strains.