猪胸膜肺炎放线杆菌PCR诊断方法的建立与应用

根据胸膜肺炎放线杆菌ApxⅣ基因设计1对引物，扩增特异的650bp棱酸片段，建立了应用PCR检测猪胸膜肺炎放线杆菌的方法。特异性试验结果表明，12个血清型的放线杆菌参考菌株均能扩增出650bp特异性的核酸片段，而大肠杆菌、多杀性巴氏杆菌、猪肺炎支原体、伤寒沙门氏菌和支气管败血性波氏杆菌的扩增结果均为阴性。敏感性试验结果表明，PCR的最低检出限量为500个放线杆菌。利用建立的PCR检测方法对22株从山东省不同地区分离的疑似胸膜肺炎放线杆菌菌株进行检测．结果14株为阳性。对感染猪病变组织的检测结果表明，病变部位不同，胸膜肺炎放线杆菌的检出率不同，其中以扁桃体的检出率最高。     

复合PCR进行胸膜肺炎放线杆菌血清型快速分型

根据胸膜肺炎放线杆菌（Actinobacillus pleuropneumoniae，APP）各血清型之间外毒素apxⅠ、apxⅡ、apxⅢ、apxⅣA基因差异，设计6对引物，对16株标准菌株进行1次5对引物的多重PCR和1次根据apxⅣA基因设计1对引物PCR的扩增，得到各血清型特异性片段，并将片段特征相同的血清型归为同一组。通过这2步PCR分组情况的不同能将16株标准菌株中的大多数血清型区别开，但是仍然不能将血清2型和8型、血清9型和11型、血清5型中的2个亚型以及血清12型和13型区分开。又根据血清2型英膜多糖（CP）基因差异设计1对引物将血清2型和8型区分开。将此分型系统应用于23株未知病原菌检测，检测到胸膜肺炎放线杆菌9株，并全部能够将其分型。本试验PCR分型体系可以作为胸膜肺炎放线杆菌血清型分型的一种快速而有效的鉴定方法。     

利用菌落多重PCR方法进行不同动物来源多杀性巴氏杆菌鉴定的研究

参照文献报道的多杀性巴氏杆菌种和荚膜型的特异基因合成6对特异引物,建立多杀性巴氏杆菌鉴定的菌落多重PCR方法,结果5株多杀性巴氏杆菌荚膜型参考菌株均扩增出了相应的预期片段,而支气管败血波氏杆菌、胸膜肺炎放线杆菌、大肠埃希菌的扩增均为阴性。利用此多重PCR方法对48株不同动物来源的多杀性巴氏杆菌进行了鉴定和荚膜型分型,同时与间接血凝试验以及Biolog细菌快速鉴定系统进行比对,结果表明,所建立的多重PCR方法与间接血凝试验、Biolog细菌快速鉴定系统的符合率均达到100%。     

猪传染性胸膜肺炎放线杆菌血清6型PCR方法的建立及初步应用

为了建立猪传染性胸膜肺炎放线杆菌血清6型分子鉴定方法,本研究根据胸膜肺炎放线杆菌从编码荚膜多糖的碱基序列设计1对引物,扩增特异性的720 bp核酸片段。结果表明,以APP为模板,均能扩增出与预期一致的1条720 bp核酸片段,所得PCR产物经测序,与Gen Bank已发表的胸膜肺炎放线杆菌血清型6型的同源性达99%以上。本研究建立了PCR检测猪传染性胸膜肺炎放线杆菌血清6型分子鉴定方法,该方法的建立为猪传染性胸膜肺炎放线杆菌病的诊断和防治及鉴定提供了基础。     

血清6型猪传染性胸膜肺炎放线杆菌的分离与鉴定

从广东某猪场出现呼吸困难、肺脏有出血性纤维渗出性病变的病死猪中分离出1株有多形性趋向的革兰阴性球杆菌,卫星现象观察、CAMP试验及V因子依赖性试验均为阳性,用PCR方法能扩增出各血清型猪传染性胸膜肺炎放线杆菌均有的apxⅣA基因长约422 bp的特异片段,小白鼠攻毒试验显示其有致病性,血清学检测表明该分离菌为血清6型猪传染性胸膜肺炎放线杆菌。     

血清6型猪传染性胸膜肺炎放线扦菌的分离与鉴定

从广东某猪场出现呼吸困难、肺脏有出血性纤维渗出性病变的病死猪中分离出1株有多形性趋向的革兰阴性球杆菌，卫星现象观察、CAMP试验及V因子依赖性试验均为阳性，用PCR方法能扩增出各血清型猪传染性胸膜肺炎放线杆菌均有的apxIVA基因长约422bp的特异片段，小白鼠攻毒试验显示其有致病性，血清学检测表明该分离茵为血清6型猪传染性胸膜肺炎放线杆菌。     

洛阳某猪场猪传染性胸膜肺炎放线杆菌的分离鉴定

为确定洛阳某猪场疑似猪传染性胸膜肺炎的病原种类及其血清型,为其临床科学防疫和合理用药提供参考方案,本试验无菌采集了病猪肺脏等病料,采用病菌培养后形态观察、革兰氏染色、生理生化特性试验、PCR诊断等技术对病原菌进行实验室分离鉴定,通过基因测序和同源性分析方法对其进行确诊,通过动物攻毒试验和药敏试验分析分离菌株的致病性和耐药性,采用5对分型引物对分离菌进行基因分型以确定病原菌血清型。结果显示,分离菌2007菌落形态为光滑、透明、边缘整齐、圆形、隆起的小菌落,革兰氏染色特征为阴性杆菌且呈多型性,具有猪传染性胸膜肺炎放线杆菌(APP)的典型培养特征,且生化结果符合猪传染性胸膜肺炎放线杆菌的生化特性。同源性分析结果显示,分离菌株2007与猪传染性胸膜肺炎放线杆菌菌株FJ848573.1同源性为99.4%,说明分离株2007是猪传染性胸膜肺炎放线杆菌。动物攻毒试验结果显示,分离菌株2007对小鼠有强致病性。药敏试验结果显示,分离株2007对泰妙菌素、氨苄西林和头孢噻呋钠等高敏,对替米考星、红霉素、氟苯尼考等20种抗菌药完全耐药,对34种抗生素的耐药率高达76.5%,具有较强的多重耐药性。分离菌2007基因分型扩增到目的基因片段与血清型5型结果相符。本试验结果为发病猪场提出了解决该病的具体防治措施,并最终获得了良好的效果,为猪传染性胸膜肺炎放线杆菌临床耐药折点的制定提供了一些参考。     

洛阳某猪场猪传染性胸膜肺炎放线杆菌的分离鉴定

为确定洛阳某猪场疑似猪传染性胸膜肺炎的病原种类及其血清型,为其临床科学防疫和合理用药提供参考方案,本试验无菌采集了病猪肺脏等病料,采用病菌培养后形态观察、革兰氏染色、生理生化特性试验、PCR诊断等技术对病原菌进行实验室分离鉴定,通过基因测序和同源性分析方法对其进行确诊,通过动物攻毒试验和药敏试验分析分离菌株的致病性和耐药性,采用5对分型引物对分离菌进行基因分型以确定病原菌血清型。结果显示,分离菌2007菌落形态为光滑、透明、边缘整齐、圆形、隆起的小菌落,革兰氏染色特征为阴性杆菌且呈多型性,具有猪传染性胸膜肺炎放线杆菌（APP）的典型培养特征,且生化结果符合猪传染性胸膜肺炎放线杆菌的生化特性。同源性分析结果显示,分离菌株2007与猪传染性胸膜肺炎放线杆菌菌株FJ848573.1同源性为99.4%,说明分离株2007是猪传染性胸膜肺炎放线杆菌。动物攻毒试验结果显示,分离菌株2007对小鼠有强致病性。药敏试验结果显示,分离株2007对泰妙菌素、氨苄西林和头孢噻呋钠等高敏,对替米考星、红霉素、氟苯尼考等20种抗菌药完全耐药,对34种抗生素的耐药率高达76.5%,具有较强的多重耐药性。分离菌2007基因分型扩增到目的基因片段与血清型5型结果相符。本试验结果为发病猪场提出了解决该病的具体防治措施,并最终获得了良好的效果,为猪传染性胸膜肺炎放线杆菌临床耐药折点的制定提供了一些参考。     

猪传染性胸膜肺炎放线杆菌血清5型的分离鉴定

新疆奇台和昌吉市规模化猪场发生育肥猪急性死亡,疑似猪传染性胸膜肺炎,采集病料进行细菌的分离培养、PCR检测、药敏试验及小鼠致病性试验。结果分离获得猪胸膜肺炎放线杆菌奇台株2株,昌吉株1株。PCR分型鉴定均为血清5型。致病性试验显示,分离株均可致死小鼠。对氟苯尼考、头孢噻呋、恩诺沙星等抗生素敏感。结论,确诊病原为猪胸膜肺炎放线杆菌血清5型。血清5型已成为新疆地区致死率较高的流行血清型。     

鲁西地区猪胸膜肺炎放线杆菌血清型多重PCR研究

本研究建立了鉴定猪胸膜肺炎放线杆菌(APP)血清型的多重PCR方法,并对鲁西地区流行的APP血清型进行了鉴定.根据猪胸膜肺炎放线杆菌的外膜脂蛋白(OmlA)基因设计1对种特异性引物;并且根据血清1型、5型、7型荚膜多(cps)基因设计型特异性引物,建立检测血清1型、5型、7型的PCR方法.运用多重PCR对临床分离鉴定的89株APP进行血清型鉴定,结果表明建立的多重PCR检测方法特异性和敏感性良好,可作为猪传染性胸膜肺炎快速诊断和流行病学调查的重要手段.     

猪胸膜肺炎放线杆菌、多杀性巴氏杆菌和副猪嗜血杆菌复合PCR检测方法的建立

目的建立可以同时检测猪胸膜肺炎放线杆菌、多杀性巴氏杆菌和副猪嗜血杆菌的快速而可靠的PCR检测方法。方法和结果根据胸膜肺炎放线杆菌的Apx-VIA基因序列、多杀性巴氏杆菌和副猪嗜血杆菌的16SrRNA基因序列设计5条引物。猪胸膜肺炎放线杆菌、多杀性巴氏杆菌和副猪嗜血杆菌模板的PCR扩增产物大小分别为342bp,485bp和1258bp。复合PCR对1～12型猪胸膜肺炎放线杆菌标准株,6株多杀性巴氏杆菌标准株,1～15型副猪嗜血杆菌以及25株经生化鉴定确认为上述三种细菌的分离株的基因组DNA作为模板进行检测,均获得预期大小的扩增产物。以猪放线杆菌、吲哚放线杆菌等14种常见细菌作为阴性对照进行PCR检测,结果仅有支气管败血波氏杆菌产生了可以和上述三个特异性条带明显区分的PCR产物。复合PCR针对胸膜肺炎放线杆菌、多杀性巴氏杆菌和副猪嗜血杆菌的敏感性分别为14pg、34pg和37pg。结论本研究建立的复合PCR特异性好,敏感性高,可以用于猪胸膜肺炎放线杆菌、多杀性巴氏杆菌和副猪嗜血杆菌的快速检测。     

Development of a multiplex PCR test for identification of Actinobacillus pleuropneumoniae serovars 1, 7, and 12

A PCR assay for simultaneous species identification and separation of Actinobacillus pleuropneumoniae serovars 1, 7 and 12 was developed. Primers specific for genes involved in biosynthesis of the capsular polysaccharides (cps genes) of serovars 1, 7, and 12 were combined with a species-specific PCR test based on the omlA gene. The PCR test was evaluated with the serovar reference strains of A. pleuropneumoniae as well as 183 Danish field isolates. For all typable strains, a complete correspondence was found between results obtained with the multiplex PCR test and results from the traditional serotyping methods. Among eight serologically cross-reacting strains designated K1:O7, seven isolates produced amplicons of similar sizes as serovar 1 and one isolate produced amplicons of similar sizes as serovar 7. The species specificity of the assay was evaluated using a collection of 126 strains representing 25 different species within the family Pasteurellaceae including 45 field strains of the phylogenetically affiliated species Actinobacillus lignieresii. All these isolates tested negative for the cps genes by the multiplex PCR test except for 6 isolates of A. lignieresii. Five of these isolates produced an amplicon identical to the cps gene of serovar 7, whereas one isolate produced an amplicon identical to the cps gene of serovar 1. In addition, four isolates of Actinobacillus genomospecies 1 tested positive for the omlA gene but negative for the cps genes. The test represents a convenient and specific method for serotyping A. pleuropneumoniae in diagnostic laboratories.     

Prevalence of "Actinobacillus porcitonsillarum" in porcine tonsils and development of a diagnosis duplex PCR differentiating between "Actinobacillus porcitonsillarum" and Actinobacillus pleuropneumoniae

"Actinobacillus porcitonsillarum" is a newly suggested commensal species colonizing porcine tonsils. In the diagnostic laboratory the sole difference to the porcine lung pathogen Actinobacillus pleuropneumoniae is a negative mannitol reaction. In order to substantiate and improve this important differentiation a PCR test was developed using the relevant reference strains including Actinobacillus minor. The practicability of the test was confirmed on 20 clinical isolates of Actinobacillus spp. cultured from 100 tonsil samples originating from 18 farms in Thailand. Applying the newly developed PCR test 10 isolates were identified as A. pleuropneumoniae, and 10 as "A. porcitonsillarum" with one of them being mannitol-positive in biochemical testing. Subsequent 16S rRNA sequencing confirmed classification of all 10 strains as "A. porcitonsillarum"/A. minor. These results emphasize that suspected A. pleuropneumoniae isolates, particularly from porcine tonsils, should be confirmed by PCR in order to prevent false positive diagnoses.     

PCR-based identification of serotype 2 isolates of Actinobacillus pleuropneumoniae biovars I and II

A genetic typing method utilizing PCR for the identification of Actinobacillus pleuropneumoniae serotype 2 isolates has been developed based on the in vitro amplification of a 1.4 kb DNA segment of the serotype 2 capsular polysaccharide genes cps2AB. The assay was tested with all serotype reference strains and a collection of 92 different A. pleuropneumoniae strains of all 15 serotypes of both biovars I and II, originating from 18 different countries worldwide. The cps2 based PCR identified the serotype 2 reference strain and all 12 serotype 2 collection strains contained in this set. DNA was not amplified from the remaining A. pleuropneumoniae reference and collection strains, indicating the PCR assay was highly specific. Furthermore, the PCR method detected all 31 A. pleuropneumoniae serotype 2 field isolates from diseased pigs that were identified in parallel as serotype 2 by agar gel diffusion. The serotype 2 PCR assay proved to be highly specific and reliable for the identification of serotype 2 isolates of A. pleuropneumoniae.     

Development and use of a multiplex polymerase chain reaction assay based on Apx toxin genes for genotyping of Actinobacillus pleuropneumoniae isolates.

Actinobacillus pleuropneumoniae (A. pleuropneumoniae) is the etiological agent of a porcine pleuropneumonia that threatens the global swine industry. The major pathogenic toxins of A. pleuropneumoniae include ApxI, ApxII, ApxIII, and ApxIV, which are serotype or serovar specific. Several techniques have been developed for the identification and typing of A. pleuropneumoniae. Serological assays are used to identify and serotype A. pleuropneumoniae, but factors such as cross-reactivity limit their specificity. Labor, time, and the requirement for specific antibodies are also drawbacks of these assays. Multistep polymerase chain reaction (PCR) techniques based on apx genes have been reported for the identification and typing of A. pleuropneumoniae. This study developed multiplex PCR for the identification and genotyping of A. pleuropneumoniae based on apx genes. This multiplex PCR technique was successful in differentiating 11 of 15 reference serotypes. Five different primer sets were used to amplify the 4 apx genes from each serotype in a single-step reaction. The multiplex PCR reported in this study was further used in genotyping 51 field isolates of A. pleuropneumoniae from different regions of Korea. The concomitant amplification of all 4 apx genes makes multiplex PCR more specific and convenient for the diagnosis and genotyping of A. pleuropneumoniae.     

致猪水肿病大肠埃希菌多重PCR检测方法的建立及应用

本研究旨在建立一种快速鉴定致猪水肿病大肠埃希菌的多重PCR检测方法.分别针对大肠埃希菌16S rDNA、志贺毒素Stx2e A亚基和菌毛F18ab A亚基保守序列设计合成3对特异性引物,优化多重PCR反应条件,并进行特异性和敏感性检测.结果显示,阳性对照菌株扩增产物大小分别为1 062、733和313 bp.特异性和灵敏性检测结果表明,与肠炎沙门菌、多杀性巴氏杆菌、胸膜肺炎放线杆菌、副猪嗜血杆菌、支气管败血波氏杆菌和猪链球菌等猪常见致病菌均无交叉反应;菌体直接扩增法最低检出量为1 875 CFU.利用建立的多重PCR检测方法对分离收集的128株大肠埃希菌进行鉴定,得到36株致猪水肿病大肠埃希菌,其中30株既有菌毛F18ab又产志贺毒素Stx2e,另外6株仅产志贺毒素Stx2e.结果表明,本试验所建立的多重PCR检测方法对致猪水肿病大肠埃希菌的快速诊断和流行病学调查具有一定的应用价值.     

Identification and detection of Actinobacillus pleuropneumoniae by PCR based on the gene apxIVA

The apxIVA gene, a recently discovered RTX determinant of Actinobacillus pleuropneumoniae, was shown to be species-specific. DNA hybridization experiments using probes for various regions of apxIVA revealed that the 3'-terminus of this gene was present in all 14 serotypes of A. pleuropneumoniae but absent from phylogenetically related species. A primer pair spanning this region specifically amplified a 422bp fragment in PCR experiments with DNA from the reference strains of the 14 serotypes and 194 field strains isolated from various geographic locations worldwide. DNA sequence analysis of PCR products derived from all serotypes were identical except in serotypes 3, 8, and 10, which showed minor differences. The PCR did not amplify any product when DNA from 17 different bacterial species closely related to A. pleuropneumoniae was used as template. In addition, the PCR was negative with DNA of several Actinobacillus sp. which were initially characterized as A. pleuropneumoniae using routine phenotypic and serological analyses but which were subsequently shown by 16S rRNA sequence analysis to belong to yet undefined Actinobacillus species. The sensitivity of the PCR was determined to be 10pg of A. pleuropneumoniae DNA. A set of nested primers amplified a 377bp fragment specifically with A. pleuropneumoniae DNA. DNA titration experiments using the flanking and nested primer pairs showed an improved level of sensitivity to approximately 10fg of genomic DNA. The nested PCR was used to monitor the spread of A. pleuropneumoniae in pigs experimentally infected with a virulent serotype 1 strain and housed in a controlled environment facility. A. pleuropneumoniae DNA could be detected by nested PCR in nasal swab samples of infected pigs receiving either a high dose (5x10(5)) or a low dose (1x10(4)) challenge and in unchallenged cohorts that were contact-infected by the inoculated animals. Furthermore, PCR confirmed the presence of A. pleuropneumoniae in 16/17 homogenates from necrotic lung lesions, while the bacterium was successfully recovered from 13 of these lesions by culture.     

产气荚膜梭菌菌落多重PCR方法的建立及初步应用

根据GenBank中已发布的产气荚膜梭菌α、β、ε、τ毒素基因序列,分别设计并合成针对4种毒素基因的特异引物,通过优化多重PCR反应条件,建立1种简单的产气荚膜梭菌定型菌落多重PCR方法。结果显示：A、B、C、D、E5型产气荚膜梭菌参考菌株均扩增出了相应的预期目的条带,而大肠杆菌、巴氏杆菌和芽孢杆菌则均未能扩增出相应条带;将单个菌落稀释100倍,仍能扩增出相应的目的片段,该方法对B型和E型参考菌株最低检测量分别为2．6×10^4cfu／mL、1．2×10^4cfu／mL。应用该多重PCR方法从106份样品中检测到30株产气荚膜梭菌且均为A型,其中病死鸡的盲肠内容物分离率为36．5％（19／52）,健康鸡群新鲜粪便样品分离率为20．4％（11／54）。本研究建立的多重PCR方法特异性强,敏感度高,重复性好,可以有效进行产气荚膜梭菌的快速检测及5种血清型的鉴别,对产气荚膜梭菌的感染及食品安全问题的研究均具有重要意义。     

猪胸膜肺炎放线杆菌PCR快速分型系统的建立及应用

根据外膜蛋白基因中间部分的差异,毒素基因和荚膜基因的型特异性,建立3个多重PCR的分型体系,可将App1～12型分成11个模式,除9型和11型外完全区分。此分型体系用于3株野毒株的分型,得出的结果和血清学分型一致。对人工发病猪扁桃体、肺脏、鼻拭子各12份分型结果与已知血清型一致。将该分型系统直接用于临床病料的鉴定并分型,实验从35份临床可疑病料中检测出2份阳性,均为7型,从健康猪扁桃体350份中检测出5份阳性,一份为4型,一份为12型,一份为3型,2份为7型。