大肠杆菌K99和F41菌毛抗原的不同缓冲液热处理提取方法比较 …

本试验用Ｔｒｉｓ－ＨＣｌ缓冲液（Ｔ）、ＰＢＳ缓冲液（Ｐ）、生理盐水（Ｓ）和２Ｍ尿素ＰＢＳ缓冲液（Ｕ）以热处理的方法提取大肠杆菌Ｋ９９和Ｆ４１菌毛抗原,并用硫酸铵盐析纯化Ｋ９９以及用１Ｎ醋酸滴定和氯化镁沉淀分别纯化Ｆ４１。根据ＳＤＳ－ＰＡＧＥ电泳和蛋白质含量测定结果,四种缓冲液对Ｋ９９的提取量依次是Ｕ〉Ｓ〉Ｐ,而Ｔ检不出Ｋ９９;对Ｆ４１的提取量依次是Ｕ〉Ｔ〉Ｐ〉Ｓ。Ｋ９９纯化后取得了满意的纯化结果,     

用大肠杆菌K99和F41菌毛抗原检测牛血清抗体的琼脂扩散试验的研究

用含２ｍｏｌ／Ｌ尿素的磷酸盐缓冲液以热处理方法提取的Ｋ９９和Ｆ４１菌毛作为抗原,对琼脂扩散试验方法进行研究。结果表明本试验方法简便,特异性强,敏感性高,可用于血清抗体检测;所制备的抗原稳定、重复性好。     

大肠杆菌新菌毛抗原的研究：Ⅵ.用沉淀反应检验菌毛抗原

大肠杆菌新菌毛抗原的研究Ⅵ．用沉淀反应检验菌毛抗原房海，陈翠珍（河北农业技术师范学院，昌黎０６６６００）对从腹泻动物所分离的大肠杆菌菌株，做菌毛抗原成分的检查是一项重要内容。常用的方法有抗甘露糖血凝试验及血凝抑制试验、用特异菌毛抗原因子血清做直接玻板...     

大肠杆菌新菌毛抗原的研究：I.菌毛抗原及其血凝活性测定

Ｎｏ．１和Ｎｏ．２两株大肠肝菌产生一种新菌毛抗原（暂定各Ｆ１９８７），并有性菌毛形成；菌毛直径３．６３６ｎｍ，性菌毛直径４．２ｎｍ。抗Ｄ－甘露糖血凝试验（ＭＲＨＡ）表明：本菌毛抗原具有独特的血凝谱、能稳定地凝集人（Ａ、Ｂ、ＡＢ、Ｏ）及貂的红血球，不凝集豚鼠、绵羊、山羊、马、牛、家兔、犬、貉子、小白鼠、鸽、鹌鹑等动物的红血球，戏猪红血球凝集不稳定；血凝作用仅能被相应菌毛因子血清所抑制，不被Ｋ８８、Ｋ     

大肠杆菌新菌毛抗原的研究Ⅰ．菌毛抗原及其血凝活性测定

Ｎｏ．１和Ｎｏ．２两株大肠杆菌产生一种新菌毛抗原（暂定名Ｆ１９８７），并有性菌毛形成；菌毛直径３．６３６ｎｍ，性菌毛直径４．２ｎｍ。抗Ｄ－甘露糖血凝试验（ＭＲＨＡ）表明：本菌毛抗原具有独特的血凝谱，能稳定地凝集人（Ａ、Ｂ、ＡＢ、Ｏ）及貂的红血球，不凝集豚鼠、绵羊、山羊、马、牛、家兔、犬、貉子、小白鼠、鸡、鸽、鹌鹑等动物的红血球，对猪红血球凝集不稳定；血凝作用仅能被相应菌毛因子血清所抑制，不被Ｋ＿８８、Ｋ＿９９、Ｆ＿４１，及ＣＦＡ／Ⅰ、ＣＦＡ／Ⅱ等菌毛因子血清所抑制。血凝作用存在４℃－３７℃－４℃的凝集－解脱－复凝集现象。用Ｍｉｎｃａ培养基做３７℃培养１８～２４ｈ，可使菌毛抗原良好表达。在玻片凝集反应、反向间接血凝及反向间接血凝抑制试验中，本菌毛抗原与动物中常见的Ｋ＿８８、Ｋ＿９９、９８７Ｐ、Ｆ＿４１，及人源ＣＦＡ／Ⅰ、ＣＦＡ／Ⅱ等菌毛抗原不存在类属反应。     

大肠杆菌的一种新型菌毛抗原（F1987）

从腹泻死亡貉病例中分离到２株（Ｎｏ１,Ｎｏ２）能产生一种新型菌毛抗原（暂定名：Ｆ１９８７）的大肠杆菌。该新型菌毛在菌体上生长致密、长短不一,直径为３．６３６ｎｍ,同时有性菌毛形成（直径４．２ｎｍ）。该菌毛在Ｍｉｎｃａ培养基上３７℃培养能良好表达,具有能稳定地凝集人及貂红细胞的特定血凝谱,血凝作用可被相应抗血清所抑制。菌毛蛋白质的分子量为１９１００,等电点为３．０,含有天门冬氨酸等１６种氨基酸。用凝集反应、沉淀反应、标记抗体技术等血清学反应能有效地检验该新型菌毛抗原。产生该新型菌毛抗原相应菌株的菌体抗原为Ｏ２３群,能产生肠毒素,人工感染能引起本动物貉发病。     

F1菌毛抗原在致病性大肠杆菌实验感染鸡体内的定殖和表述

导致鸡发生败血症的大肠杆菌一般具有Ｆ１（Ｉ型）菌毛（由Ｐｉｌ同源基因群编码）和／或Ｐ菌毛（由ｐａｐ同源基因群编码），这些菌毛通常被认为与感染和定殖有关。本实验以３株致病大肠杆菌（Ｅ．ｃｏｌｉ）Ｏ１（Ｐｉｌ＾＋／ｐａｐ＾＋）、Ｏ２（ｐｉｌ＾＋／ｐａｐ）和Ｏ７８（ｐｉｌ＾＋／ｐａｐ＾＋）通过气管内注射１．５周龄鸡，旨在探讨由不同毒力因子引起传染的动力学变化及其菌毛在体内的表述，感染后３～１４４小时剖检     

大肠杆菌新菌毛抗原的研究Ⅱ．菌毛抗原蛋白质特性测定

用保温法和裂解法可以有效提取Ｆ_(１９８７)新菌毛抗原蛋白质；该菌毛蛋白经区带电泳显示主、次两个组分，在０．０６ｍｏｌ／ＬｐＨ８．６巴比妥缓冲液电泳条件下，均向阳极泳动；免疫电泳显示两条沉淀线；其分子量为１９１００Ｄａ；等电点为３．０；由天门冬氨酸、苏氨酸、丝氨酸、谷氨酸、甘氨酸、丙氨酸、缬氨酸、异亮氨酸、亮氨酸、酪氨酸、苯丙氨酸、赖氨酸、组氨酸、精氨酸、脯氨酸、胱氨酸等１６种氨基酸组成。     

大肠杆菌K99菌毛抗原的制备及其免疫抗体效价的测定

肠毒素型大肠杆菌 (Enterotoxigenic E.coli,ETEC)是幼龄动物 (仔猪、犊牛、羔羊等 )腹泻中常见而且重要的致病菌之一 ,此类大肠杆菌能借助于其所产生的菌毛抗原粘附于动物的小肠黏膜上 ,定居并产生肠毒素 ,从而呈现出致病作用。当大肠杆菌 K99菌毛粘附于绵羊红细胞上时 ,能使红细胞发生凝集 ,且不被 D-甘露糖抑制 ,系一种甘露糖低抗血凝反应 (MRHA) ,菌毛的MRHA可被相应的抗体抑制 ,故又可用甘露糖抵抗血凝抑制反应 (MRHI)来对其作出确诊[1] 。目前在各种动物中已发现并展开研究的大肠杆菌菌毛抗原主要有 :K88(F4)、K99(F5)、987…     

羔羊大肠杆菌K_(99)F_(41)双价基因工程苗应用效果观察

羔羊是严重危害畜牧业生产的一种高发病。根据对新疆兵团十三个师（局）1995年的疫情调查统计,全兵团羔羊发病16．64万只,发病率14．80％;死亡9．11万只,死亡率8．10％,该病目前是危害养羊生产的重点疫病。为了探讨基因工程苗防治该病的可行性,我们进行了羔羊大肠杆...     

Visualization of Surface-specific Antigens in Various Strains of Enterotoxigenic E. coli

Proteinaceous surface antigens of enterotoxigenic E. coli (ETEC) appear as pili, and are important virulence factors as they allow bacteria to attach to the small intestinal mucosa. Surface antigens are classified as colonization factor antigens (CFA) and coli surface antigens (CS). Known groups include CFA/I, CFA/II (consisting of CS1, CS2 and CS3), CA/III and CFA/IV (consisting of CS4, CS5 and CS6). The goal of the present study was to examine the morphology of pili by transmission electron microscopy (TEM) and to localize specific surface antigens by immunolabelling. Using different strains of E. coli grown under various culture conditions, pili were visualized by negative staining and corresponding surface antigens were demonstrated by immunogold-labelling using both polyclonal and monoclonal antibodies. Expression of pili was dependent on culture conditions and sample handling. In contrast to CFA/I and CS3, CS6 pili were not detectable after negative staining. Selected antibodies, however, allowed surface antigens to be demonstrated unequivocally. These results will be of value in investigating the expression of colonizing factors in genetically modified bacterial strains.     

产肠毒素性大肠杆菌F41与987P菌毛蛋白的串联表达

根据GenBank中发表的E．coliF41、987P基因序列,分别设计合成一对引物。利用PCR技术．分别以大肠杆菌C83707的基因组和C83710的质粒为模板扩增F41、987P基因。通过分离、纯化、限制性核酸内切酶酶切、连接和转化,构建了含F41-987P串联表达载体的重组菌株BL21（DE3）／pETF41-987P。经酶切、PCR鉴定和DNA序列分析,证实了构建的重组质粒pETF41-987P中含有F41-987P融合基因,且基因序列和阅读框架均正确。经过SDS．PAGE分析,串联表达蛋白含量在30％左右,经Western blot检测,该串联表达蛋白能被大肠杆菌F41、987P阳性血清识别。反向间接血凝试验结果,F41效价为2^6～2^8,987P效价为2^8～2^10。说明F41-987P融合蛋白具有良好的抗原性。表明构建的重组菌株可以作为预防新生仔猪大肠杆菌性腹泻基因工程疫苗的候选菌株。     

Phenotypic expression of K88 adhesin alone or simultaneously with K99 and/or F41 adhesins in the bovine enterotoxigenic Escherichia coli strain B41

F41-positive and F41-negative derivatives of bovine enterotoxigenic Escherichia coli strain B41 carrying K88 or K88 and K99 plasmids were investigated for stability and expression of genes for their fimbrial antigens. Either K88 plasmid alone or both K88 and K99 plasmids could be maintained in these strains though stability could depend on culture medium. K99 antigen could be detected in each strain bearing K99 plasmid. Clones that produced K88 antigen or clones that did not produce this antigen could be isolated from each strain, except from the strain that possessed K99 plasmid in the strain that did not possess the ability to produce F41 antigen. Strains possessing K88 plasmid in the strain able to produce F41 antigen produced clones expressing either both K88 and F41 antigens, (also F41 appeared strongly expressed in some clones) or clones that produced only F41 antigen or no antigen at all. Clones that produced only K88 antigen or others that did not produce this antigen could be produced from a strain bearing only K88 plasmid and that did not possess the ability to produce F41 antigen. None of these strains bearing K88 plasmid alone or additionally K99 plasmid produced mannose-resistant hemagglutination of horse or sheep erythrocytes at 20°C as found for K99 and F41 ETEC natural strains, respectively. These results suggested that the structures of pili when several genetic determinants were present simultaneously may not be identical to those of original strains. In this study, clones expressing either one, two or three adhesin bearing antigens could be obtained from the strain B41.     

产肠毒素大肠杆菌双重PCR检测方法的建立

为了快速检测和鉴定产肠毒素大肠杆菌菌毛(K88和K99)基因,本研究设计合成了针对K88、K99的2对特异性引物,对扩增条件进行优化,建立了检测K88和K99的双重PCR方法。该方法对K88、K99基因的扩增产物大小分别为237和314 bp;最终确定dNTP终浓度0.4 mmol/L,K88、K99的引物终浓度均为25 μmol/L,退火温度为52℃。试验结果表明,该方法具有良好的灵敏性和特异性。用所建立的双重PCR方法对实验室分离的23株大肠杆菌进行检测,结果显示,K88单重PCR阳性2株,K99单重PCR阳性3株,K88和K99双重PCR阳性5株。本研究建立的双重PCR检测方法为致幼畜腹泻产肠毒素大肠杆菌的快速准确检测提供了方法。     

大肠杆菌耐热性肠毒素ST1—K99／LacZ基因重组的研究

将构建的ｐＢＳＴ２～６工程菌质粒用限制性内切酶ＢａｍＨＩ／ＢｇｌⅡ酶切，经琼脂糖凝胶电泳和电洗脱，回收１４７ｂｐ的目的ＳＴ１基因。随之将该基因分别重组到能有效表达Ｋ９９菌毛抗原和ＬａｃＺ酶的ｐＧＫ９９之Ｋ９９基因ＢｇｌⅡ位点和ｐＵＣ１８的ＢａｍＨＩ位点中。通过ＳＴ１基因探针菌落原位杂交、特定酶切分析及ＤＮＡ序列分析，筛选并鉴定出了理想重组子，从而构建出了能分别表达ＳＴ１融合基因产物的工程菌株ｐＳＫ２１９和ｐＸＳＴ１。     

The Use of Specific Antibodies to Demonstrate the Glycocalyx and Spatial Relationships of a K99-, F41- Enterotoxigenic Strain of Escherichia coli Colonizing the Ileum of Colostrum-deprived Calves

Electron microscopy was used to study the interaction between the glycocalyx of enterotoxigenic Escherichia coli strain 210 (09:K30+;K99-;F41-:H-) and the glycocalyx of epithelial cells in then ileum of experimentally infected newborn colostrum-deprived calves. Fixation of tissues in anti-K30 antibody and ruthenium red was used to stabilize the bacterial glycocalyx so that the spatial relationship between the bacteria and the intestinal epithelial cells could be characterized.

When strain 210 was grown in vitro and reacted with anti-K30 antibody prior to staining with ruthenium red, the extensive glycocalyx could be clearly visualized surrounding the bacterial cells. By negative staining, an unidentified pilus was also seen. Sections of ileum from infected calves, which were not fixed in antibody nor stained with ruthenium red, revealed attached bacteria which were surrounded by an electron-translucent zone and no visible bacterial glycocalyx. When ruthenium red staining was used, the bacterial glycocalyx partially collapsed during the dehydration steps of fixation, but could be seen as either a fibrous capsule or an electron-dense accretion on the bacterial cell surface. When ileal tissue was reacted for one hour in anti-K30 antibody before staining with ruthenium red, the bacterial glycocalyx was seen as a discrete electron-dense structure up to 1.0µm thick which was in intimate contact with the glycocalyx of the epithelial cells. The importance of the bacterial exopolysaccharide to microcolony formation on the villi could be clearly visualized.

     

产肠毒素大肠杆菌F41感染猪小肠上皮细胞初期lncRNA的表达谱分析

本研究旨在分析产肠毒素大肠杆菌（enterotoxigenic Escherichia coli，ETEC）感染猪小肠上皮细胞（IPEC-J2）后，在感染初期细胞内长链非编码RNA （long non coding RNA，lncRNA）的表达谱变化，探究lncRNA在ETEC感染初期所起到的调控作用。使用ETEC F41感染IPEC-J2，在感染前和感染初期（感染后4 h）收集细胞，通过Illumina Hiseq Xten平台进行高通量测序，共发现lncRNA 9 975条。感染初期与感染前相比，共发现100条差异表达lncRNA，其中40条表达上调，60条表达下调。通过miRanda-3.3a和psRobot_v1.2软件共同预测差异表达lncRNA的靶基因，并对差异表达lncRNA的靶基因进行GO功能和KEGG通路富集分析。结果显示，感染初期差异表达lncRNA的靶基因显著富集于细胞核、核仁、代谢过程调控及发育过程等GO功能条目中。KEGG分析表明，感染初期差异表达lncRNA的靶基因主要富集在PI3K-Akt信号通路、肌动蛋白细胞骨架调节、黏附斑及细胞周期等信号通路。利用实时荧光定量PCR随机验证了5条差异表达lncRNA，结果与测序分析中表达变化趋势一致。本研究对ETEC感染IPEC-J2细胞初期的lncRNA表达谱进行了差异分析，为深入探究lncRNA在ETEC感染初期中的作用机制提供了参考依据。     

Pathogenicity of porcine enterotoxigenic Escherichia coli that do not express K88, K99, F41, or 987P adhesins.

Three-week-old weaned and colostrum-deprived neonatal (less than 1 day old) pigs were inoculated to determine the pathogenicity of 2 enterotoxigenic Escherichia coli isolates that do not express K88, K99, F41, or 987P adhesins (strains 2134 and 2171). Strains 2134 and 2171 were isolated from pigs that had diarrhea after weaning attributable to enterotoxigenic E coli infection. We found that both strains of E coli adhered in the ileum and caused diarrhea in pigs of both age groups. In control experiments, adherent bacteria were not seen in the ileum of pigs less than 1 day old or 3 weeks old that were noninoculated or inoculated with a nonpathogenic strain of E coli. These control pigs did not develop diarrhea. Antisera raised against strains 2134 and 2171 and absorbed with the autologous strain, grown at 18 C, were used for bacterial-agglutination and colony-immunoblot assays. Both absorbed antisera reacted with strains 2134 and 2171, but not with strains that express K99, F41, or 987P adhesins. A cross-reaction was observed with 2 wild-type K88 strains, but not with a K12 strain that expresses K88 pili. Indirect immunofluorescence with these absorbed antisera revealed adherent bacteria in frozen sections of ileum from pigs infected with either strain. We concluded that these strains are pathogenic and express a common surface antigen that may be a novel adhesin in E coli strains that cause diarrhea in weaned pigs.