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首页> 外文期刊>Infection and immunity >Characterization of an EnterotoxigenicEscherichia coli Strain from Africa Expressing a Putative Colonization Factor
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Characterization of an EnterotoxigenicEscherichia coli Strain from Africa Expressing a Putative Colonization Factor

机译：表达推定定居因子的来自非洲的产肠毒素大肠杆菌菌株的表征

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An enterotoxigenic Escherichia coli (ETEC) strain of serotype O114:H? that expressed both heat-labile and heat-stable enterotoxins and tested negative for colonization factors (CF) was isolated from a child with diarrhea in Egypt. This strain, WS0115A, induced hemagglutination of bovine erythrocytes and adhered to the enterocyte-like cell line Caco-2, suggesting that it may elaborate novel fimbriae. Surface-expressed antigen purified by differential ammonium sulfate precipitation and column chromatography yielded a single protein band with M r 14,800 when resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (16% polyacrylamide). A monoclonal antibody against this putative fimbrial antigen was generated and reacted with strain WS0115A and also with CS1-, CS17-, and CS19-positive strains in a dot blot assay. Reactivity was temperature dependent, with cells displaying reactivity when grown at 37°C but not when grown at 22°C. Immunoblot analysis of a fimbrial preparation from strain WS0115A showed that the monoclonal antibody reacted with a single protein band. Electron microscopy and immunoelectron microscopy revealed fimbria-like structures on the surface of strain WS0115A. These structures were rigid and measured 6.8 to 7.4 nm in diameter. Electrospray mass-spectrometric analysis showed that the mass of the purified fimbria was 14,965 Da. The N-terminal sequence of the fimbria established that it was a member of the CFA/I family, with sequence identity to the amino terminus of CS19, a new CF recently identified in India. Cumulatively, our results suggest that this fimbria is CS19. Screening of a collection of ETEC strains isolated from children with diarrhea in Egypt found that 4.2% of strains originally reported as CF negative were positive for this CF, suggesting that it is biologically relevant in the pathogenesis of ETEC.
机译：O114：H血清型的产肠毒素大肠杆菌（ETEC）。它从埃及一名腹泻儿童中分离出来，既表达热不稳定的肠毒素，又表达热稳定的肠毒素，并且定殖因子（CF）呈阴性。该菌株WS0115A诱导牛红细胞血凝，并粘附于肠上皮样细胞系Caco-2，表明它可能具有新颖的菌毛。经十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（16％聚丙烯酰胺）分离后，通过差异硫酸铵沉淀和柱色谱纯化的表面表达抗原产生具有 M r 14,800的单个蛋白带）。产生了针对这种推定的纤维抗原的单克隆抗体，并在斑点印迹分析中与菌株WS0115A以及CS1，CS17和CS19阳性菌株反应。反应性是温度依赖性的，细胞在37°C下生长时表现出反应性，而在22°C下生长时则没有反应性。对来自菌株WS0115A的纤维制品的免疫印迹分析表明，单克隆抗体与单个蛋白带反应。电子显微镜和免疫电子显微镜揭示了菌株WS0115A表面上的菌毛状结构。这些结构是刚性的，直径为6.8至7.4 nm。电喷雾质谱分析表明，纯化的菌毛的质量为14,965 Da。菌毛的N端序列确定它是CFA / I家族的成员，与印度最近发现的一种新型CF CS19的氨基末端具有序列同一性。累积地，我们的结果表明该菌落是CS19。从埃及腹泻儿童中分离出的一系列ETEC菌株的筛选发现，最初报告为CF阴性的4.2％的菌株对该CF呈阳性，表明它在ETEC的发病机理上具有生物学意义。

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