Tissue tropism of enteropathogenic Escherichia coli strains belonging to the O55 serogroup
Tissue tropism of enteropathogenic Escherichia coli strains belonging to the O55 serogroup
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DOI：
10.1128/iai.70.8.4362-4368.2002
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发表时间：
2002-08-01
影响因子：
3.1
通讯作者：
Phillips, AD
中科院分区：
文献类型：
--
作者：
Fitzhenry, RJ;Reece, S;Phillips, AD
采用人肠道体外器官培养法检测了属于055血清群的4株肠致病性大肠杆菌（EPEC）（G21和G30 [均为055：H6]、G35 [055：H-]和G58 [055：H7]）的组织嗜性。菌株表现出对派尔集合淋巴结的滤泡相关上皮的附着和消退活性的限制性粘附，对十二指肠或结肠没有明显的粘附。G35和G58表达内膜粘附素γ，并显示出与表达内膜粘附素γ的肠出血性大肠杆菌相似的嗜性。大肠杆菌O 157：H7。然而，菌株G21和G30是不寻常的，因为它们表达紧密连接素α，并且具有紧密连接素γ表型的有限组织嗜性。测定了G21的紧密素羧基端280个氨基酸的氨基酸序列。与来自菌株E2348/69（0127：H6）的原型内膜蛋白α的比较显示单个氨基酸差异（对应于整个内膜中的Val 907和Ala 907）。该突变通过定点诱变在内膜素β质粒模板pCVD 438中复制，假设其可诱导向性变化。然而，当突变的质粒被放置在EPEC和EHEC背景，十二指肠粘连的方式类似于菌株E2348/69是明显的体外器官培养。因此，在055：116基因组中存在影响人肠组织向性的与紧密连接蛋白无关的其他因子。
Four enteropathogenic Escherichia coli (EPEC) strains belonging to the 055 serogroup (G21 and G30 [both 055:H6], G35 [055:H-], and G58 [055:H7]) were tested for their tissue tropism by using human intestinal in vitro organ culture. Strains showed restricted adhesion with attaching-and-effacing activity to follicle-associated epithelium of Peyer's patches, with no apparent adhesion to duodenum or colon. G35 and G58 express intimin gamma and show a similar tropism to intimin gamma-expressing enterohemorrhagic E. coli (EHEC) O157:H7. However, strains G21 and G30 were unusual because they expressed intimin (x and had a restricted tissue tropism of intimin gamma phenotype. The amino acid sequence of the carboxy-terminal 280 amino acids of intimin from G21 was determined. Comparison with the prototype intimin alpha from strain E2348/69 (0127:H6) showed a single amino acid difference (corresponding to Val907 and Ala907 in the whole intimins). This mutation was reproduced by site-directed mutagenesis in an intimin (x plasmid template, pCVD438, with the hypothesis that it may induce a change in tropism. However, when the mutated plasmid was placed in both EPEC and EHEC backgrounds, duodenal adhesion in a manner similar to strain E2348/69 was evident upon in vitro organ culture. Thus, additional factor(s) unrelated to intimin exist in the 055:116 genome that influence human intestinal tissue tropism.