Jiang Chenggang, An Tongqing, Wang Shujie, Wang Gang, Si Wei, Tu Yabin, Liu Yonggang, Wu Jianan, Liu Siguo, Cai Xuehui
State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, No. 427 Maduan Street, Harbin 150001, People's Republic of China.
Can J Microbiol. 2015 May;61(5):335-41. doi: 10.1139/cjm-2014-0824. Epub 2015 Mar 4.
Enterohemorrhagic Escherichia coli (EHEC) strains cause serious gastrointestinal disease, which can lead to potentially life-threatening systemic complications such as hemolytic uremic syndrome. Although the ehx gene is established as a major virulence factor of EHEC, the role of this gene in colonization and biofilm formation remains to be elucidated. We constructed recombinant isogenic mutants of the ehxA locus of E. coli HLJ1122 (serotype O82) using the λ Red homologous recombination system. Significantly higher levels of adherence to human epithelial cells (HEp-2) cells were observed for strain HLJ1122 compared with the mutant strain HLJ1122-ΔehxA (P < 0.05). Strain HLJ1122 also exhibited significantly higher levels of biofilm formation than strain HLJ1122-ΔehxA (P < 0.05). Mice infected with strain HLJ1122 showed severe destruction of the intestinal and gastric mucosa; in contrast, mice infected with HLJ1122-ΔehxA showed limited intestinal pathology, displaying minimal inflammatory infiltrates compared with mock-infected mice. These results showed the multifunctional role of Ehx in E. coli virulence.
肠出血性大肠杆菌（EHEC）菌株可引发严重的胃肠道疾病，进而可能导致诸如溶血尿毒综合征等危及生命的全身性并发症。尽管ehx基因已被确认为EHEC的主要毒力因子，但其在定植和生物膜形成中的作用仍有待阐明。我们利用λ Red同源重组系统构建了大肠杆菌HLJ1122（血清型O82）的ehxA基因座重组同基因突变体。与突变株HLJ1122-ΔehxA相比，HLJ1122菌株对人上皮细胞（HEp-2）的黏附水平显著更高（P < 0.05）。HLJ1122菌株形成生物膜的水平也显著高于HLJ1122-ΔehxA菌株（P < 0.05）。感染HLJ1122菌株的小鼠出现了严重的肠道和胃黏膜破坏；相比之下，感染HLJ1122-ΔehxA的小鼠肠道病理变化有限，与 mock感染小鼠相比，炎症浸润极少。这些结果表明Ehx在大肠杆菌毒力中具有多功能作用。
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