In order to investigate the role of fimH adhesins in the pathogenesis of F18ac+E.coli,F18ac△fimH isogenic mutant was generated by λ Red-based homologous recombination system.The adhesion and biofilm(BF) formation ability of F18ac△fimH mutant and wild-type strains were compared using an in vitro piglet epithelial cell infection model.In the in vitro bacterial adherence assay,our results showed that the isogenic F18ac△fimH mutant correlated with the significantly decreased adhesion to both porcine epithelial IPEC-1 and IPEC-J2 cells when compared with the F18ac+E.coli wild-type strains.In addition,the adherence of F18ac+E.coli to these cell lines was also blocked by 8% D-mannose in the cell culture medium.In consistent with less adherence ability,the F18ac△fimH mutant also reduced their ability to form biofilm.These results indicated that fimH adhesins of type Ⅰ fimbriae play an important in F18ac+E.coli adhesion.%为研究Ⅰ型菌毛FimH黏附素在F18ac+大肠杆菌(F18ac+E.coli)致病机制中的作用,采用λ-Red同源重组方法成功构建了F18ac+E.coli的fimH基因缺失株(F18ac△fimH).并使用体外仔猪上皮细胞感染模型,探讨FimH黏附素缺失后对F18ac+E.coli黏附能力和体外生物被膜形成能力的影响.结果表明,与野生株相比,F18ac△fimH缺失株对易感仔猪上皮细胞系IPEC-1和IPEC-J2的黏附能力和体外生物被膜形成能力均显著下降,且其黏附能力可被8%的D-甘露糖所抑制.但是F18ac△fimH/pfimH回补株的黏附能力以及生物被膜形成能力均基本恢复至野生株水平.可见,FimH黏附素是介导F18ac+E.coli黏附的重要黏附因子.
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