Ⅰ型菌毛对F18ac大肠杆菌粘附性能的影响

Effect of type Ⅰ fimbriae on the adherence ability of F18ac Escherichia coli

为研究Ⅰ型菌毛在F18ac大肠杆菌(F18ac E.coli)粘附过程中的作用,本研究利用λ-Red同源重组系统构建了F18ac E.coliⅠ型菌毛主亚基编码基因fim A缺失突变株(F18ac△fim A),以野生株为对照,通过体外易感细胞粘附试验和生物被膜(BF)形成定量试验,探索Ⅰ型菌毛在F18ac E.coli粘附宿主细胞过程中的作用。体外易感细胞粘附结果显示,经8%甘露糖封闭Ⅰ型菌毛受体或fim A基因缺失后,F18ac E.coli对易感仔猪上皮细胞IPEC-1的粘附能力均显著下降。BF结晶紫定量试验显示,F18ac△fim A菌株形成BF的能力显著下降,而F18ac△fim A/pfim A回补株的粘附能力以及生物被膜形成能力均得到了恢复。本研究表明Ⅰ型菌毛是F18ac E.coli重要的粘附素,介导了F18ac E.coli对仔猪易感细胞的粘附过程。本研究为进一步阐释F18ac E.coli致病机制中多毒力因子的作用提供了实验依据。

In this study, we examined the role of type I fimbriae in adherence and biofilm formation of F18ac Escherichia cob by constructing mutant strains with type I fimbrial major subunit （timA） deleted and using an in vitro cell infection model. Data showed that, in contrast to the F18ac E.coli parent strain, isogenic △timA mutant had significantly reduced the adhesion to porcine epithelial IPEC-1 cells. In addition, the adherence of F18ac E.coli to IPEC-1 cell line was blocked by presence of 8% D-mannose in the cell culture medium. Addition to the low adherence ability, the mutant strains impaired their ability to form biofilm in vitro. These results indicated that type I fimbriae might be required for efficient adhesion of F18ac E.coli to pig epithelial cells and perhaps biofilm formation. This study provide insight into the F18ac E.coli multiply virulence factors pathogenic mechanisms.