The aim of this study was to investigate whether HtrA is responsible for differences in adherence and invasion of Campylobacter jejuni towards human and chicken cell lines. Gentamicin protection assays were performed with either human Caco‐2 or chicken 2G4 cells using C. jejuni strain NCTC11168 to compare the adhesion and invasion rates towards these two cell types. The results revealed significant differences in the adhesion and invasion rates between the human and avian cells. Deletion of the Campylobacter htrA gene, coding for the dual function of serine protease and chaperonin with a role in pathogenesis, led to a reduction of the rates in both cell lines. Using a single‐amino acid substitution mutant (ΔhtrA/htrAS197A) that lacked protease activity, but retained chaperonin activity, we show that the first is involved in the invasion of human Caco‐2 and chicken 2G4 cells, whereas the latter mutant invaded at lower levels. Adherence towards the chicken cells is higher than towards Caco‐2 cells and this is also dependent on HtrA. Together, these data suggest that the proteolytic activity of HtrA is involved in the difference in host response of C. jejuni towards human and chicken‐derived cells.

中文翻译：

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空肠弯曲杆菌在人与禽细胞中的 HtrA 依赖性粘附和侵袭

本研究的目的是调查 HtrA 是否导致空肠弯曲杆菌对人和鸡细胞系的粘附和侵袭的差异。使用空肠弯曲杆菌菌株 NCTC11168 对人 Caco-2 或鸡 2G4 细胞进行庆大霉素保护试验，以比较这两种细胞类型的粘附和侵袭率。结果表明，人和禽类细胞之间的粘附和侵袭率存在显着差异。缺失弯曲杆菌 htrA 基因，编码丝氨酸蛋白酶和伴侣蛋白的双重功能，在发病机制中起作用，导致两种细胞系中的比率降低。使用缺乏蛋白酶活性但保留伴侣蛋白活性的单氨基酸替代突变体 (ΔhtrA/htrAS197A)，我们表明第一个突变体参与了人类 Caco-2 和鸡 2G4 细胞的入侵，而后者的突变体以较低水平入侵。对鸡细胞的粘附高于对 Caco-2 细胞的粘附，这也取决于 HtrA。总之，这些数据表明 HtrA 的蛋白水解活性与空肠弯曲杆菌对人和鸡源细胞的宿主反应的差异有关。