PDF(Pubmed)
Abstract：
Enteropathogenic Escherichia coli (EPEC) produce a capsule of polysaccharides identical to those composing the O-antigen polysaccharide of its LPS (lipopolysaccharide) molecules. In light of this, the impact of O26 polysaccharides on the immune evasion mechanisms of capsulated O26 EPEC compared to non-capsulated enterohemorrhagic Escherichia coli (EHEC) was investigated. Our findings reveal that there was no significant difference between the levels in EPEC and EHEC of rhamnose (2.8:2.5), a molecule considered to be a PAMP (Pathogen Associated Molecular Patterns). However, the levels of glucose (10:1.69), heptose (3.6:0.89) and N-acetylglucosamine (4.5:2.10), were significantly higher in EPEC than EHEC, respectively. It was also observed that the presence of a capsule in EPEC inhibited the deposition of C3b on the bacterial surface and protected the pathogen against lysis by the complement system. In addition, the presence of a capsule also protected EPEC against phagocytosis by macrophages. However, the immune evasion provided by the capsule was overcome in the presence of anti-O26 polysaccharide antibodies, and additionally, these antibodies were able to inhibit O26 EPEC adhesion to human epithelial cells. Finally, the results indicate that O26 polysaccharides can generate an effective humoral immune response, making them promising antigens for the development of a vaccine against capsulated O26 E. coli.
摘要：
肠致病性大肠杆菌（EPEC）产生的多糖胶囊与其LPS（脂多糖）分子的O抗原多糖相同。鉴于此,研究了与未封装的肠出血性大肠杆菌（EHEC）相比，O26多糖对封装的O26EPEC的免疫逃避机制的影响。我们的研究结果表明，鼠李糖的EPEC和EHEC水平之间没有显着差异（2.8：2.5），被认为是PAMP(病原体相关分子模式)的分子。然而,葡萄糖水平（10:1.69），庚糖（3.6：0.89）和N-乙酰葡糖胺（4.5：2.10），EPEC明显高于EHEC，分别。还观察到EPEC中胶囊的存在抑制了C3b在细菌表面上的沉积并保护病原体免受补体系统的裂解。此外,胶囊的存在还可以保护EPEC免受巨噬细胞的吞噬作用。然而,在存在抗O26多糖抗体的情况下，胶囊提供的免疫逃避被克服，此外，这些抗体能够抑制O26EPEC与人上皮细胞的粘附。最后,结果表明O26多糖能产生有效的体液免疫应答,使它们成为有前途的抗原，用于开发针对封装的O26大肠杆菌的疫苗。
