Avian pathogenic Escherichia coli (APEC), a type of extraintestinal pathogenic E. coli, causes avian colibacillosis, a disease of significant economic importance to poultry producers worldwide, which is characterized by systemic infection. However, the pathogenesis of avian pathogenic E. coli strains is not well defined. Here, the role of a flagellar rotor protein encoded by the fliG gene of avian pathogenic E. coli strain AE17 was investigated. To study the role of FliG in the pathogenicity of APEC, fliG mutant and complemented strains were constructed and characterized. The inactivation of fliG had no effect on APEC growth, but significantly reduced bacterial motility. Compared with the wild type, the fliG mutant was highly attenuated in a chick infection model and showed severe defects in its adherence to and invasion of chicken embryo fibroblast DF-1 cells. The fliG mutant also showed reduced resistance to serum in chicks. The expression of the inflammatory cytokines interleukin 1β (IL1β), IL6, and IL8 was reduced in HD-11 macrophages infected with the fliG mutant strain compared with their expression in the wild-type strain. These results demonstrate that the FliG contributes to the virulence of APEC.

禽致病性大肠杆菌(APEC) 是一种肠外致病性大肠杆菌，可引起禽大肠杆菌病，这是一种对全球家禽生产者具有重要经济意义的疾病，其特征是全身感染。然而，禽致病性大肠杆菌菌株的发病机制尚未明确。在这里，研究了由禽致病性大肠杆菌菌株 AE17的fliG基因编码的鞭毛转子蛋白的作用。为了研究 FliG 在 APEC 致病性中的作用，构建并表征了fliG突变体和互补菌株。fliG的失活对 APEC 生长没有影响，但显着降低了细菌的运动性。与野生型相比，fliG突变体在鸡感染模型中高度减毒，并且在其对鸡胚成纤维细胞 DF-1 细胞的粘附和侵袭方面表现出严重缺陷。所述fliG还突变体显示在小鸡抵抗力降低血清。与野生型菌株中的表达相比，炎症细胞因子白介素 1β (IL1β)、IL6 和 IL8 在感染fliG突变株的HD-11 巨噬细胞中的表达降低。这些结果表明 FliG 有助于 APEC 的毒力。