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Abstract：
BACKGROUND: Avian Escherichia coli (E.coli) type 1 fimbriae adhere to avian tracheal epithelial cells through the FimH protein. However, the adhesion-related antigen is still unknown. The purpose of this study was to analyze the antigenicity of the type 1 fimbrial FimH protein of wild-type avian E. coli, screen antigen epitopes, and prepare monoclonal antibodies (mAbs) that can block the adhesion of avian E. coli.
RESULTS: In this study, the nucleic acid homologies of MG2 (O11), TS12 (O18), and YR5 (O78) with K12 were 97.7%, 99.6%, and 97.7%, respectively, and the amino acid sequence similarity reached 98.7%, 99.3%, and 98.0%, respectively. The epitopes and hydrophilicities of the FimH proteins of these three strains were similar. The more obvious lectin domain epitopes were located at FimH protein positions 111-124 and 154-162. The mAbs 7C2 and 7D8 against these two epitopes were prepared. An adhesion inhibition test showed that 7C2 and 7D8 blocked bacterial adhesion to avian tracheal epithelial cells. The mAb 7C2 against the 111-124 epitope inhibited O78 strain adhesion by 93%, and the mAb 7D8 against the 154-162 epitope inhibited O78 strain adhesion by 49%, indicating that these two epitopes are closely related to the adhesion of type 1 fimbriae. However, only the 111-124 epitope-recognizing mAb 7C2 inhibited bacterial agglutination of erythrocytes, indicating that host cell receptor binding and erythrocyte agglutination are not mediated by the same spatial locations within the FimH protein.
CONCLUSIONS: The results demonstrate that the mAbs 7C2 and 7D8 against FimH protein positions 111-124 and 154-162 could inhibit the adhesion of E.coli to the chicken trachea.
RESULTS: In this study, the nucleic acid homologies of MG2 (O11), TS12 (O18), and YR5 (O78) with K12 were 97.7%, 99.6%, and 97.7%, respectively, and the amino acid sequence similarity reached 98.7%, 99.3%, and 98.0%, respectively. The epitopes and hydrophilicities of the FimH proteins of these three strains were similar. The more obvious lectin domain epitopes were located at FimH protein positions 111-124 and 154-162. The mAbs 7C2 and 7D8 against these two epitopes were prepared. An adhesion inhibition test showed that 7C2 and 7D8 blocked bacterial adhesion to avian tracheal epithelial cells. The mAb 7C2 against the 111-124 epitope inhibited O78 strain adhesion by 93%, and the mAb 7D8 against the 154-162 epitope inhibited O78 strain adhesion by 49%, indicating that these two epitopes are closely related to the adhesion of type 1 fimbriae. However, only the 111-124 epitope-recognizing mAb 7C2 inhibited bacterial agglutination of erythrocytes, indicating that host cell receptor binding and erythrocyte agglutination are not mediated by the same spatial locations within the FimH protein.
CONCLUSIONS: The results demonstrate that the mAbs 7C2 and 7D8 against FimH protein positions 111-124 and 154-162 could inhibit the adhesion of E.coli to the chicken trachea.
摘要：
背景：禽大肠杆菌（E.coli)1型菌毛通过FimH蛋白粘附于禽类气管上皮细胞。然而,粘附相关抗原仍未知.本研究的目的是分析野生型禽大肠杆菌1型菌毛FimH蛋白的抗原性,筛选抗原表位，制备能够阻断禽类大肠杆菌粘附的单克隆抗体(mAb)。
结果：在这项研究中，MG2(O11)的核酸同源性，TS12(O18),YR5(O78)和K12为97.7%，99.6%,和97.7%，分别,氨基酸序列相似性达到98.7%,99.3%,和98.0％，分别。这三种菌株的FimH蛋白的表位和亲水性相似。更明显的凝集素结构域表位位于FimH蛋白位置111-124和154-162。制备针对这两种表位的mAb7C2和7D8。粘附抑制试验显示7C2和7D8阻断细菌对禽类气管上皮细胞的粘附。抗111-124表位的mAb7C2抑制了93%的O78菌株粘附，抗154-162表位的mAb7D8抑制了49%的O78菌株粘附，表明这两个表位与1型菌毛的粘附密切相关。然而,只有111-124表位识别mAb7C2抑制红细胞的细菌凝集，表明宿主细胞受体结合和红细胞凝集不是由FimH蛋白内相同的空间位置介导的。
结论：结果表明，针对FimH蛋白位置111-124和154-162的mAbs7C2和7D8可以抑制大肠杆菌与鸡气管的粘附。
结果：在这项研究中，MG2(O11)的核酸同源性，TS12(O18),YR5(O78)和K12为97.7%，99.6%,和97.7%，分别,氨基酸序列相似性达到98.7%,99.3%,和98.0％，分别。这三种菌株的FimH蛋白的表位和亲水性相似。更明显的凝集素结构域表位位于FimH蛋白位置111-124和154-162。制备针对这两种表位的mAb7C2和7D8。粘附抑制试验显示7C2和7D8阻断细菌对禽类气管上皮细胞的粘附。抗111-124表位的mAb7C2抑制了93%的O78菌株粘附，抗154-162表位的mAb7D8抑制了49%的O78菌株粘附，表明这两个表位与1型菌毛的粘附密切相关。然而,只有111-124表位识别mAb7C2抑制红细胞的细菌凝集，表明宿主细胞受体结合和红细胞凝集不是由FimH蛋白内相同的空间位置介导的。
结论：结果表明，针对FimH蛋白位置111-124和154-162的mAbs7C2和7D8可以抑制大肠杆菌与鸡气管的粘附。
