Lun M T, Raponi G, Amatucci A M, Natali P G, Fraioli R, Mancini C
Institute of Microbiology, University of Rome La Sapienza, Italy.
J Med Microbiol. 1997 Feb;46(2):122-8. doi: 10.1099/00222615-46-2-122.
The binding capacity and the protective activity of three monoclonal antibodies (MAbs)-ARM 1-4, ARM 1-7 and ARM 2-2-obtained from spleen cells of mice immunised with Escherichia coli O6:K-pre-treated with sub-MIC of aztreonam were studied. The MAbs belonged to IgG1 isotype and showed different reactivity toward protein epitopes of E. coli in an immunoblotting assay. ARM 1-4 recognised epitopes on molecules of 30 kDa and 40 kDa. ARM 1-7 identified an epitope of a molecule of 41 kDa, and ARM 2-2 recognised epitopes of molecules of 15 kDa and 41 kDa. In ELISA the MAbs cross-reacted with E. coli O7:K-, E. coli O111:B4 and E. coli O128:K- with different binding affinity. Furthermore, the MAbs showed complement-dependent bactericidal activity. The MAbs displayed different protective capacities when given to mice 90 min before lethal challenges with 2 x LD50, 4 x LD50 and 8 x LD50 of E. coli strains. In all but one instance (ARM 1-4 versus E. coli O7:K-) it was not possible to correlate protective capacity with binding affinity of a MAb to a given bacterial cell. Therefore, the epitopes recognised by the MAb may be more closely associated with bacterial virulence than in binding to the bacterial cell.
研究了从用亚抑菌浓度氨曲南预处理的大肠杆菌O6:K免疫的小鼠脾细胞中获得的三种单克隆抗体（MAb）——ARM 1-4、ARM 1-7和ARM 2-2的结合能力和保护活性。这些单克隆抗体属于IgG1同种型，在免疫印迹分析中对大肠杆菌的蛋白质表位表现出不同的反应性。ARM 1-4识别30 kDa和40 kDa分子上的表位。ARM 1-7识别一个41 kDa分子的表位，而ARM 2-2识别15 kDa和41 kDa分子的表位。在酶联免疫吸附测定（ELISA）中，这些单克隆抗体与大肠杆菌O7:K-、大肠杆菌O111:B4和大肠杆菌O128:K-以不同的结合亲和力发生交叉反应。此外，这些单克隆抗体表现出补体依赖性杀菌活性。在用2倍半数致死剂量（LD50）、4倍LD50和8倍LD50的大肠杆菌菌株进行致死性攻击前90分钟给小鼠注射这些单克隆抗体时，它们表现出不同的保护能力。除了一个实例（ARM 1-4对大肠杆菌O7:K-）外，在所有情况下都无法将单克隆抗体对给定细菌细胞的保护能力与其结合亲和力相关联。因此，单克隆抗体识别的表位可能与细菌毒力的关联比与细菌细胞结合的关联更紧密。
