The most promising means of controlling anthrax, a lethal zoonotic disease during the early infection stages, entail restricting the resilient infectious form, i.e., the spores from proliferating to replicating bacilli in the host. The extractible antigen (EA1), a major S-layer protein present on the vegetative cells and spores of Bacillus anthracis, is highly immunogenic and protects mice against lethal challenge upon immunization. In the present study, mice were immunized with r-EA1C, the C terminal crystallization domain of EA1, to generate a neutralizing monoclonal antibody EA752–862, that was evaluated for its anti-spore and anti-bacterial properties. The monoclonal antibody EA752–862 had a minimum inhibitory concentration of 0.08 mg/ml, was bactericidal at a concentration of 0.1 mg/ml and resulted in 100% survival of mice against challenge with B. anthracis vegetative cells. Bacterial cell lysis as observed by scanning electron microscopy and nucleic acid leakage assay could be attributed as a possible mechanism for the bactericidal property. The association of mAb EA752–862 with spores inhibits their subsequent germination to vegetative cells in vitro, enhances phagocytosis of the spores and killing of the vegetative cells within the macrophage, and subsequently resulted in 90% survival of mice upon B. anthracis Ames spore challenge. Therefore, owing to its anti-spore and bactericidal properties, the present study demonstrates mAb EA752–862 as an efficient neutralizing antibody that hinders the establishment of early infection before massive multiplication and toxin release takes place.

中文翻译：

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EA752-862单克隆抗体针对炭疽芽孢杆菌营养细胞和孢子的功能表征和保护功效的评估。

控制炭疽的最有前途的手段是在感染早期即致死的人畜共患疾病，它限制了有弹性的感染形式，即孢子在宿主中从增生到复制细菌。可提取抗原（EA1）是炭疽杆菌营养细胞和孢子上存在的主要S层蛋白，具有高度免疫原性，可保护小鼠免于免疫接种的致命攻击。在本研究中，小鼠用EA1的C末端结晶域r-EA1C免疫，以产生中和性单克隆抗体EA752-862，并对其抗孢子和抗菌特性进行了评估。单克隆抗体EA752–862的最低抑制浓度为0.08 mg / ml，在0.1 mg / ml的浓度下具有杀菌作用，可导致小鼠抵抗炭疽芽孢杆菌的存活率达到100％营养细胞。通过扫描电子显微镜和核酸泄漏测定观察到的细菌细胞裂解可以被认为是杀菌特性的可能机制。单克隆抗体EA752–862与孢子的结合在体外抑制了其随后向营养细胞的萌发，增强了孢子的吞噬作用，并杀死了巨噬细胞内的营养细胞，继而导致炭疽杆菌Ames孢子攻击后小鼠的存活率为90％。因此，由于其抗孢子和杀菌特性，本研究表明mAb EA752-862是一种有效的中和抗体，可在大量繁殖和毒素释放之前阻止早期感染的建立。