Dong Na, Luo Longlong, Wu Junhua, Jia Peiyuan, Li Qian, Wang Yuxia, Gao Zhongcai, Peng Hui, Lv Ming, Huang Chunqian, Feng Jiannan, Li Hua, Shan Junjie, Han Gang, Shen Beifen
Beijing Institute of Pharmacology and Toxicology, State Key Laboratory of Toxicology and Medical Countermeasures, Beijing 100850, China.
Beijing Institute of Basic Medical Sciences, Beijing 100850, China.
Vaccine. 2015 Jul 31;33(32):3836-42. doi: 10.1016/j.vaccine.2015.06.096. Epub 2015 Jun 30.
Ricin is a glycoprotein produced in castor seeds and consists of two polypeptide chains named Ricin Toxin A Chain (RTA) and Ricin Toxin B Chain (RTB), linked via a disulfide bridge. Due to its high toxicity, ricin is regarded as a high terrorist risk for the public. However, antibodies can play a pivotal role in neutralizing the toxin. In this research, the anti-toxicant effect of mAb 4C13, a monoclonal antibody (mAb) established using detoxicated ricin as the immunized antigen, was evaluated. Compared with mAb 4F2 and mAb 5G6, the effective mechanism of mAb 4C13 was analyzed by experiments relating to its cytotoxicity, epitope on ricin, binding kinetics with the toxin, its blockage on the protein synthesis inhibition induced by ricin and the intracelluar tracing of its complex with ricin. Our result indicated that mAb 4C13 could recognize and bind to RTA, RTB and exert its high affinity to the holotoxin. Both cytotoxicity and animal toxicity of ricin were well blocked by pre-incubating the toxin with mAb 4C13. By intravenous injection, mAb 4C13 could rescue the mouse intraperitoneally (ip) injected with a lethal dose of ricin (20μg/kg) even at 6h after the intoxication and its efficacy was dependent on its dosage. This research indicated that mAb 4C13 could be an excellent candidate for therapeutic antibodies. Its potent antitoxic efficiency was related to its recognition on the specific epitope with very high affinity and its blockage of protein synthesis inhibition in cytoplasm followed by cellular internalization with ricin.
蓖麻毒素是一种在蓖麻籽中产生的糖蛋白，由两条名为蓖麻毒素A链（RTA）和蓖麻毒素B链（RTB）的多肽链组成，通过二硫键连接。由于其高毒性，蓖麻毒素被视为对公众具有高度恐怖主义风险的物质。然而，抗体在中和毒素方面可发挥关键作用。在本研究中，评估了以脱毒蓖麻毒素作为免疫抗原建立的单克隆抗体（mAb）4C13的抗毒效果。通过与其细胞毒性、蓖麻毒素上的表位、与毒素的结合动力学、对蓖麻毒素诱导的蛋白质合成抑制的阻断作用以及其与蓖麻毒素复合物的细胞内追踪相关的实验，分析了mAb 4C13与mAb 4F2和mAb 5G6相比的有效作用机制。我们的结果表明，mAb 4C13能够识别并结合RTA、RTB，并对全毒素具有高亲和力。用mAb 4C13预先孵育毒素可有效阻断蓖麻毒素的细胞毒性和动物毒性。通过静脉注射，即使在中毒后6小时，mAb 4C13也能挽救腹腔注射致死剂量蓖麻毒素（20μg/kg）的小鼠，其疗效取决于剂量。本研究表明，mAb 4C13可能是治疗性抗体的优秀候选者。其强大的抗毒效率与其以非常高的亲和力识别特定表位、阻断细胞质中的蛋白质合成抑制以及随后与蓖麻毒素的细胞内化有关。
