Potent Neutralization of Staphylococcal Enterotoxin B In Vivo by Antibodies that Block Binding to the T-Cell Receptor
Potent Neutralization of Staphylococcal Enterotoxin B In Vivo by Antibodies that Block Binding to the T-Cell Receptor
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DOI：
10.1016/j.jmb.2019.03.017
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发表时间：
2019-10-09
影响因子：
5.6
通讯作者：
Sidhu, Sachdev S.
中科院分区：
文献类型：
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作者：
Chen, Gang;Karauzum, Hatice;Sidhu, Sachdev S.
葡萄球菌肠毒素B是一种潜在的生物恐怖分子，也是引起食物中毒的主要原因。为了研制一种针对葡萄球菌肠毒素B的抗体治疗，我们研制了一种针对葡萄球菌肠毒素B的“T类”抗SEB中和抗体(GC132)，其表位与以前研制的“M类”抗体不同。将系统工程方法应用于亲和力成熟的抗体GC132，以获得具有亚纳摩尔结合亲和力的优化候选治疗抗体(GC132a)。氢-氚交换结合质谱仪绘制的结合界面图显示，SEB上的T类表位与T细胞受体结合部位重叠，而其他证据表明M类表位与主要组织相容性复合体的结合部位重叠。在免疫球蛋白形式中，GC132a在体外显示出类似于最好的M类抗体50倍的毒素中和效果，并在暴露后中毒休克模型中完全保护小鼠免受致命攻击。我们还利用两个M类结合位点和两个T类结合位点设计了四价结合的双特异性抗体(BsAbs)。与各自的单特异性抗体亚基以及两者的混合物相比，bsAbs表现出更强的毒素中和效力，这表明增强的中和效力是由于与SEB上两个不重叠的表位的异型四价结合所致。综上所述，这些结果表明T类抗SEB抗体GC132a是临床开发和bsAb工程的极佳候选者。(C)2019爱思唯尔有限公司。保留所有权利。
To develop an antibody (Ab) therapeutic against staphylococcal enterotoxin B (SEB), a potential incapacitating bioterrorism agent and a major cause of food poisoning, we developed a "class T" anti-SEB neutralizing Ab (GC132) targeting an epitope on SEB distinct from that of previously developed "class M" Abs. A systematic engineering approach was applied to affinity-mature Ab GC132 to yield an optimized therapeutic candidate (GC132a) with sub-nanomolar binding affinity. Mapping of the binding interface by hydrogen-deuterium exchange coupled to mass spectrometry revealed that the class T epitope on SEB overlapped with the T-cell receptor binding site, whereas other evidence suggested that the class M epitope overlapped with the binding site for the major histocompatibility complex. In the IgG format, GC132a showed similar to 50-fold more potent toxin-neutralizing efficacy than the best class M Ab in vitro, and fully protected mice from lethal challenge in a toxic shock post-exposure model. We also engineered bispecific Abs (bsAbs) that bound tetravalently by utilizing two class M binding sites and two class T binding sites. The bsAbs displayed enhanced toxin neutralization efficacy compared with the respective monospecific Ab subunits as well as a mixture of the two, indicating that enhanced efficacy was due to heterotypic tetravalent binding to two non-overlapping epitopes on SEB. Together, these results suggest that class T anti-SEB Ab GC132a is an excellent candidate for clinical development and for bsAb engineering. (C) 2019 Elsevier Ltd. All rights reserved.