Anthrax toxin is a key virulence factor for Bacillus anthracis. The cell-binding component of anthrax toxin, protective antigen (PA), mediates the entry of the toxin into cells by first binding to the extracellular von Willebrand factor A (VWA) domain of the cellular anthrax toxin receptor (ATR). Herein, we targeted the VWA domain of the cellular receptor to develop a more effective antitoxin agent for neutralization of anthrax toxin. We selected ATR-binding peptides by using a phage display: among these, we identified two novel peptides binding to the ATR with high affinity and specificity, and that neutralized anthrax toxicity in cells. Furthermore, to enhance the functional efficiency of the probes, the peptides were modified and conjugated to three polyvalent probe backbones: a 17 amino-acid-based cyclic form penta-unit, poly-d-lysine (PDL), or the M13 bacteriophage. One of the functionally modified polyvalent peptide probes, the penta-unit-conjugated probe (PUCP) produced the most potent neutralization of anthrax toxin, with half-maximal inhibitory concentration (IC₅₀) of 20 nM. The PUCP disrupted anthrax toxin binding to its receptor and reduced endocytosis of anthrax toxin. This peptide-based approach may, therefore, represent a promising strategy to combat anthrax toxicosis and other bacterial diseases and may be efficient for disease treatment.

炭疽毒素是一个关键致病因子炭疽杆菌。炭疽毒素的细胞结合成分，保护性抗原（PA）通过首先结合细胞炭疽毒素受体（ATR）的胞外von Willebrand因子A（VWA）域来介导毒素进入细胞。在本文中，我们针对细胞受体的VWA域开发了一种更有效的中和炭疽毒素的抗毒素剂。我们通过使用噬菌体展示选择了ATR结合肽：在这些蛋白中，我们鉴定了两种以高亲和力和特异性结合ATR的新型肽，并中和了细胞中的炭疽毒性。此外，为提高探针的功能效率，将肽修饰和缀合到三个多价探针主链：基于氨基酸17环状形式五单元，聚d-赖氨酸（PDL）或M13噬菌体。五官能团偶联探针（PUCP）是功能性修饰的多价肽探针之一，产生的炭疽毒素最强效中和，抑制最大浓度（IC ₅₀）为20 nM。PUCP破坏了炭疽毒素与其受体的结合并减少了炭疽毒素的内吞作用。因此，这种基于肽的方法可能代表了对抗炭疽中毒和其他细菌性疾病的有前途的策略，并且对于疾病治疗可能是有效的。