Beijing Institute of Biotechnology, Beijing, China.
Front Immunol. 2024 Apr 30;15:1380694. doi: 10.3389/fimmu.2024.1380694. eCollection 2024.
Botulinum neurotoxin (BoNT) produced by is one of the most potent known toxins. Moreover, BoNT is classified as one of the most important biological warfare agents that threatens the biosafety of the world. Currently, the approved treatment for botulism in humans is the use of polyvalent horse serum antitoxins. However, they are greatly limited because of insufficient supply and adverse reactions. Thus, treatment of human botulism requires the development of effective toxin-neutralizing antibodies. Considering their advantages, neutralizing nanobodies will play an increasing role as BoNTs therapeutics.
Herein, neutralizing nanobodies binding to the heavy chain (Hc) domain of BoNT/B (BHc) were screened from a phage display library. Then, BoNT/B-specific clones were identified and fused with the human Fc fragment (hFc) to form chimeric heavy chain antibodies. Finally, the affinity, specificity, and neutralizing activity of antibodies against BoNT/B were evaluated.
The B5-hFc, B9-hFc and B12-hFc antibodies demonstrated high affinity for BHc in the nanomolar range. The three antibodies were proven to have potent neutralizing activity against BoNT/B .
The results demonstrate that inhibiting toxin binding to the host receptor is an efficient strategy and the three antibodies could be used as candidates for the further development of drugs to prevent and treat botulism.
产生的肉毒神经毒素（BoNT）是已知最有效力的毒素之一。此外，BoNT 被列为对世界生物安全构成威胁的最重要的生物战剂之一。目前，批准用于人类肉毒中毒的治疗方法是使用多价马血清抗毒素。然而，由于供应不足和不良反应，它们受到了极大的限制。因此，人类肉毒中毒的治疗需要开发有效的毒素中和抗体。鉴于其优势，中和纳米抗体将在 BoNTs 治疗中发挥越来越重要的作用。
从噬菌体展示文库中筛选出与 BoNT/B 的重链（Hc）结构域结合的中和纳米抗体。然后，鉴定出 BoNT/B 特异性克隆体，并与人 Fc 片段（hFc）融合，形成嵌合重链抗体。最后，评估了针对 BoNT/B 的抗体的亲和力、特异性和中和活性。
B5-hFc、B9-hFc 和 B12-hFc 抗体对 BHc 的亲和力在纳摩尔范围内较高。这三种抗体被证明对 BoNT/B 具有强大的中和活性。
结果表明，抑制毒素与宿主受体的结合是一种有效的策略，这三种抗体可作为进一步开发预防和治疗肉毒中毒药物的候选物。
