A heteropolymer antibody for treatment of serotype B BoNT

描述（由申请人提供）：肉毒杆菌神经毒素（BoNT）是一种非常有效的神经肌肉阻滞剂，是食源性疾病、肉毒杆菌中毒和A类生物恐怖剂的原因。暴露于毒素的患者会出现呼吸麻痹，这可能是致命的。目前，BoNT暴露的唯一可用的对策是来自人或马来源的免疫血清。不幸的是，人血清的供应非常有限，而马血清可引起严重的免疫副作用。这项研究的长期目标是创建一组针对BoNT暴露的抗体治疗剂，这些抗体治疗剂能够在暴露个体中抵消7种已知BoNT血清型中的任何一种。这一目标的主要障碍是研究表明，用单一抗体不能实现BoNT的显著中和。相反，需要三种或更多种抗体的寡克隆组合，最有可能的是因为它们可以在BoNT毒害其靶神经元之前诱导BoNT从体循环中快速清除。该提议建立在新的人抗体克隆方法的基础上，该方法已经产生了以极高亲和力结合血清型B BoNT（BoNT/B）的人IgG抗体。我们将修饰该抗体，使其能够快速从血液循环中清除BoNT/B，将其与对人补体受体1（CR 1）特异性的单克隆抗体缀合。这将产生一种新产品，一种异源多聚体抗体（HP）。BoNT/B特异性HP将与红细胞表面上的CR 1结合，并将毒素递送至肝巨噬细胞进行破坏。参与BoNT的这种免疫清除机制将使HP能够以与BoNT抗血清相当的效力中和BoNT/B。该项目的结果将是一种单一的HP，它是用于治疗BoNT/B暴露的人和马BoNT抗血清的安全有效的替代品。公共卫生相关性：目前，能够治疗大规模B型肉毒杆菌神经毒素（BoNT/B）暴露（例如可能发生在生物恐怖袭击中）的人抗血清数量不足（1）。我们已经克隆了一种人抗体，其以极高的亲和力结合BoNT/B并具有部分中和活性。我们将使用杂聚物技术（2）修饰该抗体以增加其中和效力，从而使其成为BoNT/B暴露的有效对策。

DESCRIPTION (provided by applicant): Botulinum neurotoxin (BoNT) is an extremely potent neuromuscular blocker that is the cause of the food-borne illness, botulism, and a Category A Select Bioterror agent. Patients exposed to the toxin experience a respiratory paralysis that can be fatal. At present, the only available countermeasures for BoNT exposure are immune sera from either human or equine sources. Unfortunately, the human sera are in very limited supply and the equine sera can cause serious immune side effects. The long-term goal of this research is to create a panel of antibody therapeutics for BoNT exposure that are able to counteract in exposed individuals any of the 7 known BoNT serotypes. A major impediment to this objective is that studies have shown that significant neutralization of BoNT cannot be achieved with a single antibody. Rather, oligoclonal combinations of three or more antibodies are required, most likely because they can induce rapid clearance of BoNT from the systemic circulation before it can poison its target neurons. This proposal builds on a novel human antibody cloning method, which has produced a human IgG antibody that binds serotype B BoNT (BoNT/B) with extremely high affinity. We will modify this antibody such that it will be able to rapidly clear BoNT/B from the blood circulation, conjugating it to a monoclonal antibody specific for the human complement receptor 1 (CR1). This will create a new product, a heteropolymer antibody (HP). The BoNT/B specific HP will bind to CR1 on the surface of red blood cells and delivers the toxin to hepatic macrophages for destruction. Engaging this immune clearance mechanism of BoNT will enable the HP to neutralize BoNT/B with potency comparable to BoNT antisera. The result of this project will be a single HP that is a safe and effective replacement for human and equine BoNT antisera for the treatment of BoNT/B exposure. PUBLIC HEALTH RELEVANCE: At present, there are insufficient quantities of human antisera capable of treating a large-scale type B botulinum neurotoxin (BoNT/B) exposure, such as may occur in a bioterror attack (1). We have cloned a human antibody that binds BoNT/B with extremely high affinity and has partial neutralizing activity. We will modify this antibody using heteropolymer technology (2) to increase its neutralization potency so that it will be an effective countermeasure for BoNT/B exposure.