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，是食源性疾病肉毒中毒的原因，也是a类生物恐怖制剂。接触到这种毒素的病人会出现呼吸麻痹，这可能是致命的。目前，针对BoNT暴露的唯一可用对策是来自人或马的免疫血清。不幸的是，人血清的供应非常有限，马血清会引起严重的免疫副作用。这项研究的长期目标是为BoNT暴露创造一组抗体疗法，能够在暴露的个体中抵消7种已知BoNT血清型中的任何一种。实现这一目标的一个主要障碍是，研究表明单抗体不能实现BoNT的显著中和。相反，需要三种或更多抗体的寡克隆组合，很可能是因为它们可以在BoNT毒害目标神经元之前诱导其从体循环中快速清除。该建议建立在一种新的人类抗体克隆方法的基础上，该方法产生了一种与血清型B型BoNT具有极高亲和力的人IgG抗体（BoNT/B）。我们将对这种抗体进行修饰，使其能够快速清除血液循环中的BoNT/B，并将其与人类补体受体1 （CR1）特异性的单克隆抗体偶联。这将产生一种新产品——异聚抗体（HP）。BoNT/B特异性HP将与红细胞表面的CR1结合，并将毒素传递给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安全有效的HP，可替代人类和马的BoNT/B抗血清治疗BoNT/B暴露。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）暴露的人类抗血清数量不足，例如可能发生在生物恐怖袭击中(1)。我们克隆了一种结合BoNT/B的人抗体，具有极高的亲和力和部分中和活性。我们将利用杂多聚合物技术修饰该抗体(2)，以提高其中和效力，使其成为对抗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.