The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern threatens the efficacy of existing vaccines and therapeutic antibodies and underscores the need for additional antibody-based tools that potently neutralize variants by targeting multiple sites of the spike protein. We isolated 216 monoclonal antibodies targeting SARS-CoV-2 from plasmablasts and memory B cells collected from patients with coronavirus disease 2019. The three most potent antibodies targeted distinct regions of the receptor binding domain (RBD), and all three neutralized the SARS-CoV-2 Alpha and Beta variants. The crystal structure of the most potent antibody, CV503, revealed that it binds to the ridge region of SARS-CoV-2 RBD, competes with the angiotensin-converting enzyme 2 receptor, and has limited contact with key variant residues K417, E484, and N501. We designed bispecific antibodies by combining nonoverlapping specificities and identified five bispecific antibodies that inhibit SARS-CoV-2 infection at concentrations of less than 1 ng/ml. Through a distinct mode of action, three bispecific antibodies cross-linked adjacent spike proteins using dual N-terminal domain–RBD specificities. One bispecific antibody was greater than 100-fold more potent than a cocktail of its parent monoclonals in vitro and prevented clinical disease in a hamster model at a dose of 2.5 mg/kg. Two bispecific antibodies in our panel comparably neutralized the Alpha, Beta, Gamma, and Delta variants and wild-type virus. Furthermore, a bispecific antibody that neutralized the Beta variant protected hamsters against SARS-CoV-2 expressing the E484K mutation. Thus, bispecific antibodies represent a promising next-generation countermeasure against SARS-CoV-2 variants of concern.

中文翻译：

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针对刺突蛋白不同区域的双特异性抗体可有效中和令人关注的 SARS-CoV-2 变体


令人关注的严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 变体的出现威胁到现有疫苗和治疗抗体的功效，并强调需要额外的基于抗体的工具，通过靶向刺突蛋白的多个位点来有效中和变体。我们从 2019 年冠状病毒病患者收集的浆母细胞和记忆 B 细胞中分离出了 216 种针对 SARS-CoV-2 的单克隆抗体。三种最有效的抗体针对受体结合域 (RBD) 的不同区域，并且所有三种抗体都中和了 SARS-CoV -2 个 Alpha 和 Beta 变体。最有效的抗体 CV503 的晶体结构表明，它与 SARS-CoV-2 RBD 的脊区结合，与血管紧张素转换酶 2 受体竞争，并且与关键变异残基 K417、E484 和N501。我们通过结合非重叠特异性设计了双特异性抗体，并鉴定了五种能够以低于 1 ng/ml 的浓度抑制 SARS-CoV-2 感染的双特异性抗体。通过独特的作用模式，三种双特异性抗体利用双 N 端结构域 - RBD 特异性交联相邻的刺突蛋白。一种双特异性抗体在体外的效力比其亲本单克隆抗体的混合物强 100 倍以上，并且在剂量为 2.5 mg/kg 的仓鼠模型中可以预防临床疾病。我们的组中的两种双特异性抗体可中和 Alpha、Beta、Gamma 和 Delta 变体以及野生型病毒。此外，一种中和 Beta 变体的双特异性抗体可以保护仓鼠免受表达 E484K 突变的 SARS-CoV-2 的侵害。因此，双特异性抗体代表了一种有前途的针对 SARS-CoV-2 变异体的下一代对策。