Department of Medicine, Division of Infectious Diseases, Center for Antibody Therapeutics, University of Pittsburgh Medical School, Pittsburgh, PA 15261;
Department of Medicine, Division of Infectious Diseases, Center for Antibody Therapeutics, University of Pittsburgh Medical School, Pittsburgh, PA 15261.
Proc Natl Acad Sci U S A. 2020 Nov 24;117(47):29832-29838. doi: 10.1073/pnas.2010197117. Epub 2020 Nov 2.
Effective therapies are urgently needed for the SARS-CoV-2/COVID-19 pandemic. We identified panels of fully human monoclonal antibodies (mAbs) from large phage-displayed Fab, scFv, and VH libraries by panning against the receptor binding domain (RBD) of the SARS-CoV-2 spike (S) glycoprotein. A high-affinity Fab was selected from one of the libraries and converted to a full-size antibody, IgG1 ab1, which competed with human ACE2 for binding to RBD. It potently neutralized replication-competent SARS-CoV-2 but not SARS-CoV, as measured by two different tissue culture assays, as well as a replication-competent mouse ACE2-adapted SARS-CoV-2 in BALB/c mice and native virus in hACE2-expressing transgenic mice showing activity at the lowest tested dose of 2 mg/kg. IgG1 ab1 also exhibited high prophylactic and therapeutic efficacy in a hamster model of SARS-CoV-2 infection. The mechanism of neutralization is by competition with ACE2 but could involve antibody-dependent cellular cytotoxicity (ADCC) as IgG1 ab1 had ADCC activity in vitro. The ab1 sequence has a relatively low number of somatic mutations, indicating that ab1-like antibodies could be quickly elicited during natural SARS-CoV-2 infection or by RBD-based vaccines. IgG1 ab1 did not aggregate, did not exhibit other developability liabilities, and did not bind to any of the 5,300 human membrane-associated proteins tested. These results suggest that IgG1 ab1 has potential for therapy and prophylaxis of SARS-CoV-2 infections. The rapid identification (within 6 d of availability of antigen for panning) of potent mAbs shows the value of large antibody libraries for response to public health threats from emerging microbes.
针对 SARS-CoV-2/COVID-19 大流行，我们急需有效的治疗方法。我们通过对 SARS-CoV-2 刺突（S）糖蛋白受体结合域（RBD）进行淘选，从大型噬菌体展示 Fab、scFv 和 VH 文库中鉴定出了一系列全人源单克隆抗体（mAb）。从其中一个文库中筛选出一个高亲和力的 Fab，并将其转化为全长抗体 IgG1 ab1，该抗体能与人类 ACE2 竞争结合 RBD。它能有效中和有复制能力的 SARS-CoV-2，但不能中和 SARS-CoV，这通过两种不同的组织培养测定法以及在 BALB/c 小鼠中用具有复制能力的小鼠 ACE2 适应的 SARS-CoV-2 和在 hACE2 表达的转基因小鼠中用天然病毒进行的测定法得到了证实，在最低测试剂量 2 mg/kg 时就显示出活性。IgG1 ab1 在仓鼠 SARS-CoV-2 感染模型中也表现出高的预防和治疗功效。中和的机制是通过与 ACE2 的竞争，但可能涉及抗体依赖的细胞毒性（ADCC），因为 IgG1 ab1 在体外具有 ADCC 活性。ab1 序列的体细胞突变数量相对较少，这表明在自然发生的 SARS-CoV-2 感染或基于 RBD 的疫苗接种过程中，可能会迅速诱导出类似 ab1 的抗体。IgG1 ab1 不聚集，没有表现出其他开发缺陷，也不与测试的 5300 个人类膜相关蛋白中的任何一种结合。这些结果表明，IgG1 ab1 有可能用于治疗和预防 SARS-CoV-2 感染。在获得抗原用于淘选后的 6 天内，快速鉴定出有效的 mAb 表明，对于应对新兴微生物对公共卫生的威胁，大型抗体库具有重要价值。
