Structural Biology, The Rosalind Franklin Institute, Harwell Science Campus, Didcot, UK.
Division of Structural Biology, The Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.
Nat Commun. 2021 Sep 22;12(1):5469. doi: 10.1038/s41467-021-25480-z.
SARS-CoV-2 remains a global threat to human health particularly as escape mutants emerge. There is an unmet need for effective treatments against COVID-19 for which neutralizing single domain antibodies (nanobodies) have significant potential. Their small size and stability mean that nanobodies are compatible with respiratory administration. We report four nanobodies (C5, H3, C1, F2) engineered as homotrimers with pmolar affinity for the receptor binding domain (RBD) of the SARS-CoV-2 spike protein. Crystal structures show C5 and H3 overlap the ACE2 epitope, whilst C1 and F2 bind to a different epitope. Cryo Electron Microscopy shows C5 binding results in an all down arrangement of the Spike protein. C1, H3 and C5 all neutralize the Victoria strain, and the highly transmissible Alpha (B.1.1.7 first identified in Kent, UK) strain and C1 also neutralizes the Beta (B.1.35, first identified in South Africa). Administration of C5-trimer via the respiratory route showed potent therapeutic efficacy in the Syrian hamster model of COVID-19 and separately, effective prophylaxis. The molecule was similarly potent by intraperitoneal injection.
SARS-CoV-2 仍然是全球人类健康的威胁，特别是随着逃逸突变体的出现。目前迫切需要针对 COVID-19 的有效治疗方法，而中和单域抗体（纳米抗体）具有巨大的潜力。它们的体积小且稳定，这意味着纳米抗体与呼吸道给药兼容。我们报告了四种作为三聚体工程化的纳米抗体（C5、H3、C1、F2），对 SARS-CoV-2 刺突蛋白的受体结合域（RBD）具有 pmolar 亲和力。晶体结构显示 C5 和 H3 与 ACE2 表位重叠，而 C1 和 F2 结合到不同的表位。冷冻电镜显示 C5 结合导致 Spike 蛋白呈全向下排列。C1、H3 和 C5 均中和维多利亚株，以及高度传染性的 Alpha（B.1.1.7 首次在英国肯特郡发现）株，C1 还中和 Beta（B.1.35，首次在南非发现）株。通过呼吸道途径给予 C5-三聚体表现出在 COVID-19 的叙利亚仓鼠模型中的有效治疗功效，单独使用时也具有预防效果。通过腹腔注射，该分子同样有效。
