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. Neutralizing nanobodies (Nb) are of considerable interest as therapeutic agents for COVID-19 treatment. Here, the authors functionally and structurally characterize Nbs that bind with high affinity to the receptor binding domain of the SARS-CoV-2 spike protein and show that an engineered homotrimeric Nb prevents disease progression in a Syrian hamster model of COVID-19 when administered intranasally.
【저자키워드】 X-ray crystallography, Antibody fragment therapy, Cryoelectron microscopy, 【초록키워드】 COVID-19, Treatment, SARS-CoV-2, ACE2, antibody, Spike protein, Receptor binding domain, Prophylaxis, COVID-19 treatment, Disease progression, Protein, South Africa, Health, stability, nanobody, escape mutant, B.1.1.7, RBD, SARS-CoV-2 spike protein, nanobodies, Alpha, Beta, therapeutic agent, therapeutic agents, Neutralizing, respiratory, crystal structure, epitope, binding, escape mutants, administration, crystal structures, unmet need, intraperitoneal injection, overlap, Victoria, domain, therapeutic efficacy, high affinity, injection, molecule, cryo, electron, Cryo Electron Microscopy, homotrimers, respiratory route, Administered, Prevent, effective, neutralize, intranasally, the Spike, homotrimer, the SARS-CoV-2, 【제목키워드】 COVID-19, SARS-CoV-2, nanobody, therapeutic efficacy, neutralising,