Significance Neutralizing antibodies are important for immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and as therapeutics for the prevention and treatment of COVID-19. We identified high-affinity nanobodies against SARS-CoV-2 receptor-binding domain and found that nanobody cocktails consisting of two noncompeting nanobodies were able to block ACE2 engagement with RBD variants present in human populations and potently neutralize both wild-type SARS-CoV-2 and the N501Y D614G variant at low concentrations. Prophylactic administration of nanobody cocktails reduced viral loads in mice infected with the N501Y D614G SARS-CoV-2 virus, showing that nanobody cocktails are useful as prophylactic agents against SARS-CoV-2. Neutralizing antibodies are important for immunity against SARS-CoV-2 and as therapeutics for the prevention and treatment of COVID-19. Here, we identified high-affinity nanobodies from alpacas immunized with coronavirus spike and receptor-binding domains (RBD) that disrupted RBD engagement with the human receptor angiotensin-converting enzyme 2 (ACE2) and potently neutralized SARS-CoV-2. Epitope mapping, X-ray crystallography, and cryo-electron microscopy revealed two distinct antigenic sites and showed two neutralizing nanobodies from different epitope classes bound simultaneously to the spike trimer. Nanobody-Fc fusions of the four most potent nanobodies blocked ACE2 engagement with RBD variants present in human populations and potently neutralized both wild-type SARS-CoV-2 and the N501Y D614G variant at concentrations as low as 0.1 nM. Prophylactic administration of either single nanobody-Fc or as mixtures reduced viral loads by up to 10 4 -fold in mice infected with the N501Y D614G SARS-CoV-2 virus. These results suggest a role for nanobody-Fc fusions as prophylactic agents against SARS-CoV-2.
【저자키워드】 SARS-CoV-2, Crystallography, nanobodies, cryo-EM, antiviral therapeutics, 【초록키워드】 COVID-19, Treatment, ACE2, coronavirus, Immunity, Neutralizing antibodies, antibody, Therapeutics, Cryo-electron microscopy, SARS-CoV-2 virus, X-ray crystallography, Prophylactic, severe acute respiratory syndrome Coronavirus, angiotensin-converting enzyme 2, Viral, Receptor-binding domain, nanobody, mice, RBD, N501Y, D614G variant, D614G, Neutralizing, receptor, epitope mapping, respiratory, fusion, epitope, administration, Concentration, angiotensin, human populations, human population, acute respiratory syndrome, treatment of COVID-19, acute respiratory syndrome coronavirus, acute respiratory syndrome coronavirus 2, enzyme, domain, viral loads, wild-type SARS-CoV-2, receptor-binding domains, RBD variants, spike trimer, concentrations, neutralize, immunized, neutralized, blocked, antigenic site, RBD variant, reduced viral load, Significance, 【제목키워드】 variant, N501Y, SARS-CoV-2 D614G, neutralize, PROTECT,