An ultrapotent synthetic nanobody neutralizes SARS-CoV-2 by stabilizing inactive Spike.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus enters host cells via an interaction between its Spike protein and the host cell receptor angiotensin-converting enzyme 2 (ACE2). By screening a yeast surface-displayed library of synthetic nanobody sequences, we developed nanobodies that disrupt the interaction between Spike and ACE2. Cryo-electron ...
microscopy (cryo-EM) revealed that one nanobody, Nb6, binds Spike in a fully inactive conformation with its receptor binding domains locked into their inaccessible down state, incapable of binding ACE2. Affinity maturation and structure-guided design of multivalency yielded a trivalent nanobody, mNb6-tri, with femtomolar affinity for Spike and picomolar neutralization of SARS-CoV-2 infection. mNb6-tri retains function after aerosolization, lyophilization, and heat treatment, which enables aerosol-mediated delivery of this potent neutralizer directly to the airway epithelia.
Mesh Terms:
Angiotensin-Converting Enzyme 2, Animals, Antibodies, Neutralizing, Antibodies, Viral, Antibody Affinity, Chlorocebus aethiops, Cryoelectron Microscopy, Humans, Neutralization Tests, Protein Binding, Protein Stability, Single-Domain Antibodies, Spike Glycoprotein, Coronavirus, Vero Cells
Science
Date: Dec. 18, 2019
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