Humanized single domain antibodies neutralize SARS-CoV-2 by targeting the spike receptor binding domain

Nat Commun. 2020 Sep 10;11(1):4528. doi: 10.1038/s41467-020-18387-8.

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreads worldwide and leads to an unprecedented medical burden and lives lost. Neutralizing antibodies provide efficient blockade for viral infection and are a promising category of biological therapies. Here, using SARS-CoV-2 spike receptor-binding domain (RBD) as a bait, we generate a panel of humanized single domain antibodies (sdAbs) from a synthetic library. These sdAbs reveal binding kinetics with the equilibrium dissociation constant (KD) of 0.99-35.5 nM. The monomeric sdAbs show half maximal neutralization concentration (EC50) of 0.0009-0.07 µg/mL and 0.13-0.51 µg/mL against SARS-CoV-2 pseudotypes, and authentic SARS-CoV-2, respectively. Competitive ligand-binding experiments suggest that the sdAbs either completely block or significantly inhibit the association between SARS-CoV-2 RBD and viral entry receptor ACE2. Fusion of the human IgG1 Fc to sdAbs improve their neutralization activity by up to ten times. These results support neutralizing sdAbs as a potential alternative for antiviral therapies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiotensin-Converting Enzyme 2
  • Animals
  • Antibodies, Neutralizing / immunology*
  • Antibodies, Neutralizing / pharmacology
  • COVID-19
  • Chlorocebus aethiops
  • Coronavirus Infections / drug therapy
  • Coronavirus Infections / virology*
  • HEK293 Cells
  • Humans
  • Immunoglobulin G
  • Models, Molecular
  • Pandemics
  • Peptidyl-Dipeptidase A / metabolism
  • Pneumonia, Viral / drug therapy
  • Pneumonia, Viral / virology*
  • Protein Binding
  • Receptors, Virus / immunology
  • Single-Domain Antibodies / immunology*
  • Single-Domain Antibodies / pharmacology
  • Spike Glycoprotein, Coronavirus / immunology*
  • Spike Glycoprotein, Coronavirus / metabolism
  • Vero Cells

Substances

  • Antibodies, Neutralizing
  • Immunoglobulin G
  • Receptors, Virus
  • Single-Domain Antibodies
  • Spike Glycoprotein, Coronavirus
  • spike protein, SARS-CoV-2
  • Peptidyl-Dipeptidase A
  • ACE2 protein, human
  • Angiotensin-Converting Enzyme 2