High affinity nanobodies block SARS-CoV-2 spike receptor binding domain interaction with human angiotensin converting enzyme

Sci Rep. 2020 Dec 22;10(1):22370. doi: 10.1038/s41598-020-79036-0.


There are currently few approved effective treatments for SARS-CoV-2, the virus responsible for the COVID-19 pandemic. Nanobodies are 12-15 kDa single-domain antibody fragments that can be delivered by inhalation and are amenable to relatively inexpensive large scale production compared to other biologicals. We have isolated nanobodies that bind to the SARS-CoV-2 spike protein receptor binding domain and block spike protein interaction with the angiotensin converting enzyme 2 (ACE2) with 1-5 nM affinity. The lead nanobody candidate, NIH-CoVnb-112, blocks SARS-CoV-2 spike pseudotyped lentivirus infection of HEK293 cells expressing human ACE2 with an EC50 of 0.3 µg/mL. NIH-CoVnb-112 retains structural integrity and potency after nebulization. Furthermore, NIH-CoVnb-112 blocks interaction between ACE2 and several high affinity variant forms of the spike protein. These nanobodies and their derivatives have therapeutic, preventative, and diagnostic potential.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Angiotensin-Converting Enzyme 2 / genetics
  • Angiotensin-Converting Enzyme 2 / metabolism*
  • Animals
  • Antibodies, Neutralizing / immunology
  • Antibodies, Viral / immunology*
  • Antibody Affinity*
  • Binding Sites, Antibody / immunology
  • COVID-19 / metabolism*
  • COVID-19 / therapy
  • COVID-19 / virology
  • Camelids, New World
  • Drug Discovery / methods*
  • HEK293 Cells
  • Humans
  • Immunization / methods
  • Male
  • Protein Binding
  • Protein Interaction Domains and Motifs / immunology*
  • SARS-CoV-2 / chemistry*
  • Signal Transduction / genetics
  • Single-Domain Antibodies / immunology*
  • Spike Glycoprotein, Coronavirus / chemistry*
  • Spike Glycoprotein, Coronavirus / genetics
  • Transduction, Genetic
  • Transfection


  • Antibodies, Neutralizing
  • Antibodies, Viral
  • Single-Domain Antibodies
  • Spike Glycoprotein, Coronavirus
  • spike protein, SARS-CoV-2
  • ACE2 protein, human
  • Angiotensin-Converting Enzyme 2