Versatile and multivalent nanobodies efficiently neutralize SARS-CoV-2.

Yufei Xiang,Yi Shi,Heng Liu,W Paul Duprex,Cheng Zhang,Zhengyun Xiao,Sham Nambulli,Dina Schneidman-Duhovny,Zhe Sang

doi:10.1126/science.abe4747

Abstract

Cost-effective, efficacious therapeutics are urgently needed to combat the COVID-19 pandemic. In this study, we used camelid immunization and proteomics to identify a large repertoire of highly potent neutralizing nanobodies (Nbs) to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein receptor binding domain (RBD). We discovered Nbs with picomolar to femtomolar affinities that inhibit viral infection at concentrations below the nanograms-per-milliliter level, and we determined a structure of one of the most potent Nbs in complex with the RBD. Structural proteomics and integrative modeling revealed multiple distinct and nonoverlapping epitopes and indicated an array of potential neutralization mechanisms. We bioengineered multivalent Nb constructs that achieved ultrahigh neutralization potency (half-maximal inhibitory concentration as low as 0.058 ng/ml) and may prevent mutational escape. These thermostable Nbs can be rapidly produced in bulk from microbes and resist lyophilization and aerosolization.

Highlights

Cost-effective, efficacious therapeutics are urgently needed to combat the COVID-19 pandemic
SARSCoV-2 expresses a surface spike (S) glycoprotein, which consists of S1 and S2 subunits that form a homotrimeric viral spike to interact with host cells
The interaction is mediated by the S1 receptor binding domain (RBD), which binds the peptidase domain of human angiotensin-converting enzyme 2 as a host receptor [3]

Summary

Introduction

Cost-effective, efficacious therapeutics are urgently needed to combat the COVID-19 pandemic. To further characterize these activities, we separated the single-chain VHH antibodies from the IgGs. We confirmed that the singlechain antibodies achieve specific, high-affinity binding to the RBD and possess subnanometer half-maximal inhibitory concentration (IC50 = 509 pM) against the pseudotyped virus We used a SARS-CoV-2–green fluorescent protein (GFP) pseudovirus neutralization assay to screen and characterize the antiviral activities of these high-affinity Nbs. Of the tested Nbs, 94% neutralize the pseudotype virus below 3 mM (Fig. 1B), and 90% neutralize below 500 nM.

Results

Conclusion