Molecular probes of spike ectodomain and its subdomains for SARS-CoV-2 variants, Alpha through Omicron

PLoS One. 2022 May 24;17(5):e0268767. doi: 10.1371/journal.pone.0268767. eCollection 2022.

Abstract

Since the outbreak of the COVID-19 pandemic, widespread infections have allowed SARS-CoV-2 to evolve in human, leading to the emergence of multiple circulating variants. Some of these variants show increased resistance to vaccine-elicited immunity, convalescent plasma, or monoclonal antibodies. In particular, mutations in the SARS-CoV-2 spike have drawn attention. To facilitate the isolation of neutralizing antibodies and the monitoring of vaccine effectiveness against these variants, we designed and produced biotin-labeled molecular probes of variant SARS-CoV-2 spikes and their subdomains, using a structure-based construct design that incorporated an N-terminal purification tag, a specific amino acid sequence for protease cleavage, the variant spike-based region of interest, and a C-terminal sequence targeted by biotin ligase. These probes could be produced by a single step using in-process biotinylation and purification. We characterized the physical properties and antigenicity of these probes, comprising the N-terminal domain (NTD), the receptor-binding domain (RBD), the RBD and subdomain 1 (RBD-SD1), and the prefusion-stabilized spike ectodomain (S2P) with sequences from SARS-CoV-2 variants of concern or of interest, including variants Alpha, Beta, Gamma, Epsilon, Iota, Kappa, Delta, Lambda, Mu, and Omicron. We functionally validated probes by using yeast expressing a panel of nine SARS-CoV-2 spike-binding antibodies and confirmed sorting capabilities of variant probes using yeast displaying libraries of plasma antibodies from COVID-19 convalescent donors. We deposited these constructs to Addgene to enable their dissemination. Overall, this study describes a matrix of SARS-CoV-2 variant molecular probes that allow for assessment of immune responses, identification of serum antibody specificity, and isolation and characterization of neutralizing antibodies.

Publication types

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

MeSH terms

  • Antibodies, Neutralizing
  • Antibodies, Viral
  • Biotin
  • COVID-19 Serotherapy
  • COVID-19* / therapy
  • Humans
  • Immunization, Passive
  • Molecular Probes
  • Neutralization Tests
  • Pandemics
  • SARS-CoV-2* / genetics
  • Saccharomyces cerevisiae / genetics
  • Spike Glycoprotein, Coronavirus

Substances

  • Antibodies, Neutralizing
  • Antibodies, Viral
  • Molecular Probes
  • Spike Glycoprotein, Coronavirus
  • spike protein, SARS-CoV-2
  • Biotin

Supplementary concepts

  • SARS-CoV-2 variants