Identifying epitopes responsible for neutralizing antibody and DC-SIGN binding on the spike glycoprotein of the severe acute respiratory syndrome coronavirus

J Virol. 2006 Nov;80(21):10315-24. doi: 10.1128/JVI.01138-06.

Abstract

The severe acute respiratory syndrome-associated coronavirus (SARS-CoV) uses dendritic cell-specific ICAM-3 grabbing nonintegrin (DC-SIGN) to facilitate cell entry via cellular receptor-angiotensin-converting enzyme 2. For this project, we used recombinant baculoviruses expressing different lengths of SARS-CoV spike (S) protein in a capture assay to deduce the minimal DC-SIGN binding region. Our results identified the region location between amino acid (aa) residues 324 to 386 of the S protein. We then generated nine monoclonal antibodies (MAbs) against the S protein to map the DC-SIGN-binding domain using capture assays with pseudotyped viruses and observed that MAb SIa5 significantly blocked S protein-DC-SIGN interaction. An enhancement assay using the HKU39849 SARS-CoV strain and human immature dendritic cells confirmed our observation. Data from a pepscan analysis and M13 phage peptide display library system mapped the reactive MAb SIa5 epitope to aa residues 363 to 368 of the S protein. Results from a capture assay testing three pseudotyped viruses with mutated N-linked glycosylation sites of the S protein indicate that only two pseudotyped viruses (N330Q and N357Q, both of which lost glycosylation sites near the SIa5 epitope) had diminished DC-SIGN-binding capacity. We also noted that MAb SIb4 exerted a neutralizing effect against HKU39849; its reactive epitope was mapped to aa residues 435 to 439 of the S protein. We offer the data to facilitate the development of therapeutic agents and preventive vaccines against SARS-CoV infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Monoclonal
  • Antibodies, Viral
  • Antigens, Viral / genetics
  • Baculoviridae / genetics
  • Base Sequence
  • Binding Sites / genetics
  • Cell Adhesion Molecules / metabolism*
  • DNA, Viral / genetics
  • Dendritic Cells / immunology
  • Dendritic Cells / virology
  • Epitope Mapping
  • Epitopes / chemistry
  • Epitopes / genetics
  • Glycosylation
  • Humans
  • In Vitro Techniques
  • Lectins, C-Type / metabolism*
  • Membrane Glycoproteins / chemistry
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / immunology*
  • Models, Molecular
  • Mutagenesis, Site-Directed
  • Neutralization Tests
  • Protein Binding
  • Protein Structure, Tertiary
  • Receptors, Cell Surface / metabolism*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / immunology
  • Severe Acute Respiratory Syndrome / immunology
  • Severe Acute Respiratory Syndrome / virology
  • Severe acute respiratory syndrome-related coronavirus / genetics
  • Severe acute respiratory syndrome-related coronavirus / immunology*
  • Spike Glycoprotein, Coronavirus
  • Viral Envelope Proteins / chemistry
  • Viral Envelope Proteins / genetics
  • Viral Envelope Proteins / immunology*

Substances

  • Antibodies, Monoclonal
  • Antibodies, Viral
  • Antigens, Viral
  • Cell Adhesion Molecules
  • DC-specific ICAM-3 grabbing nonintegrin
  • DNA, Viral
  • Epitopes
  • Lectins, C-Type
  • Membrane Glycoproteins
  • Receptors, Cell Surface
  • Recombinant Proteins
  • Spike Glycoprotein, Coronavirus
  • Viral Envelope Proteins
  • spike glycoprotein, SARS-CoV
  • spike protein, mouse hepatitis virus