A Neutralizing Antibody Recognizing Primarily N-Linked Glycan Targets the Silent Face of the HIV Envelope

Immunity. 2018 Mar 20;48(3):500-513.e6. doi: 10.1016/j.immuni.2018.02.013. Epub 2018 Mar 13.

Abstract

Virtually the entire surface of the HIV-1-envelope trimer is recognized by neutralizing antibodies, except for a highly glycosylated region at the center of the "silent face" on the gp120 subunit. From an HIV-1-infected donor, #74, we identified antibody VRC-PG05, which neutralized 27% of HIV-1 strains. The crystal structure of the antigen-binding fragment of VRC-PG05 in complex with gp120 revealed an epitope comprised primarily of N-linked glycans from N262, N295, and N448 at the silent face center. Somatic hypermutation occurred preferentially at antibody residues that interacted with these glycans, suggesting somatic development of glycan recognition. Resistance to VRC-PG05 in donor #74 involved shifting of glycan-N448 to N446 or mutation of glycan-proximal residue E293. HIV-1 neutralization can thus be achieved at the silent face center by glycan-recognizing antibody; along with other known epitopes, the VRC-PG05 epitope completes coverage by neutralizing antibody of all major exposed regions of the prefusion closed trimer.

Keywords: HIV silent face; HIV vaccine; broadly neutralizing antibody; crystal structure; glycan cluster; glycan recognition; glycopeptide epitope; prefusion-closed Env trimer; viral escape.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Antibodies, Neutralizing / chemistry
  • Antibodies, Neutralizing / genetics
  • Antibodies, Neutralizing / immunology*
  • Antibodies, Neutralizing / metabolism
  • Antigens, Viral / chemistry
  • Antigens, Viral / immunology
  • Binding Sites
  • Epitope Mapping
  • Epitopes / chemistry
  • Epitopes / immunology
  • Epitopes / metabolism
  • Glycopeptides / chemistry
  • Glycopeptides / immunology
  • Glycosylation
  • HIV Antibodies / chemistry
  • HIV Antibodies / genetics
  • HIV Antibodies / immunology*
  • HIV Antibodies / metabolism
  • HIV Envelope Protein gp120 / chemistry
  • HIV Envelope Protein gp120 / immunology*
  • HIV Envelope Protein gp120 / metabolism
  • HIV Infections / immunology*
  • HIV-1 / immunology*
  • Humans
  • Models, Molecular
  • Molecular Conformation
  • Polysaccharides / chemistry
  • Polysaccharides / immunology*
  • Protein Binding / immunology
  • Somatic Hypermutation, Immunoglobulin / immunology
  • Structure-Activity Relationship

Substances

  • Antibodies, Neutralizing
  • Antigens, Viral
  • Epitopes
  • Glycopeptides
  • HIV Antibodies
  • HIV Envelope Protein gp120
  • Polysaccharides