Chemical cross-linking of HIV-1 Env for direct TLR7/8 ligand conjugation compromises recognition of conserved antigenic determinants

Virology. 2013 Nov;446(1-2):56-65. doi: 10.1016/j.virol.2013.07.028. Epub 2013 Aug 15.


Covalent conjugation of immune-stimulatory compounds to protein antigens is a potential means to self-adjuvant non-replicating subunit vaccines. Previously, it was demonstrated that covalent coupling of a Toll-like receptor (TLR) ligand to the exterior HIV-1 envelope glycoprotein, gp120, enhanced its immunogenicity. However, the consequences of chemical conjugation to gp120 on broadly neutralizing antibody (bNAb) epitopes were so far not examined. Here, we conjugated a TLR7/8 ligand to lysine residues on gp120 using NHS-PEO8-maleimide linkers and investigated if this affected Ab recognition of the CD4 binding site (CD4bs), a highly conserved target for bNAbs. We demonstrate that the recognition of the CD4bs was reduced following coupling, especially at a higher coupling ratio. These results have implications for the coupling of ligands to vaccine antigens where elicitation of humoral immune responses to specific neutralizing determinants is desired.

Keywords: Cross-linker; HIV-1 envelope glycoprotein; Neutralizing antibody; Toll-like receptor ligand.

Publication types

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

MeSH terms

  • CD4 Antigens / metabolism
  • Epitopes / immunology*
  • HIV Envelope Protein gp120 / chemistry
  • HIV Envelope Protein gp120 / immunology*
  • HIV Envelope Protein gp120 / metabolism
  • HIV-1 / immunology*
  • Humans
  • Protein Binding
  • Toll-Like Receptor 7 / chemistry
  • Toll-Like Receptor 7 / immunology*
  • Toll-Like Receptor 7 / metabolism


  • CD4 Antigens
  • Epitopes
  • HIV Envelope Protein gp120
  • Toll-Like Receptor 7
  • gp120 protein, Human immunodeficiency virus 1