HIV p24 as scaffold for presenting conformational HIV Env antigens

PLoS One. 2012;7(8):e43318. doi: 10.1371/journal.pone.0043318. Epub 2012 Aug 17.

Abstract

Heterologous protein scaffolds engrafted with structurally defined HIV Env epitopes recognized by broadly neutralizing monoclonal antibodies (MAbs) represent a promising strategy to elicit broad neutralizing antibodies. In such regards, a protein scaffold based on the HIV p24 CA protein is a highly attractive approach, providing also Gag epitopes for eliciting HIV non-neutralizing protective antibodies and specific CD4(+) and CD8(+) T cell responses. In the present study, computational techniques were employed to verify the presence of acceptor sites for conformational HIV Env epitopes and, as proof of concept, the analysis of HIV p24 CA-based scaffolds using a complete V3 loop in a MAb-bound conformation is presented. The V3-p24 epitope-scaffold proteins show the formation of capsomers made of hexamers similarly to the p24 wild type protein. Moreover, the conformational V3 loop presented on p24 scaffold is recognized by a panel of anti-V3 MAbs. The results suggest that HIV p24 CA protein has suitable acceptor sites for engrafting foreign epitopes, without disrupting the formation of capsomer hexamer structures, and that the V3 epitope does retain its antibody-bound conformation. This strongly support the feasibility of developing a scaffolding strategy based on p24 CA proteins displaying conformational minimal structural, antigenic HIV Env epitopes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Monoclonal / metabolism*
  • Antibodies, Neutralizing / metabolism*
  • Enzyme-Linked Immunosorbent Assay
  • Epitopes / genetics
  • Epitopes / metabolism
  • HIV Core Protein p24 / immunology
  • HIV Core Protein p24 / metabolism*
  • HIV Envelope Protein gp120 / immunology
  • HIV Envelope Protein gp120 / metabolism*
  • HIV-1 / immunology*
  • Microscopy, Electron
  • Peptide Fragments / immunology
  • Peptide Fragments / metabolism*
  • Protein Conformation

Substances

  • Antibodies, Monoclonal
  • Antibodies, Neutralizing
  • Epitopes
  • HIV Core Protein p24
  • HIV Envelope Protein gp120
  • HIV envelope protein gp120 (305-321)
  • Peptide Fragments

Grants and funding

The study was supported by the European Community’s Seventh Framework Programme “Next Generation HIV-1 Immunogens inducing broadly reactive Neutralising antibodies – NGIN” (FP7/2007–2013) under grant agreement n° 201433. Dr. Tagliamonte is funded by the NGIN Programme. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.