Proteoliposomal formulations of an HIV-1 gp41-based miniprotein elicit a lipid-dependent immunodominant response overlapping the 2F5 binding motif

Sci Rep. 2017 Jan 13:7:40800. doi: 10.1038/srep40800.

Abstract

The HIV-1 gp41 Membrane Proximal External Region (MPER) is recognized by broadly neutralizing antibodies and represents a promising vaccine target. However, MPER immunogenicity and antibody activity are influenced by membrane lipids. To evaluate lipid modulation of MPER immunogenicity, we generated a 1-Palmitoyl-2-oleoylphosphatidylcholine (POPC)-based proteoliposome collection containing combinations of phosphatidylserine (PS), GM3 ganglioside, cholesterol (CHOL), sphingomyelin (SM) and the TLR4 agonist monophosphoryl lipid A (MPLA). A recombinant gp41-derived miniprotein (gp41-MinTT) exposing the MPER and a tetanus toxoid (TT) peptide that favors MHC-II presentation, was successfully incorporated into lipid mixtures (>85%). Immunization of mice with soluble gp41-MinTT exclusively induced responses against the TT peptide, while POPC proteoliposomes generated potent anti-gp41 IgG responses using lower protein doses. The combined addition of PS and GM3 or CHOL/SM to POPC liposomes greatly increased gp41 immunogenicity, which was further enhanced by the addition of MPLA. Responses generated by all proteoliposomes targeted the N-terminal moiety of MPER overlapping the 2F5 neutralizing epitope. Our data show that lipids impact both, the epitope targeted and the magnitude of the response to membrane-dependent antigens, helping to improve MPER-based lipid carriers. Moreover, the identification of immunodominant epitopes allows for the redesign of immunogens targeting MPER neutralizing determinants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Epitopes / chemistry
  • Epitopes / immunology*
  • Female
  • HIV Envelope Protein gp41 / chemistry
  • HIV Envelope Protein gp41 / immunology*
  • Immunogenicity, Vaccine
  • Membrane Lipids / chemistry
  • Membrane Lipids / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Peptides / chemistry
  • Peptides / immunology
  • Tetanus Toxoid / chemistry
  • Tetanus Toxoid / immunology

Substances

  • Epitopes
  • HIV Envelope Protein gp41
  • Membrane Lipids
  • Peptides
  • Tetanus Toxoid