Functional characterization of two scFv-Fc antibodies from an HIV controller selected on soluble HIV-1 Env complexes: a neutralizing V3- and a trimer-specific gp41 antibody

PLoS One. 2014 May 14;9(5):e97478. doi: 10.1371/journal.pone.0097478. eCollection 2014.

Abstract

HIV neutralizing antibodies (nAbs) represent an important tool in view of prophylactic and therapeutic applications for HIV-1 infection. Patients chronically infected by HIV-1 represent a valuable source for nAbs. HIV controllers, including long-term non-progressors (LTNP) and elite controllers (EC), represent an interesting subgroup in this regard, as here nAbs can develop over time in a rather healthy immune system and in the absence of any therapeutic selection pressure. In this study, we characterized two particular antibodies that were selected as scFv antibody fragments from a phage immune library generated from an LTNP with HIV neutralizing antibodies in his plasma. The phage library was screened on recombinant soluble gp140 envelope (Env) proteins. Sequencing the selected peptide inserts revealed two major classes of antibody sequences. Binding analysis of the corresponding scFv-Fc derivatives to various trimeric and monomeric Env constructs as well as to peptide arrays showed that one class, represented by monoclonal antibody (mAb) A2, specifically recognizes an epitope localized in the pocket binding domain of the C heptad repeat (CHR) in the ectodomain of gp41, but only in the trimeric context. Thus, this antibody represents an interesting tool for trimer identification. MAb A7, representing the second class, binds to structural elements of the third variable loop V3 and neutralizes tier 1 and tier 2 HIV-1 isolates of different subtypes with matching critical amino acids in the linear epitope sequence. In conclusion, HIV controllers are a valuable source for the selection of functionally interesting antibodies that can be selected on soluble gp140 proteins with properties from the native envelope spike.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Monoclonal / immunology
  • Antibodies, Neutralizing / immunology*
  • Epitopes / immunology
  • HEK293 Cells
  • HIV Antibodies / immunology
  • HIV Envelope Protein gp120 / immunology*
  • HIV Envelope Protein gp41 / immunology*
  • HIV Infections / immunology
  • HIV-1 / immunology
  • Humans
  • Immunoglobulin Fc Fragments / immunology*
  • Neutralization Tests / methods
  • Peptide Fragments / immunology*
  • Single-Chain Antibodies / immunology*
  • env Gene Products, Human Immunodeficiency Virus / immunology*

Substances

  • Antibodies, Monoclonal
  • Antibodies, Neutralizing
  • Epitopes
  • HIV Antibodies
  • HIV Envelope Protein gp120
  • HIV Envelope Protein gp41
  • HIV envelope protein gp120 (305-321)
  • Immunoglobulin Fc Fragments
  • Peptide Fragments
  • Single-Chain Antibodies
  • env Gene Products, Human Immunodeficiency Virus
  • gp140 envelope protein, Human immunodeficiency virus 1

Grant support

This work was supported by the Dr. Bodo Sponholz-Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.