Immune focusing and enhanced neutralization induced by HIV-1 gp140 chemical cross-linking

J Virol. 2013 Sep;87(18):10163-72. doi: 10.1128/JVI.01161-13. Epub 2013 Jul 10.

Abstract

Experimental vaccine antigens based upon the HIV-1 envelope glycoproteins (Env) have failed to induce neutralizing antibodies (NAbs) against the majority of circulating viral strains as a result of antibody evasion mechanisms, including amino acid variability and conformational instability. A potential vaccine design strategy is to stabilize Env, thereby focusing antibody responses on constitutively exposed, conserved surfaces, such as the CD4 binding site (CD4bs). Here, we show that a largely trimeric form of soluble Env can be stably cross-linked with glutaraldehyde (GLA) without global modification of antigenicity. Cross-linking largely conserved binding of all potent broadly neutralizing antibodies (bNAbs) tested, including CD4bs-specific VRC01 and HJ16, but reduced binding of several non- or weakly neutralizing antibodies and soluble CD4 (sCD4). Adjuvanted administration of cross-linked or unmodified gp140 to rabbits generated indistinguishable total gp140-specific serum IgG binding titers. However, sera from animals receiving cross-linked gp140 showed significantly increased CD4bs-specific antibody binding compared to animals receiving unmodified gp140. Moreover, peptide mapping of sera from animals receiving cross-linked gp140 revealed increased binding to gp120 C1 and V1V2 regions. Finally, neutralization titers were significantly elevated in sera from animals receiving cross-linked gp140 rather than unmodified gp140. We conclude that cross-linking favors antigen stability, imparts antigenic modifications that selectively refocus antibody specificity and improves induction of NAbs, and might be a useful strategy for future vaccine design.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AIDS Vaccines / administration & dosage
  • AIDS Vaccines / chemistry
  • AIDS Vaccines / genetics
  • AIDS Vaccines / immunology*
  • Adjuvants, Immunologic / administration & dosage
  • Animals
  • Antibodies, Neutralizing / blood*
  • Cross-Linking Reagents / metabolism
  • HIV Antibodies / blood*
  • HIV Antigens / chemistry
  • HIV Antigens / immunology*
  • HIV Antigens / metabolism
  • Rabbits
  • env Gene Products, Human Immunodeficiency Virus / chemistry
  • env Gene Products, Human Immunodeficiency Virus / immunology*
  • env Gene Products, Human Immunodeficiency Virus / metabolism

Substances

  • AIDS Vaccines
  • Adjuvants, Immunologic
  • Antibodies, Neutralizing
  • Cross-Linking Reagents
  • HIV Antibodies
  • HIV Antigens
  • env Gene Products, Human Immunodeficiency Virus
  • gp140 envelope protein, Human immunodeficiency virus 1