Evolution of cross-neutralizing antibodies and mapping epitope specificity in plasma of chronic HIV-1-infected antiretroviral therapy-naïve children from India

J Gen Virol. 2017 Jul;98(7):1879-1891. doi: 10.1099/jgv.0.000824. Epub 2017 Jul 12.

Abstract

Delineating the factors leading to the development of broadly neutralizing antibodies (bnAbs) during natural HIV-1 infection and dissecting their epitope specificities generates useful information for vaccine design. This is the first longitudinal study to assess the plasma-neutralizing antibody response and neutralizing determinants in HIV-1-infected children from India. We enrolled 26 and followed up 20 antiretroviral therapy (ART)-naïve, asymptomatic, chronic HIV-1-infected children. Five (19.2 %) baseline and 10 (50 %) follow-up plasma samples neutralized ≥50 % of subtypes A, B and C tier 2 viruses at an ID50 titre ≥150. A modest improvement in neutralization breadth and potency was observed with time. At baseline, subtype C-specific neutralization predominated (P=0.026); interestingly, follow-up samples exhibited cross-neutralizing activity. Epitope mapping revealed V3C reactive antibodies with significantly increased Max50 binding titres in follow-up samples from five infected children; patient #4's plasma antibodies exhibited V3-directed neutralization. A salient observation was the presence of CD4 binding site (CD4bs)-specific NAbs in patient #18 that improved with time (1.76-fold). The RSC3 wild-type (RSC3WT) protein-depleted plasma eluate of patient #18 demonstrated a more than 50% ID50 decrease in neutralization capacity against five HIV-1 pseudoviruses. Further, the presence of CD4bs-neutralizing determinants in patient #18's plasma was confirmed by the neutralizing activity demonstrated by the CD4bs-directed IgG fraction purified from this plasma, and competition with sCD4 against JRFLgp120, identifying this paediatric donor as a potential candidate for the isolation of CD4bs-directed bnAbs. Overall, we observed a relative increase in plasma-neutralizing activity with time in HIV-1-infected children, which suggests that the bnAbs evolve.

MeSH terms

  • Adolescent
  • Antibodies, Neutralizing / blood*
  • Antibodies, Neutralizing / immunology
  • Antibodies, Viral / blood*
  • Antibodies, Viral / immunology
  • CD4 Lymphocyte Count
  • Child
  • Child, Preschool
  • Cross Protection / immunology*
  • Epitope Mapping
  • Epitopes / immunology*
  • Female
  • HIV Antibodies / blood*
  • HIV Antibodies / immunology
  • HIV Envelope Protein gp120 / immunology
  • HIV Infections / immunology
  • HIV Infections / virology
  • HIV-1 / classification*
  • HIV-1 / immunology*
  • Humans
  • Immunoglobulin G / blood
  • Immunoglobulin G / immunology
  • India
  • Longitudinal Studies
  • Male
  • Peptide Fragments / immunology

Substances

  • Antibodies, Neutralizing
  • Antibodies, Viral
  • Epitopes
  • HIV Antibodies
  • HIV Envelope Protein gp120
  • HIV envelope protein gp120 (305-321)
  • Immunoglobulin G
  • Peptide Fragments