JCI Insight (Jan 2023)

Delayed boosting improves human antigen-specific Ig and B cell responses to the RH5.1/AS01B malaria vaccine

  • Carolyn M. Nielsen,
  • Jordan R. Barrett,
  • Christine Davis,
  • Jonathan K. Fallon,
  • Cyndi Goh,
  • Ashlin R. Michell,
  • Catherine Griffin,
  • Andrew Kwok,
  • Carolin Loos,
  • Samuel Darko,
  • Farida Laboune,
  • Mehmet Tekman,
  • Ababacar Diouf,
  • Kazutoyo Miura,
  • Joseph R. Francica,
  • Amy Ransier,
  • Carole A. Long,
  • Sarah E. Silk,
  • Ruth O. Payne,
  • Angela M. Minassian,
  • Douglas A. Lauffenburger,
  • Robert A. Seder,
  • Daniel C. Douek,
  • Galit Alter,
  • Simon J. Draper

Journal volume & issue
Vol. 8, no. 2

Abstract

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Modifications to vaccine delivery that increase serum antibody longevity are of great interest for maximizing efficacy. We have previously shown that a delayed fractional (DFx) dosing schedule (0-1-6 month) — using AS01B-adjuvanted RH5.1 malaria antigen — substantially improves serum IgG durability as compared with monthly dosing (0-1-2 month; NCT02927145). However, the underlying mechanism and whether there are wider immunological changes with DFx dosing were unclear. Here, PfRH5-specific Ig and B cell responses were analyzed in depth through standardized ELISAs, flow cytometry, systems serology, and single-cell RNA-Seq (scRNA-Seq). Data indicate that DFx dosing increases the magnitude and durability of circulating PfRH5-specific B cells and serum IgG1. At the peak antibody magnitude, DFx dosing was distinguished by a systems serology feature set comprising increased FcRn binding, IgG avidity, and proportion of G2B and G2S2F IgG Fc glycans, alongside decreased IgG3, antibody-dependent complement deposition, and proportion of G1S1F IgG Fc glycan. Concomitantly, scRNA-Seq data show a higher CDR3 percentage of mutation from germline and decreased plasma cell gene expression in circulating PfRH5-specific B cells. Our data, therefore, reveal a profound impact of DFx dosing on the humoral response and suggest plausible mechanisms that could enhance antibody longevity, including improved FcRn binding by serum Ig and a potential shift in the underlying cellular response from circulating short-lived plasma cells to nonperipheral long-lived plasma cells.

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