Delayed booster dosing modulates human antigen-specific Ig and B cell responses to the RH5.1/AS01B malaria vaccine

Antibodies are crucial for vaccine-mediated protection against many pathogens. Modifications to vaccine delivery that increase antibody magnitude, longevity, and/or quality are therefore of great interest for maximising efficacy. We have previously shown that a delayed fractional (DFx) dosing schedule (0-1-6mo) - using AS01B-adjuvanted RH5.1 malaria antigen - substantially improves serum IgG durability as compared to "standard" monthly dosing (0-1-2mo; NCT02927145). However, the underlying mechanism and whether there are wider immunological changes with DFx dosing was unclear. Here, PfRH5-specific B cells were quantified by flow cytometry and sorted for single cell RNA sequencing.