biostudies-literatureNielsen CMEuropean Seventh FrameworkMedical Research CouncilUnited States Agency for International DevelopmentWellcome Truste163859https://www.ebi.ac.uk/biostudies/studies/S-EPMC9977309biostudies-literatureUnknown8(2)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, DFxJCI insightDelayed boosting improves human antigen-specific Ig and B cell responses to the RH5.1/AS01B malaria vaccine.PMC9977309106917/Z/15/ZAID-OAA-C-15-00071209200/Z/17/ZFP7/2007-2013MR/K025554/1Miura KLauffenburger DADouek DCMinassian AMGriffin CAlter GNielsen CMBarrett JRDavis CGoh CLong CALaboune FFallon JKSilk SEFrancica JRLoos CDarko SMichell ARPayne ROSeder RATekman MKwok ADiouf ARansier ADraper SJfalseDelayed boosting improves human antigen-specific Ig and B cell responses to the RH5.1/AS01B malaria vaccine.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, DFx2023-01-01T00:00:00Z2023 Jan2026-05-28T08:08:52.424Z2025-04-25T17:11:56.077ZS-EPMC99773093669201910.1172/jci.insight.163859