Fig. 3. Kinetics and breadth of functional activity.
A–F Levels of MSP1FL-specific Fc- mediated effector mechanisms of IgG (n = 13, n = 11 for Ab-NK) over time. A AbC‘; antibody- dependent complement fixation activity measured by C1q fixation. B OPA; opsonic phagocytosis activity of MSP1FL-coupled microsphere beads by THP1 cells or (C) neutrophils. D ADRB; antibody-dependent respiratory burst by neutrophils. E Ab-NK:CD107a; antibody- dependent NK cell degranulation (F) Ab-NK: IFN-γ; antibody-dependent NK cell IFN-γ production. G Heatmaps showing spearman correlations between IgG titers and effector functions and (H) effector functions with each other. Significant (p < 0.0001) spearman rank correlation coefficients for samples (n = 13) are highlighted in double digits. The colour intensity represents the strength of correlation. I A heatmap showing the activity levels of four Fc- mediated effector functions (AbC’, ADRB, THP1 OPA, neutrophils OPA) in vaccinees (n = 24) at day 85, four weeks after the last immunization. Responses above a function-specific median are shown in red. Each column is a Fc-mediated function while each row is a single volunteer. J Anti-MSP1FL IgG titers post-immunization (D85) were compared between volunteers with different function breadth scores. Each data point represents functional activity for one sample in duplicates. Box plots show the median with min/max values. Colors of the dots represent different dose cohorts: red; 25 µg (n = 3), blue; 50 µg (n = 7), black; 150 µg (n = 3). Red arrows indicate the days of immunization. The dashed line indicates reference effector functions of purified IgG from pooled sera from semi-immune individuals from Kisumu, Kenya (NIBSC code 10/198). Statistical differences between timepoints were calculated using Friedman test and Wilcoxon ranked test; and Kruskal-Wallis between titers and breadth scores. For correlations Spearman rank test was used.