Fig. 4: Functional activity of UF6b antibodies.

a–e UF6b:GLA-LSQ generates potent transmission-blocking antibodies against both lab and naturally circulating Plasmodium strains. a Representative standard membrane feeding assay (SMFA) using 50 µg/mL total IgG purified from pooled sera of mice immunized with UF6b collected on Day 98. b Representative SMFA using serial dilutions of purified IgG from Day 70 of the 98-Day study. The monoclonal antibody (mAb) 4H5B7 was included at 250 µg/mL as a positive control. c Representative SMFA in the presence of an increased parasite oocyst burden in mosquitoes (X̄ = 60) in the control group as compared to a representative lower midgut oocyst burden as shown for panel (a) controls (X̄ = 15) using 50 µg/mL total IgG purified from pooled sera of mice immunized with UF6b collected on Day 98. d-e Direct membrane feeding assay (DMFA) in Cameroon conducted with blood from 2 gametocytemic children (Case codes C514 and C519) with varying concentrations of total IgG. The peptide 7 mAb 4H5B7 served as the positive control. a–e Total IgG was purified from the same cohort of mice. Treatments without a common letter were found to be statistically significant (α = 0.05, p < 0.01, N = 14–59) as calculated by Kruskal–Wallis test with Dunn’s post hoc correction or by zero-inflated Generalized Linear Mixed Model as appropriate. Red horizontal bar indicates mean oocyst number per mosquito midgut. Mosquito sample sizes for each control/test group from left to right: (a) 39, 43, 46 (b) 18, 13, 13, 14, 13, 16, 13, 13 (c) 23, 18, 18 (d) 36, 54, 44, 40, 48 (e) 58, 48, 50. f Comparison of Ig isotypes present in antisera from the 98-Day study between UF6b alone, UF6b:GLA-LSQ and UF6b:AddaVax™. g Comparison of Ig isotypes from collections at D70, D84, and D98 from the 98-Day studies. h Ig isotypes for two replicates of the 70-Day studies. f–h Sera used at 1:1,000 dilution. Error bars indicate the SEM for replicate wells. See text for details.