Fig. 2.

Quantification of Pfs48/45 protein in Pfs48/45@PbMSP1 schizont lysate and transmission reducing (TR) activity of IgG isolated from mice immunized with Pfs48/45@PbMSP1 schizont lysates.

A. Pfs48/45@PbMSP1 schizont lysates (500 & 250 ng), P. falciparum gametocytes (Pf Gam.; 500 ng) and P. berghei WT schizont lysate (PbWT; 500 ng) were analyzed in Western blot analysis using anti-Pfs48/45 monoclonal 85RF45.1 (1:2000). Densitometry analysis was performed on signals after probing Pfs48/45@PbMSP1 schizont lysate (500 ng) and a dilution series (50, 25, 12.5, 6 and 3 ng) of recombinant Pfs48/45 (r48/45; R0.10C) with antibody 45.1. The Table shows the calculated Pfs48/45 protein content (ng) and the percentage of Pfs48/45 protein in parasite samples; see Supplementary Fig. S1 for determination of Pfs48/45 in samples. *quantification performed after subtraction of background (b/g) Optical Densitometry (OD) values and **quantitation based on regression curve calculations (see Supplementary Fig. S1).

B. Timeline showing the immunization of mice with extracts of Pfs48/45@PbMSP1 and PbWT schizont lysates and collection of sera for isolation of IgG that is tested for TR activity in standard membrane feeding assays (SMFA) of P. falciparum gametocytes to Anopheles stephensi mosquitoes (see C).

C. Left panel: First SMFA with IgGs from mice immunized with purified schizonts of Pfs48/45@PbMSP1 and PbWT. TR activity was determined by the mean number of oocysts 8 days after feeding, and significance of inhibition was determined by the zero-inflated negative binomial model described previously [29]. Right panel: Second SMFA with serially diluted IgGs. IgG from mice immunized with purified schizonts of Pfs48/45@PbMSP1 was titrated resulting in the concentrations shown in the Figure. Significant TR activity was detected until a concentration of 187 μg/ml (*p = 0.014). Significant; *p < 0.05, ***p < 0.001.