Fig. 5: The synthetic shPro peptide (aa 543–588) induces functional antibodies.

A group of ten mice were immunized with either shPro peptide conjugated with keyhole limpet haemocyanin, KLH (shPro-KLH) or KLH alone (KLH). Antibody levels in individual mice against shPro peptide (a) and KLH (b) were determined by ELISA, and the bars indicate geometric mean of the group. Reactivity of purified total IgG from each group against native Pfs230 was assessed by immunofluorescence assay (IFA, c) and western blotting (WB, d). For the IFA, P. falciparum NF54 stage V gametocytes were used. For the WB, gametocyte extracts were tested under reducing (R) and non-reducing (NR) conditions. The conformation-dependent mouse anti-Pfs230C1 (aa 443–731) monoclonal antibody, 15A4-1B12, was used as a positive control. e Anti-shPro-KLH total IgG was evaluated in three independent SMFA assays with human complement at the indicated concentrations, and one assay was conducted without complement. The solid (and dotted) line represents the best-estimate (and the 95%CI) of the linear regression of anti-shPro-KLH total IgG tested with complement. The anti-KLH total IgG tested at 1.5 mg/mL with complement showed insignificant activity (−7–30%TRA) in all three assays (Table S9). f Percent inhibition of anti-spr-KLH total IgG (3.2, 1.1 and 0.4 mg/mL) against anti-KLH total IgG (3.2 mg/mL) was determined by exflagellation assay (EXA). Median and range of per cent inhibitions from four assays are shown.