Efficacy of immunization with OML-PbMSP1. ELISA detection of antigen-specific IgG1 (A) and IgG2a (B) in mice immunized with recombinant PbMSP1 over the course of immunization. The mean optical density (OD) was determined at a wavelength of 415 nm. Each bar represents the mean ± SD for used mice per group and results are representative of two independent experiments. Different superscript letters indicate statistically significant differences (P <0.05) among groups at each time-point as determined by a one-way analysis of variance followed by Tukey’s multiple comparison test. Parasitemias (C) and survival rates (D) after challenge infection with pRBCs. Each bar represents the mean ± SD for 11 mice per group (only 6 mice for PbMSP1) and results are from two pooled independent experiments. Mice were either immunized by OML-PbMSP1 (OML-PbMSP1), OML alone (OML-PBS), or naked PbMSP1 (PbMSP1), or not immunized (None).