Figure 4

PF3D7_1363700 protein appears to be present during late intra-erythrocytic stages as shown by immunolocalization studies using confocal microscopy. Parasite-infected blood smears were triple-labelled with anti-PF3D7_1363700 polyclonal antibody (anti-PF3D7_1363700), either anti-merozoite surface protein 1 (anti-PfMSP1) monoclonal antibody for asexual stages or anti-Pfs230 monoclonal antibody for gametocytes (used as positive controls), and a nuclear stain, TO-PRO-3. Triplicate biological replicates of parasite-infected blood smears consistently show PF3D7_1363700 expression during the trophozoite, schizont and gametocyte stages. Merged images with Differential Interference Contrast (DIC) demonstrate protein co-localization with known surface proteins as shown by the yellow colour. Approximately 100–300 stage-specific parasites/replicate were observed. The bottom panel of figures show the control pre-immune serum with minimal cross-reactivity in intra-erythrocytic stage parasites (ES). Arrows denote the presence of parasites and representative images are shown with a scale bar, 5 μm.