Effect of anti-PfRH1 inhibitory mAbs on merozoite surface expression of EBA175 during invasion. (a–d) Surface expression of EBA175 and MSP1 on T994 and T994DRH1 was detected by immunofluorescence assays. Isolated T994 (a,c) or T994DRH1 (b,d) merozoites were directly incubated with erythrocytes containing 4 mM Cyto D in the absence (Control) and presence (C41) of C41 (0.2mgml1) before analysis of expression of EBA175 and MSP1 at the junction. Both differential interference contrast (DIC) and fluorescence images were captured. Nuclear DNA was counterstained with DAPI (blue). EBA175 is shown in green, whereas MSP1 is shown in red. Fluorescence images, merged fluorescence images (DAPI and green or DAPI with red) and merged fluorescence images with DIC images are shown. Scale bars=10 mM. Antibody C41 blocks surface expression of EBA175 in T994 (a lower panel), whereas it has no effect on T994DRH1 parasites (b lower panel). In the absence of C41, EBA175 is expressed on the surface of both T994 and T994DRH1 (upper panels a,b). Ab has no effect on the detection of MSP1 on the surface of merozoites (c,d).

Gao X, Gunalan K, Yap SS, Preiser PR. Triggers of key calcium signals during erythrocyte invasion by Plasmodium falciparum. Nat Commun. 2013;4:2862.