Blocking CD55 with antibody does not impact rhoptry discharge. Representative images from immunofluorescence assays showing PfRAP1 localization in WT or CD55-null RBCs with attached merozoites in the presence of cyt-D. Assays were performed twice and ~50 attached merozoites were assessed for each RBC genetic background. RAP1 staining in a donut or C-shape 369 for merozoites attached to both the WT and CD55-null cells, indicating that rhoptry discharge had occurred. In rare instances, we observed RAP1 staining associated with the RBC, as a “whorl” in WT cells with an attached merozoite (row 2), and spreading across the RBC surface in CD55-null cells with attached merozoites (row 4). Shakya B, Patel SD, Tani Y, Egan ES. Erythrocyte CD55 mediates the internalization of Plasmodium falciparum parasites. Elife. 2021 10:e61516.