Divergent roles for the RH5 complex components, CyRPA and RIPR in human-infective malaria parasites
Fig 1
Role of basigin (BSG) as a receptor for erythrocyte invasion by P. falciparum, P. knowlesi and P. vivax.
(A) Merozoite invasion inhibition assay in the presence of anti-BSG mAb MEM-M6/6 or BSG protein for P. falciparum and (B) P. knowlesi. Late schizonts of P. falciparum and P. knowlesi were manually ruptured and the merozoites added to fresh erythrocytes, either with no additives, with heparin, MEM-M6/6, or BSG. Invasion was quantified after 12 h using flow cytometry. Three independent experiments were performed for P. falciparum and two for P. knowlesi in triplicate. Invasion is normalised to the RPMI medium alone control, and mean and standard deviation are displayed. (C) Growth inhibition assay (GIA) using schizont cultures of P. falciparum and (D) P. knowlesi in the presence of serial dilutions of anti-BSG mouse mAbs MEM-M6/6 and TRA-1-85, anti-BSG goat polyclonal IgG, anti-DARC CA111 nanobody as well as non-specific mouse and goat IgG (legend in box on the right of plot D). Parasitemias of three independent experiments in triplicate were measured 40 h after setup using flow cytometry. Mean and standard error are displayed. (E) Invasion inhibition assay using anti-BSG antibodies on field isolates of P. vivax. Blood samples were taken from patients in Peru, matured to schizont stage in vitro and incubated with anti-BSG mAb MEM-M6/6 and anti-BSG goat polyclonal IgG, as well as non-specific mouse IgG and goat IgG at 10 μg/ml. Ring stage parasitemia was determined by microscopy of Giemsa-stained blood smears. The relative parasitemia (in %) is displayed for each individual sample compared to control treatment of the same sample. Color-coding highlights the same patient samples treated with either of the anti-BSG antibodies.