Figure 6

Antibody-dependent invasion inhibition assays in donor erythrocytes with different levels of surface antigens. Schizont-infected erythrocytes were co-incubated with antibody-sensitized uninfected erythrocytes from donors expressing different levels of erythrocyte receptors. The parasites’ DNA was labelled with Hoechst 33,342, 18–24 h’ post-incubation and the resulting parasitemia was quantified by flow cytometry. For each donor, the parasitemia in the corresponding mock-treated erythrocytes (similarly processed erythrocytes co-incubated with equivalent volume of RPMI 1640 with the IgY) was used to ascertain the antibody-dependent invasion inhibitory, following normalization using a single erythrocyte donor (also used for the parasites in vitro culturing). (A)–(C) represent the antibody-dependent invasion inhibition of pooled data from two different P. falciparum strains (3D7 and MISA011). (D)–(F) represent the differential expression of erythrocyte receptors assessed in (A)–(C).