Patient plasma IgG and anti-PfEMP1 IgG binding to IE. IE incubated with goat anti-human IgG conjugated to Alexa®568 (red) or goat anti-rabbit IgG Alexa®488 (green). A. Antibody selected IE (3D7) incubated with 1:50 diluted Tanzanian child's acute-phase malaria serum. The DIC images of IE show DAPI stained parasite nuclei (blue) and spots of membrane-bound IgG (Alexa®568). B. Fluorescence image of Figure 1A. C. Higher magnification DIC image of live IE (3D7) and uninfected erythrocytes, incubated with 1:100 diluted convalescent plasma from the same child. D. Fluorescence image of Figure 1C. E. DIC images of 3D7, incubated with rabbit antiserum against a recombinant Var4 PfEMP1, detected with goat anti-rabbit IgG (Alexa®488). F. Fluorescence image of Figure 1E. G. DIC and DAPI (blue) fluorescence image of immune serum-agglutinated and unagglutinated erythrocytes. IE (FCR3) selected by panning on Dynabeads coated with IgG from a pool of semi-immune Tanzanian children's sera (note DAPI-staining merozoite invading the upper IE). H. Agglutination of two IE by serum used in Figures 1C and 1D, detected with goat anti-human IgG Alexa®568. Two infected and one uninfected erythrocytes are unagglutinated and largely unstained. The invading merozoite is stained by serum IgG. Live trophozoites often do not take up DAPI but such IE can be identified by pigment or serum staining (Figure 1E). Scale bars 5 μm.