FIGURE 9.
Cross-reactivity and acquisition of Abs to DC4-containing PfEMP1 proteins. ELISA reactivity of pooled immune plasma IgG with PfEMP1 proteins (coating Ag) containing (red boxes) or not containing DC4 after depletion of reactivity with the same proteins (competing Ag). The reduction in reactivity by depletion is indicated by shading: black (>75%), dark gray (51–75%), light gray (26–50%), and white (0–25%) (A). Ab-mediated inhibition of ICAM-1 binding of DBLβ3 domains from PfEMP1 proteins containing DC4 (PFD1235w, BM021, BM028, BM048, BM057, and BM066) or not containing DC4 (Dd2var32, IT4var16) (B). The inhibitory capacity of an immune plasma pool, Abs from this pool purified on PFD1235w-DBLβ3_D4, Dd2var32-DBLα1.7-DBLβ1, IT4var16-DBLβ5, or PFD1235w-DBLβ3_D5, respectively, as well as a nonimmune plasma pool (Hu IgG) are shown. The inhibitory capacity is indicated by shading as in (A). The ability of plasma samples from P. falciparum–exposed children aged 2–4 and 5–9 y to interfere with binding of PFD1235w-DBLβ3_D4 to ICAM-1 (C). Binding relative to binding in the absence of Abs is shown for one experiment representative of a minimum of three independent experiments. Medians (center line), central 50% (shaded boxes), central 80% (whiskers), and outliers are indicated.