Figure 2. IgG antibodies against PfEMP1 variants belonging to the A or B/A groups or having the EPCR-binding phenotype are rapidly acquired during childhood.

(A) Hierarchical clustering heatmap showing IgG reactivity to each of the 35 PfEMP1 variants in 680 subjects at enrollment (May 2011 healthy baseline). Clustering was performed using the Ward.D method and the Pearson distance metric. AU refers to arbitrary concentration units, which were calculated by fitting data to a dilutional standard curve of pooled hyperimmune plasma from malaria-exposed Malian adults. (B) IgG reactivity obtained at May 2011 healthy baseline versus age for each PfEMP1 variant (solid lines) or control antigen (dotted lines) with loess fit curves and 95% confidence intervals by P. falciparum PCR status determined at enrollment.