Figure 4: Fine epitope mapping of naturally acquired human anti-Pf332-DBL antibodies on a peptide array. (a) The fine specificity of human affinity-purified anti-Pf332-DBL antibodies was analyzed by a peptide microarray with 52 overlapping peptides of 15 amino acids shifted by four residues covering 3D7 Pf332-DBL (amino acids 1–219). Two overlapping 15 mers having the peptide sequence KKDEYIDIQSRV in common were recognized by the human antibodies. Nonimmune IgG gave a reactivity lower than 250 ± 200, and is therefore not displayed in the graph. Peptides are ordered from N-terminus (top) to C-terminus (bottom). Bars represent the mean reactivity of three subarrays; error bars indicate standard deviation. (b) Mapping of epitopes recognized by the affinity-purified human anti-Pf332-DBL antibody on the 3D model of Pf332-DBL. Subdomain 1 (yellow), subdomain 2 (red), and subdomain 3 (green). The epitope recognized by the human affinity-purified anti-Pf332-DBL antibodies (blue) is located on one of the two major α-helices in subdomain 3. Disulphide bridges are displayed as spheres.