Inhibition of P vivax invasion by a mAb (25 μg/mL) specific to the 2C3 epitope of DARC, the obligatory receptor for P vivax merozoites. (A) Inhibition of P vivax (n = 10 isolates) invasion was near-total (mean 7.5% SD ± 2.9 vs 0.15% SD ± 0.28, P < .01, Wilcoxon sum of signed ranks [W] = 55.), whereas little inhibition was observed (P = .25, W = 6.0) when P falciparum (n = 3 isolates) were used in the invasion assay. The assays were conducted in triplicate for each isolate. (B) Representative micrographs are shown for the (i-ii) P vivax or (iii-iv) P falciparum invasion assays (annotations as in Figure 1). Remnants of ruptured schizonts (*), and RBCs newly invaded by 1 (black arrow) or multiple merozoites (orange arrowhead). Black scale bars on micrograph represent 10 μm.