Overall invasion efficiencies of the P vivax field isolates used in the invasion assays. (A) Average invasion efficiency of enriched ex vivo–matured P vivax schizonts isolated from 85 isolates in concentrated reticulocytes collected from 28 cord blood isolates (experiments conducted in triplicate). The mean percentage of newly invaded RBCs (dashed black line) after ∼ 24 hours of incubation was 3.7% (95% CI: 2.8-4.7%, range 0.1-22.3%). Isolates with an invasion efficiency above the quantitation limit of ≥ 0.5% parasitemia (solid red line), provide those conducting assay with a 90% (power = 0.9) chance of detecting significance changes in parasitemia between 2 paired treatment groups (for example, Ab vs control). (B) Absence of any relationship between the ex vivo invasion efficiency and the in vivo admission parasitemia for each isolate (dotted line, goodness of fit: R2 = 0.008, P = .397).
