FIG 5.

MSP-1 as target of opsonizing antibodies (antigen-reversal ADRB assay) and importance of conserved regions. ADRB activity of protein G-purified IgG from 11 semi-immune donors was analyzed against P. falciparum 3d7 (A and C) and FCB-1 (B) merozoites in the absence and presence of MSP-1D (A and B) or its processing fragment MSP-1₈₃ (C). Mean values of duplicate measurements are shown as individual columns (left) and in vertical point plots (right); statistical differences were calculated using paired t tests. The average reductions of the means in the presence of competitor were 58.6% (MSP-1D with 3d7 merozoites), 50.2% (MSP-1₈₃ with 3d7 merozoites), and 51.7% (MSP-1D with FCB1 merozoites). N, IgG from malaria-naive European donors (n = 4). ***, P ≤ 0.001.