Figure 3

Competition of naturally acquired human antibodies with anti-MSP4 specific Mabs. Serum samples were collected from individuals who acquired and were treated for P. falciparum parasitaemia at different time points; T₀, at the time of infection; T₁ and T₂₈, day 1 and day 28 following infection. a) Inhibition of Mab binding to MSP4 by a pool of human sera from infected individuals. A pool of human sera collected at the time of infection (T₀) were reacted with MSP4 by ELISA followed by addition of four Mabs (specific for the EGF like domain of MSP4) to determine the ability of human sera to inhibit the binding of Mabs. The human serum pool was able to inhibit Mab binding in a dose-dependent manner. The serum dilution is shown on the X axis and Absorbance value is shown on the Y axis. b) Heterogeneity of the human MSP4-specific antibody response. Human sera collected at different time points (T₀, T_{1 and} T₂₈) were competed with Mabs raised to different regions of MSP4 in the competition ELISA assay. Bars indicate the average percentage inhibition (%) at 1/10 dilution of 10 samples of human sera tested at each timepoint and the error bars indicate standard deviation within the sample. The P values (Wilcoxon test) between the inhibition in the matched pairs of serum samples at the different timepoints are shown.