The Fine Specificity, but Not the Invasion Inhibitory Activity, of 19-Kilodalton Merozoite Surface Protein 1-Specific Antibodies Is Associated with Resistance to Malarial Parasitemia in a Cross-Sectional Survey in The Gambia

Age-related changes in parasite density, prevalence, and anti-MSP-1₁₉ antibody responses. (a) Parasite prevalence and density by age (n = 186). (b) Distribution of antibodies to MSP-1₁₉ by age. In each plot median (line), the interquartile range (25th to 75th centile) (box) and the adjacent values (highest value within 1.5 multiplied by the interquartile range of the 75th centile and lowest value within 1.5 multiplied by the interquartile range of the 25th centile) (vertical lines) are indicated. Points falling outside this range are drawn individually. Positive sera were defined as sera with an OD of >0.77 (means ± 3 standard deviations of a panel of 37 European nonimmune sera). Number (and percentages) of positive sera/number tested in each age group are indicated at the top of the plot. (c) Correlation between binding to wild-type and modified recombinant MSP-1₁₉ antigens for individual plasma samples. Vertical dashed line indicates the OD cutoff for positive sera. The diagonal dashed line is a line of identity between mutant OD and wild-type OD. (d) Correlation between binding of plasma antibodies to wild-type recombinant MSP-1₁₉ (OD) and the ability of the same plasma to inhibit binding of MAb 12.10 to recombinant MSP-1₁₉ (percent).