Figure 6.

Antibodies to Merozoite and MSP2 Were Induced following IBSM

(A–D) IgG subclasses and IgM responses and functional capacity to fix complement (C1q), bind dimeric FcγRIIa or FcγRIIIa (surrogates for IgG antibody capacity to crosslink cellular receptors), and promote opsonic phagocytosis (OPA) to merozoites (A and C) and MSP2 (B and D) were assessed before inoculation and at EOS time points (n = 40 study participants). The positive threshold for each response is indicated by the dotted line (calculated as mean ± 3 SD of day 0 responses) and the proportion of positive responders are indicated in the bottom right of each panel. The Wilcoxon signed-rank test is <0.001 for all of the comparisons of antibody responses at day 0 to EOS, except for merozoite FcγRIIa, which was not significant (p = 0.11). The phagocytosis index for OPA refers to the percentage of THP-1 monocytes with ingested MSP2 beads. Assays were performed twice independently, with samples tested in duplicates. Boxplots are Tukey style, with median and IQR. Whiskers are to data point no further than 1.5 × IQR; dots are outlying points. Paired data are joined by lines.

(E) Spearman correlation matrix of all antibody responses to merozoites and recombinant MSP2. Only correlations <0.05 are indicated. Correlations between the same subclass/function of responses comparing merozoite and MSP2 responses are indicated by black squares.

(F) Heatmap of composition of induced antibodies following categorization as negative (below positive threshold) or low/high (based on below/above median value of all positive responses). Subjects are ranked in order of total breadth and magnitude of response.

See also Figure S3.