Antibody response and seroprevalence to Plasmodium vivax PE antigens.

(A) Serological responses at acute phase expressed as reactivity index (RI) against 7 pre-erythrocytic stage antigens including full-length, N-terminal and C-terminal PvCSP-VK210, PvSSP3, PvM2-MAEBL, PvCelTOS, PvSPECT1. (B-H) Serological responses at 4 time points: at day 0 (n = 104), and recovery at day 90 (n = 41), 270 (n = 30) and 360 (n = 27). RI value was calculated by dividing mean OD value of each patient with cut-off value. Cut-off value was calculated from mean optical density (OD) values plus 2 SD of 52 HCs. The dashed line represents the cut-off value for seropositivity (RI = 1); samples were considered as seropositive if RI was greater than 1. Percentage shown on each scatter graph represents percentage of seropositive samples among total tested samples. Statistical testing was performed by one-way ANOVA: * p<0.05; ** p<0.005; *** p<0.0005; **** p<0.0001.