Levels of naturally acquired antibody against PvRAMA in P. vivax-exposed individuals.

(A). The level of PvRAMA and PvMSP1-19-specific total IgG in 77 serum samples from P. vivax-exposed individuals, including 27 samples from the acute phase, 21 samples collected 3 months after recovery, 15 samples collected 9 months after recovery, and 14 samples collected 12 months after recovery, plus 32 serum samples from malaria-naïve individuals. (B). Stability of the antibody response against PvRAMA in a group of recovered patients at different time points (acute phase, 3 months, 9 months and 12 months of recovery). The cutoff value for seropositivity was an OD greater than the mean plus two SD of that for the naïve controls (PvRAMA cutoff OD = 0.071, PvMSP1-19 cutoff OD = 0.101). Antibody levels in different groups were compared using the Mann–Whitney U test.