Figure 3.

Assessment of functional growth inhibitory activity (GIA) induced by FMP2.1/Adjuvant System 01 vaccination. A, In vitro GIA of purified immunoglobulin G (IgG) was assessed at 10 mg/mL against 3D7 clone Plasmodium falciparum parasites at the National Institutes of Health (NIH) GIA Reference Center. Individual data and medians are shown for each group on the day before challenge (dC-1), as well as before vaccination (d0) for group 1. Responses >12% are typically regarded as positive for 3D7. B Dilution series of purified IgG from group 1 samples obtained on dC-1. C, Relationship between GIA and anti-3D7 AMA1 serum IgG concentrations, measured by enzyme-linked immunosorbent assay (ELISA) at the NIH. A nonlinear regression curve is also shown (n = 60). The level of anti-3D7 AMA1 response in this ELISA that gives 50% GIA (GIA₅₀), indicated by the dotted line, was 75.5 µg/mL, (95% confidence interval, 68.3–84.2). D, Individual half maximal effective concentration (EC₅₀) for each purified IgG is shown, as well as the GIA₅₀ titers. Individual data and medians are shown for group 1 at dC-1.