Figure 1. Measurement of GIA EC₅₀ of antigen-specific anti-PfRH5 and anti-PfAMA1 polyclonal rabbit antibodies.

Panel A - CFCA-measured antigen-specific antibody as a proportion of total IgG (measured by spectrometry) for each of ten rabbits. Individual points indicate mean of three measurements. Panel B - GIA vs. total IgG concentration, with lines connecting data for each of five PfRH5-vaccinated rabbits (red) and five PfAMA1-vaccinated rabbits (black). Each point is the mean of three replicate wells in two independent experiments, i.e. n = 6. Error bars indicate SEM. Panel C - GIA (from the experiments depicted in panel B) vs. antigen-specific antibody concentration (calculated for each sample using the data in panel A), for each of five PfRH5-vaccinated rabbits (red) and five PfAMA1-vaccinated rabbits (black). Each point is the mean of triplicate wells in two independent experiments. Panel D - antigen-specific antibody EC₅₀ values for PfRH5 and PfAMA1, calculated by interpolation from the data in panel C. Individual data-points and the median are shown. Panel E - Dose-response curve fitted to all GIA vs. antigen-specific antibody concentration data for the 3D7 parasite clone (multiple IgG dilutions for each of five rabbits for PfRH5 and PfAMA1). Dashed vertical lines indicate the fitted EC₅₀ value for anti-PfRH5 (red) or anti-PfAMA1 (black) IgG. Each GIA value is the mean of triplicate wells in each of two experiments (n = 6). Red indicates anti-PfRH5 samples; black indicates anti-PfAMA1 samples.