Fig. 5

Antibodies that target the NANP epitope of CSP can promote C1q-fixation. Antibodies from malaria-exposed adults living in PNG (n = 30) (a) and Kenya (n = 30) (b) were tested for IgG, IgM, and C1q-fixation to (NANP)₁₅ peptide by ELISA, and correlated with C1q fixation to CSP (Spearman’s correlation coefficient, rho). Results were standardized to arbitrary units (AU) based on malaria-naïve negative controls from Melbourne (seropositivity defined as AU > 1, shown as dotted lines) and mean of duplicates were graphed. c Mouse anti-CSP MAbs 2H8-IgG1/IgG2a and 3C1-IgG1/IgG3 were tested for CSP-IgG, NANP-IgG, and C1q-fixation to CSP by ELISA. Results were corrected for background reactivity using no-IgG controls, and the mean and range of duplicates were graphed. AU arbitrary units, CSP circumsporozoite protein, ELISA enzyme-linked immunosorbent assay, IgG immunoglobulin G, IgM immunoglobulin M, MAb monoclonal antibody, OD optical density, PNG Papua New Guinea