Antibodies elicited by LAGAP immunization require complement and F_CR binding for complete protection.

A) Survival of C57BL/6 mice (n = 5 mice per group) immunized and depleted of CD4 and CD8 T cells as in Fig 1. Six hours prior to challenge with 10⁴ iRBC, mice were depleted of complement by administration of 30 μg of cobra venom factor with an additional dose at 4 days post challenge. Loss of protection in 3/5 mice following complement depletion indicates a strong role for the classical complement pathway in antibody-mediated BS protection. B) Survival of FcγR^-/- given the same immunization, T cell depletion and challenge as in Fig 1 without complement depletion by CVF. Loss of protection from lethal parasitemia also implicates F_CR binding in antibody-mediated BS protection. C) The same immunization and challenge was performed with FcγR^-/- mice but with complement depletion prior to challenge as in (A). Loss of protection in 4/5 mice further confirms the role of both complement and F_CR binding as antibody effector mechanisms. D) Parasitemia of mice in (A) and (C) on day 5 post challenge. A higher peak parasitemia in complement-depleted FcγR^-/- mice confirms the role of F_CR-binding in controlling parasitemia in LAGAP-immunized mice. Comparisons were performed using one-way ANOVA with Tukey post-hoc analysis with significance indicated by: **0.01≥p>0.001; non-significant (NS) p≥0.05.