An EGF-like Protein Forms a Complex with PfRh5 and Is Required for Invasion of Human Erythrocytes by Plasmodium falciparum
Figure 9
Antibodies to PfRipr inhibit attachment of merozoites to erythrocytes and parasite growth.
(A) Anti-PfRipr/1 antibodies inhibit invasion of P. falciparum strains into erythrocytes. Shown are growth inhibition assays of the parasite strains FCR3, W2mef, T994, CSL2, E8B, MCAMP, 7G8, D10, HB3 and 3D7. The final antibody concentration is 2 mg/ml. (B) Titration of anti-PfRipr/1 antibodies in growth inhibition assays of the FCR3 strain. (C) Titration of anti-PfRipr/1 antibodies in growth inhibition assays of the 3D7 strain. (D) Pre-incubation of purified merozoites from 3D7 strain (left panel) and FCR3 strain (right panel) with protein-A purified antibodies raised against recombinant PfRipr inhibited merozoite attachment to red blood cells. Protein-A purified antibodies from normal serum were used as a negative control. The final antibody concentration is 2 mg/ml. (E) Various combinations of anti-PfRipr/1, EBA-175, PfRh2a/b and PfRh4 antibodies increase inhibitory activity for the 3D7 strain of P. falciparum. The final concentration of each antibody is 1 mg/ml. In all the cases, each graph represents three independent experiments done in triplicate with each normalised to the negative control (Protein A purified IgG from normal rabbit serum). The error bars represent standard error of the mean of the three independent experiments.