Inhibition of sporozoite invasion in vitro by antibodies against rEtAMA1, rEtESP, and rEtRON2. (a) Invasion-inhibition activities of single antibodies. Anti-rEtAMA1, rEtESP, and rEtRON2 rabbit anti-serum against recombinant EtAMA1, EtESP and EtRON2 protein, respectively; IgG, normal rabbit serum. (b) Invasion-inhibition activities of antibody combinations. Combinations of anti-rEtAMA1 and anti-rEtESP or anti-rEtRON2 were added at a ratio of 1:1 to generate a gradient concentration of IgG. All assays were performed in triplicate. *p < 0.05, **p < 0.01 and ***p < 0.001, as determined by the Student’s t-test versus the non-immunized IgG groups at the same concentration.