Fig. 3.

Combinatorial screening reveals antibody pairs with synergistic effects. Isobolograms showing the combined effect of fixed-ratio mixtures (5:0, 4:1, 3:2, 2:3, 1:4, and 0:5) of purified polyclonal antibodies on erythrocyte invasion by P. falciparum 3D7. In each case x and y axes represent the FIC₅₀ values associated with the two antibodies in each combination: EBA181/CyRPA (A), MSPR5/CyRPA (B), SERA9/CyRPA (C), Rh5/CyRPA (D), SERA9/EBA181 (E), CyRPA/RAMA (F), Rh5/RAMA (G), Rh5/MSRP5 (H), SERA9/Rh5 (I), and EBA181/Rh5 (J). Dashed lines represent the expected result under Loewe additivity (sum of FIC₅₀s equal to 1). Points below this line are suggestive of synergistic inhibition, while points above it suggest antagonistic inhibition (38).