Inhibitory effect of hybrid peptide p4/8 on binding of T. cruzi gp82 recombinant proteins to HeLa cells and on parasite invasion. In panels A and B, HeLa cells were incubated with the recombinant proteins J18 containing the full-length gp82 sequence, in the absence or presence of the indicated peptide, at 200 μg/ml. Binding was measured by ELISA. Representative results of one of three comparable experiments are shown. The values are the means ± SD of triplicates. (C) HeLa cells were incubated with metacyclic trypomastigotes in the presence of the peptide. After 3 h at 37°C, the cells were stained with Giemsa, and the number of intracellular parasites were counted in a total of 500 cells. Values are the means ± SD of three assays performed in duplicate. O.D., optical density.