Fig. 2

Host cell invasion by gp90-expressing T. cruzi metacyclic forms. a HeLa cells were incubated for 1 h with the indicated parasite strains in full nutrient DMEM. After fixation and Giemsa staining, the number of intracellular parasites was counted in a total of 250 cells. Values are the means ± SD of four independent assays performed in duplicate. As compared to CL strain, a significant lower invasion of strains 28, 588 and 1522 (***P < 0.0005), strain 515 (**P < 0.001) and strain 1434 (*P < 0.005) was detected by Student t test. b Metacyclic forms, untreated (−) or treated (+) with 2 mg/ml pepsin, at pH 3.5, were analyzed by Western blot using anti-gp90 mAb 1G7. As control of pepsin activity, BSA stained by Coomassie blue is shown. c Live parasites were incubated on ice for 1 h, in absence or in the presence of mAb 1G7. After fixation, the parasites were incubated with Alexa Fluor 488-conjugated anti-IgG and the number of fluorescent parasites was estimated