FIG. 3.

Effects of proteolytic enzymes on T. cruzi metacyclic-stage trypomastigotes. (A) Parasites, untreated or treated with pepsin or proteinase K, were analyzed by SDS-PAGE, staining with Coomassie blue, and immunoblotting with MAb 3F6. Note the pepsin digestion of bovine serum albumin, but not of metacyclic-form proteins, including gp82, which were susceptible to proteinase K digestion. (B) Live parasites, untreated (−) or treated with proteinase K (+), were reacted with MAb 3F6, fixed, and then analyzed by flow cytometry. (C) Control and proteinase K-treated metacyclic forms were used for HeLa cell invasion assay. Values represent the means ± standard deviation of three experiments.