Phosphatidylinositol-specific phospholipase C (PI-PLC) cleavage of GPI-anchored surface molecules of Trypanosoma cruzi triggers in vitro morphological reorganization of trypomastigotes

Trypanosoma cruzi trypomastigotes treated with phosphatidylinositol-specifi c phospholipase C (PI-PLC) in vitro are rapidly induced to differentiate in to round forms. Using confocal microscopy, we were able to show that trypom astigotes treated with PI-PLC initiate the process of flagellum remodeling by 30 sec after contact with the enzyme and amastigote-like forms are detec ted as early as 10 min after PI-PLC treatment. Scanning and transmission el ectron microscopy indicate that trypomastigotes undergo a previously undesc ribed process of flagellum circularization and internalization. Analysis of the flagellar complex with monoclonal antibody 4D9 shows heterogeneous lab eling among the parasites, suggesting a remodeling of these molecules. Afte r PI-PLC treatment, parasites rapidly lose the surface marker Ssp-3 and 24 h post-treatment they begin to exhibit a circular nucleus and a rod-shaped kinetoplast. By flow cytometry analysis and confocal microscopy, the Ssp-4 amastigote-specific epitope can be detected on the parasite surface. This i ndicates that thr release of trypomastigote GPI-anchored molecules by exoge nous PI-PLC in vitro can trigger morphological changes.