THE USE OF CONFOCAL LASER-SCANNING MICROSCOPY TO ANALYZE THE PROCESS OF PARASITIC PROTOZOAN HOST-CELL INTERACTION

In this communication we review the results obtained with the confocal laser scanning microscope to characterize the interaction of epimasti gote and trypomastigote forms of Trypanosoma cruzi and tachyzoites of Toxoplasma gondii with host cells. Early events of the interaction pro cess were studied by the simultaneous localization of sites of protein phosphorylation, revealed by immunocytochemistry, and sites of actin assembly, revealed by the use of labeled phaloidin. The results obtain ed show that proteins localized in the interaction sites are phosphory lated. The process of formation of the parasitophorous vacuole was mon itored by labeling the host cell surface with fluorescent probes for l ipids (PKH26), proteins (DTAF) and sialic acid (FITC-thiosemicarbazide ) before interaction with the parasites. Evidence was obtained indicat ing transfer of components of the host cell surface to the parasite su rface in the beginning of the interaction process. We also analyzed th e distribution of cytoskeletal structures (microtubules and microfilam ents visualized with specific antibodies), mitochondria (visualized wi th rhodamine 123), the Golgi complex (visualized with C6-NBD-ceramide) and the endoplasmic reticulum (visualized with anti-reticulin antibod ies and DIOC6) during the evolution of intracellular parasitism. The r esults obtained show that some, but not all, structures change their p osition during evolution of the intracellular parasitism.