Living dangerously: how Trypanosoma cruzi uses lysosomes to get inside host cells, and then escapes into the cytoplasm.

Trypanosoma cruzi invades a wide variety of vertebrate cells by a mechanism distinct from phagocytosis, that involves recruitment and fusion of lysosomes at the site of invasion. A trans-sialidase present on the surface of the trypomastigote forms is capable of removing sialic acid from lgps, major glycoproteins from host cell lysosomes. Lack of sialic acid on lgps facilitates membrane lysis by a parasite-secreted molecule, Tc-TOX, which has membrane pore-forming activity at acidic pH. We propose a sequential model in which these trypanosome products would promote parasite entry into host cells and their subsequent liberation into the cytosol.