Disassembly of focal adhesions during apoptosis of endothelial cell line ECV304 infected with Orientia tsutsugamushi

Many bacterial pathogens induce apoptosis in their host cells. We observed the cellular effect of ECV304 cells infected with Orientia tsutsugamushi. T he infected cells became rounded and floated in culture supernatant. These floating cells as well as adherent cells exhibited typical features of apop tosis, such as DNA fragmentation and TUNEL staining. As many cells detached from growth substrate, we examined the focal adhesion using the immunofluo rescence assay method and observed decreased focal adhesions in heavily inf ected cells, As endothelial cells could undergo apoptosis by the loss of fo cal adhesions, this change of focal adhesions may account for the Orientia- induced apoptosis. (C) 1999 Academic Press.