Excretion Product of Shigella dysenteriae (SdyEP) Induced Cell Death in Early Larval Stage of Zebrafish (Danio rerio): Acridine Orange and Ethidium Bromide (AO/EB) in vivo Staining

In the field of studies of bacterial toxicity, acute toxicity induced by bacterial agents, particularly bacteria of the genus Shigella sp. with Shigella dysenteriae at the top, has been relevant since the Shigella dysenteriae has been highly recognized for its production of one of the major virulence factors for humans such as Shiga toxin (Stxs). Shiga toxins are a family of genetically and functionally related cytotoxic proteins expressed by the enteric pathogens Shigella dysenteriae serotype 1 and certain serotypes of Escherichia coli (Lee et al., 2010). Recently, numerous studies have shown that Shiga toxins induce apoptosis through different mechanisms in different cell types including human epithelial cells, endothelial cells and neurons (Tesh, 2010). The use of human of renal cortical epithelial cells and a renal carcinoma cell line to investigate the cytotoxic effects of Stxs has shown the induction of apoptosis in both cell types as evidenced by nuclear fragmentation, DNA laddering, and the presence of terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labelling (TUNEL)-positive cells (Lentz et al., 2011). Stxq1-mediated apoptosis of monocytic THP-1 cells involved a novel pathway using components of both the intrinsic and extrinsic pathways of apoptosis (Lee et al., 2005). In the case of the excretion product of Shigella dysenteriae (SdyEP) as inducer of apoptosis, this process has been highlighted by the description of morphological signals, indicative of cell death Int. J. Morphol., 31(4):1175-1180, 2013.