α-Actinin Accumulation in Epithelial Cells Infected with Attaching and Effacing Gastrointestinal Pathogens

Fluorescent F-actin staining utilizing phalloidin, a highly toxic mushroom poison, is used as an indirect test to detect attaching and effacing (AE) bacteria. A study was done to determine if accumulation of alpha-actinin in infected tissue culture cells is a consistent feature and whether it corresponds with the AE response. Rearrangement of alpha-actinin was detected using immunofluorescence microscopy by incubation of infected cells with a murine monoclonal anti-alpha-actinin antibody. Foci of alpha-actinin-specific fluorescence corresponding to areas of bacterial adhesion were detected by transmission electron microscopy in HEp-2 and gastric KATO-III cells infected with only those bacterial strains that formed AE lesions. Therefore, this study shows that alpha-actinin accumulation is a consistent, specific manifestation of the AE phenotype and forms the basis for the development of a safe alternative test for detecting AE bacteria.