FIG. 1.

Changes in the distribution of apical F-actin, CD55, and CD66e in Caco-2/TC7 cells upon infection by EC7372 and TP411 (Dr-II⁺). Cells were infected for 1.5 h at 37°C. Fixed cells were stained with fluorescein-phalloidin for F-actin labeling (A, B, and G) or with polyclonal antibodies anti-CD55 (C, E, and F) or anti-CD66e (D). Apical domains of the cells were examined by epifluorescence microscopy. (A) Uninfected cells show the fine flocculated F-actin labeling which represents F-actin in the microvilli on the apical surface. (B) EC7372-infected cells show the typical Afa/Dr-induced F-actin disassembly. (C) CD55 clustering around adhering EC7372 bacteria. (D) CD66e clustering around adhering EC7372 bacteria. (E) CD55 clustering around adhering TP411 (Dr-II⁺) bacteria. (F) Lack of CD55 clustering with nonadherent DH5α bacteria. (G) TP411-infected cells show the typical Afa/Dr-induced F-actin disassembly. Magnifications, ×100.