FIG. 5.
Detection of intimin γ and Tir at the site of interaction of EHEC O157:H7 strain 85-170 Nalr with the bovine intestinal mucosa. Tir was found at the apical surface of infected enterocytes (arrowheads in the “Tir” panel), whereas intimin γ was detected on both luminal and intimately adherent bacteria (arrowheads in the “Intimin” panel of the “85-170, terminal rectum” section). An F-actin rim, which was found to be continuous and regularly distributed at the apical surface of the enterocytes on uninfected explants (“Actin” panel of the “Uninfected, terminal rectum” section), appeared to be disrupted, at least locally, in the presence of intimately adherent bacteria. Similar results were obtained with EHEC O157:H7 strain TUV 93-0. Neither Tir nor intimin was detected on uninfected cryosections. Representative micrographs from the terminal rectum are shown, and similar findings were observed in the terminal ileum and colon. Hoechst 33342 (blue, false color), nuclei and bacteria; Cy5 (intense blue, false color), O157-positive bacteria; Cy2 (green, false color), intimin γ or Tir; phalloidin-tetramethyl rhodamine isothiocyanate (TRITC) (red, false color), F-actin. Bar, 10 μm.