(a) Representative confocal micrographs showing C227 in the intestinal lumen and attached to intestinal tissue at day 3 PI in the distal colon. C227 was stained with polyclonal antisera against C227 (green) and counterstained with phalloidin-Alexa 568 (red) and DAPI (blue) to detect F-actin and nuclei, respectively. Scale bar = 100 μm (left panel) and 10 μm (right panel). (b) Representative H&E-stained colonic sections from C227 and mock-infected rabbits 3 days PI showing infiltration of heterophils (arrow) and apoptosis (enlarged box). Scale bar=100 μm. (c) Pathology scores for infiltration of heterophils and apoptosis in the distal colon of rabbits inoculated with the indicated strain. Data points represent individual rabbits from 2 and 3 days PI (C227, n=19; Δstx2, n=13; ΔpAA, n=14; Mock, n=8). Statistical analysis was performed using Kruskal-Wallis statistic with Dunn’s post-test for multiple comparisons. * P < 0.05, ** P < 0.01. (d) Colonic tissue from rabbits infected with the indicated strain stained with biotin (red) prior to sectioning, then counterstained with DAPI (blue) and phalloidin-Alexa 633 (yellow). Scale bar=20 μm.