(a) Rag1−/−, CD4-, CD8-depleted and IgG control mice were infected with NRG857c (three mice per group, representing two independent experiments). AIEC load in faecal pellets was quantified from immune-depleted mice over time. At day 21, caecal tips were scored for histopathology (b) on haematoxylin and eosin-stained sections (c); scale bar, 50 μm. (d) Caecal sections were stained with PSR for quantification of fibrosis. Original magnification, × 200. (e) Cytokines were measured from caecal explant supernatants by enzyme-linked immunosorbent assay. C57BL/6 mice were infected with NRG857c or mock infected with PBS (three mice per group were pooled and experiment was repeated three times), and at day 21 after infection the caecum was excised and lamina propria immune cells were isolated and stained for FACS analysis. (f) Percentage of CD45.2+ CD8+ lymphocytes measured by flow cytometry of lamina propria cells from AIEC-infected C57BL/6 mice (day 21). (g) The number of CD8+ IFNγ+ lamina propria cells measured by flow cytometry expressed as a percentage of the PBS control. Data are the means with s.e. *P<0.05 (Student t-test).