Fig. 1: C. parvum infection in conditional intestinal epithelial Ifnar1 knockout mice and IEC4.1 cell cultures.

a HE morphological features of small intestine of Ifnar1^fl/fl and Villin.Ifnar1^−/− neonates following infection. Neonatal mice (5 days old) were orally inoculated with C. parvum oocysts (10⁶ oocysts per animal) and ileal epithelium (4 cm of small intestine tissue from the ileocecal junction) was collected (72 h p.i.) Representative HE images from four independent experiments are shown. Insets are higher magnification of the boxed regions showing the parasites (arrows). Bars = 50 µm. b C. parvum intestinal infection burden in Ifnar1^fl/fl and Villin.Ifnar1^−/− mice. Neonatal mice were inoculated with C. parvum oocysts (10⁶ oocysts per animal) for 48 h and 72 h. Infection burden was evaluated by RT-qPCR of cp18S gene in the isolated intestinal epithelium (fold changes to Ifnar1^fl/fl normalized to host Gapdh) and parasite counting of intestine sections after immunofluorescent staining of C. parvum (average number/60X field). Data are presented as mean values ± SD, compiled from 4 independent experiments and the dots represent the mean value of each experiment with 6 mice in each group. Statistical significance was determined by two-tailed unpaired Student’s t-test. c Immunofluorescent staining of C. parvum, and PCNA and EpCAM staining of small intestine of Ifnar1^fl/fl and Villin.Ifnar1^−/− neonates with and without C. parvum infection (at 72 h p.i.). Representative images from 4 independent experiments are shown. Insets are higher magnification of the boxed regions showing the parasites revealed by immunofluorescent staining for parasite counting (arrowheads). Blue: DAPI (DNA), green: PCNA or EpCAM, red: C. parvum (arrows). Bars = 50 µm. d No significant difference in infection burden between IEC4.1 and IEC4.1-Ifnar1^−/− cells following C. parvum infection in vitro. IEC4.1 and IEC4.1-Ifnar1^−/− cells were infected with C. parvum for 2 h and 24 h. Infection burden was evaluated by RT-qPCR (cp18S, fold changes to IEC4.1 normalized to Gapdh). The dots represent data from three biological replicates. Data are presented as mean values ± SD. Blue: DAPI (DNA), red: C. parvum (arrows). Bars = 5 µm. Source data are provided as a Source Data file.