Fig. 3. A central role for IRF1 in reovirus-mediated T_H1 immunity to dietary antigen.

(A) WT and IFNAR^−/− mice were inoculated perorally with 10⁸ PFU of T1L (n = 6 mice), 10⁸ PFU of T3D-RV (n = 6 mice), or PBS (sham, n = 6 mice) for 2 days. Irf1 expression in the mLN was analyzed by means of RT-PCR. (B) OT-II⁺ CD45.1⁺ CD4⁺ T cells were transferred into WT CD45.2⁺ or IRF1^−/− CD45.2⁺ mice. One day after transfer, mice were inoculated perorally with 10⁸ PFU of T1L (n = 4 to 6 mice) or PBS (sham, n = 4 to 6 mice) and fed 1.5% OVA in the drinking water for 2 days. The expression of IL-12p40 on gated MHC-II⁺ CD11c⁺ CD103⁺ CD11b⁻ CD8α⁺ mLN DCs was evaluated by means of flow cytometry. (C to F) OT-II⁺ CD45.1⁺ CD4⁺ T cells were transferred into WT CD45.2⁺ or IRF1^−/− CD45.2⁺ mice. One day after transfer, mice were inoculated perorally with 10¹⁰ PFU of T1L (n = 5 or 6 mice) or PBS (sham, n = 4 to 6 mice) and fed 1.5% OVA in the drinking water for 6 days. Intracellular expression of Foxp3 and IFN-γ was evaluated by means of flow cytometry. Representative dot plots (C), percentages of Foxp3 (D), representative dot plots (E), and percentages of IFN-γ (F) are shown in transferred OT-II⁺ CD4⁺ T cells in the mLN. [(A) to (F)] Graphs depict two independent experiments. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001; one-way ANOVA/Tukey’s multiple comparison.