To discriminate between hematopoietic and non-hematopoietic contributions of IRF-1 expression during C. rodentium infection, we therefore next generated bone marrow chimeric mice by reconstituting lethally irradiated C57BL/6 mice with bone marrow from Irf1–/– or Irf1+/+ mice and performed infection experiments eight weeks after reconstitution. Here, IRF1 is linked to infection.