To further define if IL-23 regulates IFNγ-production in another gut bacterial infection model, we infected IL-23-/- mice with Citrobacter rodentium and analyzed IFNγ-expression on day 5 p.i. We did not detect any difference in IFNγ-expression between IL-23-/- and control mice (data not shown), in agreement with protective role of IL-23 in this infection (25, 46). The gene discussed is IL37; the disease is infection.