Conversely, dysregulation of this axis in Il23a−/− and Il22−/− mice leads to high susceptibility to infection with pathogenic bacteria such as Citrobacter rodentium (C. rodentium), a model bacterium for human enteropathogenic and enterohemorrhagic Escherichia coli infection (Mangan et al., 2006; Zheng et al., 2008). This evidence concerns the gene IL23A and infection.