CD4 and infection: Although the modest increase in Th1 and Th17 cytokine production in CD4+ T cells in response to the CRK1OE strain infection did not reach statistical significance when compared to H99 infection, we detected a significantly increased induction of Th1 and Th17 CD4+ T responses in CRK1ΔPEST-infected mice, which indicates that Crk1 protein level is important for regulation of fungal virulence33.