Microbiome features might impact antiviral immunity via stimulation of IL-33 (alarmin) released by mucosal epithelium, which suppresses local antiviral immunity by blocking the migration of effector T cells to mucosa, thereby inhibiting the production of IFN-γ, a critical cytokine for antiviral defense, at local infection sites (Oh et al., 2016). Serum levels and intestinal tissue expression of IL-33 and its receptor in CD patients were found to be increased (López-Casado et al., 2015). Here, IL33 is linked to infection.