IL25 and viral infectious disease: Interferons (IFNs) are a group of proteins usually produced in response to viral infections, and it can recruit Th1 cells to the inflammatory site and downregulate the activity of Th2 cells (T helper type 2 cells: CD4+ effector T cell that secretes IL-4, IL-5, IL-9, IL-13, and IL-17E/IL-25 and are required for humoral immunity) [130].