IFNA1 and viral infectious disease: IRF1 is expressed at low levels in unstimulated cells and is activated by many cytokines including type I (IFNα, IFNβ, and others) and II (IFNγ) interferons, tumor necrosis factor-α (TNF-α), retinoic acid, interleukin-1 (IL-1), IL-6, and viral infection [19].