Moreover, using the same IFN-β luciferase reporter mouse, Lienenklaus and collaborators have previously revealed tissue-specific expression of IFN-β following infection with influenza or La Crosse virus, but most importantly, that IFN-β is constitutively expressed in low amounts by several tissues, including thymic epithelial cells, to maintain an activated state prepared for infection by pathogens [363]. This evidence concerns the gene IFNB1 and infection.