WT C57/BL6 mice were purchased from the Jackson Laboratory, Blimp-1 control (Prdm1fl/fl), CD4-Cre transgenic, CD8-cre transgenic, IRF4 control (Irf4fl/fl) and CD45.1 congenic mice were originally from the Jackson Laboratory and bred in house. T cell-specific Blimp-1 conditional knockout (cKO) mice were generated through breeding CD4-cre to Prdm1fl/fl mice. CD8 T cell-specific IRF4 cKO mice were generated through breeding CD8-cre to Irf4fl/fl mice. IFNAR1-deficient (Ifnar1−/−) mice were originally from Dr. U. Deshmukh at the University of Virginia; Vert-X mice were originally from Dr. C. Karp from Cincinnati Children’s Hospital; STAT2-deficient (Stat2−/−) mice were originally from Dr. C. Schindler at the Columbia University. All mice were housed in a specific pathogen-free environment and all animal experiments were performed in accordance with protocols approved by the University of Virginia Animal Care and Use Committee (ACUC) or Indiana University Institutional Animal Care and Use Committee (IACUC). For influenza virus infection, mice were anesthetized first and then intranasally infected with Influenza A/PR8/34 strain (~150 pfu/mouse in serum-free IMDM media (Gibco) or PBS) as previously reported (8 (link)).