CD8A and infection: To ensure that the decreased cytokine production was indeed reflective of functional exhaustion and not a result of normal T cell kinetics or contraction, we similarly evaluated the function of donor OT-I CD8+ T cells in the lungs of WSN-OVA influenza virus infected mice 15 days post-infection, during the contraction phase of the T cell response to influenza virus infection (Supplementary Figures 2A–C).