Following active immunization with the mimotope (JT-mPD1) or, for comparison, after the application of a functional anti-mouse PD-1 mAb, which was used for the identification of the mimotope [101], mice were infected with the influenza virus strain (A/PR/8/34) and sacrificed on days five and nine post-infection for clinical and immunological evaluations (Figure S2A). Here, PDCD1 is linked to infection.