The level of PD‐L1 increased by sixfold (p = 0.0199) on the 4th‐day early stage of infection, while the mice did not show any neurological symptoms, and maintained a high level on the 5th day (p = 0.0184), 6th day (p = 0.0027), and 7th day (p = 0.0025) (Figure 1A). This evidence concerns the gene CD274 and infection.