PDCD1 and infection: The protein level was upregulated post‐infection, and PD‐L1 showed a significant difference on the 6th day (p = 0.0085) and 7th day (p = 0.0012) post‐infection, while the PD‐1 level slightly elevated on the 4th day (p = 0.0026) (Figure 1B), the protein level of β‐actin as control.