These include programmed cell death 1 (PD1), PD-Ligand 1 (PD-L1) (Bailly, 2020), and Cytotoxic T-Lymphocyte Antigen4 (CTLA4) (Aoyagi et al., 2000), that function as immune checkpoint inhibitors to modulate B-cells, CD8+ T-cells, and CD4+ T-cells, which can amplify infection and promote tissue damage. Here, PDCD1 is linked to infection.