EIF2AK4 and viral infectious disease: The four host kinases mentioned above play different roles: PKR senses dsRNA during viral infection [7]; endoplasmic reticulum (ER) stress initiates the unfolded protein response (UPR) to activate PERK [8]; HRI monitors changes in hemoglobin levels [9, 10]; and GCN2 detects amino acid starvation [11], UV damage, and viral infection [12].