EIF2AK2 and viral infectious disease: Four eIF2α kinases sense environmental stress: HRI (heme-regulated eIF2α kinase) is activated in heme deprivation and oxidative stress [11]; PKR, (Protein Kinase RNA-dependent) is a double-stranded RNA (dsRNA)-dependent protein kinase activated by viral infection [12]; PERK/PEK (PKR-like ER kinase) is activated during hypoxia and in response to misfolded proteins in the ER [13]; and GCN2 (general control non-derepressible-2) is activated during amino acid depravation and UV irradiation [14].