EIF2AK1 and viral infectious disease: The family consists of the heme-regulated inhibitor (HRI) activated by heme-deficiency in erythrocytes; the protein kinase RNA-dependent kinase (PKR) activated by double stranded (ds) RNA and virus infection; the PKR-like endoplasmic reticulum (ER) resident kinase (PERK) activated by the accumulation of misfolded proteins in the ER; and the general control non-derepressible 2 (GCN2) activated by uncharged tRNAs from amino acid deprivation [5, 6].