The dsRNAs generated during viral replication activate PKR, which in turn phosphorylates eIF2a [30] . Also 59-triphosphated single-stranded RNAs activate PKR [31] . The eIF2a is a component of eIF2, which binds to GTP and Met-tRNA to deliver the Met-tRNA to the start codon in capped mRNA, forming a 43S pre-initiation complex [32] . Upon the binding of the 60S ribosomal subunits to the 43S preinitiation complex, eIF2-GDP is released from the ribosome and undergoes a GTP exchange reaction catalyzed by binding with eIF2B, and the resultant eIF2-GTP is recycled for the next round of translation initiation. The phosphorylated eIF2a binds to eIF2B with a high affinity and prevents eIF2B to be used for the subsequent eIF2-GDP-to-eIF2-GTP exchange reaction, leading to the suppression of translation initiation. Hence, the phosphorylation status of eIF2a plays a critical role in translational control [32] .