Standard molecular biological techniques, including a PCRbased mutagenesis method, were used for plasmid constructions. PCR fragments encoding PKRDE7 ORF with an N-terminal Flag-tag sequence were cloned between the Hpa I and Spe I sites of pProT7-S(+) plasmid [19] , designated as pProT7-S(+)-PKRDE7. PCR fragments encoding the rLuc ORF or NSs with a C-terminal Flag-tag sequence were cloned between the Hpa I and Spe I sites of the pProT7-S(+) plasmid, designated as pProT7-S(+)-rLuc-Flag or pProT7-S(+)-NSs-Flag, respectively. All of the constructs were confirmed to have the expected sequences. The PCR product of the entire human PKR ORF carrying a point mutation at K296R and the N-terminal myc tag was cloned between KpnI and XhoI of pcDNA3.1myc-His (Invitrogen), resulted in pcDNA3.1-Myc-PKR296R.