Current strategies against the human immunodeficiency virus type 1 (HIV-1), including nucleoside analogues and protease inhibitors, have limited effectiveness as shown by the evolution of resistant retroviral strains and the presence of latent HIV-1 reservoirs. Therefore, it is necessary to look beyond anti-retroviral strategies and to rely on the body's immune system to inhibit HIV-1 replication. In this study, we approach the inhibition of HIV-1 replication by upregulation of the antiviral pathway that is natural to mammalian cells. Vectors were constructed which were capable of transferring the antiviral enzyme, p68 kinase (PKR), into target SupT1 lymphoblastoid cells under HIV-1 LTR transcriptional regulation via a retroviral-mediated shuttle system. We report a significant inhibition of HIV-1 replication in HIV-1 LTR-PKR cDNA transduced clones (105-10 : 239 and 106-4 : 560) expressing different PKR levels as measured by inhibition of HIV-1 induced syncytia formation and HIV-1 reverse transcriptase activity. Whereas the expression of PKR in parental vector transduced clone (N2-20P) is down-regulated 48 h after HIV-1 infection, the two transduced clones (one with PKR in the forward orientation and one in the reverse orientation) demonstrate increased PKR expression through 96 h post-infection, concomitant with an increase in eIF-2alpha phosphorylation and an increase in NF-kappaB activity at 72 h postinfection. These results demonstrate that the overexpression of PKR can inhibit HIV-1 replication and confirm the involvement of PKR in the IFN-associated antiviral pathway against HIV-1 infection. Finally, the treatment of the transduced clone 106-4 : 560 with AZT resulted in complete inhibition of HIV-1 replication.