FIG. 1.

Design of bicistronic HIV-1 plasmids. (A) Schematic representation of the functional domains in the HIV-1 5′ leader. The RNA 5′ leader region contains the trans-activation-responsive region (TAR), the poly(A) hairpin, the primer binding site (PBS), the dimer initiation site (DIS), the major splice donor (SD), the core packaging signal (ψ), and a hairpin containing the initiator AUG (AUG loop). The asterisks denote the start and end points of deletion mutations that were used in this study. The black box represents the initiator AUG. Adapted from Berkhout (10). (B) Schematic representation of the dual luciferase reporter plasmid used in this study. The different HIV-1 fragments were subcloned into the intercistronic region as described in Materials and Methods. ΔEMCV is the encephalomyocarditis virus IRES which contains an inhibitory deletion (24, 83). (C) PCR-generated fragments of HIV-1 used in this study. The hatched boxes represent leader sequences; the white boxes represent gag coding region sequences.