Figure 6

The natural viral UTRs can substitute for the RSE after the gag termination codon, but not after a premature termination codon. A. Diagram of the viral UTR cloning strategy. The UTRs of pol, env, and src (black arrows) were cloned after the gag natural stop codon (grey octagon) and after a premature termination codon (white octagon) within gag at position 1250. B. The pol and src UTRs were able to maintain wild-type RNA levels when placed after the gag natural termination codon. None of the UTRs other than the RSE was capable of stabilizing the RNA when placed after a premature termination codon. RNA levels were assayed by RNase protection assay. Representative gels are shown below each graph. Stars indicate a significant reduction compared to the wild-type virus (**: p < 0.001; ***: p < 0.0001)