Figure 1

5' and 3' truncations of the RSE indicated that the minimal functional element is 155 nts. Truncations from the 5' and 3' end of the RSE were generated by PCR and cloned after the gag natural termination codon. Nomenclature of each construct indicates the nucleotide residue number. Diagram of deletions is to scale, with the location of the RPA probe used indicated. Each construct was transiently transfected into CEFs and RNA steady-state levels were assayed 48 hours later by RNase protection assay. Transfection efficiency was normalized using a wild-type viral loading control. RNA levels are reported as a fraction of wild-type RNA. Standard deviations are represented on the bar graph. Values represent the average of at least four experiments. Stars indicate a significant reduction compared to the wild-type virus (**: p < 0.001; ***: p < 0.0001).