FIG. 6.

(A) Schematic diagram of the vIRF promoter and a series of nested deletion mutants. Putative transcription elements located within the vIRF promoter are shown. AP, activator protein; SP, stimulating protein; TATA, TATA box. The numbers indicate the positions relative to the major transcription start site, which was defined as +1. (B) Transactivation of the vIRF promoter by the ORF50-cDNA clone in 293T cells. The indicated deletion mutants of the vIRF promoter were cotransfected into 293T cells with a transactivator (pcDNA3.1-ORF50-cDNA) or empty vector (pcDNA3.1) as a negative control. Cells were harvested 48 h after transfection and assayed for luciferase activity. The luciferase activity values were normalized to a cotransfected internal control plasmid (pCMV-β-gal). The activation was indicated as a percentage of that of the full-length vIRF promoter, which was defined as 100%. Each experiment was repeated at least three times with similar results. The average value (with standard deviation) of duplicate experiments is shown.