FIG. 5.

(A) PRE-2 SV40 constructs. Four copies of PRE-2 were inserted into the BglII site, upstream of the SV40 promoter in the pGL3 luciferase vector, in both a positive and a negative orientation. The position and sequence of PRE-2 are conserved among the mucosal epitheliotropic papillomaviruses BPV-4, BPV-3, and BPV-6. (B) PRE-2 strongly represses SV40 promoter activity in an orientation-independent manner in both PalK and PalF cells. PalK and PalF cells were transfected with the indicated amounts of pGL3PRO, PRO4XPRE-2, and PRO4XPRE-2(−). Results are expressed relative to the luciferase activity of pGL3PRO (set arbitrarily at 100%), which contains only the SV40 promoter.