question: What is the role of the positive effector of transcription (pet) in the hepatitis B virus?
answer: This element, which we have named pet (positive effector of transcription), exerts its effect in cis in a position and orientation-dependent manner, suggesting that it may function as part of the nascent pregenome transcript.  In the presence of this region, deletion of pet activates transcription from downstream promoters, suggesting that pregenome transcription complexes fail to reach the downstream promoters. In vitro transcription experiments support the model that pet is required for transcription elongation on the DHBV template. We speculate that pet is required to suppress transcription termination during the first passage of pregenome transcription complexes through a viral termination region on the circular viral DNA.