Identification of a novel promoter in the E2 open reading frame of the human papillomavirus type 18 genome

Abstract

Northern blot and RT-PCR analyses indicated that the human papillomavirus E4 open reading frame is expressed in HeLa cells. Because integration at the E1 or E2 open reading frame would place the viral upstream regulatory region downstream of the viral late genes, the expression of E4 in HeLa cells is most likely regulated by host cellular promoter(s) or unidentified viral promoter(s) in the E2 region. Primer extension analysis and transient transfection experiments with luciferase reporter constructs under the transcriptional control of various subgenomic fragments of HPV-18 were carried out to identify and characterize functional promoters within the E2 region. The in vivo activity of a novel promoter located within the 5'-end region of the E2 open reading frame of human papillomavirus type 18 is demonstrated.