The bovine papillomavirus type 4 long control region contains an epithelial specific enhancer

Bovine papillomavirus type 4 (BPV-4) is a mucosal epitheliotropic virus tha t is a causative agent in alimentary carcinoma of cattle. The long control region (LCR) of this virus controls expression of the transforming proteins , E8 and E7. Deletion mutants of the LCR were prepared and assayed for thei r ability to activate transcription from the LCR promoter in primary bovine palate keratinocytes (the natural target cell for BPV-4) and fibroblasts. The LCR was at least an order of magnitude more active in keratinocytes tha n in fibroblasts. An epithelial specific enhancer was identified that activ ated transcription from the SV40 promoter to levels identical to the full-l ength LCR. One of the active sites in the enhancer is 100% conserved in the LCR of human papillomavirus type 16. The results demonstrate that the BPV- 4 LCR has an epithelial specific enhancer, which offers the opportunity to study epithelial specific transcriptional regulation of papillomavirus prom oters.