Induction of E6/E7 expression in cottontail rabbit papillomavirus latency following UV activation

Latent human papillomavirus (HPV) infections are widespread in the genital and respiratory tracts and are a source of recurrent disease. This study us ed a cottontail rabbit papillomavirus (CPRV) model to determine the presenc e of E1, E6, and E7 transcripts in latent infection and to determine the te mporal change in transcripts following UV activation. We found E1 transcrip ts in all latent infected sites but no detectable E6 and E7 transcripts, co nsistent with our earlier studies of HPV6/11 latency. These results suggest that this transcription pattern is broadly characteristic of latent papill omavirus infections. E6/E7 transcripts were detectable within 1 week of irr adiation, with maximal induction (approximately 40% of sites) at 2 weeks po stirradiation. Papillomas were induced in approximately 26% of irradiated s ites after a 3- to 5-week lag. Sites that did not form papillomas by 3 mont hs after irradiation were CRPV DNA Positive but E6/E7 RNA negative. Thus, o nly a subset of latent infections can be induced to express E6/E7 transcrip ts and form papillomas. We propose CRPV can be used to study the molecular processes regulating papillomavirus activation. (C) 1999 Academic Press.