Human papillomaviruses (HPV) activate a number of host factors to control their differentiation-dependent life cycles. The transcription factor signal transducer and activator of transcription (STAT)-3 is important for cell cycle progression and cell survival in response to cytokines and growth factors. STAT3 requires phosphorylation on Ser727, in addition to phosphorylation on Tyr705 to be transcriptionally active. In this study, we show that STAT3 is essential for the HPV life cycle in undifferentiated and differentiated keratinocytes. Primary human keratinocytes containing high-risk HPV18 genomes display enhanced STAT3 phosphorylation compared to normal keratinocytes. Expression of the E6 oncoprotein is sufficient to induce the dual phosphorylation of STAT3 at Ser727 and Tyr705 by a mechanism requiring Janus kinases and members of the MAPK family. E6-mediated activation of STAT3 induces the transcription of STAT3 responsive genes including cyclin D1 and Bcl-xL. Silencing of STAT3 protein expression by siRNA or inhibition of STAT3 activation by small molecule inhibitors, or by expression of dominant negative STAT3 phosphorylation site mutants, results in blockade of cell cycle progression. Loss of active STAT3 impairs HPV gene expression and prevents episome maintenance in undifferentiated keratinocytes and upon differentiation, lack of active STAT3 abolishes virus genome amplification and late gene expression. Organotypic raft cultures of HPV18 containing keratinocytes expressing a phosphorylation site STAT3 mutant display a profound reduction in suprabasal hyperplasia, which correlates with a loss of cyclin B1 expression and increased differentiation. Finally, increased STAT3 expression and phosphorylation is observed in HPV positive cervical disease biopsies compared to control samples, highlighting a role for STAT3 activation in cervical carcinogenesis. In summary, our data provides evidence of a critical role for STAT3 in the HPV18 life cycle.

IntroductionBASHH have recently updated guidelines as regards criteria for hepatitis B and C testing. Are patients accessing the service offered hepatitis B and C testing appropriately? Furthermore can this data be extrapolated to calculate potential cost reductions should audit data suggest overtesting.Methods100 case notes SHHAPT coded as T6 from 2 local clinics were scrutinised as to whether testing followed BASHH guidelines. In addition 50 case notes were randomly selected to ascertain whether a T6 code should have been applied.Results87/100 (87%) underwent hepatitis B testing of which 10/87(11%) were found to be inappropriate The reasons for testing in this 11% included sexual exposure in a low prevalence (mostly in Europe), saliva exposure, and a history of an ex-partner with multiple contacts – 38/100 underwent hepatitis C testing of which 14/38 (36%) were tested inappropriately—the reasons given included contact with men having sex with men(MSM) with no history of chemsex, contact with a HIV infected patient, sexual assault, sexual contact with an intravenous drug user and sexual exposure in Europe. In the audit of random selection of 50 casenotes- there were no cases of missed opportunities for hepatitis testing. Extrapolation of data showed that £1739 annually could be saved if all testing for hepatitis B and C was based on national guidance.DiscussionGiven the proven overtesting in the audit, guidelines are to be reiterated to clinical staff. It is hoped that this would translate to costs savings on an overstretched service pathology budget.