A NOVEL DRUG SCREENING ASSAY FOR PAPILLOMAVIRUS SPECIFIC ANTIVIRAL ACTIVITY

Discovery and development of human papillomavirus (HPV) specific antiv iral agents have been hampered by the lack of an in vitro assay permis sive to HPV replication. An experimental assay system for monitoring H PV-11 DNA replication has been optimized for use as a papillomavirus a ntiviral drug screening tool. Cloned HPV DNA was introduced into SCC-4 cells by electroporation and viral DNA replication monitored by South ern blot. Kinetic studies demonstrated an increased HPV genome copy nu mber with time. Viral DNA replicated as episomal, unit length genome a nd remained episomal after multiple passages. These data suggested the basis for an in vitro replication assay for evaluating the antiviral activity of potential chemotherapeutic agents directly on HPV. This mo del was used to investigate antiviral activities of current anti-HPV t herapies such as 5-fluorouracil (5-FU) and alpha-interferon (alpha-IFN ) and potential therapies such as sodium butyrate, 5-bromo-2O-deoxyuri dine (BrdU) and antisense oligonucleotides. HPV-11 replication is sign ificantly inhibited by BrdU and sodium butyrate; however 5-FU and a-IF N did not give consistent dose response results. Finally, ISIS 2105, a 20-mer phosphorothioate antisense oligonucleotide, which targets HPV- 11 E2, gene product, showed potent antiviral activity in this assay wi th an IC50 of approximate to 70 nM. (C) 1998 Elsevier Science B.V. All rights reserved.