title: Exploring gene-deleted adenoviral vectors for delivery of short hairpin RNAs and reduction of hepatitis B virus infection in mice.
abstract: BACKGROUND
  RNA interference based therapeutic approaches hold promise for the treatment of patients chronically infected with hepatitis B virus (HBV). To conquer HBV infection, long-term suppression of target transcripts in all hepatocytes without toxic effects may be required. The present study explored gene-deleted adenoviral vectors (GD-AdV) lacking all viral coding sequences for delivery of the previously described short hairpin RNA (shRNA) HBVU6no.2, which was demonstrated to result in post-transcriptional knock-down of HBV transcripts.
  
  
  METHODS
  We established conditions for shRNA delivery expressed from GD-AdV in vitro and in vivo and observed up to 96% shRNA-mediated knockdown of luciferase expressed in mouse liver. To investigate in vivo efficacy of HBVU6no.2 expressed from a GD-AdV, we explored a transient and a transgenic mouse model for HBV infection.
  
  
  RESULTS
  We observed an up to 68% drop in serum HBV surface antigen (HBsAg) levels in the transient and the transgenic mouse model for HBV infection, respectively. Interestingly, we detected an up to 86% drop in HBsAg levels in both animal models after administration of a control GD-AdV encoding beta-galactosidase. In concordance with reduced serum HBsAg levels, we observed reduced HBV replication as demonstrated by Southern blot analysis of HBV genomes.
  
  
  CONCLUSIONS
  The present study demonstrates that GD-AdV can be used against HBV infection but the design of DNA sequences including shRNAs contained in the vector and virus-host interactions during superinfection needs to be carefully considered.
authors.affiliation: Max von Pettenkofer-Institute, Department of Virology, Ludwig-Maximilians-Universität München, Munich, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Rauschhuber
authors.forename: Hui
authors.initials: H
authors.lastname: Xu
authors.forename: Felix H
authors.initials: FH
authors.lastname: Salazar
authors.forename: Patricia L
authors.initials: PL
authors.lastname: Marion
authors.forename: Anja
authors.initials: A
authors.lastname: Ehrhardt
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D006509:Hepatitis B / Q000628:therapy*; D006514:Hepatitis B Surface Antigens / Q000235:genetics; D006515:Hepatitis B virus / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000627:therapeutic use*
chemical_list: D006514:Hepatitis B Surface Antigens; D034741:RNA, Small Interfering