title: Comparative inhibitory potential of differently modified antisense oligodeoxynucleotides on hepatitis C virus translation.
abstract: BACKGROUND
  A completely modified phosphorothioate antisense oligodeoxynucleotide (cS-ODN 4) directed against nucleotides 326-348 of the hepatitis C virus (HCV) 5' non-coding region (NCR) efficiently inhibits viral gene expression. As cS-ODN exerts undesired side-effects in vivo, we synthesized partially modified ODN 4 that contained only six modified nucleotides which are located at the ODN termini or are scattered along the molecule. The tested modifications were polar phosphorothioates (S) and non-polar methyl- (M) or benzylphosphonates (B).
  
  
  RESULTS
  In an in vitro translation system, specific inhibition of HCV gene expression by M-ODN 4 or B-ODN 4 was observed if terminally modified ODN were used; the maximal inhibition was 92.3% +/- 1.9% and 87.1% +/- 3.7%, respectively, at 10 microgram mol L-1 concentration. S-ODN 4 specifically suppressed viral translation irrespective of the location of the modifications, resulting in a maximal inhibition of 86.3% +/- 3.3%. For all terminally modified ODNs the therapeutic index was high, with tB-ODN 4 the second best at 3.8. Inhibition correlated with efficient RNase H-associated cleavage of target RNA. In transient co-transfection experiments of HepG2 cells with a reporter gene construct and the ODN, terminally modified B-ODN 4 was the most effective and specific inhibitor. At a concentration of 5 microgram mol L-1 the suppression of HCV translation was 96.3% +/- 0.7%.
  
  
  CONCLUSIONS
  These data demonstrate that terminally modified B-ODN 4 is a potent inhibitor of HCV gene expression in vitro and in HepG2 cell culture and may be valuable for future antiviral treatment.
authors.affiliation: Max Planck Institute for Biochemistry, Martinsried, Bonn, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Alt
authors.forename: S
authors.initials: S
authors.lastname: Eisenhardt
authors.forename: M
authors.initials: M
authors.lastname: Serwe
authors.forename: R
authors.initials: R
authors.lastname: Renz
authors.forename: J W
authors.initials: JW
authors.lastname: Engels
authors.forename: W H
authors.initials: WH
authors.lastname: Caselmann
mesh_terms: D000818:Animals; D001483:Base Sequence; D006528:Carcinoma, Hepatocellular; D015967:Gene Expression Regulation, Viral / Q000187:drug effects*; D016174:Hepacivirus / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D008113:Liver Neoplasms; D008156:Luciferases / Q000235:genetics; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology*; D063065:Organophosphonates; D014176:Protein Biosynthesis / Q000187:drug effects*; D011817:Rabbits; D011994:Recombinant Proteins / Q000096:biosynthesis; D012156:Reticulocytes / Q000378:metabolism; D016914:Ribonuclease H / Q000378:metabolism; D013329:Structure-Activity Relationship; D013873:Thionucleotides; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
chemical_list: D020319:Oligodeoxyribonucleotides, Antisense; D063065:Organophosphonates; D011994:Recombinant Proteins; D013873:Thionucleotides; D008156:Luciferases; D016914:Ribonuclease H