title: Synergistic inhibition of intracellular hepatitis C virus replication by combination of ribavirin and interferon- alpha.
abstract: Treatment of hepatitis C virus (HCV) infection with interferon (IFN)- alpha and ribavirin combination therapy results in superior clinical antiviral responses than does monotherapy with IFN. To explore the virological basis of the effects of combination therapy, we analyzed the effects of IFN- alpha and ribavirin, singly and in combination, on intracellular HCV replication by use of an HCV replicon system. A new replicon that expressed a selectable chimeric reporter protein comprising firefly luciferase and neomycin phosphotransferase was constructed. The replicon was highly sensitive to IFN-alpha (50% inhibitory concentration [IC(50)], 0.5 U/mL). Therapy with ribavirin showed weak suppression of HCV replication at a lower concentration (IC(50), 126 mu mol/L). The nucleotide sequence diversity of the replicon was increased significantly by therapy with ribavirin, suggesting that error-prone HCV replication was induced by the drug. Importantly, use of a clinically achievable concentration of ribavirin (approximately 10 mu mol/L) in combination with IFN showed strong synergistic inhibitory effects on HCV replication. Our results suggest that the direct effects of ribavirin on the genetic stability of the HCV subgenome and its synergistic action combined, with IFN-alpha, may explain the improved clinical responses to combination therapy.
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Tanabe
authors.forename: Naoya
authors.initials: N
authors.lastname: Sakamoto
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Enomoto
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kurosaki
authors.forename: Eri
authors.initials: E
authors.lastname: Ueda
authors.forename: Shinya
authors.initials: S
authors.lastname: Maekawa
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Yamashiro
authors.forename: Mina
authors.initials: M
authors.lastname: Nakagawa
authors.forename: Cheng-Hsin
authors.initials: CH
authors.lastname: Chen
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Kanazawa
authors.forename: Sei
authors.initials: S
authors.lastname: Kakinuma
authors.forename: Mamoru
authors.initials: M
authors.lastname: Watanabe
mesh_terms: D000595:Amino Acid Sequence; D000998:Antiviral Agents / Q000494:pharmacology*; D001483:Base Sequence; D015152:Blotting, Northern; D045744:Cell Line, Tumor; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D016174:Hepacivirus / Q000187:drug effects* / Q000502:physiology; D006526:Hepatitis C / Q000821:virology*; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000494:pharmacology*; D008969:Molecular Sequence Data; D017354:Point Mutation; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics; D011994:Recombinant Proteins; D012093:Replicon / Q000187:drug effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012254:Ribavirin / Q000494:pharmacology*; D016415:Sequence Alignment; D014162:Transfection; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D000077190:Interferon alpha-2; D016898:Interferon-alpha; D012367:RNA, Viral; D011994:Recombinant Proteins; D012254:Ribavirin