Kinetic profile of a heterocyclic HCV replicon RNA synthesis inhibitor.
Recently, a benzo-1,2,4-thiadiazine was shown to be a potent, specific inhibitor of the hepatitis C virus (HCV) RNA polymerase [J. Biol. Chem. 277 (2002) 32327]. Herein, we present several lines of evidence to demonstrate that thiadiazine compound 4 (C(21)H(21)N(3)O(4)S) is highly synergistic with interferon-alpha (IFN-alpha) and disrupts HCV replicon RNA synthesis with a distinct kinetic profile. A time course analysis after a single treatment with 5 microM compound 4 showed a loss of viral RNA consistent with replicon RNA half-life, suggesting inhibition of 90% of ongoing or newly initiated replicative intermediates. This finding is consistent with the mechanism of action recently reported for compound 4, an RNA synthesis initiation inhibitor [J. Biol. Chem. 278 (2003) 16602]. Further, unlike IFN-alpha, an immediate reduction of HCV replicon RNA synthesis was apparent upon addition of compound 4. Treatment with IFN-alpha showed a delay of approximately 4h prior to inhibition of viral RNA replication, consistent with its signaling kinetics.
Johnston
Victor K
VK
Department of Virology, The Metabolic and Viral Diseases Center of Excellence for Drug Discovery, GlaxoSmithKline Pharmaceuticals, Collegeville, Pennsylvania 19426, USA.
Maley
Derrick
D
Gagnon
Robert C
RC
Grassmann
Claus W
CW
Behrens
Sven-Erik
SE
Sarisky
Robert T
RT
D000998:Antiviral Agents / Q000493:pharmacokinetics*; D002460:Cell Line; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D016174:Hepacivirus / Q000235:genetics*; D006801:Humans; D020128:Inhibitory Concentration 50; D016898:Interferon-alpha / Q000378:metabolism; D007700:Kinetics; D015233:Models, Statistical; D019384:Nucleic Acid Synthesis Inhibitors / Q000493:pharmacokinetics*; D012313:RNA / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013829:Thiadiazines / Q000493:pharmacokinetics*; D013997:Time Factors
D000998:Antiviral Agents; D016898:Interferon-alpha; D019384:Nucleic Acid Synthesis Inhibitors; D013829:Thiadiazines; D012313:RNA