Drug Screening Assay for Hepatitis C Virus RNA Helicase

Non-A non-B hepatitis (NANBH) is a major cause of morbidity and mortality. The principal etiologicNANBH is hepatitis C virus (HCV). The estimated worldwide prevalence of HCV is 0.5-1-5%. HCV can estlong asymptomatic carrier state. At least 50% of infected persons will develop chronic hepatitis; 20develop cirrhosis. Chronic HCV infection can lead to development of hepatocellular carcinoma. Curren(IFN-alpha) is the only drug approved for treatment of hepatitis due to HCV. While IFN-alpha treatmeassociated with improved serum liver enzyme response in 20-40% of patients, its effectiveness is varlow. Clearly, additional therapeutic drugs are needed for control of hepatitis C. In this proposal,of the HCV NS3 protein will be the focus of antiviral drug discovery and development. This activitywith a purified recombinant NS3 protein, and a gel migration assay for the activity has been establiobservations will be extended to the development of a high capacity drug screening assay. There arethis Phase I project: i) further characterization of the enzymologic features and the nucleic acid sNS3 helicase; ii) development of a high capacity assay for the quantitative measurement of NS3 helicvalidation of this assay in a microplate format for screening purposes. Results of this Phase I worka Phase II project which will involve 1) utilization of this microplate assay for screening compoundii) establishment of an analogous assay with other viral and host cell helicases to allow rapid asseselectivity and specificity; iii) development of a secondary cell-based confirmatory assay; iv) medistudies to develop more potent and selective HCV helicase inhibitors; and v) evaluation of active cotoxicity, bioavailability, and metabolic stability. Compounds meeting our criteria of potency, speciand bioavailability will be considered lead compounds and will be further advanced as HCV antiviralPhase III follow-on development work.