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Updated: Jun 14, 2026
Development of a Hepatitis B Virus Reporter System to Monitor the Early Stages of the Replication Cycle
Published on: February 1, 2017
A cell-based reporter assay for inhibitor screening of hepatitis C virus RNA-dependent RNA polymerase
Jin-Ching Lee1, Chin-kai Tseng, Kuan-Jen Chen
1Department of Biotechnology, College of Life Science, Kaohsiung Medical University, San Ming District, Kaohsiung City, Taiwan, ROC. jclee@kmu.edu.tw
Abstract:
The hepatitis C virus (HCV) NS5B, a RNA-dependent RNA polymerase (RdRp), is an attractive target for anti-HCV agents. The major disadvantages of the commonly used polymerase inhibitor screening involving the assessment of in vitro RNA synthesis are that it is incapable of demonstrating the cellular permeability and the cytotoxicity of compounds. To overcome these limitations, we created the BHK-NS5B-FRLuc reporter cell line that carries stably transfected NS5B and a bicistronic reporter gene, (+)FLuc-(-)UTR-RLuc, which can be used to simultaneously measure cellular toxicity and intracellular RdRp activity. The (+)FLuc-(-)UTR-RLuc construct comprises the firefly luciferase (FLuc) gene and the Renilla luciferase (RLuc) gene in reverse orientation flanked by both negative strands of the HCV 5'- and 3'-untranslated regions (UTRs), in which FLuc and RLuc reporter proteins are regulated by host polymerase and functional NS5B polymerase, respectively. The reporter system was validated with specific agents against NS5B polymerization. Additionally, this assay was placed in 96-well plates and had a Z'-factor value of approximately 0.75, which is amenable for facilitating high-throughput screening operations. Notably, in combination with the structured-based virtual screening, an imidazole derivative compound was evaluated as a candidate HCV RdRp inhibitor.
Insights
Researchers developed a novel reporter cell line to screen for hepatitis C virus (HCV) RNA-dependent RNA polymerase (RdRp) inhibitors. This system efficiently assesses compound cytotoxicity and intracellular RdRp activity for drug discovery.
Area of Science:
- Virology
- Molecular Biology
- Drug Discovery
Background:
- Hepatitis C virus (HCV) NS5B RNA-dependent RNA polymerase (RdRp) is a key target for antiviral therapies.
- Current screening methods for NS5B inhibitors lack cellular permeability and cytotoxicity assessments.
Purpose of the Study:
- To develop a robust reporter cell line for simultaneous evaluation of intracellular RdRp activity and cytotoxicity.
- To facilitate high-throughput screening (HTS) of potential anti-HCV agents targeting NS5B.
Main Methods:
- Creation of a BHK-NS5B-FRLuc reporter cell line with stably transfected NS5B and a bicistronic reporter gene.
- The reporter construct (+)FLuc-(-)UTR-RLuc allows independent measurement of host and viral polymerase activity.
- Validation of the system using known NS5B inhibitors and assessment of its suitability for HTS (Z'-factor ~0.75).
Main Results:
- The reporter cell line successfully measures intracellular NS5B RdRp activity and cellular toxicity.
- The assay demonstrated high performance for HTS applications.
- An imidazole derivative was identified as a potential HCV RdRp inhibitor through combined virtual and cell-based screening.
Conclusions:
- The developed reporter cell line is a valuable tool for efficient screening of HCV NS5B inhibitors.
- This system overcomes limitations of traditional in vitro assays by incorporating cellular parameters.
- It enables the discovery of novel anti-HCV drug candidates with improved drug-like properties.
