Hepatitis B virus (HBV) is a major cause of chronic viral hepatitis that increases dramatically the risk of liver cancer and other end-stage liver diseases such as cirrhosis. HBV belongs to the Hepadnaviridae, a family of para-retroviruses that have a small DNA genome and replicate through an RNA intermediate (the pregenomic RNA, or pgRNA), by a unique reverse transcription pathway. The initiation of reverse transcription in HBV is accomplished via a novel protein priming mechanism whereby the viral reverse transcriptase (RT) serves as a specific protein primer. Following protein priming, the immature (containing pgRNA) nucleocapsid (NC) carries out reverse transcription, leading to the conversion of pgRNA to the characteristic, relaxed circular (RC) DNA. The DNA-containing (mature) NC is selectively enveloped and secreted extracellularly as virions. A host- derived protein kinase is packaged by the viral nucleocapsids and its role in viral replication remains unclear. Using recently established cell-free and cell culture systems and newly developed approaches and models, we propose to (1) define the viral and host requirements for HBV protein priming;(2) determine the role of the packaged host CDK2 in NC uncoating and infection;and (3) determine the mechanisms of regulation of HBV virion morphogenesis. Novel and specific models regarding HBV protein priming, NC uncoating, and virion formation will be tested. Recent studies suggest that effective antiviral interventions in chronic viral hepatitis ca block or reverse virus-induced liver damage and its associated liver diseases. Unfortunately, current therapies for HBV infections are very limited. The elucidation of the viral and host factor that modulate three critical stages of viral replication and assembly, i.e., the protein-primed initiation of reverse transcription, NC uncoating, and virion formation, will not only provide important new insights into mechanisms of hepadnavirus replication and virus-host interactions but also facilitate the development of novel and effective anti-HBV strategies targeted at these factors.

Public Health Relevance

The hepatitis B virus (HBV) is a global cause of chronic liver diseases, including liver cirrhosis and cancer. We propose to elucidate the mechanisms of, and viral and host factors involved in, three critical stages of HBV replication, protein-primed initiation of reverse transcription, viral nucleocapsid uncoating, and nucleocapsid envelopment and virion secretion. These studies should bring novel insights into HBV reverse transcription and the mechanisms of HBV assembly and disassembly, and facilitate the development of novel antiviral agents targeted at these essential steps of viral replication.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
5R01AI043453-17
Application #
8675785
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Koshy, Rajen
Project Start
Project End
Budget Start
Budget End
Support Year
17
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Pennsylvania State University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
City
Hershey
State
PA
Country
United States
Zip Code
17033
Ludgate, Laurie; Liu, Kuancheng; Luckenbaugh, Laurie et al. (2016) Cell-Free Hepatitis B Virus Capsid Assembly Dependent on the Core Protein C-Terminal Domain and Regulated by Phosphorylation. J Virol 90:5830-44
Cui, Xiuji; Clark, Daniel N; Liu, Kuancheng et al. (2016) Viral DNA-Dependent Induction of Innate Immune Response to Hepatitis B Virus in Immortalized Mouse Hepatocytes. J Virol 90:486-96
Luckenbaugh, L; Kitrinos, K M; Delaney 4th, W E et al. (2015) Genome-free hepatitis B virion levels in patient sera as a potential marker to monitor response to antiviral therapy. J Viral Hepat 22:561-70
Clark, Daniel N; Hu, Jianming (2015) Hepatitis B virus reverse transcriptase - Target of current antiviral therapy and future drug development. Antiviral Res 123:132-7
Liu, Kuancheng; Ludgate, Laurie; Yuan, Zhenghong et al. (2015) Regulation of multiple stages of hepadnavirus replication by the carboxyl-terminal domain of viral core protein in trans. J Virol 89:2918-30
Clark, Daniel N; Hu, Jianming (2015) Unveiling the roles of HBV polymerase for new antiviral strategies. Future Virol 10:283-295
Hu, Jianming; Seeger, Christoph (2015) Hepadnavirus Genome Replication and Persistence. Cold Spring Harb Perspect Med 5:a021386
Jones, Scott A; Clark, Daniel N; Cao, Feng et al. (2014) Comparative analysis of hepatitis B virus polymerase sequences required for viral RNA binding, RNA packaging, and protein priming. J Virol 88:1564-72
Jones, Scott A; Hu, Jianming (2013) Hepatitis B virus reverse transcriptase: diverse functions as classical and emerging targets for antiviral intervention. Emerg Microbes Infect 2:e56
Ludgate, Laurie; Ning, Xiaojun; Nguyen, David H et al. (2012) Cyclin-dependent kinase 2 phosphorylates s/t-p sites in the hepadnavirus core protein C-terminal domain and is incorporated into viral capsids. J Virol 86:12237-50

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