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
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
Boregowda, Rajeev K; Adams, Christina; Hu, Jianming (2012) TP-RT domain interactions of duck hepatitis B virus reverse transcriptase in cis and in trans during protein-primed initiation of DNA synthesis in vitro. J Virol 86:6522-36
Jones, Scott A; Boregowda, Rajeev; Spratt, Thomas E et al. (2012) In vitro epsilon RNA-dependent protein priming activity of human hepatitis B virus polymerase. J Virol 86:5134-50
Boregowda, Rajeev K; Lin, Li; Zhu, Qin et al. (2011) Cryptic protein priming sites in two different domains of duck hepatitis B virus reverse transcriptase for initiating DNA synthesis in vitro. J Virol 85:7754-65
Ning, Xiaojun; Nguyen, David; Mentzer, Laura et al. (2011) Secretion of genome-free hepatitis B virus--single strand blocking model for virion morphogenesis of para-retrovirus. PLoS Pathog 7:e1002255
Ludgate, Laurie; Adams, Christina; Hu, Jianming (2011) Phosphorylation state-dependent interactions of hepadnavirus core protein with host factors. PLoS One 6:e29566
Hu, Jianming; Lin, Li (2009) RNA-protein interactions in hepadnavirus reverse transcription. Front Biosci 14:1606-18
Heipertz Jr, Richard A; Starkey, Jason L; Miller, Thomas G et al. (2009) trans-Complementation of HBV rtM204I mutant replication by HBV wild-type polymerase. Virology 388:57-67
Badtke, Matthew P; Khan, Irfan; Cao, Feng et al. (2009) An interdomain RNA binding site on the hepadnaviral polymerase that is essential for reverse transcription. Virology 390:130-8
Nguyen, David H; Hu, Jianming (2008) Reverse transcriptase- and RNA packaging signal-dependent incorporation of APOBEC3G into hepatitis B virus nucleocapsids. J Virol 82:6852-61

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