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. Hepadnaviruses initially assemble an immature nucleocapsid (NC) composed of multiple copies of the capsid protein, and the packaged pgRNA and the virally encQded reverse transcriptase (RT). The immature NC undergoes a process of maturation whereby pgRNA is converted to the characteristic, partially double stranded (OS), relaxed circular (RC) DNA by RT-mediated reverse transcription. The RC DNA-containing, mature NC is then selectively enveloped with the viral envelope (surface) proteins and secreted extracellularly as virions. Using recently established cell-free and cell culture systems and newly developed approaches and models, we propose (1) to determine the nature of nucleic acid within NC that blocks or triggers NC envelopment;(2) to determine the maturation-associated NC structural changes and their role in NC envelopment;and (3) to determine the role of host factors in regulating selective NC envelopment. These Revised Specific Aims are derived from the three sUb-aims of Specific Aim 3 as proposed in the original application. These stUdies are selected because of their likelihood for successful completion within the two year time-frame supported by the the American Recovery and Reinvestment Act of 2009 funding. Also, they still constitute a coherent and sound project separate from Specific Aims 1 and 2 of the original application. The elucidation of the molecular basis of, and viral and host factors involved in, selective NC envelopment will not only provide important insights into the mechanisms of hepadnavirus replication and virus-host interactions but may 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, two unique stages of HBV replication, namely the early stage of protein-primed initiation of reverse transcription and the later stage of viral nucleocapsid maturation and virion secretion. These studies should bring novel insights into HBV reverse transcription and the mechanism of HBV assembly as a para-retrovirus, and facilitate the development of novel antiviral agents targeted at these critical steps of viral replication.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI043453-15
Application #
8316154
Study Section
Virology - B Study Section (VIRB)
Program Officer
Koshy, Rajen
Project Start
1999-02-15
Project End
2013-08-31
Budget Start
2012-09-01
Budget End
2013-08-31
Support Year
15
Fiscal Year
2012
Total Cost
$387,750
Indirect Cost
$137,750
Name
Pennsylvania State University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
129348186
City
Hershey
State
PA
Country
United States
Zip Code
17033
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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
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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
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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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