The goal of the proposed research is to define the pathways of hepadnaviral replication leading to persistent infection of hepatocytes. We chose the duck hepatitis B virus (DHBV) for these studies because of the advantages it offers both experimentally and as a simple model for chronic hepatitis B virus infections. Using this experimental system, we can produce genetically altered viral genomes by in vitro mutagenesis of cloned viral DNA. Mutant genomes can be packaged into DHBV particles which can infect cultured hepatocytes. Steps in viral replication can also be studied in a chicken hepatoma cell line which is highly susceptible to transfection with cloned DHBV DNA. Moreover, chronic DHBV infections can be easily established in newly hatched ducklings, which are commercially available. Thus, the DHBV model offers a variety of possibilities for the design of studies to understand the mechanisms of replication and the basis for viral persistence. Using this system, we propose to (i) investigate the role of the preS/S envelope protein of DHBV in regulating replication, virus production, and virulence of DHBV in hepatocytes and ducklings, (ii) determine the basis of the relationship between viral DNA synthesis and nucleocapsid maturation, (iii) define the mechanisms responsible for expression and packaging of pregenomes into nucleocapsids, and (iv) evaluate the importance of extra-cellular virus production in establishing and maintaining of a chronic infection, (v) and determine the lifetime of biologically active cccDNA in vivo and in the absence of DNA replication.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Unknown (R35)
Project #
5R35CA042542-13
Application #
2712601
Study Section
Special Emphasis Panel (SRC (88))
Program Officer
Cole, John S
Project Start
1986-08-01
Project End
2000-05-31
Budget Start
1998-07-15
Budget End
1999-05-31
Support Year
13
Fiscal Year
1998
Total Cost
Indirect Cost
Name
University of New Mexico
Department
Physiology
Type
Schools of Medicine
DUNS #
829868723
City
Albuquerque
State
NM
Country
United States
Zip Code
87131
Yu, M; Summers, J (1994) Multiple functions of capsid protein phosphorylation in duck hepatitis B virus replication. J Virol 68:4341-8
Yu, M; Summers, J (1994) Phosphorylation of the duck hepatitis B virus capsid protein associated with conformational changes in the C terminus. J Virol 68:2965-9
Lenhoff, R J; Summers, J (1994) Coordinate regulation of replication and virus assembly by the large envelope protein of an avian hepadnavirus. J Virol 68:4565-71
Huang, M; Summers, J (1994) pet, a small sequence distal to the pregenome cap site, is required for expression of the duck hepatitis B virus pregenome. J Virol 68:1564-72
Calvert, J; Summers, J (1994) Two regions of an avian hepadnavirus RNA pregenome are required in cis for encapsidation. J Virol 68:2084-90
Lenhoff, R J; Summers, J (1994) Construction of avian hepadnavirus variants with enhanced replication and cytopathicity in primary hepatocytes. J Virol 68:5706-13
Summers, J; Smith, P M; Huang, M J et al. (1991) Morphogenetic and regulatory effects of mutations in the envelope proteins of an avian hepadnavirus. J Virol 65:1310-7
Mason, W S; Summers, J; Liu, C et al. (1991) Chronic hepadnavirus infections. Prog Clin Biol Res 364:235-42
Huang, M J; Summers, J (1991) Infection initiated by the RNA pregenome of a DNA virus. J Virol 65:5435-9
Summers, J; Smith, P M; Horwich, A L (1990) Hepadnavirus envelope proteins regulate covalently closed circular DNA amplification. J Virol 64:2819-24

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