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Generation of replication-competent hepatitis B virus nucleocapsids in insect cells
M Seifer1, R Hamatake, M Bifano
1Pharmaceutical Research Institute, Bristol-Myers Squibb, Wallingford, Connecticut 06492, USA.
Journal of Virology
|April 3, 1998
Summary
Researchers developed new methods to study hepatitis B virus (HBV) replication within viral cores. These novel HBV core reagents enable in vitro analysis of HBV polymerase activity, aiding drug development.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Hepatitis B virus (HBV) replication involves reverse transcription of its RNA genome by viral polymerase (Pol).
- Current studies often use unencapsidated Pol, limiting understanding of replication within viral nucleocapsids (cores).
Purpose of the Study:
- To develop and characterize replicative HBV cores for studying HBV replication in its natural environment.
- To compare the activity of encapsidated HBV polymerase with unencapsidated forms.
Main Methods:
- Coexpression of HBV core and Pol proteins in insect cells using a recombinant baculovirus system to produce cis and trans HBV cores.
- Isolation and biochemical analysis of these cores, including in vitro endogenous polymerase assays.
Main Results:
- Both cis and trans cores contained Pol-linked HBV DNA. Trans cores showed high activity for de novo priming and reverse transcription of HBV minus strands.
- Encapsidated HBV polymerase exhibited enhanced processivity and plus-strand synthesis compared to unencapsidated Pol.
- The epsilon stem-loop element enhanced minus-strand synthesis, with two epsilons providing up to a 10-fold increase.
Conclusions:
- Novel cis and trans HBV core reagents facilitate the study of HBV replication within the capsid.
- Encapsidated HBV polymerase activity suggests a role for the core protein in replication.
- These reagents can advance the development of new anti-HBV drug screens.