scholarly journals Persistence of hepatitis B virus covalently closed circular DNA in hepatocytes: molecular mechanisms and clinical significance

2014 ◽  
Vol 3 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Hung-Chih Yang ◽  
Jia-Horng Kao
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Clinical Significance ◽  
Molecular Mechanisms ◽  
Circular Dna ◽  
Covalently Closed Circular Dna ◽  
B Virus

scholarly journals Characterization of the Termini of Cytoplasmic Hepatitis B Virus Deproteinated Relaxed Circular DNA

2020 ◽  
Vol 95 (1) ◽  
Author(s):  
Dawei Cai ◽  
Ran Yan ◽  
Jerry Z. Xu ◽  
Hu Zhang ◽  
Sheng Shen ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Molecular Mechanisms ◽  
Direct Repeat ◽  
Hydroxyl Group ◽  
Viral Polymerase ◽  
Circular Dna ◽  
Phosphodiester Bond ◽  
Covalently Closed Circular Dna ◽  
B Virus

ABSTRACT The biosynthesis of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) requires the removal of the covalently linked viral polymerase from the 5′ end of the minus strand [(−)strand] of viral relaxed circular DNA (rcDNA), which generates a deproteinated rcDNA (DP-rcDNA) intermediate. In the present study, we systematically characterized the four termini of cytoplasmic HBV DP-rcDNA by 5′/3′ rapid amplification of cDNA ends (RACE), 5′ radiolabeling, and exonuclease digestion, which revealed the following observations: (i) DP-rcDNA and rcDNA possess an identical 3′ end of (−)strand DNA; (ii) compared to rcDNA, DP-rcDNA has an extended but variable 3′ end of plus strand [(+)strand] DNA, most of which is in close proximity to direct repeat 2 (DR2); (iii) DP-rcDNA exhibits an RNA primer-free 5′ terminus of (+)strand DNA with either a phosphate or hydroxyl group; and (iv) the 5′ end of the DP-rcDNA (−)strand is unblocked at nucleotide G1828, bearing a phosphate moiety, indicating the complete removal of polymerase from rcDNA via unlinking the tyrosyl-DNA phosphodiester bond during rcDNA deproteination. However, knockout of cellular 5′ tyrosyl-DNA phosphodiesterase 2 (TDP2) did not markedly affect rcDNA deproteination or cccDNA formation. Thus, our work sheds new light on the molecular mechanisms of rcDNA deproteination and cccDNA biogenesis. IMPORTANCE The covalently closed circular DNA (cccDNA) is the persistent form of the hepatitis B virus (HBV) genome in viral infection and an undisputed antiviral target for an HBV cure. HBV cccDNA is converted from viral genomic relaxed circular DNA (rcDNA) through a complex process that involves removing the covalently bound viral polymerase from rcDNA, which produces a deproteinated-rcDNA (DP-rcDNA) intermediate for cccDNA formation. In this study, we characterized the four termini of cytoplasmic DP-rcDNA and compared them to its rcDNA precursor. While rcDNA and DP-rcDNA have an identical 3′ terminus of (−)strand DNA, the 3′ terminus of (+)strand DNA on DP-rcDNA is further elongated. Furthermore, the peculiarities on rcDNA 5′ termini, specifically the RNA primer on the (+)strand and the polymerase on the (−)strand, are absent from DP-rcDNA. Thus, our study provides new insights into a better understanding of HBV rcDNA deproteination and cccDNA biosynthesis.

scholarly journals Duck hepatitis B virus covalently closed circular DNA appears to survive hepatocyte mitosis in the growing liver

Virology ◽  
2013 ◽  
Vol 446 (1-2) ◽  
pp. 357-364 ◽  
Author(s):  
Georget Y. Reaiche-Miller ◽  
Michael Thorpe ◽  
Huey Chi Low ◽  
Qiao Qiao ◽  
Catherine A. Scougall ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Duck Hepatitis B Virus ◽  
Circular Dna ◽  
Covalently Closed Circular Dna ◽  
Duck Hepatitis ◽  
B Virus
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