The rcDNA can be converted into a stable covalently closed circular DNA
(cccDNA) in the nucleus, after which it serves as the original template for viral replication and plays an important role in HBV persistence in the nucleus of infected hepatocytes (7), which may explain HBV reactivation and why HBV cannot be completely eliminated by antiviral agents (7, 8).
Conversion of viral genome to a covalently closed circular DNA
(cccDNA), which is formed in the nuclei of infected hepatocytes within the first 24h following virus inoculation and forming of a minichromosome after binding to proteins, is the molecular basis of persistence13.
DNA extracts were treated with Plasmid-Safe ATP-Dependent DNase (Epicenter Biotechnologies, Madison, WI, USA) to selectively hydrolyze linear double-stranded chromosomal DNA while leaving HBV covalently closed circular DNA
To evaluate the nuclease activity of the refolded protein, a test digestion was performed using 1 [micro]g rENDOG and 1 [micro]g of covalently closed circular DNA
with the buffer Tango[TM] 1x (Fermentas[c]) for 2 h at room temperature and 37[degrees]C.
In the process of HBV replication, the pregenomic RNA, which is transcribed from covalently closed circular DNA
(cccDNA), is reverse-transcribed by the polymerase protein of HBV.