Objective To study the replication of hepatitis B virus (HBV) in HepG2 cells infected with Ad-1.2 HBV. Methods HepG2 cells were transfected with adenovirus containing 1.2 copies of HBV DNA. The expression of HBV antigens were detected in the culture medium by means of enzyme-linked immunosorbent assay (ELISA), and the covalently closed circular DNA (cccDNA) in the cells was extracted with plasmid extraction kit and detected by real-time PCR with selective primer after treatment with mung bean nuclease. Resu...