title: Enhanced specificity of real-time PCR for measurement of hepatitis B virus cccDNA using restriction endonuclease and plasmid-safe ATP-dependent DNase and selective primers.
abstract: The persistence of covalently closed circular DNA (cccDNA) of hepatitis B virus (HBV) in hepatocytes plays a key role in viral persistence and resistance to therapy. Therefore, quantitative cccDNA measurement is of clinical importance for evaluating the efficacy of antiviral drugs, selecting an appropriate treatment strategy, and predicting the prognosis. Current established methods for measurement of cccDNA need further improvement. A modified method was developed using digestion with restriction endonucleases that do not recognize sites in the HBV DNA and plasmid-safe ATP-dependent DNase (PSAD), and using a cccDNA-specific primer set in a real-time PCR reaction. The cccDNA-specific primer has a similar amplification efficiency as a commercial kit. Treatment of samples with restriction endonuclease followed by PSAD digestion increased significantly the specificity of a cccDNA-selective primer set compared with other treatments (P<0.05). Analysis of 35 serum and liver DNA samples from patients with hepatocellular carcinoma demonstrated that the amount of serum cccDNA is beyond the minimum detection limit and that the liver cccDNA quantity is about 0-49.2 copies/cell, consistent with previous reports. Taken together, this method has the potential for evaluating the efficacy of antiviral drugs.
authors.affiliation: Key Laboratory of Artificial Cell, Institute for Hepatobiliary Disease, Tianjin Third Central Hospital, Tianjin, China.
authors.forename: Ying-Tang
authors.initials: YT
authors.lastname: Gao
authors.forename: Tao
authors.initials: T
authors.lastname: Han
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Bin
authors.initials: B
authors.lastname: Yang
authors.forename: Yi-Jun
authors.initials: YJ
authors.lastname: Wang
authors.forename: Feng-Mei
authors.initials: FM
authors.lastname: Wang
authors.forename: Xiang
authors.initials: X
authors.lastname: Jing
authors.forename: Zhi
authors.initials: Z
authors.lastname: Du
mesh_terms: D000328:Adult; D006528:Carcinoma, Hepatocellular / Q000821:virology; D017931:DNA Primers / Q000235:genetics; D004262:DNA Restriction Enzymes / Q000378:metabolism; D004279:DNA, Viral / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D043211:Exodeoxyribonuclease V / Q000378:metabolism; D005260:Female; D006509:Hepatitis B / Q000175:diagnosis* / Q000821:virology; D006515:Hepatitis B virus / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D008099:Liver / Q000821:virology; D008113:Liver Neoplasms / Q000821:virology; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D044967:Serum / Q000821:virology; D014773:Virology / Q000379:methods*
chemical_list: D017931:DNA Primers; D004279:DNA, Viral; D043211:Exodeoxyribonuclease V; D004262:DNA Restriction Enzymes