title: Reduction of covalently closed circular DNA with long-term nucleos(t)ide analogue treatment in chronic hepatitis B.
abstract: Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA), a mini-chromosome essential for HBV replication, is supposed to be resistant to nucleos(t)ide analogue treatment. We investigated the effect of long-term nucleos(t)ide analogue treatment on cccDNA.
  
  
  
  Among 129 patients who had been enrolled in previous international nucleos(t)ide analogue clinical trials and had liver biopsies at baseline and one year after treatment, we recruited 43 patients on long-term continuous treatment for 72 to 145months for a third liver biopsy. Serum HBV DNA, hepatitis B surface antigen (HBsAg) levels, total intrahepatic HBV DNA (ihHBV DNA), cccDNA, HBV pregenomic RNA (pgRNA) as well as histologic changes were examined.
  
  
  
  At the time of the third biopsy, serum HBV DNA levels were undetectable in all but one patient. The median levels of HBsAg, ihHBV DNA, and cccDNA were 2.88logIU/ml, 0.03copies/cell, and 0.01copies/cell, respectively. Compared to baseline levels, there was reduction of HBsAg levels by 0.54log (71.46%), ihHBV DNA levels by 2.81log (99.84%), and cccDNA levels by 2.94log (99.89%), with 49% having cccDNA levels below the detection limit. One patient had undetectable HBsAg. The median pgRNA level, measured only in the third biopsy, was 0.021copies/cell, with 40% of patients having undetectable pgRNA.
  
  
  
  Long-term nucleos(t)ide analogue treatment induced marked depletion of cccDNA in the majority of patients while serum HBsAg levels, though reduced, were detectable in all but one patient. Whether cccDNA depletion is sustained and associated with better patient outcome requires further study.
  
  
  
  It is generally presumed that a form of hepatitis B virus DNA, called covalently closed circular DNA (cccDNA), which hides inside the nuclei of liver cells of patients with chronic hepatitis B, cannot be reduced by antiviral treatment. The present study showed that with prolonged treatment (median period 126months), cccDNA can be markedly reduced, with 49% of liver biopsies having undetectable cccDNA. This suggests that viral replication capacity would be very low after prolonged antiviral treatment.
authors.affiliation: Department of Medicine, The University of Hong Kong, Hong Kong; State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong. Electronic address: hrmelcl@hku.hk.
authors.forename: Ching-Lung
authors.initials: CL
authors.lastname: Lai
authors.affiliation: Department of Medicine, The University of Hong Kong, Hong Kong; State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong. Electronic address: dannykhwong@gmail.com.
authors.forename: Danny
authors.initials: D
authors.lastname: Wong
authors.affiliation: Department of Pathology, The University of Hong Kong, Hong Kong.
authors.forename: Philip
authors.initials: P
authors.lastname: Ip
authors.affiliation: Department of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Kopaniszen
authors.affiliation: Department of Medicine, The University of Hong Kong, Hong Kong; State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong.
authors.forename: Wai-Kay
authors.initials: WK
authors.lastname: Seto
authors.affiliation: Department of Medicine, The University of Hong Kong, Hong Kong; State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong.
authors.forename: James
authors.initials: J
authors.lastname: Fung
authors.affiliation: Department of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Fung-Yu
authors.initials: FY
authors.lastname: Huang
authors.affiliation: Johns Hopkins University School of Medicine, MD, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Lee
authors.affiliation: Department of Medicine, Columbia University Medical Campus, New York City, NY, USA.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Cullaro
authors.affiliation: Department of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Chun Kong
authors.initials: CK
authors.lastname: Chong
authors.affiliation: Department of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Ringo
authors.initials: R
authors.lastname: Wu
authors.affiliation: Department of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Charles
authors.initials: C
authors.lastname: Cheng
authors.affiliation: Department of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: John
authors.initials: J
authors.lastname: Yuen
authors.affiliation: Department of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Vincent
authors.initials: V
authors.lastname: Ngai
authors.affiliation: Department of Medicine, The University of Hong Kong, Hong Kong; State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong.
authors.forename: Man-Fung
authors.initials: MF
authors.lastname: Yuen
mesh_terms: D000225:Adenine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D000998:Antiviral Agents / Q000008:administration & dosage / Q000493:pharmacokinetics; D001706:Biopsy / Q000379:methods; D004270:DNA, Circular / Q000032:analysis; D004279:DNA, Viral / Q000097:blood; D005260:Female; D006515:Hepatitis B virus / Q000187:drug effects / Q000235:genetics; D019694:Hepatitis B, Chronic / Q000188:drug therapy / Q000821:virology; D006801:Humans; D019259:Lamivudine / Q000008:administration & dosage / Q000493:pharmacokinetics; D008099:Liver / Q000473:pathology / Q000821:virology; D008297:Male; D008875:Middle Aged; D009705:Nucleosides / Q000494:pharmacology; D063065:Organophosphonates / Q000008:administration & dosage / Q000493:pharmacokinetics; D017063:Outcome Assessment, Health Care; D000077712:Telbivudine; D013936:Thymidine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D013995:Time; D014779:Virus Replication / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D004270:DNA, Circular; D004279:DNA, Viral; D009705:Nucleosides; D063065:Organophosphonates; D000077712:Telbivudine; D019259:Lamivudine; C053001:adefovir; D000225:Adenine; D013936:Thymidine
keywords: Antiviral therapy; Circular DNA; Hepatitis B virus; Liver biopsy; Virus replication