Hepatitis B virus genome recycling and de novo secondary infection events maintain stable cccDNA levels

JOURNAL OF HEPATOLOGY

卷:69

Article

Ko, Chunkyu¹  Chakraborty, Anindita^1,2  Chou, Wen-Min¹  Hasreiter, Julia¹  Wettengel, Jochen M.¹  Stadler, Daniela¹  Bester, Romina¹  Asen, Theresa¹  Zhang, Ke¹  Wisskirchen, Karin¹  McKeating, Jane A.^2,3  Ryu, Wang-Shick⁴  Protzer, Ulrike^1,2,5 

[1] Tech Univ Munich, Helmholtz Zentrum Munchen, Inst Virol, Trogerstr 30, D-81675 Munich, Germany

[2] Tech Univ Munich, Inst Adv Study, Munich, Germany

[3] Univ Oxford, Nuffield Dept Med, Oxford, England

[4] Yonsei Univ, Dept Biochem, Seoul, South Korea

[5] German Ctr Infect Res DZIF, Munich Partner Site, Munich, Germany

关键词: HBV;    Hepatitis B virus;    cccDNA;    NTCP;    Replenishment;    Viral spread;    Transmission;    Intracellular recycling;   

DOI  :  10.1016/j.jhep.2018.08.012

来源: Elsevier

【 摘 要 】

Background & Aims: Several steps in the HBV life cycle remain obscure because of a lack of robust in vitro infection models. These steps include particle entry, formation and maintenance of covalently closed circular (ccc) DNA, kinetics of gene expression and viral transmission routes. This study aimed to investigate infection kinetics and cccDNA dynamics during long-term culture. Methods: We selected a highly permissive HepG2-NTCP-K7 cell clone engineered to express sodium taurocholate cotransporting polypeptide (NTCP) that supports the full HBV life cycle. We characterized the replication kinetics and dynamics of HBV over six weeks of infection. Results: HBV infection kinetics showed a slow infection process. Nuclear cccDNA was only detected 24 h post-infection and increased until 3 days post-infection (dpi). Viral RNAs increased from 3 dpi reaching a plateau at 6 dpi. HBV protein levels followed similar kinetics with HBx levels reaching a plateau first. cccDNA levels modestly increased throughout the 45-day study period with 5-12 copies per infected cell. Newly produced relaxed circular DNA within capsids was reimported into the nucleus and replenished the cccDNA pool. In addition to intracellular recycling of HBV genomes, secondary de novo infection events resulted in cccDNA formation. Inhibition of relaxed circular DNA formation by nucleoside analogue treatment of infected cells enabled us to measure cccDNA dynamics. HBV cccDNA decayed slowly with a half-life of about 40 days. Conclusions: After a slow infection process, HBV maintains a stable cccDNA pool by intracellular recycling of HBV genomes and via secondary infection. Our results provide important insights into the dynamics of HBV infection and support the future design and evaluation of new antiviral agents. Lay summary: Using a unique hepatocellular model system designed to support viral growth, we demonstrate that hepatitis B virus (HBV) has remarkably slow infection kinetics. Establishment of the episomal transcription template and the persistent form of the virus, so called covalently closed circular DNA, as well as viral transcription and protein expression all take a long time. Once established, HBV maintains a stable pool of covalently closed circular DNA via intracellular recycling of HBV genomes and through infection of naive cells by newly formed virions. (C) 2018 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

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