title: Early events in hepatitis B virus infection: From the cell surface to the nucleus.
abstract: While most adults are able to clear acute hepatitis B virus (HBV) infection, chronic HBV infection is recalcitrant to current therapy because of the persistence of covalently closed circular DNA in the nucleus. Complete clearance of the virus in these patients is rare, and long-term therapy with interferon and/or nucleoside analogues may be required in an attempt to suppress viral replication and prevent progressive liver damage. The difficulty of establishing HBV infection in cell culture and experimental organisms has hindered efforts to elucidate details of the HBV life cycle, but it has also revealed the importance of the cellular microenvironment required for HBV binding and entry. Recent studies have demonstrated an essential role of sodium-taurocholate cotransporting polypeptide as a functional receptor in HBV infection, which has facilitated the development of novel infection systems and opened the way for more detailed understanding of the early steps of HBV infection as well as a potential new therapeutic target. However, many gaps remain in understanding of how HBV recognizes and attaches to hepatocytes prior to binding to sodium-taurocholate cotransporting polypeptide, as well as events that are triggered after binding, including entry into the cell, intracellular transport, and passage through the nuclear pore complex. This review summarizes current knowledge of the initial stages of HBV infection leading to the establishment of covalently closed circular DNA in the nucleus.
authors.affiliation: Department of Gastroenterology and Metabolism, Applied Life Sciences, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.|Laboratory for Digestive Diseases, Center for Genomic Medicine, RIKEN, Hiroshima, Japan.|Liver Research Project Center, Hiroshima University, Hiroshima, Japan.
authors.forename: C Nelson
authors.initials: CN
authors.lastname: Hayes
authors.affiliation: Department of Gastroenterology and Metabolism, Applied Life Sciences, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.|Liver Research Project Center, Hiroshima University, Hiroshima, Japan.
authors.forename: Yizhou
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Gastroenterology and Metabolism, Applied Life Sciences, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.|Liver Research Project Center, Hiroshima University, Hiroshima, Japan.
authors.forename: Grace Naswa
authors.initials: GN
authors.lastname: Makokha
authors.affiliation: Liver Research Project Center, Hiroshima University, Hiroshima, Japan.
authors.forename: Md Zobaer
authors.initials: MZ
authors.lastname: Hasan
authors.affiliation: Liver Research Project Center, Hiroshima University, Hiroshima, Japan.
authors.forename: Magot D
authors.initials: MD
authors.lastname: Omokoko
authors.affiliation: Department of Gastroenterology and Metabolism, Applied Life Sciences, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.|Laboratory for Digestive Diseases, Center for Genomic Medicine, RIKEN, Hiroshima, Japan.|Liver Research Project Center, Hiroshima University, Hiroshima, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Chayama
mesh_terms: D021581:Active Transport, Cell Nucleus; D000208:Acute Disease; D000818:Animals; D002467:Cell Nucleus / Q000821:virology*; D060833:Cellular Microenvironment; D004270:DNA, Circular; D004279:DNA, Viral; D004705:Endocytosis; D011992:Endosomes / Q000821:virology; D006509:Hepatitis B; D006515:Hepatitis B virus / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity / Q000502:physiology; D019694:Hepatitis B, Chronic / Q000188:drug therapy / Q000821:virology*; D022781:Hepatocytes / Q000648:ultrastructure / Q000821:virology*; D006801:Humans; D008018:Life Cycle Stages; D008247:Lysosomes / Q000821:virology; D008564:Membrane Potentials / Q000502:physiology; D008870:Microtubules / Q000821:virology; D029363:Organic Anion Transporters, Sodium-Dependent; D011991:Receptors, Virus; D027981:Symporters; D014779:Virus Replication
chemical_list: D004270:DNA, Circular; D004279:DNA, Viral; D029363:Organic Anion Transporters, Sodium-Dependent; D011991:Receptors, Virus; D027981:Symporters; C071908:sodium-bile acid cotransporter
keywords: NTCP; endocytosis; heparan sulfate proteoglycans; hepatocyte; nuclear import