title: Intracellular accumulation of subviral HBsAg particles and diminished Nrf2 activation in HBV genotype G expressing cells lead to an increased ROI level.
abstract: OBJECTIVE
  Hepatitis B virus genotype G (HBV/G) is characterized by a lack of HBeAg secretion and very low HBsAg secretion. This study aimed at (1) comparing HBV genotype G and A2 with respect to morphogenesis and release of HBV-derived particles, (2) characterizing factors contributing to HBV/G-associated pathogenesis.
  
  
  METHODS
  HBV/G- and HBV/A-expressing hepatoma cells and infected HepaRG cells were analyzed by confocal laser scanning microscopy, Western blot, real-time PCR, density gradient centrifugation, and electron microscopy. Modulation of the transcription factors Nrf2 and AP-1 was analyzed.
  
  
  RESULTS
  While the release of viral particles is not affected in HBV/G replicating cells, the secretion of subviral particles is impaired, although they are produced in high amounts. These subviral particles, which display an increased density and a predominantly filamentous morphology, accumulate at the endoplasmic reticulum. The PreS1PreS2 domain of genotype G, which forms aggregates, causes the block of HBsAg-secretion at the ER and leads to decreased transcriptional activator function of LHBs. Intracellular accumulation of HBsAg and impaired induction of the cytoprotective transcription factor Nrf2 lead to an elevated level of ROIs. This results in activation of JNK and as a consequence in Ser-phosphorylation of IRS-1, which is known to impair insulin signaling, a key factor for liver regeneration.
  
  
  CONCLUSIONS
  Although competent for release of viral particles, secretion of subviral particles is impaired in HBV/G expressing cells leading to ER-stress. In parallel, HBV-induced Nrf2 activation diminishes, which causes a decrease of the capacity to inactivate ROIs. This might be related to genotype-specific pathogenesis.
authors.affiliation: Goethe-University Hospital Frankfurt, Department of Gastroenterology and Hepatology, D-60590 Frankfurt am Main, Germany; Paul Ehrlich Institut, Division of Virology, D-63325 Langen, Germany. Electronic address: kai-henrik.peiffer@kgu.de.
authors.forename: Kai-Henrik
authors.initials: KH
authors.lastname: Peiffer
authors.affiliation: Paul Ehrlich Institut, Division of Virology, D-63325 Langen, Germany.
authors.forename: Sami
authors.initials: S
authors.lastname: Akhras
authors.affiliation: Paul Ehrlich Institut, Division of Virology, D-63325 Langen, Germany.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Himmelsbach
authors.affiliation: Paul Ehrlich Institut, Division of Virology, D-63325 Langen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Hassemer
authors.affiliation: Paul Ehrlich Institut, Division of Virology, D-63325 Langen, Germany.
authors.forename: Malin
authors.initials: M
authors.lastname: Finkernagel
authors.affiliation: Paul Ehrlich Institut, Division of Virology, D-63325 Langen, Germany.
authors.forename: Gert
authors.initials: G
authors.lastname: Carra
authors.affiliation: Paul Ehrlich Institut, Division of Virology, D-63325 Langen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Nuebling
authors.affiliation: Paul Ehrlich Institut, Division of Virology, D-63325 Langen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Chudy
authors.affiliation: Justus-Liebig University, Institute of Medical Virology, National Reference Centre for Hepatitis B and D Viruses, D-35392 Giessen, Germany; DZIF, German Center for Infection Research, Germany.
authors.forename: Hauke
authors.initials: H
authors.lastname: Niekamp
authors.affiliation: Justus-Liebig University, Institute of Medical Virology, National Reference Centre for Hepatitis B and D Viruses, D-35392 Giessen, Germany; DZIF, German Center for Infection Research, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Glebe
authors.affiliation: Goethe-University Hospital Frankfurt, Department of Gastroenterology and Hepatology, D-60590 Frankfurt am Main, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Sarrazin
authors.affiliation: Goethe-University Hospital Frankfurt, Department of Gastroenterology and Hepatology, D-60590 Frankfurt am Main, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Zeuzem
authors.affiliation: Paul Ehrlich Institut, Division of Virology, D-63325 Langen, Germany; DZIF, German Center for Infection Research, Germany. Electronic address: eberhard.hildt@pei.de.
authors.forename: Eberhard
authors.initials: E
authors.lastname: Hildt
mesh_terms: D045744:Cell Line, Tumor; D005838:Genotype; D006509:Hepatitis B / Q000276:immunology*; D006514:Hepatitis B Surface Antigens / Q000276:immunology*; D006513:Hepatitis B e Antigens / Q000276:immunology*; D006515:Hepatitis B virus / Q000235:genetics* / Q000276:immunology; D022781:Hepatocytes / Q000276:immunology; D006801:Humans; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014771:Virion / Q000378:metabolism
chemical_list: D006514:Hepatitis B Surface Antigens; D006513:Hepatitis B e Antigens; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D018808:Transcription Factor AP-1
keywords: Genotypes; HBV; Morphogenesis; Signal transduction