title: Hepatitis C Virus Is Released via a Noncanonical Secretory Route.
abstract: We analyzed hepatitis C virus (HCV) morphogenesis using viral genomes encoding a mCherry-tagged E1 glycoprotein. HCV-E1-mCherry polyprotein expression, intracellular localization, and replication kinetics were comparable to those of untagged HCV, and E1-mCherry-tagged viral particles were assembled and released into cell culture supernatants. Expression and localization of structural E1 and nonstructural NS5A followed a temporospatial pattern with a succinct decrease in the number of replication complexes and the appearance of E1-mCherry punctae. Interaction of the structural proteins E1, Core, and E2 increased at E1-mCherry punctae in a time-dependent manner, indicating that E1-mCherry punctae represent assembled or assembling virions. E1-mCherry did not colocalize with Golgi markers. Furthermore, the bulk of viral glycoproteins within released particles revealed an EndoH-sensitive glycosylation pattern, indicating an absence of viral glycoprotein processing by the Golgi apparatus. In contrast, HCV-E1-mCherry trafficked with Rab9-positive compartments and inhibition of endosomes specifically suppressed HCV release. Our data suggest that assembled HCV particles are released via a noncanonical secretory route involving the endosomal compartment.
  
  
  OBJECTIVE
  The goal of this study was to shed light on the poorly understood trafficking and release routes of hepatitis C virus (HCV). For this, we generated novel HCV genomes which resulted in the production of fluorescently labeled viral particles. We used live-cell microscopy and other imaging techniques to follow up on the temporal dynamics of virus particle formation and trafficking in HCV-expressing liver cells. While viral particles and viral structural protein were found in endosomal compartments, no overlap of Golgi structures could be observed. Furthermore, biochemical and inhibitor-based experiments support a HCV release route which is distinguishable from canonical Golgi-mediated secretion. Since viruses hijack cellular pathways to generate viral progeny, our results point toward the possible existence of a not-yet-described cellular secretion route.
authors.affiliation: Institute of Virology, Helmholtz Zentrum München-German Research Center for Environmental Health, Munich, Germany.
authors.forename: Karen
authors.initials: K
authors.lastname: Bayer
authors.affiliation: Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany.
authors.forename: Carina
authors.initials: C
authors.lastname: Banning
authors.affiliation: Institute of Virology, Helmholtz Zentrum München-German Research Center for Environmental Health, Munich, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Bruss
authors.affiliation: University Hospital Tübingen, Institute for Medical Virology and Epidemiology of Viral Diseases, Tübingen, Germany.
authors.forename: Linda
authors.initials: L
authors.lastname: Wiltzer-Bach
authors.affiliation: Institute of Virology, Helmholtz Zentrum München-German Research Center for Environmental Health, Munich, Germany michael.schindler@med.uni-tuebingen.de.|University Hospital Tübingen, Institute for Medical Virology and Epidemiology of Viral Diseases, Tübingen, Germany.|Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schindler
mesh_terms: D002451:Cell Compartmentation; D002460:Cell Line; D011992:Endosomes / Q000821:virology; D016679:Genome, Viral; D006056:Golgi Apparatus / Q000821:virology; D016174:Hepacivirus / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics; D008358:Mannose / Q000737:chemistry; D011993:Recombinant Fusion Proteins / Q000235:genetics; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019065:Virus Assembly / Q000235:genetics / Q000502:physiology; D057074:Virus Release / Q000235:genetics / Q000502:physiology*; D014779:Virus Replication / Q000235:genetics / Q000502:physiology; D020691:rab GTP-Binding Proteins / Q000378:metabolism; D000097573:Red Fluorescent Protein
chemical_list: D008164:Luminescent Proteins; D008358:Mannose; D011993:Recombinant Fusion Proteins; D014759:Viral Envelope Proteins; D020691:rab GTP-Binding Proteins; D000097573:Red Fluorescent Protein; C087035:E1 protein, Hepatitis C virus; C079856:RAB9A protein, human