title: Hepatitis B and D viruses exploit sodium taurocholate co-transporting polypeptide for species-specific entry into hepatocytes.
abstract: OBJECTIVE
  Hepatitis B and D viruses (HBV and HDV) are human pathogens with restricted host ranges and high selectivity for hepatocytes; the HBV L-envelope protein interacts specifically with a receptor on these cells. We aimed to identify this receptor and analyze whether it is the recently described sodium-taurocholate co-transporter polypeptide (NTCP), encoded by the SLC10A1 gene.
  
  
  METHODS
  To identify receptor candidates, we compared gene expression patterns between differentiated HepaRG cells, which express the receptor, and naïve cells, which do not. Receptor candidates were evaluated by small hairpin RNA silencing in HepaRG cells; the ability of receptor expression to confer binding and infection were tested in transduced hepatoma cell lines. We used interspecies domain swapping to identify motifs for receptor-mediated host discrimination of HBV and HDV binding and infection.
  
  
  RESULTS
  Bioinformatic analyses of comparative expression arrays confirmed that NTCP, which was previously identified through a biochemical approach is a bona fide receptor for HBV and HDV. NTCPs from rat, mouse, and human bound Myrcludex B, a peptide ligand derived from the HBV L-protein. Myrcludex B blocked NTCP transport of bile salts; small hairpin RNA-mediated knockdown of NTCP in HepaRG cells prevented their infection by HBV or HDV. Expression of human but not mouse NTCP in HepG2 and HuH7 cells conferred a limited cell-type-related and virus-dependent susceptibility to infection; these limitations were overcome when cells were cultured with dimethyl sulfoxide. We identified 2 short-sequence motifs in human NTCP that were required for species-specific binding and infection by HBV and HDV.
  
  
  CONCLUSIONS
  Human NTCP is a specific receptor for HBV and HDV. NTCP-expressing cell lines can be efficiently infected with these viruses, and might be used in basic research and high-throughput screening studies. Mapping of motifs in NTCPs have increased our understanding of the species specificities of HBV and HDV, and could lead to small animal models for studies of viral infection and replication.
authors.affiliation: Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Yi
authors.initials: Y
authors.lastname: Ni
authors.affiliation: Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Florian A
authors.initials: FA
authors.lastname: Lempp
authors.affiliation: Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Mehrle
authors.affiliation: Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Shirin
authors.initials: S
authors.lastname: Nkongolo
authors.affiliation: Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Kaufman
authors.affiliation: German Cancer Research Center and National Center for Tumor Diseases, Unit Cancer Genome Research, Heidelberg, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Fälth
authors.affiliation: Clinic for Gastroenterology, Hepatology and Infectiology, University Hospital Düsseldorf, Düsseldorf, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Stindt
authors.affiliation: Department of Internal Medicine II, University Hospital Freiburg, Freiburg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Königer
authors.affiliation: Department of Internal Medicine II, University Hospital Freiburg, Freiburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Nassal
authors.affiliation: Clinic for Gastroenterology, Hepatology and Infectiology, University Hospital Düsseldorf, Düsseldorf, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Kubitz
authors.affiliation: German Cancer Research Center and National Center for Tumor Diseases, Unit Cancer Genome Research, Heidelberg, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Sültmann
authors.affiliation: Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, Heidelberg, Germany. Electronic address: Stephan.Urban@med.uni-heidelberg.de.
authors.forename: Stephan
authors.initials: S
authors.lastname: Urban
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D019295:Computational Biology; D020869:Gene Expression Profiling / Q000379:methods; D056945:Hep G2 Cells; D006515:Hepatitis B virus / Q000502:physiology*; D003698:Hepatitis Delta Virus / Q000502:physiology*; D022781:Hepatocytes / Q000378:metabolism* / Q000821:virology; D054884:Host-Pathogen Interactions; D006801:Humans; D008024:Ligands; D055666:Lipopeptides / Q000378:metabolism; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D029363:Organic Anion Transporters, Sodium-Dependent / Q000235:genetics / Q000378:metabolism*; D054730:Protein Interaction Domains and Motifs; D025941:Protein Interaction Mapping; D034622:RNA Interference; D051381:Rats; D013045:Species Specificity; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D013656:Taurocholic Acid / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection; D014759:Viral Envelope Proteins / Q000378:metabolism; D053585:Virus Attachment; D053586:Virus Internalization
chemical_list: C096362:L protein, hepatitis B virus; D008024:Ligands; D055666:Lipopeptides; D029363:Organic Anion Transporters, Sodium-Dependent; D027981:Symporters; D014759:Viral Envelope Proteins; C571888:myrcludex-B; C071908:sodium-bile acid cotransporter; D013656:Taurocholic Acid
keywords: Myrcludex B; Species Specificity; Virology; Virus Entry