title: Cyclosporin A inhibits hepatitis B and hepatitis D virus entry by cyclophilin-independent interference with the NTCP receptor.
abstract: OBJECTIVE
  Chronic hepatitis B and hepatitis D are global health problems caused by the human hepatitis B and hepatitis D virus. The myristoylated preS1 domain of the large envelope protein mediates specific binding to hepatocytes by sodium taurocholate co-transporting polypeptide (NTCP). NTCP is a bile salt transporter known to be inhibited by cyclosporin A. This study aimed to characterize the effect of cyclosporin A on HBV/HDV infection.
  
  
  METHODS
  HepaRG cells, primary human hepatocytes, and susceptible NTCP-expressing hepatoma cell lines were applied for infection experiments. The mode of action of cyclosporin A was studied by comparing the effect of different inhibitors, cyclophilin A/B/C-silenced cell lines as well as NTCP variants and mutants. Bile salt transporter and HBV receptor functions were investigated by taurocholate uptake and quantification of HBVpreS binding.
  
  
  RESULTS
  Cyclosporin A inhibited hepatitis B and D virus infections during and--less pronounced--prior to virus inoculation. Binding of HBVpreS to NTCP was blocked by cyclosporin A concentrations at 8 μM. An NTCP variant deficient in HBVpreS binding but competent for bile salt transport showed resistance to cyclosporin A. Silencing of cyclophilins A/B/C did not abrogate transporter and receptor inhibition. In contrast, tacrolimus, a cyclophilin-independent calcineurin inhibitor, was inactive.
  
  
  CONCLUSIONS
  HBV and HDV entry via sodium taurocholate co-transporting polypeptide is inhibited by cyclosporin A. The interaction between the drug and the viral receptor is direct and overlaps with a functional binding site of the preS1 domain, which mediates viral entry.
authors.affiliation: Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, D 69120 Heidelberg, Germany.
authors.forename: Shirin
authors.initials: S
authors.lastname: Nkongolo
authors.affiliation: Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, D 69120 Heidelberg, Germany.
authors.forename: Yi
authors.initials: Y
authors.lastname: Ni
authors.affiliation: Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, D 69120 Heidelberg, Germany.
authors.forename: Florian A
authors.initials: FA
authors.lastname: Lempp
authors.affiliation: Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, D 69120 Heidelberg, Germany; Department of Nuclear Medicine, University Hospital Heidelberg, D 69120 Heidelberg, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Kaufman
authors.affiliation: Department of Nuclear Medicine, University Hospital Heidelberg, D 69120 Heidelberg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lindner
authors.affiliation: Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, D 69120 Heidelberg, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Esser-Nobis
authors.affiliation: Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, D 69120 Heidelberg, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Lohmann
authors.affiliation: Department of Nuclear Medicine, University Hospital Heidelberg, D 69120 Heidelberg, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Mier
authors.affiliation: Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, D 69120 Heidelberg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Mehrle
authors.affiliation: Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, D 69120 Heidelberg, Germany. Electronic address: Stephan.Urban@med.uni-heidelberg.de.
authors.forename: Stephan
authors.initials: S
authors.lastname: Urban
mesh_terms: D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D021983:Cyclophilins / Q000494:pharmacology; D016572:Cyclosporine / Q000494:pharmacology*; D014644:Genetic Variation; D056945:Hep G2 Cells; D006515:Hepatitis B virus / Q000187:drug effects* / Q000472:pathogenicity / Q000502:physiology; D003698:Hepatitis Delta Virus / Q000187:drug effects* / Q000472:pathogenicity / Q000502:physiology; D054884:Host-Pathogen Interactions / Q000187:drug effects / Q000502:physiology; D006801:Humans; D055666:Lipopeptides / Q000494:pharmacology; D050505:Mutant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D029363:Organic Anion Transporters, Sodium-Dependent / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D027981:Symporters / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D016559:Tacrolimus / Q000494:pharmacology; D053586:Virus Internalization / Q000187:drug effects*
chemical_list: D055666:Lipopeptides; D050505:Mutant Proteins; D029363:Organic Anion Transporters, Sodium-Dependent; D027981:Symporters; C571888:myrcludex-B; C071908:sodium-bile acid cotransporter; D016572:Cyclosporine; D021983:Cyclophilins; D016559:Tacrolimus
keywords: Binding domain; Cyclosporin A; Hepatitis B; Hepatitis D; Immunosuppressive; Myrcludex B; Sodium taurocholate cotransporting polypeptide; Tacrolimus; Viral entry