title: Hepatitis C virus cell-cell transmission in hepatoma cells in the presence of neutralizing antibodies.
abstract: Hepatitis C virus (HCV) infection of Huh-7.5 hepatoma cells results in focal areas of infection where transmission is potentiated by cell-cell contact. To define route(s) of transmission, HCV was allowed to infect hepatoma cells in the presence or absence of antibodies that neutralize cell-free virus infectivity. Neutralizing antibodies (nAbs) reduced cell-free virus infectivity by >95% and had minimal effect(s) on the frequency of infected cells in the culture. To assess whether cell-cell transfer of viral infectivity occurs, HCV-infected cells were cocultured with fluorescently labeled naïve cells in the presence or absence of nAbs. Enumeration by flow cytometry demonstrated cell-cell transfer of infectivity in the presence or absence of nAbs and immunoglobulins from HCV(+) patients. The host cell molecule CD81 and the tight junction protein Claudin 1 (CLDN1) are critical factors defining HCV entry. Soluble CD81 and anti-CD81 abrogated cell-free infection of Huh-7.5 and partially inhibited cell-cell transfer of infection. CD81-negative HepG2 hepatoma cells were resistant to cell-free virus infection but became infected after coculturing with JFH-infected cells in the presence of nAb, confirming that CD81-independent routes of cell-cell transmission exist. Further experiments with 293T and 293T-CLDN1 targets suggested that cell-cell transmission is dependent on CLDN1 expression.
  
  
  CONCLUSIONS
  These data suggest that HCV can transmit in vitro by at least two routes, cell-free virus infection and direct transfer between cells, with the latter offering a novel route for evading nAbs.
authors.affiliation: Institute for Biomedical Research, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Timpe
authors.forename: Zania
authors.initials: Z
authors.lastname: Stamataki
authors.forename: Adam
authors.initials: A
authors.lastname: Jennings
authors.forename: Ke
authors.initials: K
authors.lastname: Hu
authors.forename: Michelle J
authors.initials: MJ
authors.lastname: Farquhar
authors.forename: Helen J
authors.initials: HJ
authors.lastname: Harris
authors.forename: Anne
authors.initials: A
authors.lastname: Schwarz
authors.forename: Isabelle
authors.initials: I
authors.lastname: Desombere
authors.forename: Geert Leroux
authors.initials: GL
authors.lastname: Roels
authors.forename: Peter
authors.initials: P
authors.lastname: Balfe
authors.forename: Jane A
authors.initials: JA
authors.lastname: McKeating
mesh_terms: D000914:Antibodies, Viral / Q000502:physiology; D015703:Antigens, CD / Q000502:physiology*; D062445:Claudin-1; D006367:HeLa Cells; D016174:Hepacivirus / Q000276:immunology / Q000502:physiology*; D006801:Humans; D008565:Membrane Proteins / Q000502:physiology*; D011991:Receptors, Virus / Q000502:physiology; D060225:Tetraspanin 28
chemical_list: D000914:Antibodies, Viral; D015703:Antigens, CD; C554798:CD81 protein, human; C568108:CLDN1 protein, human; D062445:Claudin-1; D008565:Membrane Proteins; D011991:Receptors, Virus; D060225:Tetraspanin 28