title: Cryoglobulin-associated uptake of hepatitis C virus into human hepatocytes.
abstract: OBJECTIVE
  The mechanisms of binding and uptake of hepatitis C-virus (HCV) are critical determinants of the infection-reinfection cycle but due to ongoing absence of a robust cell culture system, these mechanisms are still largely hypothetical. Cryoglobulins are atypical immunoglobulins, present in 40% of HCV patients. The aim of this study was to determine the role of these HCV-containing cryoglobulins as carrier molecules for viral uptake into primary human hepatocytes.
  
  
  METHODS
  Cryoglobulins were precipitated from serum of chronically HCV-infected patients, labeled with biotin and incubated with freshly prepared hepatocytes from human liver tissue. Binding and endocytosis of HCV-cryoglobulins were studied by specific assays, ligand blot analysis and electron microscopy on hepatocellar plasma membranes.
  
  
  RESULTS
  Biotinylated HCV-cryoglobulins specifically bound to hepatocytes and inhibitors of homotypic endosomal fusion reduced their uptake and intracellular trafficking, Ligand-blot and electron microscopy analysis revealed adhesion to hepatocellular plasma membranes. Inoculation of human hepatocytes with HCV-cryoglobulins but not serum from the same patients induced HCV infection in vitro.
  
  
  CONCLUSIONS
  HCV may enter hepatocytes in conjunction with cryoglobulins via immunoglobulin or related receptors. We hypothesize, that this mechanism plays a role in chronic hepatitis to support the infection-reinfection cycle of the virus.
authors.affiliation: Department of Gastroenterology and Hepatology, University Hospital Essen, Essen, Germany. philip.hilgard@uni-essen.de
authors.forename: Philip
authors.initials: P
authors.lastname: Hilgard
authors.forename: Ulrich
authors.initials: U
authors.lastname: Treichel
authors.forename: Volker
authors.initials: V
authors.lastname: Dries
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Dienes
authors.forename: Guido
authors.initials: G
authors.lastname: Gerken
mesh_terms: D000368:Aged; D002462:Cell Membrane; D002478:Cells, Cultured; D003449:Cryoglobulinemia / Q000378:metabolism; D003450:Cryoglobulins / Q000378:metabolism*; D005260:Female; D016174:Hepacivirus / Q000378:metabolism*; D019698:Hepatitis C, Chronic / Q000503:physiopathology; D022781:Hepatocytes / Q000821:virology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011485:Protein Binding; D012367:RNA, Viral / Q000032:analysis; D011991:Receptors, Virus / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D003450:Cryoglobulins; D012367:RNA, Viral; D011991:Receptors, Virus