Cryoglobulin-associated uptake of hepatitis C virus into human hepatocytes.
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.
Hilgard
Philip
P
Department of Gastroenterology and Hepatology, University Hospital Essen, Essen, Germany. philip.hilgard@uni-essen.de
Treichel
Ulrich
U
Dries
Volker
V
Dienes
Hans Peter
HP
Gerken
Guido
G
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
D003450:Cryoglobulins; D012367:RNA, Viral; D011991:Receptors, Virus