Receptor-mediated entry of hepatitis B virus particles into liver cells.
In previous reports several receptors for either natural hepatitis B virus (HBV) particles or genetically engineered virus have been described, whereby endocytosis represents a putative uptake mechanism for HBV particles. We have found that HBV-particles from viremic carriers could bind to the human asialoglycoprotein receptor (ASGPR), which mediates glycoprotein uptake into liver cells. The HBV-ASGPR interaction was studied in a cell culture system using hepatoma HepG2 and HuH7 cells compared to COS cells as controls. About 50% of HBsAg-secretion into the cell culture supernatant after HBV-inoculation as a function of HBV-uptake could be inhibited by the specific ASGPR-ligand asialofetuin. COS-cells did not show HBsAg-secretion. If the cells were grown as clones, 15% of HepG2-cells demonstrated HBsAg-secretion but only 5% in the presence of asialofetuin. HBV-particle uptake was further confirmed by HBV-DNA analysis using PCR. HBV-ASGPR interaction was studied with purified, biotin-conjugated human ASGPR. Quantitative inhibition with asialofetuin indicated a high-affinity binding of HBV-particles to purified ASGPR. After denaturing polyacrylamid gel electrophoresis and transblotting of isolated HBV-particles a receptor-blotting system was established which identified distinct binding sites for biotinylated receptors. These results suggest that the ASGPR is capable of specifically binding HBV-particles and, moreover, to mediate their hepatic endocytosis which ultimately could be responsible for the HBV-infection of liver cells.
Treichel
U
U
Department of Internal Medicine, Johannes-Gutenberg-University Mainz, Federal Republic of Germany.
Meyer zum Büschenfelde
K H
KH
Dienes
H P
HP
Gerken
G
G
D000818:Animals; D001212:Asialoglycoproteins / Q000378:metabolism*; D019556:COS Cells; D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens / Q000032:analysis / Q000378:metabolism; D006515:Hepatitis B virus / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D008099:Liver / Q000166:cytology / Q000648:ultrastructure / Q000821:virology*; D011498:Protein Precursors / Q000032:analysis; D011991:Receptors, Virus / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D001212:Asialoglycoproteins; D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens; D011498:Protein Precursors; D011991:Receptors, Virus; C050806:presurface protein 1, hepatitis B surface antigen