HEPATITIS-B VIRUS BINDING TO LEUKOCYTE PLASMA-MEMBRANES UTILIZES A DIFFERENT REGION OF THE PRES1 DOMAIN TO THE HEPATOCYTE RECEPTOR-BINDING SITE AND DOES NOT REQUIRE RECEPTORS FOR OPSONINS

A quantitative assay of hepatitis B virus (HBV) binding to hepatocyte plasma membranes was adapted to show that leucocyte plasma membranes b ind serum-derived HBV saturably, and that this binding is inhibited us ing synthetic peptides representative of the large envelope protein of HBV. Using a panel of ligand-blocking monoclonal antibodies (mAb) to opsonin receptors, it was shown that the three classes of Fc gamma R a nd CR3 are not major receptors for HBV on leucocytes or hepatocytes. I t was also shown that HBV does not utilize the receptor for IgA, Fc al pha R, for attachment to leucocytes, despite reported sequence homolog y between the large envelope protein of HBV and the Fc portion of huma n IgA. Evidence is presented that the receptor for HBV on leucocytes m ay differ from the hepatocyte receptor(s), based on synthetic peptide inhibition assays of HBV binding. Furthermore, it was observed that gl ycosaminoglycans influence the HBV-liver and leucocyte interactions, p roviding evidence that HBV attachment may be a multi-stage process.