Human liver plasma membranes contain receptors for the hepatitis B virus pre-S1 region and, via polymerized human serum albumin, for the pre-S2 region.
Hepatitis B virus particles contain three related viral envelope proteins, the small, middle, and large S (surface) proteins. All three proteins contain the small S amino acid sequence at their carboxyl terminus. It is not clear which of these S proteins functions as the viral attachment protein, binding to a target cell receptor and initiating infection. In this report, recombinant hepatitis B surface antigen (rHBsAg) particles, which contain only virus envelope proteins, were radioactively labeled, and their attachment to human liver membranes was examined. Only the rHBsAg particles containing the large S protein were capable of directly attaching to liver plasma membranes. The attachment was saturable and could be prevented by competition with unlabeled particles or by a monoclonal antibody specific for the large S protein. In the presence of polymerized human serum albumin, both large and middle S protein-containing rHBsAg particles were capable of attaching to the liver plasma membranes. Small S protein-containing rHBsAg particles were not able to attach even in the presence of polymerized human serum albumin. These results indicate that the large S protein may be the viral attachment protein for hepatocytes, binding directly to liver plasma membranes by its unique amino-terminal (pre-S1) sequence. These results also indicate that polymerized human serum albumin or a similar molecule could act as an intermediate receptor, attaching to liver plasma membranes and to the amino acid sequence (pre-S2) shared by the middle and large S proteins but not contained in the small S protein.
Pontisso
P
P
Department of Immunology/Microbiology, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612-3864.
Petit
M A
MA
Bankowski
M J
MJ
Peeples
M E
ME
D001665:Binding Sites; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D006514:Hepatitis B Surface Antigens / Q000378:metabolism; D006515:Hepatitis B virus / Q000378:metabolism*; D007158:Immunologic Techniques; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000382:microbiology*; D008854:Microscopy, Electron; D011108:Polymers; D011991:Receptors, Virus / Q000378:metabolism*; D012709:Serum Albumin / Q000378:metabolism; D014759:Viral Envelope Proteins / Q000378:metabolism*
D006514:Hepatitis B Surface Antigens; D011108:Polymers; D011991:Receptors, Virus; D012709:Serum Albumin; D014759:Viral Envelope Proteins