title: Characterization of a pre-S polypeptide on the surfaces of infectious avian hepadnavirus particles.
abstract: DNA from the pre-S region of the duck hepatitis B virus (DHBV) genome was inserted into an open reading frame vector designed to give high-level expression in Escherichia coli. The resulting fusion protein contained the first 8 amino acids of beta-galactosidase, 86 amino acids of the DHBV pre-S region, and 219 amino acids of chloramphenicol acetyltransferase at the C terminus (beta-gal:pre-S:CAT). Rabbit antiserum against purified beta-gal:pre-S:CAT was used to identify pre-S-containing polypeptides in DHBV particles by Western blotting. A dominant species of 36 kilodaltons (kDa) was identified. Antiserum against the major 17-kDa DHBsAg polypeptide also reacted with the 36-kDa protein. This suggests that the DHBV envelope gene polypeptides share the same carboxyl terminus, but differ in the sites from which translation is initiated. N-linked carbohydrate was not detected on either the 17- or 36-kDa envelope proteins. Anti-beta-gal:pre-S:CAT abolished infectivity of the virus in an in vitro assay. Thus, the pre-S region is exposed on the surfaces of infectious virions and may be directly involved in binding of virus to host-cell receptors.
mesh_terms: D000914:Antibodies, Viral / Q000276:immunology; D000956:Antigens, Viral / Q000032:analysis; D003001:Cloning, Molecular; D004372:Ducks; D000939:Epitopes; D006023:Glycoproteins / Q000032:analysis; D006514:Hepatitis B Surface Antigens / Q000032:analysis*; D006515:Hepatitis B virus / Q000032:analysis* / Q000235:genetics; D007158:Immunologic Techniques; D008970:Molecular Weight; D009500:Neutralization Tests; D011498:Protein Precursors / Q000032:analysis* / Q000276:immunology; D014158:Transcription, Genetic; D014759:Viral Envelope Proteins / Q000032:analysis* / Q000235:genetics / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D000939:Epitopes; D006023:Glycoproteins; D006514:Hepatitis B Surface Antigens; D011498:Protein Precursors; D014759:Viral Envelope Proteins