Identification and localization of pre-s-encoded polypeptides from woodchuck and ground squirrel hepatitis viruses.
A segment from the pre-s region of the woodchuck hepatitis virus (WHV) was inserted into an open reading frame vector allowing for the expression in Escherichia coli of viral determinants as part of a fusion protein. The bacterially synthesized fusion molecule contained eight amino acids from beta-galactosidase (beta-gal) at the N terminus, followed by 89 pre-s-encoded amino acids and 219 amino acids of chloramphenicol acetyltransferase (CAT) at the C terminus (beta-gal:pre-s:CAT). This tribrid protein was used to generate antiserum which had a significant titer to the viral portion of the fusion polypeptide. Anti-beta-gal:pre-s:CAT was used in Western blot analysis to identify viral proteins containing pre-s-encoded determinants. Antiserum to the tribrid molecule recognized four WHV polypeptides with molecular masses of 33, 36, 45, and 47 kilodaltons, each of which was also recognized by a monoclonal antibody to WHV surface antigen. Using the same anti-tribrid serum, we also identified analogous polypeptides from ground squirrel hepatitis virus. The antiserum was also used to immunoprecipitate virus particles containing endogenous DNA polymerase activity, indicating that pre-s determinants are found on the surface of mature virions. Based on previous computer studies and the location of pre-s-encoded molecules on the surface of virus particles, a role in hepadnavirus host cell entry is suggested for these polypeptides.
D000818:Animals; D004259:DNA-Directed DNA Polymerase / Q000032:analysis; D005814:Genes, Viral; D005822:Genetic Vectors; D006518:Hepatitis Viruses / Q000235:genetics* / Q000302:isolation & purification; D006520:Hepatitis, Animal / Q000382:microbiology; D008392:Marmota / Q000382:microbiology; D010957:Plasmids; D011994:Recombinant Proteins / Q000032:analysis / Q000276:immunology; D012376:Rodent Diseases / Q000382:microbiology; D012589:Sciuridae / Q000382:microbiology; D014764:Viral Proteins / Q000235:genetics* / Q000276:immunology; D014771:Virion / Q000032:analysis
D011994:Recombinant Proteins; D014764:Viral Proteins; D004259:DNA-Directed DNA Polymerase