title: Characterization of complex B cell epitopes on woodchuck hepatitis virus surface antigens by using plasmids encoding chimeric proteins and DNA immunization.
abstract: The conformational nature of the B cell epitopes on the hepadnavirus surface antigens makes its characterization difficult. Here, a new approach by DNA vaccination with plasmids expressing chimeric hepadnavirus surface antigens was explored to determine B cell epitopes on the surface antigens of woodchuck hepatitis virus (WHsAg). A series of chimeric genes consisting of complementary fragments of WHsAg and hepatitis B virus surface antigens (HBsAg) was constructed. These plasmids expressed the following: (i) middle chimeric surface antigens (MCSAgs), including pre-S2 region and small surface antigens; (ii) small chimeric surface antigens (CSAgs); (iii) a mutated WHsAg with two amino acid substitutions, the Leu 136 to Thr and Ala 140 to Asp, within the central immunogenic region. The mutated region from amino acid 135 to 143 within WHsAg mimics the second loop of the HBsAg a-determinant. MCSAgs and CSAgs were expressed in transiently transfected mammalian cells and were reactive to anti-HBsAg and anti-WHsAg, as shown by indirect immunofluorescence staining and ELISA. Vaccination with plasmids encoding MCSAgs induced strong antibody responses to the pre-S2 region. Anti-pre-S2 antibodies were directed to a linear, immunodominant region within the amino-terminal region of the pre-S2 region and were able to precipitate serum WHsAg. Vaccinations with the plasmids expressing the CSAgs led to the conclusion that an extended region aa 116-169 of WHsAg, analogous to the HBsAg a-determinant, was sufficient for the induction of anti-WHsAg antibodies. The mutated WHsAg with the second loop of the HBsAg a-determinant efficiently induced anti-WHsAg antibodies, but also a low titer of anti-HBsAg. Thus, multiple B cell epitopes of a linear and conformational nature are present on WHsAg. We presented an efficient and broadly applicable strategy for analysis of complex immunogenic determinants of natural or mutated viral antigens.
authors: Institut für Virologie, Universitätsklinikum Essen, Essen, Germany.
authors: Xin
authors: X
authors: Zheng
authors: Reinhold
authors: R
authors: Schirmbeck
authors: Gero
authors: G
authors: Hilken
authors: Jennifer A
authors: JA
authors: Waters
authors: Dongliang
authors: D
authors: Yang
authors: Jörg
authors: J
authors: Reimann
authors: Michael
authors: M
authors: Roggendorf
authors: Mengji
authors: M
authors: Lu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D000954:Antigens, Surface / Q000235:genetics* / Q000276:immunology; D001665:Binding Sites; D002460:Cell Line; D006224:Cricetinae; D004279:DNA, Viral / Q000276:immunology*; D018985:Epitopes, B-Lymphocyte / Q000235:genetics* / Q000276:immunology; D015870:Gene Expression; D006514:Hepatitis B Surface Antigens / Q000276:immunology; D017919:Hepatitis B Virus, Woodchuck / Q000235:genetics* / Q000276:immunology; D006801:Humans; D008392:Marmota; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D011498:Protein Precursors / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D014611:Vaccination; D019444:Vaccines, DNA / Q000276:immunology*; D014759:Viral Envelope Proteins / Q000235:genetics* / Q000276:immunology; D014765:Viral Vaccines / Q000235:genetics / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D000954:Antigens, Surface; D004279:DNA, Viral; D018985:Epitopes, B-Lymphocyte; D006514:Hepatitis B Surface Antigens; D011498:Protein Precursors; D011993:Recombinant Fusion Proteins; D019444:Vaccines, DNA; D014759:Viral Envelope Proteins; D014765:Viral Vaccines; C050807:presurface protein 2, hepatitis B surface antigen