title: Recombinant Semliki Forest virus vectors encoding hepatitis B virus small surface and pre-S1 antigens induce broadly reactive neutralizing antibodies.
abstract: Most hepatitis B virus (HBV) vaccines consist of viral small surface (S) protein subtype adw2 expressed in yeast cells. In spite of good efficacy, HBV-genotype and subtype differences, escape mutants and insufficient Th1 activation remain potential problems. To address these problems, we generated recombinant Semliki Forest virus (rSFV) vectors encoding S protein, subtype adw2 or ayw2, or a fragment of the large surface protein, amino acids 1-48 of the pre-S1 domain, fused to S (pre-S1.1-48/S). The antigen loop in S protein and the selected pre-S1 sequences are known targets of neutralizing antibodies. BALB/c mice were immunized intravenously with 10(7) rSFV particles and 10(8) rSFV particles 3 weeks later. Antibodies induced by rSFV encoding S proteins reacted preferentially with subtype determinants of yeast-derived S antigen but equally well with patient-derived S antigen. Immunization with rSFV encoding pre-S1.1-48/S resulted in formation of pre-S1- and S-specific immunoglobulin G (IgG), while immunization with the isogenic mutant without S start codon induced pre-S1 antibodies only. Neutralizing antibodies were determined by mixing with plasma-derived HBV/ayw2 and subsequent inoculation of susceptible primary hepatocyte cultures from Tupaia belangeri. S/adw2 antisera neutralized HBV/ayw2 as effectively as antisera raised with S/ayw2. The pre-S1 antibodies also completely neutralized HBV infectivity. The IgG1/IgG2a ratios ranged from 0.28 to 0.88 in the four immunized groups and were lowest for the pre-S1.1-48/S vector, indicating the strongest Th1 response. This vector type may induce subtype-independent and S-escape-resistant neutralizing antibodies against HBV.
authors.affiliation: Biomedical Research and Study Centre, University of Latvia, Riga, Latvia, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Niedre-Otomere
authors.forename: A
authors.initials: A
authors.lastname: Bogdanova
authors.forename: D
authors.initials: D
authors.lastname: Skrastina
authors.forename: A
authors.initials: A
authors.lastname: Zajakina
authors.forename: R
authors.initials: R
authors.lastname: Bruvere
authors.forename: V
authors.initials: V
authors.lastname: Ose
authors.forename: W H
authors.initials: WH
authors.lastname: Gerlich
authors.forename: H
authors.initials: H
authors.lastname: Garoff
authors.forename: P
authors.initials: P
authors.lastname: Pumpens
authors.forename: D
authors.initials: D
authors.lastname: Glebe
authors.forename: T
authors.initials: T
authors.lastname: Kozlovska
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood*; D002478:Cells, Cultured; D004337:Drug Carriers; D005260:Female; D005822:Genetic Vectors; D006510:Hepatitis B Antibodies / Q000097:blood; D006511:Hepatitis B Antigens / Q000235:genetics / Q000276:immunology*; D006514:Hepatitis B Surface Antigens / Q000235:genetics / Q000276:immunology*; D017325:Hepatitis B Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D022781:Hepatocytes / Q000821:virology; D006801:Humans; D007275:Injections, Intravenous; D051379:Mice; D008807:Mice, Inbred BALB C; D009500:Neutralization Tests; D011498:Protein Precursors / Q000235:genetics / Q000276:immunology*; D012672:Semliki forest virus / Q000235:genetics*; D014417:Tupaia; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology
chemical_list: D057134:Antibodies, Neutralizing; D004337:Drug Carriers; D006510:Hepatitis B Antibodies; D006511:Hepatitis B Antigens; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines; D011498:Protein Precursors; D014614:Vaccines, Synthetic; C050806:presurface protein 1, hepatitis B surface antigen