title: Immunization with the gene expressing woodchuck hepatitis virus nucleocapsid protein fused to cytotoxic-T-lymphocyte-associated antigen 4 leads to enhanced specific immune responses in mice and woodchucks.
abstract: A number of options are available to modify and improve DNA vaccines. An interesting approach to improve DNA vaccines is to fuse bioactive domains, like cytotoxic-T-lymphocyte-associated protein 4 (CTLA-4), to an antigen. Such fusion antigens are expressed in vivo and directed to immune cells by the specific bioactive domain and therefore possess great potential to induce and modulate antigen-specific immune responses. In the present study, we tested this new approach for immunomodulation against hepadnavirus infection in the woodchuck model. Plasmids expressing the nucleocapsid protein (WHcAg) and e antigen (WHeAg) of woodchuck hepatitis virus (WHV) alone or in fusion to the extracellular domain of woodchuck CTLA-4 and CD28 were constructed. Immunizations of mice with plasmids expressing WHcAg or WHeAg led to a specific immunoglobulin G2a (IgG2a)-dominant antibody response. In contrast, fusions of WHcAg to CTLA-4 and CD28 induced a specific antibody response with comparable levels of IgG1 and IgG2a. Furthermore, the specific IgG1 response to WHcAg/WHeAg developed immediately after a single immunization with the CTLA-4-WHcAg fusion. Woodchucks were immunized with plasmids expressing WHeAg or the CTLA-4-WHcAg fusion and subsequently challenged with WHV. CTLA-4-WHcAg showed an improved efficacy in induction of protective immune responses to WHV. In particular, the anti-WHsAg antibody response developed earlier after challenge in woodchucks that received immunizations with CTLA-4-WHcAg, consistent with the hypothesis that anti-WHs response is dependent on a Th cell response to WHcAg. In conclusion, the use of fusion genes represents a generally applicable strategy to improve DNA vaccination.
authors.affiliation: Institut für Virologie, Universitätsklinikum Essen, Hufelandstrasse 55, Essen D-45122, Germany. mengji.lu@uni-essen.de
authors.forename: Mengji
authors.initials: M
authors.lastname: Lu
authors.forename: Masanori
authors.initials: M
authors.lastname: Isogawa
authors.forename: Yang
authors.initials: Y
authors.lastname: Xu
authors.forename: Gero
authors.initials: G
authors.lastname: Hilken
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000276:immunology; D018106:CD28 Antigens / Q000276:immunology; D060908:CTLA-4 Antigen; D004353:Drug Evaluation, Preclinical; D006509:Hepatitis B / Q000097:blood / Q000276:immunology* / Q000517:prevention & control; D006510:Hepatitis B Antibodies / Q000097:blood*; D017325:Hepatitis B Vaccines / Q000008:administration & dosage / Q000276:immunology*; D017919:Hepatitis B Virus, Woodchuck / Q000276:immunology*; D006524:Hepatitis, Viral, Animal / Q000097:blood / Q000276:immunology* / Q000517:prevention & control; D007074:Immunoglobulin G / Q000097:blood; D007273:Injections, Intramuscular; D008392:Marmota; D051379:Mice; D008807:Mice, Inbred BALB C; D019251:Nucleocapsid / Q000276:immunology*; D019590:Nucleocapsid Proteins; D010957:Plasmids / Q000378:metabolism; D014611:Vaccination; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000276:immunology*; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000276:immunology
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D018106:CD28 Antigens; D060908:CTLA-4 Antigen; C556707:Ctla4 protein, mouse; D006510:Hepatitis B Antibodies; D017325:Hepatitis B Vaccines; D007074:Immunoglobulin G; D019590:Nucleocapsid Proteins; D019444:Vaccines, DNA; D014614:Vaccines, Synthetic; C099600:nucleocapsid protein, Hepatitis virus