title: Enhanced protective immune response to PCV2 subunit vaccine by co-administration of recombinant porcine IFN-γ in mice.
abstract: The capsid (Cap) protein of PCV2 is the major immunogenic protein that is crucial to induce PCV2-specific neutralizing antibodies and protective immunity; thus, it is a suitable target antigen for the research and development of genetically engineered vaccines against PCV2 infection. IFN-γ has exhibited potential efficacy as an immune adjuvant that enhances the immunogenicity of certain vaccines in experimental animal models. In this study, three recombinant proteins: PCV2-Cap protein, porcine IFN-γ (PoIFN-γ), and the fusion protein (Cap-PoIFN-γ) of PCV2-Cap protein and PoIFN-γ were respectively expressed in the baculovirus system, and analyzed by Western blot and indirect ELISA. Additionally, we evaluated the enhancement of the protective immune response to the Cap protein-based PCV2 subunit vaccine elicited by co-administration of PoIFN-γ in mice. Vaccination of mice with the PCV2-Cap+PoIFN-γ vaccine elicited significantly higher levels of PCV2-specific IPMA antibodies, neutralizing antibodies, and lymphocyte proliferative responses compared to the Cap-PoIFN-γ vaccine, the PCV2-Cap vaccine, and LG-strain. Following virulent PCV2 challenge, no viraemia was detected in all immunized groups, and the viral loads in lungs of the PCV2-Cap+PoIFN-γ group were significantly lower compared to the Cap-PoIFN-γ group, the LG-strain group, and the mock group, but slightly lower compared to the PCV2-Cap group. These findings suggested that PoIFN-γ substantially enhanced the protective immune response to the Cap protein-based PCV2 subunit vaccine, and that the PCV2-Cap+PoIFN-γ subunit vaccine potentially serves as an attractive candidate vaccine for the prevention and control of PCV2-associated diseases.
authors.affiliation: Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, China.
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Wang
authors.forename: Dan
authors.initials: D
authors.lastname: Liu
authors.forename: Long-Jun
authors.initials: LJ
authors.lastname: Guo
authors.forename: Qing-Hai
authors.initials: QH
authors.lastname: Tang
authors.forename: Yan-Wu
authors.initials: YW
authors.lastname: Wei
authors.forename: Hong-Li
authors.initials: HL
authors.lastname: Wu
authors.forename: Jian-Bo
authors.initials: JB
authors.lastname: Liu
authors.forename: Sheng-Bin
authors.initials: SB
authors.lastname: Li
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Huang
authors.forename: Chang-Ming
authors.initials: CM
authors.lastname: Liu
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D015153:Blotting, Western; D036022:Capsid Proteins / Q000235:genetics / Q000276:immunology; D018173:Circoviridae Infections / Q000276:immunology / Q000517:prevention & control*; D017925:Circovirus / Q000235:genetics / Q000276:immunology*; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D007371:Interferon-gamma / Q000008:administration & dosage*; D051379:Mice; D008807:Mice, Inbred BALB C; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D022223:Vaccines, Subunit / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014765:Viral Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D014766:Viremia / Q000517:prevention & control
chemical_list: D000276:Adjuvants, Immunologic; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D036022:Capsid Proteins; D011994:Recombinant Proteins; D022223:Vaccines, Subunit; D014614:Vaccines, Synthetic; D014765:Viral Vaccines; D007371:Interferon-gamma