Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, China.
Vaccine. 2013 Jan 21;31(5):833-8. doi: 10.1016/j.vaccine.2012.11.062. Epub 2012 Dec 3.
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.
PCV2 的衣壳 (Cap) 蛋白是主要的免疫原性蛋白，对于诱导 PCV2 特异性中和抗体和保护性免疫至关重要；因此，它是研究和开发针对 PCV2 感染的基因工程疫苗的合适靶抗原。IFN-γ 作为一种免疫佐剂具有潜在的功效，可增强某些疫苗在实验动物模型中的免疫原性。在这项研究中，三种重组蛋白：PCV2-Cap 蛋白、猪 IFN-γ（PoIFN-γ）和 PCV2-Cap 蛋白和 PoIFN-γ的融合蛋白（Cap-PoIFN-γ）分别在杆状病毒系统中表达，并通过 Western blot 和间接 ELISA 进行分析。此外，我们评估了在小鼠中共同给予 PoIFN-γ对基于 Cap 蛋白的 PCV2 亚单位疫苗诱导的保护性免疫反应的增强作用。与 Cap-PoIFN-γ 疫苗、PCV2-Cap 疫苗和 LG 株相比，用 PCV2-Cap+PoIFN-γ 疫苗接种的小鼠产生的 PCV2 特异性 IPMA 抗体、中和抗体和淋巴细胞增殖反应水平显著更高。在强毒 PCV2 攻毒后，所有免疫组均未检测到病毒血症，PCV2-Cap+PoIFN-γ 组的肺部病毒载量明显低于 Cap-PoIFN-γ 组、LG 株组和空白对照组，但略低于 PCV2-Cap 组。这些发现表明，PoIFN-γ 显著增强了基于 Cap 蛋白的 PCV2 亚单位疫苗的保护性免疫反应，PCV2-Cap+PoIFN-γ 亚单位疫苗可能成为预防和控制 PCV2 相关疾病的有吸引力的候选疫苗。
