Preparation and immunogenicity analysis of a porcine circovirus 2 vaccine candidate
10.13200/j.cnki.cjb.004645
- VernacularTitle:猪圆环病毒2型候选疫苗的制备及免疫原性分析
- Author:
Jinjin ZHANG
1
Author Information
1. *School of Life Sciences, Ningxia University, Yinchuan 750021, Ningxia Hui Autonomous Region, China
- Publication Type:Journal Article
- Keywords:
Porcine circovirus 2(PCV2);
Capsid(Cap) protein;
Insect-baculovirus expression system;
Vaccine;
Immunogenicity
- From:
Chinese Journal of Biologicals
2026;39(02):129-136+143
- CountryChina
- Language:Chinese
-
Abstract:
Objective To express the capsid(Cap) protein of porcine circovirus 2(PCV2) by insect-baculovirus expression system, evaluate its immunogenicity as a vaccine candidate, and explore whether it can induce humoral and cellular immune responses in BALB/c mice.Methods Following codon optimization, the PCV2 Cap gene was cloned into pFastBac Dual vector and transformed into E.coli DH10 Bac cells. After Bacmid extraction, PCR amplification was carried out with M13 universal primers. The appropriately identified Bacmid was then transfected into Sf9 cells to express Cap protein, and the protein was quantified. Forty-five female BALB/c mice were randomly divided into three groups: PBS control, Cap and commercial vaccine YI Cap group, 15 mice in each group, which were immunized subcutaneously on the back once at 14-day intervals, for a total of three times, with PBS 100 ??L, Cap 10 ??g, and commercial vaccine YI Cap 10 ??g respectively each time. The serum IgG level of mice was measured by ELISA, the cellular immune response type was analyzed by flow cytometry, and the histocompatibility of the subunit vaccine was observed by H&E staining.Results The insect-baculovirus expression system effectively expressed the target protein, and the Cap protein with enhanced green fluorescent protein(eGFP) colocalized with the cell's plasma membrane. Transmission electron microscopy revealed that the Cap protein could self-assemble to produce virus-like particles(VLPs) before constructing another recombinant vector sans the eGFP fluorescent flag. SDS-PAGE and Western blot analysis revealed the conspicuous bands at the desired area. The IgG content of Cap vaccine candidate mice reached the highest level at 42 days. The levels of IFNγ and IL-4 were(27. 75 ± 0. 99) and(17. 63 ± 1. 13) pg/mL, respectively, both of which were significantly higher than those of PBS group(F = 14. 89 and 0. 211 9,P < 0. 05 and < 0. 001, respectively). The stimulation index(SI) of splenic lymphocytes in the Cap group reached 6. 72, which was significantly higher than that in the PBS group(F = 1. 228, P < 0. 001). The Cap vaccine candidate could induce Th1-type cellular immune response and exhibited good histocompatibility.Conclusion The Cap protein was successfully expressed in the insect-baculovirus expression system. The Cap vaccine candidate can induce humoral and cellular immune responses in mice after immunization, which is a potential vaccine candidate for further development of more effective vaccines against PCV-related diseases.
