Key Laboratory of Animal Immunology of the Ministry of Agriculture, Henan Provincial Key Laboratory of Animal Immunology, Henan Academy of Agricultural Sciences, Zhengzhou, 450002, Henan, China.
College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450002, Henan, China.
BMC Vet Res. 2020 Aug 27;16(1):313. doi: 10.1186/s12917-020-02527-9.
Porcine circovirus type 2 (PCV2) is the main causative agent of porcine circovirus diseases (PCVDs) which causes huge yearly economic losses in the swine industry. Capsid protein (Cap) is the major structural protein of PCV2 that can induce a protective immune response. Therefore, developing a novel and safe subunit vaccine against PCV2 infection is needed.
In this study, the Cap gene was bound to the truncated calreticulin (CRT) (120-250 aa/120-308 aa) at the N/C terminal, and then the CRT-Cap fusion genes were expressed in Escherichia coli (E.coli). The size-exclusion chromatography and dynamic light scattering (DLS) data showed that the purified recombinant CRT-Cap fusion protein (rP5F) existed in the form of polymers. Immunization with rP5F stimulated high levels of PCV2 specific antibody and neutralization antibody in mice, which were almost identical to those induced by the commercial subunit and inactivated vaccines. The lymphocyte proliferation and cytokine secretion were also detected in rP5F immunized mice. According to the results of PCV2-challenge experiment, the virus loads significantly decreased in mice immunized with rP5F. The data obtained in the current study revealed that rP5F had the potential to be a subunit vaccine candidate against PCV2 in the future.
We have successfully expressed Cap-CRT fusion proteins in E.coli and optimized rP5F could form into immunogenic polymers. Mice immunized with rP5F efficiently induced humoral and part of cellular immune responses and decreased the virus content against PCV2-challenge, which suggested that rF5P could be a potential subunit vaccine candidate.
猪圆环病毒 2 型（PCV2）是猪圆环病毒病（PCVD）的主要病原体，给养猪业造成了巨大的经济损失。衣壳蛋白（Cap）是 PCV2 的主要结构蛋白，可诱导保护性免疫反应。因此，需要开发针对 PCV2 感染的新型安全亚单位疫苗。
在本研究中，Cap 基因与截短的钙网蛋白（CRT）（120-250 aa/120-308 aa）的 N/C 末端结合，然后在大肠杆菌（E.coli）中表达 CRT-Cap 融合基因。分子筛层析和动态光散射（DLS）数据表明，纯化的重组 CRT-Cap 融合蛋白（rP5F）以聚合物的形式存在。rP5F 免疫可刺激小鼠产生高水平的 PCV2 特异性抗体和中和抗体，与商业亚单位和灭活疫苗诱导的抗体水平几乎相同。还检测了 rP5F 免疫小鼠的淋巴细胞增殖和细胞因子分泌。根据 PCV2 攻毒实验的结果，rP5F 免疫的小鼠病毒载量显著降低。本研究结果表明，rP5F 有可能成为未来针对 PCV2 的亚单位疫苗候选物。
我们已成功在大肠杆菌中表达 Cap-CRT 融合蛋白，并优化了 rP5F 可形成免疫原性聚合物。rP5F 免疫的小鼠可有效诱导体液和部分细胞免疫应答，并降低 PCV2 攻毒后的病毒含量，这表明 rP5F 可能是一种有潜力的亚单位疫苗候选物。
