Du Qian, Shi Tengfei, Wang Huaxin, Zhu Changlei, Yang Nan, Tong Dewen, Huang Yong
College of Veterinary Medicine, Northwest A&F University, Xianyang, China.
Engineering Research Center of Efficient New Vaccines for Animals, Ministry of Education, Xianyang, China.
Front Microbiol. 2023 Jan 11;13:1077026. doi: 10.3389/fmicb.2022.1077026. eCollection 2022.
Nowadays, vaccines are broadly used to prevent porcine circovirus type 2 (PCV2) infection-induced expenditures, but the virus is still spreading among pigs. The current PCV2 vaccines all rely on the immunogenicity of Cap, yet our previous studies found that Cap is also the major component mediating the PCV2 infection-induced immune suppression through its interaction with host gC1qR. Thereby, new vaccines are still necessary for PCV2 prevention and control. In this study, we constructed a new PCV2 DNA vaccine expressing the gC1qR binding site mutant Cap. We introduced the Intron A and WPRE elements into the vector to improve the Cap expression level, and fused the IL-2 secretory signal peptides to the N-terminal of Cap to mediate the secretion of Cap. We also screened and selected chemokines CXCL12, CCL22, and CCL25 to migrate dendritic cells. In addition, we contained the vectors with PEI and then ultrasonic them into nano size to enhance the entrance of the vectors. Finally, the animal experiments showed that the new PCV2 DNA vaccine expressing the gC1qR binding site mutant Cap could induce stronger humoral and cellular immune responses than the PCV2 DNA vaccine expressing the wild-type Cap and the non-ultrasonic treated PCV2 DNA vaccine in mice, and protect the mice from PCV2 infection and lung lesions. The results indicate the new PCV2 DNA vaccine expressing the gC1qR binding site mutant Cap has a certain development value, and provide new insight into the development of novel PCV2 vaccines.
如今，疫苗被广泛用于预防猪圆环病毒2型（PCV2）感染引发的相关支出，但该病毒仍在猪群中传播。目前的PCV2疫苗均依赖于Cap的免疫原性，然而我们之前的研究发现，Cap也是通过与宿主gC1qR相互作用介导PCV2感染诱导的免疫抑制的主要成分。因此，仍需要新型疫苗来防控PCV2。在本研究中，我们构建了一种表达gC1qR结合位点突变型Cap的新型PCV2 DNA疫苗。我们将内含子A和WPRE元件引入载体以提高Cap的表达水平，并将IL-2分泌信号肽融合到Cap的N端以介导Cap的分泌。我们还筛选并选择了趋化因子CXCL12、CCL22和CCL25来迁移树突状细胞。此外，我们用聚乙烯亚胺包裹载体，然后将其超声处理成纳米尺寸以增强载体的进入。最后，动物实验表明，表达gC1qR结合位点突变型Cap的新型PCV2 DNA疫苗在小鼠中能诱导比表达野生型Cap的PCV2 DNA疫苗和未超声处理的PCV2 DNA疫苗更强的体液免疫和细胞免疫反应，并保护小鼠免受PCV2感染和肺部病变。结果表明，表达gC1qR结合位点突变型Cap的新型PCV2 DNA疫苗具有一定的开发价值，为新型PCV2疫苗的开发提供了新的思路。
