State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China.
World Organization for Animal Health Reference Laboratory for Classical Swine Fever, China Institute of Veterinary Drug Control, Beijing 100081, China.
Int J Mol Sci. 2023 Jul 26;24(15):11954. doi: 10.3390/ijms241511954.
Classical swine fever (CSF) and porcine epidemic diarrhea (PED) are highly contagious viral diseases that pose a significant threat to piglets and cause substantial economic losses in the global swine industry. Therefore, the development of a bivalent vaccine capable of targeting both CSF and PED simultaneously is crucial. In this study, we genetically engineered a recombinant classical swine fever virus (rCSFV) expressing the antigenic domains of the porcine epidemic diarrhea virus (PEDV) based on the modified infectious cDNA clone of the vaccine strain C-strain. The S1N and COE domains of PEDV were inserted into C-strain cDNA clone harboring the mutated 136th residue of N and substituted 3'UTR to generate the recombinant chimeric virus vC/SM3'UTR-S1NCOE. To improve the efficacy of the vaccine, we introduced the tissue plasminogen activator signal (tPAs) and CARD domain of the signaling molecule VISA into vC/SM3'UTR-S1NCOE to obtain vC/SM3'UTR-tPAsS1NCOE and vC/SM3'UTR-CARD/tPAsS1NCOE, respectively. We characterized three vaccine candidates in vitro and investigated their immune responses in rabbits and pigs. The N mutant exhibited normal autoprotease activity and mitigated the inhibition of IFN-β induction. The introduction of tPAs and the CARD domain led to the secretory expression of the S1NCOE protein and upregulated IFN-β induction in infected cells. Immunization with recombinant CSFVs expressing secretory S1NCOE resulted in a significantly increased in PEDV-specific antibody production, and coexpression of the CARD domain of VISA upregulated the PEDV-specific IFN-γ level in the serum of vaccinated animals. Notably, vaccination with vC/SM3'UTR-CARD/tPAsS1NCOE conferred protection against virulent CSFV and PEDV challenge in pigs. Collectively, these findings demonstrate that the engineered vC/SM3'UTR-CARD/tPAsS1NCOE is a promising bivalent vaccine candidate against both CSFV and PEDV infections.
经典猪瘟（CSF）和猪流行性腹泻（PED）是高度传染性的病毒性疾病，对仔猪构成严重威胁，并在全球养猪业造成巨大经济损失。因此，开发一种能够同时针对 CSF 和 PED 的双价疫苗至关重要。在这项研究中，我们基于疫苗株 C 株的改良传染性 cDNA 克隆，通过基因工程技术构建了一种表达猪流行性腹泻病毒（PEDV）抗原结构域的重组经典猪瘟病毒（rCSFV）。将 PEDV 的 S1N 和 COE 结构域插入携带 N 位 136 位突变和替代 3'UTR 的 C 株 cDNA 克隆中，生成重组嵌合病毒 vC/SM3'UTR-S1NCOE。为了提高疫苗的效力，我们将组织型纤溶酶原激活物信号（tPAs）和信号分子 VISA 的 CARD 结构域引入 vC/SM3'UTR-S1NCOE 中，分别获得 vC/SM3'UTR-tPAsS1NCOE 和 vC/SM3'UTR-CARD/tPAsS1NCOE。我们在体外对三种候选疫苗进行了表征，并在兔子和猪中研究了它们的免疫反应。N 位突变体表现出正常的自蛋白酶活性，并减轻了 IFN-β诱导的抑制。tPAs 和 CARD 结构域的引入导致 S1NCOE 蛋白的分泌表达，并上调感染细胞中 IFN-β的诱导。用表达分泌型 S1NCOE 的重组 CSFV 免疫可显著增加 PEDV 特异性抗体的产生，而 VISA 的 CARD 结构域的共表达上调了接种动物血清中的 PEDV 特异性 IFN-γ水平。值得注意的是，接种 vC/SM3'UTR-CARD/tPAsS1NCOE 可保护猪免受强毒 CSF 和 PEDV 的攻击。总之，这些发现表明，工程化的 vC/SM3'UTR-CARD/tPAsS1NCOE 是一种针对 CSF 和 PEDV 感染的有前途的双价疫苗候选物。
