Yan Xiaoling, Zhang Xiaoli, Lyu Xiaocheng, Zheng Yaoyao, Li Qianniu, Zhao Xiaoya, Fu Jun, Ma Jingyun
State Key Laboratory of Swine and Poultry Breeding Industry, College of Animal Science, South China Agricultural University, Guangzhou, China.
Research and Development Department, ArtemisShield Animal Health Co., Ltd., Guangzhou, China.
Front Immunol. 2025 Aug 6;16:1633661. doi: 10.3389/fimmu.2025.1633661. eCollection 2025.
Swine acute diarrhea syndrome coronavirus (SADS-CoV) is an emerging porcine enteric coronavirus that can cause diarrhea in piglets younger than 5 days of age. However, infection of pigs older than 5 days of age does not usually result in obvious clinical symptoms. This relative intrinsic safety in older animals prompted us to investigate the potential of SADS-CoV as a viral vector for porcine diarrhea virus vaccines.
We utilized Gibson assembly to clone the SADS-CoV sequence into an artificial bacterial chromosome (BAC) vector. Further manipulation was carried out by recombineering to generate four attenuated recombinant SADS-CoV strains expressing a PEDV protective antigen fused with peptides that target immune cells. Subsequently, the biological characteristics and immunogenic efficacy of these four recombinant strains were systematically assessed through cell models and animal challenge experiments.
The recombinant viruses exhibited a proliferation profile similar to that of the wild-type virus in Vero cells, maintained stable cytopathic effects, retained the exogenous sequences for up to 20 passages, and consistently expressed the PEDV antigen fusion protein. Immunizing pregnant sows with these recombinant viruses effectively enhanced both cellular and mucosal immune responses and provided significant clinical protection against PEDV to their offspring. This study not only generated a vaccine candidate for PEDV but also established a pipeline for using the SADS-CoV as a vector for vaccine development.
猪急性腹泻综合征冠状病毒（SADS-CoV）是一种新出现的猪肠道冠状病毒，可导致5日龄以下仔猪腹泻。然而，5日龄以上的猪感染通常不会导致明显的临床症状。大龄动物相对较高的内在安全性促使我们研究SADS-CoV作为猪腹泻病毒疫苗载体的潜力。
我们利用吉布森组装法将SADS-CoV序列克隆到人工细菌染色体（BAC）载体中。通过重组工程进行进一步操作，以产生四种表达与靶向免疫细胞的肽融合的PEDV保护性抗原的减毒重组SADS-CoV毒株。随后，通过细胞模型和动物攻毒实验系统地评估了这四种重组毒株的生物学特性和免疫原性效力。
重组病毒在Vero细胞中的增殖情况与野生型病毒相似，维持稳定的细胞病变效应，外源序列在传代20次后仍保持稳定，并持续表达PEDV抗原融合蛋白。用这些重组病毒免疫妊娠母猪可有效增强细胞免疫和黏膜免疫反应，并为其后代提供针对PEDV的显著临床保护。本研究不仅产生了一种PEDV疫苗候选物，还建立了一条利用SADS-CoV作为疫苗开发载体的途径。
