Yu Ruiming, Bai Yingjie, Zhang Liping, Zhou Peng, Zhang Zhongwang, Yang Jun, Lu Yanzhen, Wang Dongsheng, Peng Yousheng, Li Dan, He Jian, Wang Yonglu, Zhang Quanwei, Yuan Ligang, Guo Huichen, Pan Li, Liu Xinsheng
State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou University, Lanzhou, China.
Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou, China.
J Virol. 2025 Aug 6:e0084925. doi: 10.1128/jvi.00849-25.
As an emerging swine enteric coronavirus, porcine deltacoronavirus (PDCoV) poses a severe threat to the global swine industry and has demonstrated potential for cross-species transmission. Therefore, the development of safe and effective vaccines is a top priority for the future prevention and control of PDCoV. In this study, we first designed and prepared an mRNA vaccine, S2P-mRNA-LNP, that expresses the full-length S2P (E855P, V856P) protein of PDCoV. Animal experiments demonstrated that S2P-mRNA-LNP induced significantly stronger humoral and cellular immune responses in mice than did an inactivated vaccine. Then, we introduced the P2A self-cleaving peptide into the S2P-mRNA-LNP design, generating SMN-mRNA-LNP, an LNP-encapsulated mRNA vaccine that allows the simultaneous expression of three major structural proteins of PDCoV (S, M, and N) from a single mRNA. The immunization of piglets demonstrated that both S2P-mRNA-LNP and SMN-mRNA-LNP induced robust humoral immune responses. Notably, SMN-mRNA-LNP conferred significantly superior active immune protection in piglets (5/5) than did S2P-mRNA-LNP (4/5). Further immunization experiments in pregnant sows showed that piglets born to SMN-mRNA-LNP-vaccinated sows acquired high levels of IgG, IgA, and neutralizing antibodies through the ingestion of colostrum, conferring complete passive protection (5/5). The protective efficacy of SMN-mRNA-LNP was markedly superior to that of the inactivated vaccine. In conclusion, these findings demonstrate that SMN-mRNA-LNP is a novel and highly efficacious candidate vaccine against PDCoV. In addition, the design strategy of single mRNA-LNP simultaneously delivering multiple viral antigens in this study provides a new idea for the development of porcine intestinal coronavirus mRNA vaccine in the future.IMPORTANCEIn this study, we designed and developed a novel mRNA vaccine, SMN-mRNA-LNP, capable of expressing the three major structural proteins (S, M, and N) of PDCoV from a single mRNA. This vaccine conferred superior active immune protection on piglets to that conferred by S2P-mRNA-LNP expressing only the S protein. Furthermore, following the immunization of pregnant sows with SMN-mRNA-LNP, their colostrum showed remarkably high IgA antibody titers reaching 1∶10, representing a 25-fold increase over that in the inactivated vaccine group. By suckling, newborn piglets acquired significantly greater passive immunity, which ultimately conferred complete protection against PDCoV challenge.
作为一种新兴的猪肠道冠状病毒，猪德尔塔冠状病毒（PDCoV）对全球养猪业构成严重威胁，并已显示出跨物种传播的潜力。因此，开发安全有效的疫苗是未来预防和控制PDCoV的首要任务。在本研究中，我们首先设计并制备了一种mRNA疫苗S2P-mRNA-LNP，其表达PDCoV的全长S2P（E855P，V856P）蛋白。动物实验表明，S2P-mRNA-LNP在小鼠中诱导的体液免疫和细胞免疫反应明显强于灭活疫苗。然后，我们将P2A自切割肽引入S2P-mRNA-LNP设计中，生成了SMN-mRNA-LNP，这是一种LNP包裹的mRNA疫苗，能够从单个mRNA同时表达PDCoV的三种主要结构蛋白（S、M和N）。仔猪免疫实验表明，S2P-mRNA-LNP和SMN-mRNA-LNP均能诱导强烈的体液免疫反应。值得注意的是，SMN-mRNA-LNP在仔猪中（5/5）提供的主动免疫保护明显优于S2P-mRNA-LNP（4/5）。对怀孕母猪的进一步免疫实验表明，接种SMN-mRNA-LNP的母猪所产仔猪通过摄入初乳获得了高水平的IgG、IgA和中和抗体，从而提供了完全的被动保护（5/5）。SMN-mRNA-LNP的保护效果明显优于灭活疫苗。总之，这些发现表明SMN-mRNA-LNP是一种针对PDCoV的新型高效候选疫苗。此外，本研究中单个mRNA-LNP同时递送多种病毒抗原的设计策略为未来猪肠道冠状病毒mRNA疫苗的开发提供了新思路。重要性在本研究中，我们设计并开发了一种新型mRNA疫苗SMN-mRNA-LNP，它能够从单个mRNA表达PDCoV的三种主要结构蛋白（S、M和N）。这种疫苗对仔猪的主动免疫保护优于仅表达S蛋白的S2P-mRNA-LNP。此外，用SMN-mRNA-LNP免疫怀孕母猪后，它们的初乳显示出极高的IgA抗体滴度，达到1∶10，比灭活疫苗组高出25倍。通过哺乳，新生仔猪获得了显著更强的被动免疫力，最终对PDCoV攻击提供了完全保护。
