Zhao Jingang, Xiao Peng, Xin Aiguo, Zhu Heran, Wang Hao, Xiao Jinlong, Gao Hong
College of Animal Science and Technology, Yunnan Agricultural University, Kunming, China.
Yunnan Tropical and Subtropical Animal Virus Disease Laboratory, Yunnan Academy of Animal Husbandry and Veterinary Sciences, Kunming, China.
Front Microbiol. 2025 Apr 28;16:1503191. doi: 10.3389/fmicb.2025.1503191. eCollection 2025.
Foot-and-mouth disease virus (FMDV) is one of the most significant animal pathogens worldwide, severely impacting the health and productivity of pigs, cattle, sheep, and other ungulates. Although the traditional vaccines have played a crucial role in epidemic control, inactivated vaccines face persistent challenges concerning the potential for virus dissemination and pressures from serotype and subtype matching. However, the manufacture of attenuated vaccines is forbidden, and the efficiency of alternative vaccines for immune protection is still inadequate. Consequently, there exists an urgent need for safer and more effective innovative vaccines in animal husbandry. In this study, we aimed to develop a lipid nanoparticle mRNA vaccine based on VP1-3A-3D epitopes from serotype O FMD and to verify its specific expression within cytoplasmic and injection sites. Our findings demonstrated that mRNA transfected into primary spleen cells derived from guinea pigs induced cytokine release, promoted differentiation of both CD4 T and CD8 T lymphocytes, and enhanced lymphocyte proliferation rates. Following immunization of mRNA vaccine in guinea pigs, we observed increased differentiation of both CD4 T and CD8 T cells, alongside elevated levels of cytokine secretion. Additionally, this vaccination induced the production of specific IgG antibodies as well as neutralizing antibodies. Importantly, our vaccine provided complete protection for all six guinea pigs against a lethal challenge of 100 GPID, with histopathological scores indicating protection equivalent to that conferred by the inactivated vaccine. The viral load results demonstrated that the vaccine group significantly reduced viral copy numbers in serum and effectively decreased the concentration of the inflammatory cytokine IL-1β. Furthermore, during the pre-immune phase following vaccination with the mRNA vaccine in pigs, heightened cytokine secretion was observed, along with the inhibition of viral replication. Simultaneously, the neutralizing antibody titer in the serum remained stable over 4 months. Immunofluorescence analysis of spleen tissues from both guinea pigs and pigs demonstrated marked activation and increased expression of CD4 and CD8 T lymphocytes, as well as macrophages, in the mRNA vaccine group. In summary, this study suggests that the serotype O FMD mRNA vaccine is a promising candidate for further development in the fight against FMDV.
口蹄疫病毒（FMDV）是全球最重要的动物病原体之一，严重影响猪、牛、羊及其他有蹄类动物的健康和生产力。尽管传统疫苗在疫情控制中发挥了关键作用，但灭活疫苗在病毒传播可能性以及血清型和亚型匹配压力方面面临持续挑战。然而，减毒疫苗的生产被禁止，替代疫苗的免疫保护效率仍不足。因此，畜牧业迫切需要更安全、更有效的创新疫苗。在本研究中，我们旨在开发一种基于O型口蹄疫VP1 - 3A - 3D表位的脂质纳米颗粒mRNA疫苗，并验证其在细胞质和注射部位的特异性表达。我们的研究结果表明，转染到豚鼠原代脾细胞中的mRNA可诱导细胞因子释放，促进CD4 T淋巴细胞和CD8 T淋巴细胞的分化，并提高淋巴细胞增殖率。在豚鼠中接种mRNA疫苗后，我们观察到CD4 T细胞和CD8 T细胞的分化均增加，同时细胞因子分泌水平升高。此外，这种疫苗接种诱导了特异性IgG抗体以及中和抗体的产生。重要的是，我们的疫苗为所有六只豚鼠提供了针对100个豚鼠感染剂量（GPID）致死性攻击的完全保护，组织病理学评分表明其保护效果与灭活疫苗相当。病毒载量结果表明，疫苗组显著降低了血清中的病毒拷贝数，并有效降低了炎性细胞因子IL - 1β的浓度。此外，在猪接种mRNA疫苗后的免疫前阶段，观察到细胞因子分泌增加，同时病毒复制受到抑制。同时，血清中的中和抗体滴度在4个月内保持稳定。对豚鼠和猪的脾组织进行免疫荧光分析表明，mRNA疫苗组中CD4和CD8 T淋巴细胞以及巨噬细胞有明显的激活和表达增加。总之，本研究表明O型口蹄疫mRNA疫苗是对抗FMDV进一步开发的有前景的候选疫苗。
