Division of Livestock Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
Division of Livestock Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
J Virol. 2020 Jul 30;94(16). doi: 10.1128/JVI.00990-20.
Foot-and-mouth disease (FMD), which is caused by FMD virus (FMDV), remains a major plague among cloven-hoofed animals worldwide, and its outbreak often has disastrous socioeconomic consequences. A live-attenuated FMDV vaccine will greatly facilitate the global control and eradication of FMD, but a safe and effective attenuated FMDV vaccine has not yet been successfully developed. Here, we found that the internal ribosome entry site (IRES) element in the viral genome is a critical virulence determinant of FMDV, and a nucleotide substitution of cytosine (C) for guanine (G) at position 351 of the IRES endows FMDV with temperature-sensitive and attenuation () phenotypes. Furthermore, we demonstrated that the C351G mutation of IRES causes a temperature-dependent translation defect by impairing its binding to cellular pyrimidine tract-binding protein (PTB), resulting in the phenotypes of FMDV. Natural hosts inoculated with viruses carrying the IRES C351G mutation showed no clinical signs, viremia, virus excretion, or viral transmission but still produced a potent neutralizing antibody response that provided complete protection. Importantly, the IRES C351G mutation is a universal determinant of the phenotypes of different FMDV strains, and the C351G mutant was incapable of reversion to virulence during and passages. Collectively, our findings suggested that manipulation of the IRES, especially its C351G mutation, may serve as a feasible strategy to develop live-attenuated FMDV vaccines. The World Organization for Animal Health has called for global control and eradication of foot-and-mouth disease (FMD), the most economically and socially devastating disease affecting animal husbandry worldwide. Live-attenuated vaccines are considered the most effective strategy for prevention, control, and eradication of infectious diseases due to their capacity to induce potent and long-lasting protective immunity. However, efforts to develop FMD virus (FMDV) live-attenuated vaccines have achieved only limited success. Here, by structure-function study of the FMDV internal ribosome entry site (IRES), we find that the C351 mutation of the IRES confers FMDV with an ideal temperature-sensitive attenuation phenotype by decreasing its interaction with cellular pyrimidine tract-binding protein (PTB) to cause IRES-mediated temperature-dependent translation defects. The temperature-sensitive attenuated strains generated by manipulation of the IRES address the challenges of FMDV attenuation differences among various livestock species and immunogenicity maintenance encountered previously, and this strategy can be applied to other viruses with an IRES to rationally design and develop live-attenuated vaccines.
口蹄疫（FMD）是由口蹄疫病毒（FMDV）引起的，仍然是全球偶蹄动物的主要瘟疫之一，其爆发常常会带来灾难性的社会经济后果。一种减毒的 FMDV 疫苗将极大地促进全球对 FMD 的控制和根除，但安全有效的减毒 FMDV 疫苗尚未成功开发。在这里，我们发现病毒基因组中的内部核糖体进入位点（IRES）元件是 FMDV 的关键毒力决定因素，IRES 末端的胞嘧啶（C）突变为鸟嘌呤（G）（位置 351）使 FMDV 具有温度敏感和衰减（）表型。此外，我们证明 IRES 的 C351G 突变通过损害其与细胞嘧啶核苷酸结合蛋白（PTB）的结合，导致 IRES 依赖性翻译缺陷，从而导致 FMDV 的表型。接种携带 IRES C351G 突变的病毒的天然宿主没有出现临床症状、病毒血症、病毒排出或病毒传播，但仍产生了有效的中和抗体反应，提供了完全的保护。重要的是，IRES C351G 突变是不同 FMDV 株的表型的普遍决定因素，并且 C351G 突变体在和传代过程中不能恢复毒力。总之，我们的研究结果表明，操纵 IRES，特别是其 C351G 突变，可能成为开发减毒 FMDV 疫苗的可行策略。世界动物卫生组织呼吁全球控制和根除口蹄疫（FMD），这是一种对全球畜牧业造成最严重经济和社会破坏的疾病。由于活疫苗能够诱导强大且持久的保护性免疫，因此被认为是预防、控制和根除传染病的最有效策略。然而，开发口蹄疫病毒（FMDV）活疫苗的努力仅取得了有限的成功。在这里，我们通过对口蹄疫病毒内部核糖体进入位点（IRES）的结构功能研究发现，IRES 的 C351 突变通过降低其与细胞嘧啶核苷酸结合蛋白（PTB）的相互作用，导致 IRES 介导的温度依赖性翻译缺陷，赋予 FMDV 理想的温度敏感衰减表型。通过操纵 IRES 产生的温度敏感减毒株解决了先前遇到的不同牲畜物种之间 FMDV 衰减差异和免疫原性维持的挑战，并且该策略可应用于具有 IRES 的其他病毒，以合理设计和开发活疫苗。
