Xie Yinli, Li Haitao, Qi Xingcai, Ma Youji, Yang Bo, Zhang Shumin, Chang Huiyun, Yin Xiangping, Li Zhiyong
State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Grazing Animal Diseases of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agriculture Sciences, Lanzhou, Gansu, China; College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China.
College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, Gansu, China.
Vaccine. 2019 Mar 28;37(14):2016-2025. doi: 10.1016/j.vaccine.2019.02.032. Epub 2019 Feb 23.
Foot-and-mouth disease virus (FMDV) is the etiological agent of a highly contagious disease that affects cloven-hoofed animal species. The FMDV capsid is highly acid labile and viral particles lose their immunogenicity when they disassemble at mildly acidic pHs. The viral capsid of FMDV serotype O is more sensitive than those of other serotypes, making it more difficult to acquire enough empty-capsid-like particles in the acidic insect cell environment for research. In this study, novel FMDV mutants with increased acid resistance were isolated using BHK-21 cell cultured under low-pH conditions. Amino acid substitutions Q25R, K41E, and N85A in the VP1 capsid protein and K154Q in the VP3 capsid protein were detected in all six mutants. Based on these amino acid replacements, empty-capsid-like particles of FMDV serotype O, which were resistant to the acid-induced dissociation of the capsid into pentameric subunits, were produced in insect cells. We characterized the protective immunity induced by these acid-resistant empty capsid particles. Significant humoral and cellular immune responses were elicited in mice after immunization with the acid-resistant empty capsid particles. The acid-resistant empty-capsid-like particles also induced strong neutralizing antibodies in guinea pigs and protected all the guinea pigs from FMDV challenge. Our results suggest that these acid-resistant empty-capsid-like particles have potential utility as a vaccine against serotype O FMDV infection.
口蹄疫病毒（FMDV）是一种高度传染性疾病的病原体，可感染偶蹄类动物。FMDV衣壳对酸高度不稳定，当病毒颗粒在轻度酸性pH值下解体时会失去免疫原性。FMDV O型血清型的病毒衣壳比其他血清型的更敏感，这使得在酸性昆虫细胞环境中获取足够的空衣壳样颗粒用于研究更加困难。在本研究中，利用在低pH条件下培养的BHK-21细胞分离出了具有增强耐酸性的新型FMDV突变体。在所有六个突变体中均检测到衣壳蛋白VP1中的氨基酸替换Q25R、K41E和N85A以及衣壳蛋白VP3中的K154Q。基于这些氨基酸替换，在昆虫细胞中产生了对酸诱导的衣壳解离为五聚体亚基具有抗性的FMDV O型血清型空衣壳样颗粒。我们对这些耐酸性空衣壳颗粒诱导的保护性免疫进行了表征。用耐酸性空衣壳颗粒免疫小鼠后，小鼠产生了显著的体液免疫和细胞免疫反应。耐酸性空衣壳样颗粒还在豚鼠中诱导产生了强中和抗体，并保护所有豚鼠免受FMDV攻击。我们的结果表明，这些耐酸性空衣壳样颗粒作为抗O型FMDV感染疫苗具有潜在用途。
