A型口蹄疫病毒与中和性抗体的复合物结构解析
张泽林#，武山权#，李凤娟，泽让扎西，卢曾军，李 坤*，雷东升*
（1．物理科学与技术学院兰州大学电镜中心，兰州大学，甘肃兰州730000；
2．家畜疫病病原生物学国家重点实验室，兰州大学动物医学与生物安全学院，中国农业科学院兰州兽医研究所，甘肃兰州730000）
摘 要 口蹄疫病毒（foot-and-mouth disease virus, FMDV）是感染猪、牛、羊等偶蹄动物的烈性病原，严重危害畜牧业的发展以及相关产品的对外贸易。FMDV包含七个血清型，其中A型FMDV抗原结构变异最大，因此解析A型FMDV保守抗原结构对广谱疫苗分子设计具有重要指导意义。据此，本文作者利用冷冻电镜技术解析了A型FMDV与中和性抗体P22C复合物的三维结构。发现P22C结合于A型FMDV颗粒的3重轴附近，接触面多数氨基酸位于衣壳蛋白VP2 B-C环，其次是E-F/H-I环以及VP3 B-B “结节”上不连续的少量氨基酸。其中，VP2的72、77与195位氨基酸通过氢键与抗体相互作用，可能是影响结合的关键位点。进一步的结合自由能分析支持该猜测，提示72位点是组成抗原表位的关键决定簇，而H77W和S195L突变则可进一步降低结合自由能从而提高与抗体的亲和力。结合自由能分析也说明了P22C具有较高的成熟度。研究结果揭示了A型FMDV的抗原结构信息，为FMDV疫苗分子设计提供了一个重要靶点。
关键词 口蹄疫病毒；中和性抗体；冷冻电镜；结合自由能；
中图分类号： S852.65；Q336 文献标识码：A doi:10.3969/j.issn.1000-6281.2023.01.006
Structure of foot-and-mouth disease virus serotype A with neutralizing antibody
ZHANG Ze-lin#，WU Shan-quan#，LI Feng-juan，ZERANG Zha-xi, LU Zeng-jun,LI Kun*, LEI Dong-sheng*
(1．School of Physical Science and Technology，Lanzhou University EMC, Lanzhou University，Lanzhou Gansu 730000；2．State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou Gansu 730000, China)
Abstract Foot-and-mouth disease virus (FMDV) is a contagious pathogen that infects cloven-hoofed animals. Among the seven serotypes of FMDV, serotype A shows the largest structural variation. Understanding its conserved structure and interactions with antibodies is critical for the development of universal vaccine against FMDV. Here we reconstruct the three-dimensional structure of FMDV serotype A in complex with neutralizing antibody P22C by Cryo-electron microscopy. We find that P22C binds to the three-fold axis of FMDV, in which most residues contacting with P22C are located in the VP2 B-C/E-F/H-I loops, and the VP3 B-B “knob” of an adjacent protomer. Residues 72,77 and 195 of VP2 form hydrogen bonds with P22C，which may be the key sites for antibody binding. This hypothesis is supported by further binding free energy analysis, which suggests that residue 72 is the major determinant of P22C binding, and H77W and S195L mutations could further improve antibody binding affinity. Besides, binding free energy analysis suggests the high maturity of P22C. This study reveals the structure of FMDV serotype A in complex with neutralizing antibody, providing new targets for the design of vaccine against FMDV.
Keywords foot-and-mouth disease virus; neutralizing antibody; Cryo-EM; binding free energy
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