Gu Ying, Tang Xuhua, Zhang Xiao, Song Cuiling, Zheng Minghua, Wang Kaihang, Zhang Jun, Ng Mun-Hon, Hew Choy-Leong, Li Shaowei, Xia Ningshao, Sivaraman J
1] State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, Xiamen University, Xiamen, Fujian 361005, China [2] National Institute of Diagnostics and Vaccine Development in Infectious Disease, School of Public Health, Xiamen University, Xiamen, Fujian 361005, China.
1] Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore [2] Current address: Institute of Molecular and Cell Biology, Singapore 138673, Singapore.
Cell Res. 2015 May;25(5):604-20. doi: 10.1038/cr.2015.34. Epub 2015 Mar 20.
Hepatitis E virus (HEV), a non-enveloped, positive-sense, single-stranded RNA virus, is a major cause of enteric hepatitis. Classified into the family Hepeviridae, HEV comprises four genotypes (genotypes 1-4), which belong to a single serotype. We describe a monoclonal antibody (mAb), 8G12, which equally recognizes all four genotypes of HEV, with ∼ 2.53-3.45 nM binding affinity. The mAb 8G12 has a protective, neutralizing capacity, which can significantly block virus infection in host cells. Animal studies with genotypes 1, 3 and 4 confirmed the cross-genotype neutralizing capacity of 8G12 and its effective prevention of hepatitis E disease. The complex crystal structures of 8G12 with the HEV E2s domain (the most protruded region of the virus capsid) of the abundant genotypes 1 and 4 were determined at 4.0 and 2.3 Å resolution, respectively. These structures revealed that 8G12 recognizes both genotypes through the epitopes in the E2s dimerization region. Structure-based mutagenesis and cell-model assays with virus-like particles identified several conserved residues (Glu549, Lys554 and Gly591) that are essential for 8G12 neutralization. Moreover, the epitope of 8G12 is identified as a key epitope involved in virus-host interactions. These findings will help develop a common strategy for the prevention of the most abundant form of HEV infection.
戊型肝炎病毒（HEV）是一种无包膜的正链单链RNA病毒，是肠道肝炎的主要病因。HEV被归类于戊型肝炎病毒科，包含四种基因型（基因型1-4），属于单一血清型。我们描述了一种单克隆抗体（mAb）8G12，它能同等识别HEV的所有四种基因型，结合亲和力约为2.53-3.45 nM。单克隆抗体8G12具有保护性中和能力，可显著阻断病毒在宿主细胞中的感染。对基因型1、3和4进行的动物研究证实了8G12的跨基因型中和能力及其对戊型肝炎疾病的有效预防作用。分别以4.0 Å和2.3 Å的分辨率测定了8G12与丰富基因型1和4的HEV E2s结构域（病毒衣壳最突出的区域）的复合物晶体结构。这些结构表明，8G12通过E2s二聚化区域中的表位识别这两种基因型。基于结构的诱变和使用病毒样颗粒的细胞模型试验确定了几个对8G12中和至关重要的保守残基（Glu549、Lys554和Gly591）。此外，8G12的表位被确定为参与病毒-宿主相互作用的关键表位。这些发现将有助于制定一种预防最常见形式的HEV感染的通用策略。
