Huang Sheng-Wen, Huang Yi-Hui, Tsai Huey-Pin, Kuo Pin-Hwa, Wang Shih-Min, Liu Ching-Chuan, Wang Jen-Ren
Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan.
Department of Medical Laboratory Science and Biotechnology, National Cheng Kung University, Tainan, Taiwan.
J Virol. 2017 Nov 14;91(23). doi: 10.1128/JVI.01062-17. Print 2017 Dec 1.
RNA viruses accumulate mutations to rapidly adapt to environmental changes. Enterovirus A71 (EV-A71) causes various clinical manifestations with occasional severe neurological complications. However, the mechanism by which EV-A71 evolves within the human body is unclear. Utilizing deep sequencing and haplotype analyses of viruses from various tissues of an autopsy patient, we sought to define the evolutionary pathway by which enterovirus A71 evolves fitness for invading the central nervous system in humans. Broad mutant spectra with divergent mutations were observed at the initial infection sites in the respiratory and digestive systems. After viral invasion, we identified a haplotype switch and dominant haplotype, with glycine at VP1 residue 31 (VP1-31G) in viral particles disseminated into the integumentary and central nervous systems. viral growth and fitness analyses indicated that VP1-31G conferred growth and a fitness advantage in human neuronal cells, whereas VP1-31D conferred enhanced replication in human colorectal cells. A higher proportion of VP1-31G was also found among fatal cases, suggesting that it may facilitate central nervous system infection in humans. Our data provide the first glimpse of EV-A71 quasispecies from oral tissues to the central nervous system within humans, showing broad implications for the surveillance and pathogenesis of this reemerging viral pathogen. EV-A71 continues to be a worldwide burden to public health. Although EV-A71 is the major etiological agent of hand, foot, and mouth disease, it can also cause neurological pulmonary edema, encephalitis, and even death, especially in children. Understanding selection processes enabling dissemination and accurately estimating EV-A71 diversity during invasion in humans are critical for applications in viral pathogenesis and vaccine studies. Here, we define a selection bottleneck appearing in respiratory and digestive tissues. Glycine substitution at VP1 residue 31 helps viruses break through the bottleneck and invade the central nervous system. This substitution is also advantageous for replication in neuronal cells Considering that fatal cases contain enhanced glycine substitution at VP1-31, we suggest that the increased prevalence of VP1-31G may alter viral tropism and aid central nervous system invasion. Our findings provide new insights into a dynamic mutant spectral switch active during acute viral infection with emerging viral pathogens.
RNA病毒通过积累突变来快速适应环境变化。肠道病毒A71（EV - A71）可引发多种临床表现，偶尔还会出现严重的神经并发症。然而，EV - A71在人体内的进化机制尚不清楚。我们利用一名尸检患者各种组织中的病毒进行深度测序和单倍型分析，试图确定肠道病毒A71进化出适应入侵人类中枢神经系统能力的进化途径。在呼吸道和消化系统的初始感染部位观察到具有不同突变的广泛突变谱。病毒入侵后，我们鉴定出一个单倍型转换和优势单倍型，在传播到皮肤和中枢神经系统的病毒颗粒中，VP1蛋白第31位残基为甘氨酸（VP1 - 31G）。病毒生长和适应性分析表明，VP1 - 31G赋予在人神经元细胞中的生长和适应性优势，而VP1 - 31D则赋予在人结肠直肠细胞中增强的复制能力。在致命病例中也发现较高比例的VP1 - 31G，这表明它可能促进人类中枢神经系统感染。我们的数据首次展示了人类体内从口腔组织到中枢神经系统的EV - A71准种情况，对这种重新出现的病毒病原体的监测和发病机制具有广泛意义。EV - A71仍然是全球公共卫生的负担。尽管EV - A71是手足口病的主要病原体，但它也可引起神经源性肺水肿、脑炎甚至死亡，尤其是在儿童中。了解病毒传播的选择过程并准确估计EV - A71在人类入侵过程中的多样性对于病毒发病机制和疫苗研究的应用至关重要。在此，我们定义了出现在呼吸道和消化组织中的一个选择瓶颈。VP1蛋白第31位残基的甘氨酸替代有助于病毒突破瓶颈并入侵中枢神经系统。这种替代对于在神经元细胞中的复制也有利。鉴于致命病例中VP1 - 31处的甘氨酸替代增加，我们认为VP1 - 31G患病率的增加可能改变病毒嗜性并有助于中枢神经系统入侵。我们的发现为急性病毒感染新兴病毒病原体期间活跃的动态突变谱转换提供了新见解。
