IRES在调节在小RNA病毒感染的神经毒性方面起着极其关键的作用，EV71 作为神经毒性仅次于脊髓灰质炎病毒的小RNA病毒科成员，其致神经毒性机理仍是个迷。在本研究中，我们将利用UDPS对不同临床症状的样品进行分析，确定IRES上的突变热点区域，找出IRES在群体内的突变规律，揭示EV71致神经毒性的分子基础。通过突变以及片段置换等技术，构建一组带有IRES上不同位点突变的复制子和重组病毒，在神经细胞和非神经细胞内检测不同的复制子和重组病毒对病毒复制效率、病毒和宿主蛋白翻译能力的影响，鉴定EV71 与神经毒性相关的蛋白, 解析IRES的突变与神经毒性变化的关系；利用动物感染实验测试不同的重组病毒在不同组织内的分布，病理变化以及不同组织内病毒载量的差异；比较不同重组病毒对宿主组织嗜性的变化，阐明EV71致神经毒性靶位点与宿主免疫系统相互作用，以及EV71 致神经毒性的分子机制。

IRES (Internal Ribosome Entry Site) plays a key role in modulating neurotoxicity after picornavirus infection. EV71 is second to poliovirus in neurotoxicity. However, the mechanism of this is still unknown. In our study, we will locate the mutation hot spots of the samples showed different clinical symptoms via UDPS (Ultra Deep Pyrosequencing), find the IRES mutation pattern in human population, and reveal the molecular mechanism of neurotoxicity caused by EV71 infection. By site-specific mutation and fragment replacement, we will construct a series of replicons and recombinant EV71 viruses containing differently mutated IRES. Then we will evaluate virus replication efficiency and host protein translation capacity in neuronal or non-neuronal cells, identify neurotoxicity-associated proteins, analyze the relationship between IRES mutation and neurotoxicity; we will also test the distribution pattern, pathological changes, and virus load of recombinant EV71 viruses in different organs in suckling mice. These will help us better understand the tissue tropism variation and the mechanism of the interaction between neurotoxicity-dominated sites and host immune system, thus unveil the mystery of neurotoxicity.