Zika Virus Capsid Protein Mediated Blockage of host microRNA machinery

总结 寨卡病毒（ZIKV）是黄病毒科的单链RNA病毒。它迅速蔓延到世界各地， 2015-2016年，与胎儿小头畸形、宫内发育迟缓和其他 先天性畸形据报道，ZIKV在怀孕期间感染胎盘和胎儿大脑，特别是在妊娠期间。 靶向人神经干细胞和祖细胞（NSC）。在黄病毒家族中，只有ZIKV与 小头畸形，表明ZIKV感染与其他成员相比具有独特性，这需要更好的治疗方法。 了解胎儿脑中ZIKV免疫逃避和发病机制的分子驱动因素。此外，主持人 ZIKV蛋白的分子靶标仍然难以捉摸，这不仅限制了我们对ZIKV感染的理解， ZIKV的发病机制，而且还阻碍了抗ZIKV药物的开发。 自2015年ZIKV爆发以来，我们一直专注于了解ZIKV感染的复杂性， 小头畸形的发病机制。为了充分了解病毒蛋白在ZIKV生命周期中的作用，我们 在人iPSC衍生的NSC中建立了ZIKV-宿主相互作用组。通过分析这种ZIKV-宿主相互作用组， 我们发现关键的microRNA加工蛋白DICER是ZIKV衣壳蛋白的最高靶标，DICER 缺乏促进小鼠胚胎NSC中的ZIKV感染。microRNA的失调已经被 与许多人类疾病相关的疾病，包括发育性神经障碍， 小头畸形更重要的是，DICER依赖性microRNA的产生通常被植物、真菌和真菌所使用。 无脊椎动物，并保持活跃的哺乳动物干细胞产生抗病毒的小RNA从病毒 基因组，通过RISC介导的RNA干扰抑制病毒复制。机械地，我们进一步 鉴定了ZIKV衣壳直接与DICER相互作用，并阻断其核糖核酸酶活性，抑制了 病毒干扰RNA和宿主microRNA的产生是神经发生所必需的。 因此，我们假设ZIKV可以有效地抑制DICER介导的抗病毒viRNA途径。 ZIKV衣壳通过其衣壳蛋白与宿主细胞的相互作用;并且通过拮抗宿主microRNA机制，ZIKV衣壳也进行干预。 神经发育和导致小头畸形和其他出生缺陷。根据目前的申请，我们建议 为了进一步研究作为ZIKV免疫调节的独特决定因素的DICER功能的caplycoprotein依赖性抑制， 逃避和发病机制，使用不同的ZIKV毒株和衣壳变体在人胎儿NSC和人胚胎NSC中进行研究。 产前感染的小鼠模型。通过了解DICER在ZIKV感染中的独特作用及其在ZIKV感染中的作用， 相关的小头畸形，我们希望确定一个capthalm依赖的差异之间的巴西和非洲 菌株（AIM 1-2），并提供了一个概念验证，无论是加强这种viRNA依赖性先天免疫 该系统适用于作为逆转胎儿脑中ZIKV发病机制的新方法（AIM 2-3）。的 该应用的结果也将为其他CNS感染性疾病提供更广泛的见解。

SUMMARY Zika virus (ZIKV) is a single-stranded RNA virus of the Flaviviridae family. It rapidly spread worldwide during 2015-2016 and is causally associated with fetal microcephaly, intrauterine growth retardation, and other congenital malformations. ZIKV is reported to infect placenta and fetal brain during pregnancy, particularly targeting human neural stem and progenitor cells (NSCs). Among the flavivirus family, only ZIKV is linked to microcephaly, suggesting uniqueness of ZIKV infection compared to other members, which calls for a better understanding of the molecular drivers of ZIKV immune evasion and pathogenesis in fetal brain. In addition, host molecular targets of ZIKV proteins remain elusive, which not only limits our understanding of ZIKV infection and pathogenesis, but also impedes anti-ZIKV drug development. Since the ZIKV outbreak in 2015, we have focused on understanding the complexity of ZIKV infection and pathogenesis of microcephaly. To fully understand the roles of viral proteins during ZIKV life cycle, we established the ZIKV-host interactome in human iPSC-derived NSCs. By analyzing this ZIKV-host interactome, we found that the key microRNA processing protein DICER was the top target of ZIKV capsid protein, and DICER deficiency facilitated ZIKV infection in mouse embryonic NSCs. Dysregulation of microRNAs has been associated with many human disease diseases, including developmental neurological disorders such as microcephaly. More importantly, DICER-dependent microRNA production is commonly used by plants, fungi and invertebrates, and remains active in mammalian stem cells to produce antiviral small RNAs from the viral genomes, which inhibits viral replication via RISC-mediated RNA interference. Mechanistically, we further identified that ZIKV capsid directly interacts with DICER and blocks its ribonuclease activity, dampening the production of both viral interfering RNAs and host microRNAs that are essential for neurogenesis. Therefore, we hypothesize that ZIKV can efficiently suppress the DICER-mediated antiviral viRNA pathway in host cells with its capsid protein; and by antagonizing host microRNA machinery, ZIKV capsid also intervenes neural development and causes microcephaly and other birth defects. Under the current application, we propose to further investigate capsid-dependent suppression of DICER function as a unique determinant of ZIKV immune evasion and pathogenesis, using different ZIKV strains and capsid variants in both human fetal NSCs and a mouse model of prenatal infection. By understanding the unique role of DICER in ZIKV infection and its associated microcephaly, we hope to define a capsid-dependent difference between the Brazilian and African strains (AIMs 1-2), and provide a proof-of-concept whether boosting this viRNA-dependent innate immune system is applicable as a novel approach to reverse the pathogenesis of ZIKV in fetal brain (AIMs 2-3). The outcomes of this application will also provide broader insight for other CNS infectious diseases.