Novel Translational Control Mechanisms in Host Range Restriction of Poxvirus

所有病毒都依赖宿主翻译机器进行蛋白质合成。因此，翻译 控制构成了针对病毒的通用宿主防御。对主机如何工作的新认识 调节对病毒感染的应答的翻译，以及病毒如何逃避这种宿主应答将 为病毒的发病机理提供了基本的见解，并有利于开发新的抗病毒药物 战略布局 痘病毒包括一些危险的新兴病原体以及一些有前途的疫苗 向量。与许多其他病毒不同，痘病毒的宿主范围不受进入步骤的影响， 受到细胞内过程的限制。特别地，细胞翻译控制途径具有 深刻影响痘病毒宿主范围，这些途径的痘病毒抑制剂可以 表现为关键的宿主范围因素。最著名的例子是PKR介导的对 两种痘苗病毒宿主范围蛋白E3的翻译起始及其拮抗作用 还有K3。关于PKR非依赖性途径的了解要少得多，这一途径由两个关键的 VACV宿主范围蛋白，K1和C7。K1和C7缺失的VACV无法复制 在大多数哺乳动物细胞中，由于病毒和宿主蛋白质合成的关闭。有趣的是， 翻译关闭不依赖于PKR和RNaseL，似乎不涉及任何 翻译起始因子一对旁系同源的干扰素刺激基因SAMD 9和 SAMD 9 L（SAMD9&L）是K1的特异性靶基因 C7的。然而，它们是如何调节蛋白质合成和限制痘病毒宿主范围的， 这是一个未知的问题，也是这个问题的焦点。 我们对K1/C7及其细胞的理解做出了持续的贡献。 十多年来的目标，包括确定K1/C7的结构和 鉴定SAMD 9 L作为K1/C7的细胞靶标。此外，我们还获得了令人信服的 初步数据导致了我们的新假设，这些假设将与 具体目标。 目标1.确定SAMD 9如何被激活以抑制蛋白质合成。 目标2.确定激活的SAMD 9如何抑制蛋白质合成。 目标3：为了确定宿主种特异性SAMD 9 & L OPXV抑制剂。

All viruses rely on host translational machinery for protein synthesis. As such, translation control constitutes a universal host defense against viruses. A new understanding on how host regulates translation in response to viral infection and how viruses evade this host response will provide fundamental insight into viral pathogenesis and benefit the development of new antiviral strategies. Poxviruses include some dangerous emerging pathogens as well as some promising vaccine vectors. Unlike many other viruses, poxvirus host range is not affected by the entry step but restricted by intracellular processes. Particularly, cellular translational control pathways have a profound impact on poxvirus host range, and poxvirus inhibitors of these pathways could manifest as critical host-range factors. The best-known example is PKR-mediated control of translation initiation and its antagonism by two vaccinia virus (VACV) host-range proteins E3 and K3. Much less is understood about a PKR-independent pathway targeted by two critical VACV host-range proteins, K1 and C7. VACV with deletion in both K1 and C7 fails to replicate in most mammalian cells due to a shut-off of viral and host protein synthesis. Intriguingly, the translational shut-off is independent of PKR and RNaseL and appears not to involve any translation initiation factors. A paralogous pair of interferon-stimulated genes, SAMD9 and SAMD9L (SAMD9&L), were recently identified by us and others as the specific targets of K1 and C7. However, how they regulate protein synthesis and restrict poxvirus host range is unknown and is the focus of this proposal. We have made sustained contributions to the understanding of K1/C7 and their cellular targets for over a decade, including the determination of the structures of K1/C7 and the identification of SAMD9L as a cellular target of K1/C7. In addition, we have obtained compelling preliminary data that led to our novel hypotheses, which will be addressed separately with the following specific aims. Aim 1. To determine how SAMD9 is activated to inhibit protein synthesis. Aim 2. To determine how activated SAMD9 inhibits protein synthesis. Aim 3. To determine the molecular basis underlying the host species-specific SAMD9&L inhibition by OPXV inhibitors.