Molecular Mechanism of Poxvirus Host Range Genes

描述：正痘病毒在体外可以在非常广泛的细胞系中进行高效复制，但在某些特定细胞系中的复制是失败的，除非所谓的“宿主范围”基因在其基因组中完好无损。在我们的初步研究中，我们发现牛痘病毒(W)在原代人细胞中高效复制和在小鼠模型中产生W毒力也需要一个功能性宿主基因K1L、C7L或CP77。然而，这些宿主范围的基因支持病毒在非允许宿主中生长的机制尚不清楚。K1L、C7L和CP77没有明显的氨基酸序列同源性，但CP77和K1L都编码多个锚蛋白重复序列。由于锚蛋白重复序列蛋白通常在介导特异性蛋白-蛋白相互作用中起作用[2,3]，我们假设CP77和K1L通过它们的锚蛋白重复序列与特异性病毒或/和细胞因子相互作用，以绕过痘病毒复制的一些细胞内屏障。这一假设得到了我们的初步研究的支持，这些研究表明：(1)几个连续的K1L锚蛋白重复序列的可变表面残基对其在人类细胞中的宿主范围功能至关重要；(2)病毒复制过程中K1L与wc10l蛋白相互作用；(3) K1L直接与细胞外信号调节激酶5 （ERK5）相互作用，ERK5是丝裂原活化蛋白激酶（MAPK）级联反应的重要组成部分，调节多种细胞过程。我们将通过实现以下具体目标来进一步检验我们的假设：通过对k1landcp77的结构-功能分析，探讨其宿主功能的分子基础。2. 确定K1L是否通过与ERK5的相互作用介导其宿主范围功能。完成这两个特定的目标将提供一些关于正型病毒复制的细胞内屏障和病毒绕过这些屏障的策略的基本知识。这将有利于开发更安全的疫苗和针对致病性正痘病毒（如天花病毒和猴痘病毒）的新型抗病毒药物。

DESCRIPTION: Orthopoxviruses can replicate productively in a very broad range of cell lines in vitro, but their replications in some specific cell lines are abortive unless the so-called "host-range" genes are intact in their genome [1]. In our preliminary studies, a functional host-range gene, either K1L or C7L or CP77, was found to be also required for vaccinia virus (W) to replicate productively in primary human cells and for W virulence in a mouse model. However, the mechanisms by which these host-range genes support viral growth in otherwise non-permissive host are not clear. K1L, C7L and CP77 share no significant amino acid sequence homology, but both CP77 and K1L encode multiple ankyrin repeats. Because ankyrin repeats proteins typically function in mediating specific protein-protein interactions [2, 3], we hypothesize that CP77 and K1L interact with specific viral or/and cellular factors via their ankyrin repeats to circumvent some intracellular barriers of poxvirus replication. This hypothesis is supported by our preliminary studies that demonstrated: (1) variable surface residues of a few consecutive K1L ankyrin repeats are essential for its host-range function in human cells;(2) K1L interacts with W C10L protein during viral replication; and (3) K1L interacts directly with extracellular signal-regulated kinase 5 (ERK5), a crucial component of mitogen- activated protein kinase (MAPK) cascades regulating multiple cellular processes. We will further test our hypothesis by accomplishing the following specific aims: 1. To explore the molecular basis for the host-range function through structure-function analysis ofK1LandCP77. 2. To determine whether K1L mediates its host-range function through interactions with ERK5 . and WCIOL Accomplishing these two specific aims will provide some fundamental knowledge about the intracellular barriers of orthopoxviral replication and viral strategies of circumventing these barriers. This will benefit the development of safer vaccines and novel antivirals for pathogenic Orthopoxviruses such as variola virus and monkeypox virus.