Translational Control of Cytomegalovirus Gene Expression

描述(申请人提供)：人类巨细胞病毒(HCMV)导致大量的发病率和死亡率，主要是在新生儿和免疫功能低下的患者中。与其他病毒一样，HCMV必须逃避多种宿主细胞的抗病毒防御机制，其中之一是阻断干扰素诱导的双链RNA(DsRNA)激活的蛋白激酶R(PKR)介导的整体蛋白质合成。HCMV编码两种蛋白，pTRS1和pIRS1，它们可以阻断PKR的激活。除了自结合和与dsRNA和PKR结合外，这些蛋白还具有前所未有的作用，使PKR重新定位到细胞核。为了阐明pTRS1和pIRS1对PKR的作用机制和意义，我们提出了精确描述pTRS1和pIRS1与RNA和蛋白质相互作用的结构域的实验。这些研究还将揭示pTRS1和pIRS1对PKR的核重新定位是一种不寻常的病毒策略，用于将PKR从其细胞质靶标中移除，还是作为一种促进PKR尚未确定的核功能的手段，这可能对病毒有利。最后，实验将直接检验这一假设，即pTRS1或pIRS1，特别是它们与dsRNA和PKR结合的能力，对HCMV复制是必不可少的。了解巨细胞病毒干扰PKR途径的机制将有助于从新的角度研究在其他系统中抑制PKR所需的生化相互作用，以及深入了解PKR核再分配活性的意义，到目前为止，PKR核再分配活性似乎是BetaherpeVirus的独特特性。对这些非常规HCMV dsRNA结合蛋白的研究也将有助于在其他系统中发现新的dsRNA结合蛋白，并分析它们在对抗PKR和其他dsRNA激活反应中的功能。最后，由于缺乏阻断PKR激活能力的突变病毒在动物模型中的毒力大大降低，这些研究结果可能在开发新的抗病毒策略和开发减毒活疫苗方面具有应用价值。

DESCRIPTION (provided by applicant): Human cytomegalovirus (HCMV) causes substantial morbidity and mortality, primarily in newborns and immunocompromised patients. Like other viruses, HCMV must evade myriad host cell antiviral defense mechanisms, among which is the shut off of overall protein synthesis mediated by the interferon-induced, double-stranded RNA (dsRNA)-activated protein kinase R (PKR). HCMV encodes two proteins, pTRS1 and pIRS1, that block PKR activation. In addition to self-associating and to binding to dsRNA and to PKR, these proteins have the unprecedented effect of causing PKR to relocalize to the nucleus. In order to elucidate the mechanism and significance of pTRS1 and pIRS1 effects on PKR, experiments are proposed to precisely delineate the domains of pTRS1 and pIRS1 responsible for their interactions with RNA and proteins. These studies will also reveal whether the nuclear relocalization of PKR by pTRS1 and pIRS1 serves as an unusual viral strategy for removing PKR from its cytoplasmic targets or as a means of facilitating an as-yet-unidentified nuclear function of PKR that may be beneficial to the virus. Finally, experiments will directly test the hypothesis that either pTRS1 or pIRS1, and in particular their ability to bind to dsRNA and PKR, is essential for HCMV replication. Understanding the mechanism by which HCMV interferes with the PKR pathway will contribute new perspectives into biochemical interactions required for PKR inhibition in other systems as well as insights into the significance of the PKR nuclear redistribution activity which thus far seems to be a unique property of betaherpeviruses. The insights gained from studies of these unconventional HCMV dsRNA-binding proteins will also contribute to identifying new dsRNA-binding proteins in other systems and for analyzing their functions in counteracting PKR and other dsRNA-activated responses. Finally, since mutant viruses lacking the ability to block PKR activation have greatly reduced virulence in animal models, results of these studies may have applications in the development of new antiviral strategies and for the development of live attenuated vaccines.