Control of innate immunity and apoptosis by Measles virus P, V and C proteins

描述（由申请人提供）：成功的病毒复制不仅需要子代的有效生产和传播，还需要通过杀死感染细胞来逃避限制复制的宿主防御机制。几乎所有的病毒都有逃避宿主防御的机制，如干扰素（IFN）激活和/或凋亡诱导。与大多数病毒一样，麻疹病毒（MV）在感染细胞后会产生多种细胞内抗病毒反应。更好地了解麻疹病毒如何逃避宿主防御机制将有助于设计一种更弱的疫苗株，用于免疫抑制患者或开发新的溶瘤病毒用于潜在的癌症治疗。近年来，人们已经清楚，副粘病毒家族病毒P基因的蛋白产物会特异性降低细胞内抗病毒反应的有效性。MV P基因编码三种蛋白质，磷蛋白P和两种辅助蛋白V和C。所有这三种蛋白质都与先天免疫控制有关，但它们的作用机制仍不清楚。本文的研究将进一步阐明P基因产物在控制MV诱导的抗病毒反应中的功能。我们的研究将使用双重方法进行，包括研究单独表达的蛋白质的功能以及在病毒感染的背景下。为了这个目标，我们已经产生了表达质粒编码的个别蛋白质P/V和重组病毒中的一个或两个的V和C蛋白的缺陷，我们将表征其逃避宿主防御机制的能力。在目标1中，我们将描述最近确定的酪氨酸丰富的结构域的P/V蛋白的共同区域中的作用，并评估其在抑制IFN信号转导的重要性。为了了解该结构域的分子作用机制，将分析IFN信号传导途径的不同步骤，并尝试鉴定与该结构域相互作用的细胞伴侣。在目标2中，我们将研究V和C蛋白的潜在新功能，包括保护细胞免受凋亡诱导。我们将表征在没有V和C蛋白的情况下在感染细胞中激活的凋亡途径。在一个平行的方法中，我们将研究V和C蛋白对细胞凋亡的外部诱导物的保护特性。这些研究对于理解麻疹病毒如何从先天免疫中逃逸具有重要意义。拟议的研究与公共卫生有关，因为更好地了解麻疹病毒如何逃避宿主防御将有助于设计用于免疫抑制患者的更减毒疫苗株或开发用于癌症治疗的新溶瘤病毒。

DESCRIPTION (provided by applicant): Successful viral replication requires not only the efficient production and spread of progeny, but also evasion of host defense mechanisms that limit replication by killing infected cells. Almost all viruses have developed mechanisms to evade host defense, such as interferon (IFN) activation and/or apoptosis induction. Like most viruses, upon infection of cells, measles virus (MV) is subjected to a variety of intracellular antiviral responses. A better understanding of how measles virus evades the host defense mechanisms will facilitate the design of a more attenuated vaccine strain for use in immunosuppressed patients or for the development of new oncolytic viruses for potential cancer therapy. In recent years, it has become clear that protein products from the P gene of viruses within the Paramyxovirus family specifically reduce the effectiveness of the intracellular antiviral responses. The MV P gene encodes for three proteins, the phosphoprotein P, and two accessory proteins V and C. All three proteins have been implicated in innate immune control, but their mechanisms of action still remains unclear. The research proposed here will further characterize the functions of the P gene products in the control of the antiviral response induced by MV. Our study will be conducted using a dual approach that includes a study of the function of the proteins expressed alone as well as in the context of a viral infection. Toward this goal, we have produced expression plasmids encoding for the individual proteins P/V and recombinant viruses deficient in one or both of the V and C proteins and we will characterize their abilities to evade host defense mechanisms. In aim 1, we will characterize the role of a recently identified tyrosine-rich domain in the common region of the P/V protein and assess its importance in the inhibition of IFN signaling. To understand the molecular mechanism of action of this domain, different steps of the IFN signaling pathway will be analyzed and an identification of cellular partners interacting with this domain will be attempted. In aim 2, we will investigate a potential new function for the V and C proteins that consists to protect the cell against induction of apoptosis. We will characterize the apoptotic pathways activated in infected cells in the absence of the V and C proteins. And in a parallel approach we will investigate the protective properties of the V and C proteins against external inducers of apoptosis. The proposed studies are of an important area to understand how measles virus escapes from innate immunity. The proposed research has relevance to public health, as a better understanding of how measles virus evade host defense will facilitate the design of more attenuated vaccine strain for use in immunosuppressed patients or the development of new oncolytic viruses for cancer therapy.