Immune Mechanisms That Control Ectromelia Virus Infection

描述(申请人提供)：病毒和它们的宿主共同进化出一种错综复杂的相互作用，在感染过程中得到微妙的平衡。探索这种自然关系的价值，而不是目前盛行的不匹配的实验系统，正变得越来越明显。本节目将直接关注ECTROMELIA病毒(ECTV)，这是一种真正的老鼠病原体，具有几个吸引人的特性。首先，传播途径与其他正痘病毒科的自然宿主相似。其次，鼠痘疾病与人类猴痘和天花非常相似。第三，一些小鼠品系对ECTV具有抵抗力，而另一些品系则高度敏感，类似于人类种群中的自然变异。对于痘苗病毒(VACV)来说，这一切都不是真的，VACV是一种来源不明的正痘病毒，经常用于小鼠免疫模型，以下给出的初步结果使人更加怀疑。该计划由三名在宿主防御痘病毒方面具有丰富经验的PI领导，将全面剖析ECTV与耐/敏感小鼠品系之间的相互作用，并在适当时参考VACV。项目1将检查先天系统的细胞和细胞因子，这些细胞和细胞因子在控制感染部位的病毒方面发挥关键作用。项目2通过检查1型干扰素限制病毒在引流淋巴结外扩散的机制，继续检查先天/自然免疫。最后，项目2和项目3将调查适应性免疫系统的所有三个主要分支，以了解它们如何防御初次感染并建立针对后续挑战的保护。这三个项目都将审查ECTV为挫败这些不同水平的主持人防御而采取的战略。管理、生物试剂和成像核心组件将为该计划提供广泛的支持，后两者将开展自己的探索性项目。我们用这个假设驱动的、高度互动的程序的目标是发展对病毒-宿主关系的理解，为许多其他自然病毒感染提供一个框架。 项目1：感染部位对鼠痘的先天免疫反应(Norbury，C) 项目1描述(由申请人提供)：在自然病毒感染期间，小剂量的传染性病毒沉积在外围感染部位，然后发生“竞赛”，其中复制的病毒试图“超过”宿主的免疫系统。在感染的早期阶段，先天免疫系统必须在形成适应性反应之前遏制感染。在项目1中，我们将研究先天免疫系统用来遏制鼠痘感染的机制，鼠痘是一种由鼠痘病毒(ECTV)引起的致命小鼠疾病，ECTV是一种独有的老鼠病原体。这个系统是独一无二的，因为它允许我们检查敏感和耐药小鼠品系的先天反应。这三个具体目标将检查在感染部位减缓ECTV系统性传播所需的细胞，介导其迁移到感染部位的趋化物质，以及病毒和免疫系统在病毒与细胞相互作用期间使用的细胞生物学机制。在目标1中，我们将描述耐药或易感小鼠中ECTV感染部位的细胞渗透特征，并确定减缓ECTV全身传播所需的先天免疫效应细胞类型，并允许发展出能够清除感染的适应性反应。在这个目标中，我们还将研究先天免疫细胞所需的效应器功能，以延缓ECTV感染。在目标2中，我们将确定在耐药或易感ECTV感染的小鼠中表达的趋化因子和趋化因子受体，以及对吸引先天效应细胞(减缓病毒复制和传播)至关重要的趋化因子。我们还将研究ECTV编码的细胞迁移免疫调节剂在对病毒的先天反应中的作用，并将在体内确定这些基因的靶点。在目标3中，我们将研究ECTV和天然免疫细胞在体外的相互作用，主要集中在巨噬细胞吞噬，这是最近被描述为正痘病毒的感染方式。巨噬细胞吞噬作用在启动适应性免疫反应的细胞外溶质采样中起着重要作用，我们将检查它对启动先天免疫反应的环境采样的贡献。我们还将研究TLR9的转运到大针体的情况，TLR9是一种先天受体，是在ECTV挑战中生存所必需的。该项目的结果将提供对外周病毒感染的先天反应的全面图景。

DESCRIPTION (provided by applicant): Viruses and their hosts have co-evolved an intricate interplay that is delicately balanced during the course of infection. The value of exploring such a natural relationship, rather than the mismatched experimental systems that currently prevail, is becoming increasingly clear. This program will focus squarely upon ectromelia virus (ECTV), a genuine mouse pathogen with several attractive properties. First, routes of transmission are similar to those of other orthopoxviridae in their natural hosts. Second, mousepox disease is remarkably similar to that of human monkeypox and smallpox. Third, some mouse strains are resistant to ECTV while others are highly susceptible, analogous to natural variations within human populations. None of this is true for vaccinia virus (VACV), an orthopoxvirus of unknown origin, frequently used in mouse models of immunity, and made all the more suspect by preliminary results presented below. Headed by three PIs with extensive experience in host defense against poxviruses, the program will comprehensively dissect the interplay between ECTV and resistant/susceptible strains of mice, referencing to VACV when appropriate. Project 1 will examine the cells and cytokines of the innate system that play critical roles in keeping the virus in check at the site of infection. Project 2 continues inspection of innate/natural immunity by examining the mechanisms by which type 1 interferons limit spread of the virus beyond the draining lymph node. Finally, Projects 2 and 3 will investigate all three major arms of the adaptive immune system to understand how they defend against primary infection and establish protection from subsequent challenge. All three projects will examine strategies by ECTV to thwart these different levels of host defense. Administrative, Biological Reagent, and Imaging Core Components will provide a wide range of support to the program, with the latter two carrying out their own exploratory projects. Our goal with this hypothesis-driven, highly interactive program is to develop an understanding of virus-host relationships that provides a framework for many other natural virus infections. PROJECT 1: THE INNATE IMMUNE RESPONSE TO MOUSEPOX AT THE SITE OF INFECTION (Norbury, C) PROJECT 1 DESCRIPTION (provided by applicant): During a natural virus infection small doses of infectious virus are deposited at a peripheral infection site and then a "race" ensues, in which the replicating virus attempts to "outpace" the host's immune system. In the early phases of infection, the innate immune system must contain the infection prior to the development of an adaptive response. In Project 1 we will examine the mechanisms that are used by the innate immune system to contain infection with mousepox, a lethal mouse disease caused by ectromelia virus (ECTV), an exclusive mouse pathogen. This system is unique because it allows us to examine the innate response in susceptible and resistant mouse strains. The three Specific Aims will examine the cells that are required to slow the systemic spread of ECTV at the site of infection, the chemoattractants that mediate their migration to the site of infection and the cell biological mechanisms that are used by both the virus and the immune system during virus-cell interaction. In Aim 1 we will characterize the cellular infiltrate to the site of ECTV infection in resistant or susceptible mice and identify the innate immune effector cell types that are required to slow the systemic spread of ECTV and allow the development of an adaptive response that can clear the infection. In this aim we will also examine the effector functions that are required by innate immune cells to retard ECTV infection. In Aim 2 we will determine the chemokines and chemokine receptors expressed at the site of ECTV infection in resistant or susceptible mice, and the chemokines that are essential to attract innate effector cells that slow replication and spread of the virus. We will also study the role of immune modifiers of cellular migration encoded by ECTV in the innate response to the virus, and will identify the targets of these genes in vivo. In Aim 3 we will study the interaction of ECTV and innate immune cells in vitro, focusing primarily upon macropinocytosis, which has recently been described as the mode of infection of orthopoxviruses. Macropinocytosis has an important role in the sampling of extracellular solute for initiation of an adaptive immune response and we will examine its contribution to sampling of the environment for initiation of an innate response. We will also examine the trafficking to macropinosomes of TLR9, an innate receptor that is required for survival from ECTV challenge. The results from this Project will provide a comprehensive picture of the innate response to a peripheral virus infection.