Cellular sources of interferon-beta in virus-infected organs of the mouse

抗病毒宿主防御在很大程度上依赖于I型干扰素(干扰素-α/β)系统。然而，令人惊讶的是，人们对感染组织中I型干扰素的细胞来源知之甚少。为了研究这个问题，我们使用了一只含有萤火虫荧光素酶基因的转基因报告鼠来代替干扰素-β编码区。在这只报告鼠中，产生干扰素-β的细胞可以通过同时对感染病毒的器官进行荧光素酶和细胞标记的免疫染色来识别，或者通过产生在特定细胞类型中唯一表达荧光素酶的条件性报告鼠来识别。使用这个系统，我们最近证明了星形胶质细胞是La Crosse病毒感染小鼠大脑中令人惊讶的强大的干扰素-β产生者。我们进一步证明，如果病毒编码的干扰素拮抗因子NS1没有解除这些细胞的武装，流感病毒感染的巨噬细胞和肺上皮细胞很容易合成干扰素-β。通过经典的育种策略，我们最近培育出了缺乏功能性I型干扰素受体的报告小鼠。这些小鼠代表了一种新的工具，可以用来研究哪些细胞类型需要正反馈环(启动)来有效地合成I型干扰素，以应对病毒感染。目前的项目有两个主要目标：(I)评估从我们以前的工作中得出的假设，即星形胶质细胞是感染病毒的大脑中干扰素-β的主要来源，无论是哪种嗜神经病毒在起作用，以及(Ii)确定在全身或局部病毒感染后产生大量I型干扰素的启动依赖和启动非启动细胞类型。为了解决第一个问题，我们将尝试确定感染泰尔斯小鼠脑炎病毒或狂犬病病毒的小鼠大脑中干扰素-β的细胞来源。为了解决第二个问题，我们将试图揭示在感染托戈托病毒或裂谷热病毒变种的小鼠中产生干扰素-β的细胞的身份，该病毒变种在缺乏或具有功能性I型干扰素受体的小鼠中强烈激活I型干扰素基因的表达。

The antiviral host defense is largely dependent on the type I interferon (IFN-alpha/beta) system. However, surprisingly little is known about the cellular sources of type I IFN in infected tissues. To investigate this issue, we are employing a transgenic reporter mouse that contains the firefly luciferase gene in place of the IFN-beta coding region. In this reporter mouse, IFN-beta-producing cells can be identified by simultaneous immunostaining of virus-infected organs for luciferase and cellular markers, or by generating conditional reporter mice that express luciferase exclusively in defined cell types. Using this system we recently demonstrated that astrocytes are surprisingly potent producers of IFN-beta in the brain of La Crosse virus-infected mice. We further showed that influenza virus-infected macrophages and lung epithelial cells readily synthesize IFN-beta if the virus-encoded IFN-antagonistic factor NS1 is not disarming these cells. By a classical breeding strategy we recently generated reporter mice that lack functional type I IFN receptors. These mice represent a novel tool to investigate the question which cell types require a positive feedback loop (priming) for efficient type I IFN synthesis in response to viral infection. The current project has two main goals: (i) to evaluate the hypothesis derived from our previous work that astrocytes are the main source of IFN-beta in virus-infected brains, irrespective of which neurotropic viruses is at work, and (ii) to identify priming-dependent and priming-independent cell types which produce large amounts of type I IFN after systemic or local viral infection. To address the first question, we will try to identify the cellular sources of IFN-beta in brains of mice infected with either Theilers murine encephalitis virus or rabies virus. To address the second question, we will try to reveal the identity of IFN-beta-producing cells in mice infected either with Thogoto virus or a Rift Valley fever virus variant which strongly activates expression of type I IFN genes both in mice lacking or possessing functional type I IFN receptors.