Division of Pathway Medicine, University of Edinburgh Medical School, Edinburgh, UK.
J Virol. 2011 Oct;85(19):10286-99. doi: 10.1128/JVI.00373-11. Epub 2011 Jul 20.
Activated macrophages play a central role in controlling inflammatory responses to infection and are tightly regulated to rapidly mount responses to infectious challenge. Type I interferon (alpha/beta interferon [IFN-α/β]) and type II interferon (IFN-γ) play a crucial role in activating macrophages and subsequently restricting viral infections. Both types of IFNs signal through related but distinct signaling pathways, inducing a vast number of interferon-stimulated genes that are overlapping but distinguishable. The exact mechanism by which IFNs, particularly IFN-γ, inhibit DNA viruses such as cytomegalovirus (CMV) is still not fully understood. Here, we investigate the antiviral state developed in macrophages upon reversible inhibition of murine CMV by IFN-γ. On the basis of molecular profiling of the reversible inhibition, we identify a significant contribution of a restricted type I IFN subnetwork linked with IFN-γ activation. Genetic knockout of the type I-signaling pathway, in the context of IFN-γ stimulation, revealed an essential requirement for a primed type I-signaling process in developing a full refractory state in macrophages. A minimal transient induction of IFN-β upon macrophage activation with IFN-γ is also detectable. In dose and kinetic viral replication inhibition experiments with IFN-γ, the establishment of an antiviral effect is demonstrated to occur within the first hours of infection. We show that the inhibitory mechanisms at these very early times involve a blockade of the viral major immediate-early promoter activity. Altogether our results show that a primed type I IFN subnetwork contributes to an immediate-early antiviral state induced by type II IFN activation of macrophages, with a potential further amplification loop contributed by transient induction of IFN-β.
激活的巨噬细胞在控制感染引起的炎症反应中起着核心作用，并且受到严格调控，以迅速对感染性挑战做出反应。I 型干扰素（α/β干扰素[IFN-α/β]）和 II 型干扰素（IFN-γ）在激活巨噬细胞并随后限制病毒感染方面起着至关重要的作用。这两种类型的 IFNs 通过相关但不同的信号通路传递信号，诱导大量重叠但可区分的干扰素刺激基因。IFNs（特别是 IFN-γ）抑制 DNA 病毒（如巨细胞病毒[CMV]）的确切机制尚未完全阐明。在这里，我们研究了在通过 IFN-γ可逆抑制鼠 CMV 后巨噬细胞中发展出的抗病毒状态。基于对可逆抑制的分子谱分析，我们确定了与 IFN-γ激活相关的受限 I 型 IFN 子网的重要贡献。在 IFN-γ刺激的情况下，敲除 I 型信号通路的遗传缺陷，揭示了在巨噬细胞中发展出完全抗性状态时，预先存在的 I 型信号过程的基本要求。在使用 IFN-γ激活巨噬细胞时，也可以检测到 IFN-β的短暂瞬时诱导。在 IFN-γ的剂量和动力学病毒复制抑制实验中，证明了抗病毒作用的建立发生在感染的最初几个小时内。我们表明，在这些非常早期的时间点，抑制机制涉及阻断病毒主要即刻早期启动子活性。总的来说，我们的结果表明，预先存在的 I 型 IFN 子网有助于 II 型 IFN 激活巨噬细胞诱导的即刻早期抗病毒状态，潜在的进一步扩增环由 IFN-β的短暂诱导贡献。
