Paramyxovirus Activation and Inhibition of Complement Pathways

说明(申请人提供)：补体系统是所有动物病毒在自然感染过程中遇到的先天免疫反应的关键组成部分。虽然补体(C‘)显然是许多RNA病毒中和的一个重要因素，但关于C’如何调节呼吸道副粘病毒感染和病理的机制细节知之甚少。在这里，我们试图填补补体(C‘)与副粘病毒猿猴病毒5(SV5)、腮腺炎病毒(Muv)和呼吸道合胞病毒(RSV)相互作用的认识空白。该项目源于最近的发现：1)C‘在中和SV5和MUV中起重要作用；2)SV5和RSV诱导细胞补体激活调节因子(RCA)的表达，一些RCA被整合到SV5、MUV和RSV病毒粒子中；3)C’缺乏小鼠肺中SV5的生长被促进，但鼻部组织的生长不受影响。我们的长期目标是了解细胞和病毒因素，这些因素决定了副粘病毒与感染动物呼吸道中的C‘相互作用的结果。目的1研究RCAs与SV5、MUV和RSV病毒粒子结合的机制，以及病毒粒子相关RCAs在体内的中和和病理中的作用。这将涉及使用创新的EM方法、VLP和过度表达RCA的新型病毒。Aim 2的工作将确定SV5、Muv和RSV上调RCA表达的差异机制，以及感染细胞如何免于裂解。我们的结果表明，在C‘缺乏小鼠的肺组织中，SV5的生长得到了促进，但在鼻部组织中却没有。在目标3中，我们将使用遗传缺陷小鼠来区分C‘在SV5和RSV中和中和中的直接作用，以及C’在免疫细胞向组织的差异化募集中的作用。从我们的工作中出现的新概念解决了以下问题：1)单个RCA如何促进呼吸道病毒的清除和致病，2)什么信号直接将RCA掺入萌芽颗粒中，3)副粘病毒利用什么信号通路使细胞抵抗C‘介导的裂解，以及4)C’在限制感染动物的肺组织而不是鼻组织中的病毒载量方面的不同作用机制。解决这些概念将对我们理解这一对病毒天然免疫研究不足的领域产生重大影响。

DESCRIPTION (provided by applicant): The complement system is a critical component of the innate immune response that all animal viruses encounter during natural infections. While it is clear that complement (C') is an important factor in neutralization of many RNA viruses, very few mechanistic details are known about how C' regulates paramyxovirus infections and pathology in the respiratory tract. Here, we seek to fill gaps in understanding of interactions of complement (C') with the paramyxoviruses Simian Virus 5 (SV5), Mumps virus (MuV) and Respiratory Syncytial Virus (RSV). This project emerged from recent findings that: 1) C' plays an essential role in neutralization of both SV5 and MuV, 2) SV5 and RSV induce expression of cellular Regulators of Complement Activation (RCA) and some RCAs are incorporated into SV5, MuV and RSV virions, and 3) SV5 growth is enhanced in lungs of C'-depleted mice, but growth in the nasal tissue is not affected. Our long term goal is to understand the cellular and viral factors that dictate the outcome of interactions of paramyxoviruses with C' in the respiratory tract of infected animals. Aim 1 will determine the mechanism of incorporation of RCAs into SV5, MuV and RSV virions and the role of virion-associated RCAs in neutralization and pathology in vivo. This will involve the use of an innovative EM approach, VLPs, and novel viruses that overexpress RCAs. Work in Aim 2 will define the mechanisms by which SV5, MuV and RSV differentially upregulate RCA expression and how infected cells are spared from lysis. Our results show that SV5 growth is enhanced in the lung but not the nasal tissue of C'-depleted mice. In Aim 3 we will use genetically deficient mice to distinguish between a direct role for C' in SV5 and RSV neutralization versus a role for C' in differential recruitment of immune cells to tissues. New concepts that have emerged from our work address the questions of: 1) how individual RCAs contribute to viral clearance and pathogenesis in the respiratory tract, 2) what signals direct RCA incorporation into budding particles, 3) what signaling pathways are exploited by paramyxoviruses to make cells resistant to C'-mediated lysis, and 4) what mechanisms dictate differential roles for C' in limiting viral load in the lung but not in the nasal tissue of infected animals. Addressing these concepts will have a significant impact on our understanding of this understudied area of innate immunity to viruses.