Viral Chemokine Alteration of Neutrophil Functions

描述（由申请人提供）：中性粒细胞是人体抵御感染的第一道防线。它们通过释放趋化因子或细胞因子来对抗感染，这些因子或细胞因子会引发其他免疫介质和细胞类型的级联反应。中性粒细胞本身首先通过趋化因子向感染部位移动。一旦它们到达感染部位，中性粒细胞就被激活。这种激活可以采取多种形式：增加胞吐和吞噬，延长其寿命，改变粘附分子以增强其特异性和移动性。尽管中性粒细胞的快速反应和灵活性使它们成为人体免疫系统不可或缺的一部分，但具有讽刺意味的是，人类巨细胞病毒（HCMV）可能利用中性粒细胞激活来获得自身的进化优势。HCMV可能使用中性粒细胞传播或吸引其他类型的细胞，在这些细胞中HCMV可以保持潜伏。毒力强的HCMV产生一种功能性趋化因子vCXCL-1Tol，它可以通过吸引和激活中性粒细胞来模拟机体的正常免疫反应，然而这种趋化因子与宿主ELR-CXC趋化因子Gro1只有22%相同。这种病毒趋化因子的基因是HCMV基因组中变化最大的基因之一，来自不同分离株的vCXCL-1蛋白彼此之间的同源性只有32%。使用来自移植患者和艾滋病患者的病毒趋化因子，我们将这些病毒趋化因子与来自毒性和减毒巨细胞病毒株的趋化因子进行比较。我们将解决的问题是：1)这些病毒趋化因子是否具有独特的结合和功能结果？2)这些差异是否与病毒在体内的发病机制有关？我们从代表vCXCL-1家族分化的四个不同临床分离株中表达并分离了vCXCL-1蛋白。我们的下一步将是评估病毒趋化因子受体使用、结合和信号特征以及细胞过程的差异。首先，我们将重点研究来自C956菌株的变异趋化因子，该菌株与vCXCL-1Tol的同源性最低，以及来自无毒的Towne菌株的趋化因子。然后，我们将这些体外差异与这些蛋白在病毒传播和发病机制中所起的作用联系起来，使用小鼠CMV作为HCMV趋化因子基因的替代品。通过了解这些新型病毒趋化因子如何在体外和体内发挥作用，我们将开始更多地了解巨细胞病毒生命周期、其对中性粒细胞功能的影响以及疾病之间的复杂关系。本提案通过促进美国公众健康来支持NIH的使命。HCMV感染/再激活是免疫功能低下宿主发病的主要原因，也是子宫内感染后听力损失和智力迟钝的主要原因。了解HCMV传播/生存的额外机制将为探索新的抗病毒药物在免疫功能低下的宿主中对抗HCMV疾病提供新的途径。

DESCRIPTION (provided by applicant): Neutrophils provide the body's first line of defense against infection. They fight infections by, among other things, releasing chemokines or cytokines which initiate cascades of other immune mediators and cell types. Neutrophils themselves are first signaled to move to the site of infection via chemokines. Once they arrive at the infection site, the neutrophils are activated. This activation can take many forms: increased exocytosis and phagocytosis, extension of their life span, and alteration of adhesion molecules for enhancing their specificity and mobility. Although the rapid response and flexibility of neutrophils make them an integral part of the body's immune system, human cytomegalovirus (HCMV), ironically, may use neutrophil activation for its own evolutionary advantage. HCMV may use neutrophils for dissemination or for attracting other cell types within which HCMV can remain latent. Virulent HCMV produces a functional chemokine, vCXCL-1Tol, that can mimic the body's normal immune response by attracting and activating neutrophils, yet this chemokine is only 22% identical to the host ELR-CXC chemokine, Gro1. The gene for this viral chemokine is one of the most variable in the HCMV genome with the vCXCL-1 proteins from different isolates having as little as 32% identity with each other. Using viral chemokines from a transplant patient and AIDS patients, we will compare these viral chemokines to chemokines from virulent and attenuated CMV strains. The questions that we will address are: 1) Do these viral chemokines have unique binding and functional outcomes? 2) Do these differences relate to viral pathogenesis in vivo? We have expressed and isolated the vCXCL-1 proteins from four different clinical isolates representing divergence in the vCXCL-1 family. Our next step will be to assess the differences in viral chemokine receptor usage, binding and signaling characteristics, and cellular processes. Initially we will focus on the variant chemokine from the C956 strain, which has the least homology to vCXCL-1Tol and the chemokine from the avirulent Towne strain. We will then relate these in vitro differences to the role that these proteins play in viral dissemination and pathogenesis using murine CMV as a surrogate for the HCMV chemokine genes. By understanding how these novel viral chemokines function in vitro and in vivo, we will begin to understand more about the complex relationship between the CMV life cycle, its impact on neutrophil functions, and disease. Narrative: This proposal supports the NIH mission by contributing to better public health within the United States. HCMV infection/reactivation is a leading cause of morbidity in immunocompromised hosts as well as hearing loss and mental retardation following in utero infection. Understanding an additional mechanism that HCMV exploits for dissemination/survival will provide a new avenue for exploration of novel anti-virals to combat HCMV disease in immunocompromised hosts.