A novel role of the viral protein HBZ in mediating HTLV-1 infection.

项目总结 在感染人类T细胞白血病病毒1型(HTLV-1)逆转录病毒的1000万人中，约5% 将发展为致命的白血病/淋巴瘤，高达3%的人将发展为进行性神经退行性疾病。 这些疾病是由数千个T细胞中的一个或几个感染的T细胞首先成为致病细胞引起的 不断演变的生存和扩散优势。这些财产被认为是通过一系列 最初感染后的相互关联的事件。与这些总体观察相一致的是， 新感染的T细胞最终致病的可能性很低。因此，HTLV-1的效率 宿主内部的传播在决定感染是否会导致疾病方面发挥着重要作用。其中 T细胞，HTLV-1感染是通过感染细胞与靶细胞直接接触而发生的。这些相互作用 由感染细胞上的细胞间黏附分子1(ICAM-1)启动和稳定，与 靶细胞上的淋巴细胞功能相关抗原1。这种细胞间黏附事件触发了形成 细胞-细胞交界处的超分子复合体，称为病毒学突触(VS)。病毒颗粒 在VS处积累，这为这些粒子向目标传递提供了专门的微环境 手机。一种名为Tax的病毒蛋白已被发现在VS的形成和感染中发挥核心作用。初步 该应用中的数据显示，另一种称为HBZ的病毒蛋白可增强HTLV-1的感染，这是 与其激活ICAM-1和NRP-1表达的能力有关。NRP-1是HTLV-1的一种 受体；然而，在感染细胞的背景下，其作用尚未确定。有趣的是， NRP-1的功能被精确地调整为将病毒颗粒滞留在受感染的细胞表面和 将粒子移位到VS。这一应用是基于HBZ增强HTLV-1的假设 通过激活ICAM-1和NRP-1的表达而感染。具体目标1是描述HBZ的贡献 与感染有关。首先，我们将研究HBZ是否会增强原代人类CD4+T细胞和树突状细胞的感染 细胞。这些细胞类型对于HTLV-1在宿主内传播是必不可少的。第二，我们将研究一种税收-- HBZ在促进感染中的独立作用，这将解释从头感染如何在宿主中持续存在 当税收表达较低或不存在时。具体目标2是分析ICAM-1和NRP-1对 HTLV-1感染。我们将测试感染的T细胞表面ICAM-1的表达增加是否 感染的要求，这是以前没有报道过的。我们还将讨论以下潜在角色： NRP-1在VS形成和启动/稳定感染T细胞/树突状细胞相互作用中的作用。具体目标3是 描述HBZ激活ICAM-1和NRP-1表达的机制。鉴于HBZ是一个 转录调节，我们将重点研究病毒蛋白如何影响ICAM1和Nrp1基因的水平 抄写。这些目标的结果将定义HTLV-1感染所涉及的新过程，即 对于设计防止HTLV-1在宿主内传播的治疗方法这一更广泛的目标至关重要。

PROJECT SUMMARY Of the 10 million people infected with the Human T-cell Leukemia Virus type 1 (HTLV-1) retrovirus, about 5% will develop a fatal leukemia/lymphoma, and up to 3% will develop a progressive neurodegenerative disorder. These diseases arise from one or a few infected T-cells among many thousands becoming pathogenic by first evolving survival and proliferation advantages. These properties are believed to be acquired through a series of interconnected events following the initial infection. Consistent with these overall observations, the probability of a newly infected T-cell ultimately becoming pathogenic is low. Therefore, the efficiency of HTLV-1 spread within the host plays an important role in determining whether the infection will lead to disease. Among T-cells, HTLV-1 infection occurs through direct contact between infected and target cells. These interactions are initiated and stabilized by intercellular adhesion molecule 1 (ICAM-1) on the infected cell engaging with lymphocyte function-associated antigen 1 on the target cell. This intercellular adhesion event triggers formation of a supramolecular complex at the cell-cell junction known as a virological synapse (VS). Viral particles accumulate at the VS, which provides a specialized microenvironment for these particles to transit to the target cell. One viral protein, Tax, has been found to play a central role in VS formation and infection. Preliminary data in this application reveal that a second viral protein known as HBZ enhances HTLV-1 infection, which is correlated with its ability to activate expression of ICAM-1 and neuropilin-1 (Nrp-1). Nrp-1 is one of the HTLV-1 receptors; however, in the context of the infected cell, its role has not yet been characterized. Interestingly, the functions of Nrp-1 are precisely adapted for retention of viral particles on the infected cell-surface and translocation of particles to the VS. This application is based on the hypothesis that HBZ enhances HTLV-1 infection by activating ICAM-1 and Nrp-1 expression. Specific Aim 1 is to characterize the contribution of HBZ to infection. First, we will examine whether HBZ enhances infection of primary human CD4+ T-cell and dendritic cells. These cell-types are essential for HTLV-1 spread within the host. Second, we will examine a Tax- independent role of HBZ in promoting infection, which would explain how de novo infection persists in the host when Tax expression is low or absent. Specific Aim 2 is to analyze the contribution of ICAM-1 and Nrp-1 to HTLV-1 infection. We will test whether an increase in ICAM-1 expression on the surface of the infected T-cell is a requirement for infection, which has not been reported previously. We will also address the potential role of Nrp-1 in VS formation and in initiating/stabilizing infected T-cell/dendritic cell interactions. Specific Aim 3 is to characterize the mechanisms used by HBZ to activate ICAM-1 and Nrp-1 expression. Given that HBZ is a transcriptional regulator, we will focus on how the viral protein affects the level of ICAM1 and NRP1 gene transcription. Results from these aims will define novel processes involved in HTLV-1 infection, which is essential for the broader goal of designing therapeutic approaches that prevent HTLV-1 spread within the host.