The role of myeloid cells in viral replication, persistence and neuroinvasion

描述(申请人提供)：髓系细胞(巨噬细胞/小胶质细胞)是灵长类慢病毒(HIV/SIV)在中枢神经系统(CNS)建立病毒库的中心，这种病毒库的存在突显了病毒感染的神经致病表现。然而，除了它们在中枢神经系统感染中的作用外，单核/巨噬细胞是否对HIV/SIV感染宿主是必需的还不清楚，也缺乏明确的实验来证明这种重要作用。我们对HIV-髓系细胞相互作用的研究揭示了病毒决定因素的存在，这些决定因素专门作用于单核/巨噬细胞。这些决定因素对于病毒入侵细胞的能力和病毒维持持续感染的能力是必不可少的。在此基础上，我们假设髓系细胞对宿主的感染是必不可少的，并提出截断髓系细胞感染的策略将通过减少病毒持久性、神经侵袭和致病性从根本上影响感染过程。为了探索这一假说，我们提出了以下具体目标：目的1：检测不能感染髓系细胞的SIV突变体的体内表型(复制、持久性、神经侵袭)。我们的研究已经确定了一种病毒决定簇(VPR/VPX)，它对于HIV/SIV感染髓系细胞是必不可少的，但对于CD4+T淋巴细胞的感染是必不可少的。用这些突变体感染猕猴将使我们能够确定髓系细胞库如何在体内塑造病毒复制、持久性和致病性的过程。目的2：通过使用缩短受感染巨噬细胞存活的药物，评估髓系贮存库在慢性病毒感染中的作用。我们的研究已经建立了一种单核/巨噬细胞抵抗病毒细胞病变效应的机制，该机制依赖于感染的巨噬细胞产生和传递存活细胞因子单核细胞集落刺激因子(MCSF)。我们已经确定，干扰MCSF受体功能的药物可以恢复巨噬细胞对病毒介导的细胞病变的敏感性。我们将检验药物对存活细胞因子信号的抑制是否限制了病毒在猕猴SHIVDH12感染的巨噬细胞阶段的持续。目的3：明确调节灵长类慢病毒感染髓系细胞的细胞因子。APOBEC 3G和Tetherin等抗病毒限制措施引起了该领域的浓厚兴趣。我们的研究揭示了一种新的抗病毒因子的存在，这种因子由髓系细胞特异性表达。这种限制有效地抑制了HIV/SIV对髓系细胞的感染，病毒VPR/VPX蛋白抵消了这种限制的抗病毒活性。我们将使用生化和遗传学方法来表征调节髓系细胞感染的细胞活动。这项提案中概述的研究将确定髓系细胞库在灵长类慢病毒生物学和灵长类慢病毒与宿主相互作用中的作用。这些信息将被用来制定防止在宿主中建立艾滋病毒-1感染的战略，以及遏制病毒感染的慢性性质的战略。

DESCRIPTION (provided by applicant): Myeloid lineage cells (macrophage/microglia) are central to the ability of primate lentiviruses (HIV/SIV) to establish a viral reservoir in the central nervous system (CNS) and the presence of such a reservoir underscores the neuropathogenic manifestations of virus infection. However, beyond their role in CNS infection, it is not known whether monocyte/macrophage are even necessary for infection of the host by HIV/SIV and definitive experiments demonstrating such an essential role are lacking. Our studies on HIV- myeloid cell interaction have revealed the existence of viral determinants that specifically operate in monocyte/macrophage. These determinants are essential for the ability of the virus to invade the cell and for the ability of the virus to maintain a persistent infection. Based on this, we hypothesize that myeloid cells are essential for infection of the host and propose that strategies that truncate myeloid cell infection will fundamentally impact the course of infection by curtailing viral persistence, neuroinvasion and pathogenicity. To pursue this hypothesis, we propose the following specific aims: Aim 1: Examine the in vivo phenotype (replication, persistence, neuroinvasion) of SIV mutants incapable of infecting myeloid lineage cells. Our research has defined a viral determinant (Vpr/Vpx) that is essential for the infection of myeloid cells by HIV/SIV yet that is dispensable for infection of CD4+ T lymphocytes. Infection of macaques with these mutants will allow us to define how the myeloid cell reservoir shapes the course of viral replication, persistence and pathogenicity in vivo. Aim 2: Evaluate the contribution of myeloid reservoirs to chronic virus infection through the use of pharmacologic agents that truncate infected macrophage survival. Our research has established a mechanism by which monocyte/macrophage resist viral cytopathic effects that relies on the production and signaling of the survival cytokine monocyte colony stimulating factor (MCSF) by infected macrophage. We have determined that agents that interfere with the function of the MCSF receptor restore the sensitivity of macrophage to virus-mediated cytopathicity. We will examine whether pharmacologic inhibition of survival cytokine signaling curtails viral persistence in the macrophage phase of SHIVDH12 infection in macaques. Aim 3: Define the cellular factors that regulate myeloid cell infection by primate lentiviruses. Antiviral restrictions such as Apobec 3G and Tetherin have generated intense interest in the field. Our research reveals the existence of a novel antiviral factor that is specifically expressed by myeloid cells. This restriction potently inhibits myeloid cell infection by HIV/SIV and the viral Vpr/Vpx proteins counteract the antiviral activity of this restriction. We will use biochemical and genetic approaches to characterize the cellular activity that regulates myeloid cell infection. Studies outlined in this proposal will define the role of the myeloid cell reservoir in the biology of primate lentiviruses and in the interaction of primate lentiviruses with their hosts. This information will be used to devise strategies with which to prevent the establishment of HIV-1 infection in the host as well as strategies to curtail the chronic nature of virus infection.