Delineating Viral Determinants of HAD using SCID Mice

描述(由申请人提供)：该项目旨在测试HIV-1 B和C亚型之间的差异是否导致美国和印度人群中HIV相关痴呆(HAD)的不同发病率，据报道，美国和印度的HAD发病率分别为15%-30%和0.5%。我们之前已经证明，这种不同的发病率与C亚型HIV Tat蛋白的趋化因子基序的特定缺陷有关。B亚型Tat含有二半胱氨酸基序并显示单核细胞趋化功能，而C亚型Tat则缺乏这两种功能。该项目的具体目标是：(1)与南卡罗来纳医科大学的William Tyor博士、印度班加罗尔的JNCASR博士和AECOM的Hoby Hetherington博士合作，检测B型和C型HIV-1在SCID小鼠中诱导HIV-1脑炎的不同能力。在这个小鼠模型中，颅内注射感染HIV-1的人单核细胞诱导了一系列类似的神经病理和认知变化。我们将尝试：(I)测试C亚型HIV是否不能引发HAD/HIVE，以及(Ii)确认TAT的作用，并为识别在HAD中起作用的其他病毒基因奠定基础。兰加博士将从HAD低发病率报告的同一人群中产生C亚型HIV的分子克隆。在与Tyor和Hetherington博士的合作下，我们将测试这两种亚型HIV在小鼠身上引发蜂房/HAD症状的能力。在颅内注射感染艾滋病毒的人MDM后，我们将：(I)使用Morris水迷宫评估认知功能；(Ii)使用磁共振光谱成像评估神经元损伤的程度和严重程度；(Iii)评估神经元凋亡和胶质细胞增生(激活的小鼠单核细胞/小胶质细胞迁移到注射部位)。我们将把成像、病理学和认知研究的结果联系起来。在目标2中，我们将通过比较表达B分支或C分支TAT蛋白的人MDM在SCID蜂箱模型中诱导HAD的能力，如认知缺陷、神经元丢失或胶质增生，来检验TAT蛋白中缺乏功能性趋化因子基序是导致C亚型HIV感染者HAD发生率低的原因的假说。神经元的丢失将通过两种磁共振成像来确定，而神经元的凋亡和胶质增生将通过使用爱因斯坦病理学核心的组织病理学来评估。这项工作对人类健康的影响在于，有可能确定HAD的病毒决定因素，有望导致旨在直接干预HAD的研究。

DESCRIPTION (provided by applicant): This project aims to test whether differences between HIV-1 subtypes B and C are responsible for differential incidence of HIV-associated dementia (HAD) between US & Indian populations, where HAD occurs reportedly at rates of 15-30% or 0.5% respectively. We previously showed that this differential incidence correlates with a specific defect in the chemokine motif of the subtype C HIV Tat protein. While subtype B Tat contains a dicysteine motif and displays monocyte chemotactic function, the subtype C Tat lacks both. Specific aims of this project are: (1) To examine the differential ability of subtype B and C HIV-1 to induce HIV-1 encephalitis in SCID mice in collaboration with Dr. William Tyor (Medical University of South Carolina), Dr. U. Ranga (JNCASR, Bangalore, India) and Dr. Hoby Hetherington (AECOM). In this mouse model, intracranial injection of HIV-1 infected human monocytes induces a spectrum of neuropathological and cognitive changes that mimic HAD. We will attempt to: (i) test if subtype C HIV is unable to induce HAD/HIVE and (ii) confirm a role for Tat and set the stage to identify other viral genes that play a role in HAD. Dr. Ranga will generate molecular clones of subtype C HIV from the same population where the low incidence of HAD was reported. In collaboration with Drs. Tyor and Hetherington, we will test the ability of the two subtypes of HIV to induce HIVE/HAD symptoms in mice. Following intracranial injection of HIV-infected human MDM, we will: (i) assess cognitive function using a Morris water maze; (ii) evaluate the extent and severity of neuronal injury using MR spectroscopic imaging; (iii) evaluate neuronal apoptosis and gliosis (migration of activated murine monocytes/microglia to the site of injection). We will correlate results from imaging, pathology and cognitive studies. In Aim 2, we will examine the hypothesis that absence of a functional chemokine motif in Tat protein is responsible for the low incidence of HAD in subtype C HIV-infected individuals by comparing the ability of human MDM expressing clade B or clade C Tat proteins to induce HAD in SCID HIVE model, such as cognitive defect, neuronal loss or gliosis. The neuronal loss will be determined by both MR imaging, while neuronal apoptosis and gliosis will be evaluated by histopathology using the Einstein Pathology core. The implications of this work to human health lie in the possibility that viral determinants of HAD can be identified hopefully leading to studies aimed at direct interventions for HAD.