HTLV Pathogenesis in SCID-IL2R-gamma-null Mice

描述（由申请人提供）：HTLV-1与成人T细胞白血病（ATL）和称为HAM/TSP的神经系统疾病的发生有关。在理解HTLV致白血病的基本机制方面的局限性主要是由于缺乏概括发病机制的动物模型。HTLV-1感染人造血祖细胞和干（CD 34+）细胞（分别为HPC和HSC），并且用感染的CD 34+细胞接种NOD/SCID小鼠导致人血淋巴细胞生成和病毒感染传播至成熟的人T细胞和单核细胞。HTLV-1感染和Tax 1在CD 34 + HSC中的表达可能在维持病毒潜伏期、病毒隔离和HTLV感染在体内分化过程中的传播中起作用。我们推测，HTLV-1感染的CD 34+细胞在BM中作为一个水库的病毒感染在体内和Tax 1在这些细胞中的表达启动诱变事件，表现在ATL的发展。新开发的NOD-scid IL 2 R-无效小鼠将用于表征HTLV体内复制的动力学，并确定感染是否导致白血病发生。用慢病毒载体（LV）介导Tax 1转导人CD 34+细胞，将评价该病毒癌蛋白在NOD-scid IL 2 R-null hu小鼠中对T淋巴细胞生成的作用。我们建议评估HTLV感染的细胞亚群中通常与ATL发展相关的肿瘤抑制基因突变。我们独特的专业知识组合将使我们能够开发一种新的范式来检查HTLV感染和Tax表达诱导的造血干细胞中的分子事件，这有助于病毒介导的白血病发生。具体目标是：目标1：表征在具有HTLV-1感染的CD 34 + HPC的NOD-scid IL 2 R缺失小鼠中重建人造血后的HTLV感染、复制嗜性和白血病发生。确定HTLV-1感染是否干扰体内造血并诱导白血病发生。确定肿瘤抑制基因的突变是否发生在由感染HTLV的造血干细胞和祖细胞引起的淋巴增殖中，与ATL患者中的突变相似。目标二：在NOD-scid IL 2 R-null-hu小鼠模型中，使用慢病毒载体（LV）介导的CD 34 + HPC转导和造血重建检查Tax 1和Tax 2对T淋巴细胞生成的作用。目标3：使用含有异源Tax基因的HTLV-1和HTLV-2的感染性重组前病毒克隆研究NOD-scid IL 2 R-null-hu小鼠的感染。确定HTLV HBZ在体内的复制动力学和发病机制。人T细胞白血病病毒（HTLV）引起成人T细胞白血病（ATL）和称为HAM/TSP的神经系统疾病。我们推测，HTLV感染人类干细胞，使细胞易于成为白血病，导致感染的“癌症干细胞”。在支持人淋巴细胞发育的免疫缺陷小鼠中建模HTLV感染将使我们能够定义由HTLV感染在人干细胞中诱导的导致白血病的分子事件。

DESCRIPTION (provided by applicant): HTLV-1 has been linked to the development of adult T cell leukemia (ATL) and a neurological disorder termed HAM/TSP. Limitations in the understanding of fundamental mechanisms of leukemogenesis by HTLV have predominantly been hampered by the lack of an animal model which recapitulates pathogenesis. HTLV-1 infects human hematopoietic progenitor and stem (CD34+) cells (HPCs and HSCs, respectively) and inoculation of NOD/SCID mice with infected CD34+ cells results in human hematolymphopoiesis and dissemination of viral infection to mature human T cells and monocytes. HTLV-1 infection and Tax1 expression in CD34+ HSCs may play a role in maintenance of viral latency, sequestration of virus and in dissemination of HTLV infection during differentiation in vivo. We postulate that HTLV-1 infected CD34+ cells in the BM serve as a reservoir for viral infection in vivo and that Tax1 expression in these cells initiates mutagenic events which manifest in development of ATL. The newly-developed NOD- scid IL2R-null mouse will be used to characterize the kinetics of HTLV replication in vivo and determine if infection results in leukemogenesis. Lentiviral vector (LV) mediated transduction of Tax1 into human CD34+ cells will evaluate the role of this viral oncoprotein on T lymphopoiesis in NOD-scid IL2R-null hu mice. We propose to evaluate HTLV-infected cell subpopulations for mutations in tumor suppressor genes commonly associated with ATL development. Our unique combination of expertise will allow us to develop a novel paradigm to examine the molecular events in hematopoietic stem cells induced by HTLV infection and Tax expression which contributes to virally-mediated leukemogenesis. Specific Aims are: Aim 1: Characterize HTLV infection, replication tropism and leukemogenesis following reconstitution of human hematopoiesis in NOD-scid IL2R-null mice with HTLV-1 infected CD34+ HPCs. Establish if HTLV-1 infection perturbs hematopoiesis in vivo and induces leukemogenesis. Determine whether mutations in tumor suppressor genes occur in lymphoproliferations arising from infected HTLV-infected hematopoietic stem and progenitor cells are similar to those in ATL patients. Aim 2: Examine the role of Tax1 and Tax2 on T lymphopoiesis using lentivirus vector (LV) -mediated transduction of CD34+ HPCs and reconstitution of hematopoiesis in the NOD- scid IL2R-null -hu mouse model. Aim 3: Investigate infection of the NOD-scid IL2R-null -hu mouse using infectious recombinant proviral clones of HTLV-1 and HTLV-2 containing the heterologous Tax genes. Determine the replication kinetics and pathogenesis of HTLV HBZ in vivo. Human T cell leukemia virus (HTLV) causes Adult T cell leukemia (ATL) and a neurological disorder termed HAM/TSP. We speculate that HTLV infects human stem cells and predisposes cells to become leukemogenic, resulting in an infected "cancer stem cell". Modeling HTLV infection in an immune deficient mouse which supports the development of human lymphocytes will allow us to define molecular events induced by HTLV infection in human stem cells which result in leukemia.