Modeling HTLV-1 infection and cellular immune response in HLA-A2-transgenic mice

描述(申请人提供)：到目前为止，缺乏合适的小动物模型阻碍了我们在体内系统中了解HTLV-1的免疫和神经发病机制的探索。这是由于HTLV-1外膜与小鼠细胞融合效率低下所致。最近，一种利用Moloney-小鼠白血病病毒包膜基因的嵌合HTLV-1病毒已经被开发出来，从而使嵌合病毒与小鼠细胞融合。利用这种嵌合病毒，我们最近已经证明，在CD11c-DTR转基因小鼠中，DC的耗尽增加了对HTLV-1无细胞感染的敏感性(Rahman等人，J.免疫，在出版社)。这些小鼠被独特地设计成在体内选择性地耗尽DC。与猿猴和人类细胞不同，小鼠细胞通常对白喉毒素(DT)屈光。在CD11c-DTR-TG小鼠体内，DTR转基因与CD11c启动子的融合(主要在小鼠脾DC中表达)允许在DT存在的情况下完全消融DC，而不影响其他APC，如B细胞和巨噬细胞。该系统已被用于研究DC在包括LCMV、HSV-1和最近的HTLV-1在内的几种病毒的发病中的作用(Rahman等人，J.免疫，在出版社)。然而，由于小鼠的MHC背景，这些小鼠在研究人类MHC I类相关免疫反应(如在HAM/TSP患者中观察到的免疫反应)方面仍然存在问题。这个问题已经在另一种被称为HHD II的小鼠身上得到了解决，这种小鼠表达人类HLA-A2.1分子，并敲除了小鼠H-2DB MHC I类分子和β2-微球蛋白，因此只携带人类HLAI类分子。我们以前已经在这些小鼠中证明了TAX11-19特异性CTL反应的免疫和诱导(Manuel等人，J.Leuk。Biol.，2009)。本研究试图建立一种新的转基因小鼠株(HHD II/DTR-TG)，以研究HTLV-1感染和随后的树突状细胞(DC)存在下的HLA-A2限制性细胞免疫反应。新产生的菌株可以进一步用于研究HTLV-1介导的免疫致病过程中DC：T细胞相互作用的机制。在体内选择性地去除DC的能力为探索这一独特的细胞群在各种感染和疾病模型中的作用提供了一个强大的工具。新的杂交毒株(HHD II/DTR-TG)的发展将极大地促进未来对HTLV-1免疫/神经发病机制的研究，同时也为科学界提供了一个有价值的工具。 公共卫生相关性：拟议的研究与公共健康相关，并将揭示在复杂的自身免疫/神经炎性疾病(如HAM/TSP和多发性硬化症)中树突状细胞调节的T细胞反应的重要信息。此外，这些研究的结果还将阐明在HTLV-1、HIV-1、肝炎病毒和单纯疱疹病毒等慢性病毒感染期间免疫细胞相互作用的动态。

DESCRIPTION (provided by applicant): To date, the lack of a suitable small animal model has hindered our quest to understand the immuno- and neuropathogenesis of HTLV-1 in an in vivo system. This is due to the inefficient fusion of HTLV-1 envelope with murine cells. Recently, a chimeric HTLV-1 virus has been developed that utilizes the envelope gene of the Moloney-murine leukemia virus thereby allowing fusion of the chimeric virus with murine cells. Utilizing this chimeric virus we have recently demonstrated that depletion of DCs enhances susceptibility to cell-free infection of HTLV-1 in CD11c-DTR-transgenic mice (Rahman et al., J. Immunol, in press). These mice are uniquely designed to selectively deplete DCs in vivo. Murine cells, unlike simian and human cells, are generally refractive to diphtheria toxin (DT). The fusion of DTR transgene to the CD11c promoter (largely expressed in murine splenic DCs) in CD11c-DTR-Tg mice allows for the complete ablation of DCs in the presence of DT without affecting other APCs such as B cells and macrophages. This system has been used to study role of DCs in the pathogenesis of several viruses including LCMV, HSV-1, and recently HTLV-1 (Rahman et al., J. Immunol., in press). However, these mice still pose problem in studying human MHC class I-associated immune responses (such as those observed in HAM/TSP patients) due to the mouse MHC background. This issue has been addressed in a separate strain of mice, known as line HHD II, which express human HLA-A2.1 molecule and are knockout for the mouse H-2Db MHC class I molecule and beta2-microglobulin thereby carrying only human HLA class I molecules. We have previously demonstrated the immunization and induction of Tax 11-19-specific CTL response in these mice (Manuel et al., J. Leuk. Biol., 2009). The study proposed herein attempts to generate a new transgenic strain (HHD II/DTR-Tg) of mice to study HTLV-1 infection and subsequent HLA-A2-restrticted cellular immune response in the absence and presence of DCs. The newly generated strain could be further utilized to investigate mechanistic aspects of DC:T cell interaction during HTLV-1-mediated immunopathogenesis. The ability to selectively ablate DCs in vivo offers a powerful tool to explore the role of this unique cell population in various infection and disease models. The development of a new hybrid strain (HHD II/DTR-Tg), as proposed here, will greatly facilitate future studies of HTLV-1 immuno/neuropathogenesis in addition to providing a valuable tool to the scientific community in general. PUBLIC HEALTH RELEVANCE: The proposed studies are relevant to public health and will reveal significant information concerning the dendritic cells-regulated T cell responses during complex autoimmune/neuroinflammatory diseases such as HAM/TSP and multiple sclerosis. Additionally the results of these studies will shed light on the dynamics of immune cell interactions during chronic viral infections such as HTLV-1, HIV-1, hepatitis virus and herpes simplex virus.