Tailoring AAV Vectors for Glioma Immunotherapy

描述（由申请人提供）：腺相关病毒（AAV）是目前正在开发的一种领先的基因传递系统。AAV血清型是高度神经营养型，在中枢神经系统（CNS）单次注射后能够长期高水平地表达基因。胶质瘤（GL）模型中的AAV基因转移表明，不同血清型之间的转导效率差异很大，尽管有报道称体外小胶质细胞（MG）的AAV转导有限，但这些细胞在动物中的转导很差。本研究的主要目标是开发以GL细胞和浸润肿瘤的MG选择性转导为特征的AAV载体，并将这些AAV和天然AAV血清型应用于GL免疫治疗。除了针对GL细胞本身，浸润GL的大量MG提示了开发GL基因治疗的另一个潜在的可利用靶点。MG细胞是中枢神经系统的主要免疫效应器，具有体外肿瘤杀伤能力。支持体内类似作用的证据来自于发现丰富的、活化的MG是人类和实验GL的一致特征。然而，MG和其他GL浸润淋巴细胞（如细胞毒性T细胞）的功能在免疫抑制的GL微环境中受到抑制。因此，我们将验证以下假设：(1)可以选择具有GL和肿瘤浸润性MG选择性转导谱的AAV载体，用于以随机病毒粒子表面环为特征的复制能力的AAV组合衣壳蛋白文库；(2)在衣壳表面显示显性t细胞表位，同时表达全长GL抗原的AAV载体可作为GL免疫治疗的“prime-boost”疫苗载体；(3)表达MG免疫修饰因子和/或调节性t细胞的AAV载体的全身和中枢递送可以引发对GL的有效免疫反应。在推进AAV载体平台的同时，这些载体的开发和表征将为对GL的免疫反应提供有价值的见解。此外，选择性靶向MG的AAV载体的开发将在广泛的中枢神经系统疾病中具有广泛的适用性。

DESCRIPTION (provided by applicant): Adeno-associated virus (AAV) is a leading gene delivery system currently under development. AAV serotypes are highly neurotrophic and capable of high levels of long term gene expression following a single injection in the central nervous system (CNS). AAV gene transfer in glioma (GL) models has revealed that transduction efficiencies are highly variable between serotypes, and despite reports of limited AAV transduction of microglia (MG) in vitro, transduction of these cells in animals is poor. The major goal of this proposal is to develop AAV vectors characterized by selective transduction of GL cells as well as the MG that infiltrate these tumors, and to apply these and native AAV serotypes in GL immunotherapy. In addition to targeting the GL cells themselves, the high number of MG that infiltrate GL suggests another potentially exploitable target for developing GL gene therapy. MG cells are the primary immune effectors of the CNS with demonstrated tumor killing capacity in vitro. Evidence to support a similar role in vivo comes from the finding that abundant, activated MG are a consistent feature of human and experimental GL. Yet the function of MG and other GL infiltrating lymphocytes (such as cytotoxic T cells) are inhibited within the immunosuppressive GL microenvironment. Therefore, we will test the hypotheses that (1) AAV vectors with GL and tumor-infiltrating MG selective transduction profiles can be selected for using replication-competent AAV combinatorial capsid protein libraries characterized by randomized virion surface loops; (2) AAV vectors that display dominant T-cell epitopes on the capsid surface, while simultaneously expressing the full length GL antigen, can be employed as "prime-boost" vaccine carriers for GL immunotherapy; and (3) systemic and central delivery of AAV vectors that express immune modifiers of MG and/or regulatory T-cells can elicit potent immune responses to GL. While advancing the AAV vector platform generally, the development and characterization of these vectors will provide valuable insight into the immune response to GL. Furthermore, the development of AAV vectors that selectively target MG would have broad applicability in a wide range of CNS disorders. Public Health Relevance: Glioma is the most common brain tumor in adults. Despite aggressive treatment with surgery, radiotherapy, and chemotherapy prognosis for survival is poor. Significant advances have been made in understanding anti-tumor immunity in the glioma patient This proposal evaluates the potential of adeno-associated virus gene therapy to boost the immune system's ability to mount a more effective attack on glioma tumor cells.