Non-Integrating Lentiviral Vectors: Potential as Vaccines

描述(由申请人提供)：尽管艾滋病毒-1疗法取得了重大进展，但艾滋病毒-1/艾滋病的流行仍在继续增长，突出了开发有效疫苗的必要性。尽管具有复制能力的减毒HIV-1疫苗存在不可接受的风险，但之前对SIV减毒株的研究已经导致了关于灵长类动物模型中疫苗效力的几个重要观察结果。在病毒感染的背景下，慢性呈现低水平的病毒抗原提供了保护。在逆转录病毒感染期间，除了负责产生新病毒后代的整合前病毒外，未整合的染色体外DNA(E-DNA)在感染细胞中积累。E-DNA已被证明即使在没有可检测到的血浆病毒血症的情况下也能在体内持续存在。我们和其他人一样，已经证明E-DNA在体外在未分裂的细胞中是稳定的，并且在转录上活跃，产生功能性病毒蛋白。然而，尽管能产生病毒蛋白，E-DNA却不能维持病毒复制。这一提议的中心假设是，从HIV-1E-DNA持续产生病毒蛋白是表达病毒蛋白和诱导免疫反应的一种有效和安全的方式。病毒蛋白是在感染循环的背景下提出的，具有安全特征，包括不生产复制病毒和不整合。为了验证这一假设，我们将测试整合酶缺陷慢病毒载体在包括树突状细胞(DC)在内的专业抗原提呈细胞(APC)中产生病毒E-DNA和蛋白质的效率。这些被转导的细胞被效应性T细胞识别并诱导反应的能力也将被评估。最后，我们将使用小鼠模型来确定肌肉内IN缺陷载体产生E-DNA和病毒蛋白的动力学，并确定其表达是否与可测量的免疫反应有关。这些可行性研究将确定是否应将IN缺陷载体用于疫苗开发。

DESCRIPTION (provided by applicant): Despite major advancements in HIV-1 therapeutics, the HIV-1/AIDS epidemic continues to grow, highlighting the need for the development of an effective vaccine. Although an attenuated replication competent HIV-1 vaccine presents unacceptable risks, prior work with attenuated strains of SIV has led to several important observations concerning vaccine efficacy in the primate model. Chronic presentation of low levels of viral antigens in the setting of a viral infection provides protection. During retroviral infection, high levels of unintegrated extrachromosomal DNA (E-DNA) accumulate in the infected cells in addition to integrated provirus responsible for production of new viral progeny. E- DNA has been shown to persist in vivo even in the absence of detectable plasma viremia. We, as well as others, have shown that E-DNA is stable in vitro in non-dividing cells and is transcriptionally active producing functional viral proteins. However, despite the production of viral protein, E-DNA does not sustain viral replication. The central hypothesis of this proposal is that sustained viral protein production from HIV-1 E-DNA is an efficient and safe way to express viral proteins and induce an immune response. Viral proteins are presented in the context of an infectious cycle with the safety features including the lack of production of replicating virus and the absence of integration. To test this hypothesis, we will test the efficiency of integrase defective lentiviral vectors to produce viral E-DNA and proteins in professional antigen presenting cells (APC) including dendritic cells (DC). The ability of these transduced cells to be recognized by and induce a response in effector T-cells will be evaluated as well. Finally we will use a murine model to determine the kinetics of E-DNA and viral protein production from IN-defective vectors delivered intramuscularly as well as determine if the expression is associated with a measurable immune response. These feasibility studies will establish whether IN-defective vectors should be exploited for vaccine development.