UNC Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Curr Gene Ther. 2010 Oct;10(5):319-340. doi: 10.2174/156652310793180706.
Adeno-Associated Virus based vectors (rAAV) are advantageous for human gene therapy due to low inflammatory responses, lack of toxicity, natural persistence, and ability to transencapsidate the genome allowing large variations in vector biology and tropism. Over sixty clinical trials have been conducted using rAAV serotype 2 for gene delivery with a number demonstrating success in immunoprivileged sites, including the retina and the CNS. Furthermore, an increasing number of trials have been initiated utilizing other serotypes of AAV to exploit vector tropism, trafficking, and expression efficiency. While these trials have demonstrated success in safety with emerging success in clinical outcomes, one benefit has been identification of issues associated with vector administration in humans (e.g. the role of pre-existing antibody responses, loss of transgene expression in non-immunoprivileged sites, and low transgene expression levels). For these reasons, several strategies are being used to optimize rAAV vectors, ranging from addition of exogenous agents for immune evasion to optimization of the transgene cassette for enhanced therapeutic output. By far, the vast majority of approaches have focused on genetic manipulation of the viral capsid. These methods include rational mutagenesis, engineering of targeting peptides, generation of chimeric particles, library and directed evolution approaches, as well as immune evasion modifications. Overall, these modifications have created a new repertoire of AAV vectors with improved targeting, transgene expression, and immune evasion. Continued work in these areas should synergize strategies to improve capsids and transgene cassettes that will eventually lead to optimized vectors ideally suited for translational success.
腺相关病毒载体（rAAV）由于其低炎症反应、缺乏毒性、天然持久性以及能够转衣壳化基因组，从而允许载体生物学和嗜性发生很大变化，因此非常适合用于人类基因治疗。已经进行了超过六十项使用 rAAV 血清型 2 进行基因传递的临床试验，其中一些在免疫特权部位（包括视网膜和中枢神经系统）取得了成功。此外，越来越多的利用其他 AAV 血清型来利用载体嗜性、运输和表达效率的试验已经启动。虽然这些试验在安全性方面取得了成功，并且在临床结果方面也取得了新的成功，但一个好处是发现了与载体在人体中的给药相关的问题（例如，预先存在的抗体反应的作用、非免疫特权部位中转基因表达的丧失以及转基因表达水平低）。出于这些原因，正在使用几种策略来优化 rAAV 载体，从添加用于免疫逃逸的外源性试剂到优化转基因盒以提高治疗效果。到目前为止，绝大多数方法都集中在对病毒衣壳的遗传操作上。这些方法包括合理的诱变、靶向肽的工程设计、嵌合颗粒的生成、文库和定向进化方法以及免疫逃逸修饰。总的来说，这些修饰创造了具有改进的靶向性、转基因表达和免疫逃逸的新型 AAV 载体。在这些领域继续开展工作，应该能够协同优化衣壳和转基因盒的策略，最终会得到非常适合转化成功的优化载体。
