目前基因治疗表达载体有病毒表达载体及质粒表达载体，一般多含有大量病毒或细菌DNA序列,会引发人体较严重的免疫反应，细胞炎症，或细胞毒性副作用，以及基因表达沉默化，是基因治疗应用于人类的一大障碍。本项目拟研发一种新型的、基于腺相关病毒（AAV）倒置末端重复序列（ITR）的基因表达单链微载体。AAV-ITR单链微载体DNA两端为AAV基因组的125个核苷酸的ITR序列，使得其在细胞中形成稳定的环状多聚体和类染色质结构，从而，能在细胞中长期，稳定存在，目的基因也就能长期，稳定表达；AAV-ITR单链微载体内侧仅含有启动子、目的基因及polyA序列，几乎不含细菌或病毒的DNA系列，使得免疫反应，细胞炎症，细胞毒性，基因表达沉默化降到最低；AAV-ITR单链微载体分子较小，有利于细胞转化，基因表达。本研究项目将建立一种快速人工合成安全有效的新型基因表达微载体，为基因治疗提供一种有效的新方法。

Two gene expression vectors, virus and plasmid, are used in gene therapy. Generally, both of them carries exogenous (virus and bacterium) DNA sequences which could induce severe immunologic, inflammatory reactions, cause cytotoxicity and result in gene silence. The aim of this research project is to develop a safe and high effcient mini gene expression vector based on AAV ITR sequences (AAV-ITR gene expression mini vector). The AAV-ITR mini gene expression vector is a single strand DNA, has the minimal gene expression cassette and 125 nt AAV ITR sequences at each end. AAV ITR could fold back and form a stable T-shaped hairpin structure which will protect the AAV-ITR from the degradation by the neclerase in the cell. The T-shaped hairpin structure also will mediate recombination between AAV-ITR molecules and result in the formation of concatemers. The concatemer will stably remain inside the necleus as an episome in the chromatin-like structure which ensures the long term gene expression. AAV-ITR mini gene expression vector has little viral DNA sequces and maximally minimizes the immunologic, inflammatory reactions, cytotoxicity and prevents the gene silence. AAV-ITR mini gene expression vector has reduced vector molecular size which will greatly befit the cell transformation and gene expression. This research project will explore a way of fast biosysthesis of a safe, efficient gene expression mini vector and create a new avenue of human gene therapy.