scAAV5-Syn-GFP

One of the advantages of AAV as a gene therapy vector is that these viruses do not cause any disease. In addition, AAV can be produced at very large titers, support long-term transgene expression even in the absence of transgene integration into the host genome, and infect a wide variety of different cells. By using capsid proteins of different viral serotypes, both natural (serotypes 1-12) and synthetic serotypes, AAV vectors can be designed to target specific cells and tissues, at least to some extent. The main disadvantages of AAV as a gene transfer vector are its low transduction efficiency, the need for high vector doses, and its small transgene capacity of approximately 4.5 kb. The latter hinders the utilization of a key property of wild-type AAV, namely its genomic site-preferential integration into the AAVS1 locus on human chromosome 19. This process requires the larger rep78/68 genes of AAV, which, together with the therapeutic transgene, in most cases exceeds the transgene capacity of the vector. To overcome this problem and exploit the site-preferential integration ability of wtAAV for genomic integration of therapeutic transgenes, several different hybrid vectors have been developed. Such hybrid vectors are designed by placing the AAV rep gene and the therapeutic transgene flanked by the ITRs on a vector genome derived from another virus, such as AdV or herpes virus. Another disadvantage of standard rAAV vectors is that transgene expression requires prior second-strand synthesis, which can delay gene expression, at least in post-mitotic cells such as neurons. To address this issue, self-complementary (sc) AAV vector genomes have been developed that can self-anneal and support gene expression without prior second-strand synthesis.