Glauser Daniel L, Ackermann Mathias, Saydam Okay, Fraefel Cornel
Institute of Virology, University of Zurich, Switzerland.
Curr Gene Ther. 2006 Jun;6(3):315-24. doi: 10.2174/156652306777592090.
Chimeric or hybrid herpes simplex virus type 1/adeno-associated virus amplicon vectors combine the large transgene capacity of HSV-1 with the potential for site-specific genomic integration and stable transgene expression of AAV. These chimeric vectors have been demonstrated to support transgene expression for significantly longer periods than standard HSV-1 amplicons. Moreover, HSV/AAV hybrid vectors can mediate integration at the AAVS1 pre-integration site on human chromosome 19 at a relatively high rate, although random integration has also been observed. One major remaining hurdle of HSV/AAV hybrid vectors is the low packaging efficiency and titers when AAV rep sequences are included in the amplicon vector. In the conditions prevalent during the replication/packaging of HSV/AAV hybrid amplicons into HSV-1 virions, in particular the presence of HSV-1 replication factors and AAV Rep protein, at least three different viral origins of DNA replication are active: the HSV-1 ori, the AAV inverted terminal repeats (ITRs), and the p5 promoter/ori driving expression of the AAV rep gene. A detailed understanding of the properties of these origins of DNA replication and the molecular mechanisms of interactions between them, may allow designing novel hybrid vectors that allow the efficient and precise integration of large transgenes in the human genome.
1型单纯疱疹病毒/腺相关病毒嵌合或杂交扩增载体结合了HSV-1的大转基因容量以及AAV位点特异性基因组整合和稳定转基因表达的潜力。这些嵌合载体已被证明能支持转基因表达的时间比标准HSV-1扩增子长得多。此外，HSV/AAV杂交载体可以以相对较高的速率介导在人类19号染色体上的AAVS1预整合位点整合，尽管也观察到了随机整合。HSV/AAV杂交载体仍然存在的一个主要障碍是，当扩增子载体中包含AAV rep序列时，包装效率和滴度较低。在HSV/AAV杂交扩增子复制/包装到HSV-1病毒粒子的普遍条件下，特别是存在HSV-1复制因子和AAV Rep蛋白时，至少有三种不同的DNA复制病毒起源是活跃的：HSV-1 ori、AAV反向末端重复序列（ITRs）以及驱动AAV rep基因表达的p5启动子/ori。对这些DNA复制起源的特性及其相互作用的分子机制的详细了解，可能有助于设计新型杂交载体，使大转基因能够高效、精确地整合到人类基因组中。
