pRSET.GCaMP5G(7.35) AAV (Serotype 8)

Recombinant adeno-associated virus (rAAV) vectors have evolved into highly successful tools for human gene therapy. AAV vectors have demonstrated impressive long-term therapeutic success in clinical trials for a variety of applications. Many current trials rely on AAV serotypes 1, 2, or 8. The availability of a range of AAV serotypes with alternative cell tropisms is being exploited to effectively target specific cell types in various tissues. The first commercial human gene therapy product certified by the European Medicines Agency (EMA) was based on an intramuscularly injected AAV1 vector for the treatment of lipoprotein lipase deficiency. Other successful clinical trials were aimed at the treatment of hemophilia B, where factor IX expression in the liver was achieved by intravenous application of an AAV8 vector. For rAAV production, the therapeutic transgene is flanked by AAV inverted terminal repeats (ITRs). The AAV genes rep and cap are expressed in trans in the cell system of choice for vector packaging. Regardless of the serotype and respective tropism, the transduction mechanism appears to be similar. In brief, AAV enters the cell via endocytosis following receptor and/or co-receptor binding. After AAV enters the cell, it begins retrograde transport to the trans-Golgi network (TGN) within endocytic vesicles with the help of essential host cell factors such as the AAV receptor (AAVR). During entry, endosomal acidification and possibly other factors lead to major structural changes within the capsid, resulting in viral escape into the cytosol. Next, the intact capsid enters the nucleus through the nuclear pore complex (NPC), where the single-stranded genome is released from the capsid and converted into a double-stranded DNA (dsDNA) molecule. The dsDNA can then persist as a circular episome or as a linear or episomal concatemer and express viral genes or recombinant transgenes. Notably, in rare cases, the recombinant AAV genome can also integrate into the host genome.