Syn-FLEX-CaMPARI AAV (Serotype 8)

Adeno-associated virus (AAV) is one of the most promising vectors for human gene therapy due to its durability, high efficiency, and non-pathogenicity in gene delivery. Clinical trials have demonstrated long-term efficacy and safety of AAV-mediated gene therapy for patients with Leber congenital amaurosis type 2 or hemophilia B. In addition, AAV has achieved good results in gene therapy in the liver, retina, brain, cardiovascular system, and muscle, with long-term and non-toxic transgene expression. AAV8 has been identified as an excellent in vivo gene delivery vector. It has been reported that a single tyrosine mutation on the AAV8 capsid enables the vector to escape intracellular phosphorylation and subsequent ubiquitination and proteasome-mediated degradation, thereby significantly enhancing gene expression. AAV was originally discovered as a contaminant of adenoviral preparations and was found to require the presence of adenovirus, HSV, vaccinia virus, or human papillomavirus for replication. Due to its dependence on other viruses, AAV became a founding member of the Dependoparvovirus genus of the Parvoviridae family. The wild-type AAV2 (wtAAV2) ssDNA genome is approximately 4.7 kb in length and has two 145 bp long inverted terminal repeats (ITRs) that form a T-shaped hairpin structure, acting as self-priming origins of replication on the left and right sides of the AAV2 genome and playing important roles in integration and packaging. ITRs also flank the rep and cap genes. Within the rep region, three promoters (p5, p19, and p40) drive transcription of six different mRNAs. Transcription from the p5 promoter produces two large rep proteins (Rep78 and Rep68) through alternative splicing. Similarly, the p19 promoter drives transcription of two smaller Rep proteins (Rep52 and Rep40). In the presence of a helper virus, the large rep proteins play a central role in replication, transcriptional control, and nearly all other aspects of the viral life cycle. Surprisingly, in the absence of helper virus, the large rep protein catalyzes the insertion of the wtAAV2 genome into the human genome, preferentially into the AAVS1 region located on human chromosome 19.