scAAV6-Syn-GFP

Adeno-associated virus (AAV) is a small (25 nm), non-enveloped virus belonging to the family Parvoviridae and the genus Dependovirus. The AAV capsid encapsidates a single-stranded (ssDNA) genome of approximately 4.7 kb in length. The wild-type genome consists of two open reading frames flanked by two inverted terminal hairpin repeats (ITRs). Each ITR is 145 nucleotides and is the only cis-element required for successful packaging in the AAV genome. The AAV capsid consists of 60 (T = 1) viral protein subunits VP1, VP2, and VP3 in a ratio of approximately 1:1:10. These three distinct subunits are generated by overlapping reading frames and interact within the capsid through a common VP3 subunit region. The largest VP1 subunit is known to have a phospholipase A2 domain required for infectivity. Due to its broad tropism, lack of pathogenicity, and flexibility in genomic content, AAV has emerged as a promising candidate for therapeutic gene transfer applications. Over the past 20 years, AAV has been used as a gene transfer vector in multiple Phase I and II clinical trials for the treatment of various genetic diseases.

Different AAV serotypes infect cells by contacting various cell surface glycans and coreceptors followed by endocytic uptake. Viral particles are then thought to escape from endosomes and translocate into the nucleus, where the ssDNA genome is released and second-strand synthesis proceeds. Engineered AAV genomes containing mutant 3' ITRs have been shown to package dimeric, self-complementary DNA (scDNA). Such scAAV vectors have the advantage of escaping ssDNA degradation and bypassing second-strand synthesis, which is the rate-limiting step prior to transgene expression from AAV vectors. These features have been shown to enable rapid onset of transgene expression from scAAV vectors.