AAV3-GFP

AAV is a small, 4.7 kb, linear, single-stranded DNA (ssDNA) virus in the Parvoviridae family that infects a wide range of tissue types. The AAV genome consists of two open reading frames, Cap and Rep, flanked by inverted terminal repeats (ITRs). The ITRs are the only elements of the AAV genome that must be transmitted in cis. Rep is translated to produce proteins required for AAV replication (Rep 40, 52, 68, and 78), while Cap is translated to produce the structural proteins VP1, VP2, and VP3, which form a 20- to 25-nm icosahedral capsid in a 1:1:10 ratio. Cap also produces a nonstructural protein, assembly-activating protein, which is involved in the assembly of the capsid. The ITRs allow the formation of a hairpin structure that permits primase-independent second DNA strand synthesis by the host cell DNA polymerase.

To date, 11 natural serotypes of AAV have been identified, which have different capsid structures, resulting in different tropisms. AAV tropism can be further altered by creating recombinant versions of multiple AAV serotypes, a process called pseudotyping. These pseudotyped viruses can enhance tropism for specific cell types and improve transduction efficiency in neurons.