AAV1-CAG-GCaMP6s

Adeno-associated virus (AAV) is a small, single-stranded DNA-dependent virus belonging to the family Parvoviridae. The 4.7 kb wild-type (wt) AAV genome consists of two genes encoding four replication proteins and three capsid proteins, flanked by 145 bp inverted terminal repeats (ITRs). The virion is composed of three capsid proteins, Vp1, Vp2, and Vp3, generated in a 1:1:10 ratio from the same open reading frame, but from differential splicing (Vp1) and alternative translation start sites (Vp2 and Vp3, respectively). Vp3 is the most abundant subunit in the virion and is involved in cell surface receptor recognition, determining viral tropism. A phospholipase domain essential for viral infection is found at the unique N-terminus of Vp1. Similar to wild-type AAV, recombinant AAV (rAAV) utilizes a cis-acting 145 bp ITR linked to the vector transgene cassette, providing up to 4.5 kb of space for packaging foreign DNA. Following infection, rAAV can express therapeutic genes and persist in the host genome by existing as circular head-to-tail concatemers without integrating into the host genome. To date, more than 100 unique AAV isolates have been identified, at least 10 of which have been developed as gene therapy vectors by cross-packaging AAV2-based vector genomes into various serotype capsids. These alternative serotype vectors have been shown to confer different tissue type tropisms, presumably in part due to their putative cell surface receptors.