AAV Genome Structure (ITR,Rep,Cap,VP1,VP2,VP3) and AAV virus assembly

The AAV shell is approximately 25nm in diameter and encapsidates a single-stranded DNA genome of 4.7 kilobases. The genome consists of two large open reading frames (ORFs) flanked by 145bp inverted terminal repeats (ITR), which are the only cis-acting elements required for AAV genome replication and AAV packaging. The left ORF encodes four replication proteins, Rep40, Rep52, Rep68, and Rep78, in charge of site-specific integration, as well as regulation of AAV capsid formation initiation within the AAV genome, while the right ORF encodes the viral structural proteins, VP1, VP2, and VP3, which interact together to assemble into icosahedral virion shells comprising 60 subunits each (Figure1).