AAV8-CAG-FLPo

Adeno-associated virus (AAV) is a single-stranded DNA packaging virus of the family Parvoviridae and belongs to the genus Dependoparvovirus. AAV-based vectors are being developed and used as gene delivery biologics to treat a variety of monogenetic diseases. Thirteen human and primate AAV serotypes and a large number of genomic isolates have been described and assigned to six clades A–F or individual clonal isolates. AAV virions consist of nonenveloped capsids with T = 1 icosahedral symmetry and a diameter of approximately 260 Å. They are assembled from 60 viral proteins (VPs): VP1 (≈82 kDa), VP2 (≈73 kDa), and VP3 (≈61 kDa) in a ratio of approximately 1:1:10. VPs share a common C-terminus that includes the entire VP3. Compared to VP3, VP1 and VP2 have an extended N-terminus with a shared ≈65 amino acid (aa) region, while VP1 (VP1u) has an N-terminal extension of ≈137 amino acids more than VP2. The N-terminal regions of VP1 and VP2 contain conserved elements required for AAV infection, such as the phospholipase A2 (PLA2) domain, the calcium-binding domain, and the nuclear localization signal. Overall, the VP1 amino acid sequence identity among AAV serotypes varies between 57% and 99%. Gene therapy based on adeno-associated virus (AAV) vectors has achieved many successes. In 2012, the first gene therapy product was approved in Europe, Glybera, an AAV1-LDL vector for the treatment of lipoprotein lipase deficiency. Additionally, clinical trials based on AAV vectors have reported positive results for the treatment of early childhood blindness, Leber congenital amaurosis (LCA2), and hemophilia B. AAV-based gene delivery vectors contain an AAV capsid carrying a therapeutic transgene, with the capsid selected based on tropism for the target tissue. For example, the LCA2 trial evaluated AAV2 because of its preference for retinal pigment epithelial (RPE) cells. AAV8 can transduce human hepatocytes and is the choice for the hemophilia B trial.