Syn-FLEX-GCaMP6f AAV (Serotype 9)

The FDA approval of an adeno-associated virus (AAV)-based vector for gene therapy for the blinding disease Leber’s congenital amaurosis type 2 has established AAV as a powerful tool for therapeutic transgene delivery. In addition, several late-stage clinical trials have further highlighted the versatility and effectiveness of AAV in the treatment of spinal muscular atrophy 1 and hemophilia A and B, and multiple Phase I/II clinical trials are ongoing.

AAV is an icosahedral virus particle from the Parvoviridae family that can only replicate in the presence of a helper virus, such as adenovirus, and is less pro-inflammatory than other helper viruses, such as adenovirus and herpes viruses. Its genome is flanked by inverted terminal repeats (ITRs) that serve as packaging signals for the AAV single-stranded DNA genome, which consists of three open reading frames (ORFs): rep, encoding four proteins responsible for aiding regulation, replication, and assembly; cap, encoding three overlapping capsid proteins that form a 60-mer icosahedral capsid; and the AAP gene located within cap as an alternative reading frame that aids in capsid assembly. For therapeutic applications, the viral genes are placed on a separate helper construct and replaced with a recombinant cargo single-stranded gene cassette up to 4.7 kb long. The flanking ITRs then serve as replication origins and packaging signals, allowing the cassette to be packaged into infectious but replication-incompetent AAV virions.