Adeno‑Associated Virus 1 (AAV1) is a natural serotype of adeno‑associated virus originally isolated from primate tissues. It is a small non‑enveloped virus with an icosahedral capsid about 25 nm in diameter and a 4.7 kb single‑stranded DNA genome. AAV1 binds to terminal sialic acid on cell surfaces and uses the universal AAV receptor (AAVR) to enter cells, conferring a natural tropism for skeletal muscle, heart and central nervous system tissues.
Explanation
AAV1 belongs to the genus Dependoparvovirus of the family Parvoviridae and cannot replicate without co‑infection by adenovirus or a related helper virus. Its genome contains rep and cap genes flanked by inverted terminal repeats (ITRs) that are essential for replication and packaging. Wild‑type infection is typically asymptomatic and results in stable episomal DNA in the nucleus without integrating at high frequency. Because of its affinity for striated muscle and its ability to transduce both dividing and non‑dividing cells, AAV1 has become a prominent platform for gene transfer. Recombinant AAV1 vectors lack the rep and cap genes and instead carry therapeutic cassettes. Preclinical studies demonstrate long‑term expression in skeletal muscle, heart and brain. Nevertheless, pre‑existing neutralizing antibodies are common in human populations and can reduce transduction efficiency. This has prompted development of engineered capsids and transient immunomodulation strategies to improve delivery.
Therapeutic applications and key findings
The first gene therapy approved in Europe, Glybera, used an rAAV1 vector to deliver a functional lipoprotein lipase gene to skeletal muscle in patients with lipoprotein lipase deficiency, leading to improved fat metabolism. Recombinant AAV1 has been evaluated in clinical trials to deliver α‑1 antitrypsin for inherited emphysema, factor IX for haemophilia and SERCA2a for heart failure. In preclinical models, rAAV1 efficiently delivers genes to cochlear hair cells, spinal motor neurons and salivary glands, supporting research into deafness and neurodegenerative disorders. High transduction efficiency in rodent and non‑human primate muscle has made AAV1 a preferred vector for ex vivo and in vivo studies of muscular dystrophy. Limitations include variable efficacy in large animals and the need to overcome neutralizing antibodies in patients. AAV1 is a muscle‑tropic adeno‑associated virus serotype that has played a key role in the development of gene therapy. Its ability to deliver genes to striated muscle and other tissues with minimal pathogenicity underpins its ongoing research and clinical use, although immune barriers remain an important consideration. Related Terms: Adeno‑Associated Virus 2, Adeno‑Associated Virus 6, Adeno‑Associated Virus 8, Adeno‑Associated Virus 9, Adenovirus