AAV9-TRE-GFP

Adeno-associated virus (AAV) was discovered in the 1960s as a contaminant of a preparation of simian adenovirus type 15. Since then, AAV has been successfully developed as a viral vector for clinical use. AAV belongs to the genus Dependoparvovirus in the family Parvoviridae. At least 12 naturally occurring serotypes have been discovered, which vary in their tissue tropism. This special aspect can be used to target AAV gene therapy vectors to target sites. AAV infects a variety of animals, including humans, and is found worldwide, with human seroprevalence ranging from approximately 15% to more than 90%.

Infection with AAV is asymptomatic and can last a lifetime. As the genus name suggests, AAV can replicate only in the presence of helper factors, which are provided by co-infection with helper viruses from the herpesviridae (e.g., HSV-1 and human cytomegalovirus, HCMV), adenoviruses (e.g., AdV5), and papillomaviruses (e.g., human papillomavirus type 16, HPV-16), as well as other viruses such as baculovirus and human bocavirus 1. Interestingly, AAV replication can also be induced by treating AAV-infected cells with physical or chemical carcinogens, and is therefore not intrinsically dependent on viral co-infection but rather on drastic changes in the cellular environment. In the absence of helper factors, AAV delivers its genome into host cells, where most copies are cleared within a short period of time, while some AAV genomes persist for a long time. Long-term persistence is thought to occur primarily in episomal circular forms. Latent persisters of AAV are reactivated upon co-infection with a helper virus, resulting in the production of progeny viruses.