AAV is an acronym for Adeno-associated virus. They are the leading platform for gene delivery for the treatment of a variety of human diseases. The first AAV-based gene therapy drug, Glybera, was approved by the European Medicines Agency in 2012. This <a href="https://www.nature.com/articles/s41573-019-0012-9" target="_blank" rel="noopener">article</a> has much more information.