The propagation of AAV in tissue culture requires the help of another virus in which adenovirus (AdV) and herpes virus (HSV) are traditionally used as AAV helper viruses. The AAV vector is a recombinant variant of the wild-type AAV virus in which the native coding region and the non-coding region have been replaced by the gene of interest.
https://www.creative-biolabs.com/vaccine/adeno-associated-virus-AAV-as-vaccine-vectors.htm