Abstract: A composition for delivering at least one DNA sequence encoding a desired protein or polypeptide (such as a therapeutic agent) to a cell. The composition comprises an adeno-associated virus rep protein (or a nucleic acid sequence encoding an adeno-associated virus rep protein) and a genetic construct including at least one DNA sequence encoding a protein or polypeptide or genetic transcript of interest and a promoter controlling the at least one DNA sequence. The genetic construct also includes a first adeno-associated virus ITR or protein or derivative thereof and a second adeno-associated virus ITR or a portion or derivative thereof. The first and second adeno-associated virus ITRs or portions or derivatives thereof flank the at least one DNA sequence encoding the protein or polypeptide or genetic transcript of interest and the promoter controlling the at least one DNA sequence encoding the protein or polypeptide or genetic transcript of interest.

Abstract: A vector system comprising a first vector, which is an adeno-associated viral vector, and which includes an adeno-associated virus 5'ITR, an adeno-associated virus 3'ITR, and at least one heterologous DNA sequence. The vector system also includes a second vector which includes an inducible origin of replication, such as an SV40 origin of replication, which is capable of being induced or activated by an agent, such as the SV40 T-antigen. The second vector also includes DNA sequences encoding the adeno-associated virus rep and cap proteins. When induced by an agent, the second vector may replicate to a high copy number, and thereby increased numbers of infectious adeno-associated viral particles may be generated.