Trans-splicing vectors expand the utility of adeno-associated virus for gene therapy

Adeno-associated viral (AAV) vectors have demonstrated considerable promise for gene therapy of inherited diseases. However, with a packaging size of <5 kb. applications have been limited to relatively small disease genes. Ba sed on the finding that AAV genomes undergo intermolecular circular concata merization after transduction in muscle, we have developed a paradigm to in crease the size of delivered transgenes with this vector through trans-spli cing between two independent vectors coadministered to the same tissue. Whe n two vectors encoding either the 5' or 3' portions of the erythropoietin g enomic locus were used, functional erythropoietin protein was expressed in muscle subsequent to the formation of intermolecular circular concatamers i n a head-to-tail orientation through transsplicing between these two indepe ndent vector genomes, These findings will allow for the application of AAV technologies to a wider variety of diseases for which therapeutic transgene s exceed the packaging limitation of present AAV vectors.