Generation of a high-capacity hybrid vector: Packaging of recombinant adenoassociated virus replicative intermediates in adenovirus capsids overcomesthe limited cloning capacity of adenoassociated virus vectors

Gene therapy aims to complement or, ideally, correct defective genes. The b road clinical application of this emerging technology requires the developm ent of safe high-capacity gene delivery vehicles that combine efficient tra nsduction of dividing as well as quiescent cells with sustained transgene e xpression. Here we present a new hybrid vector system that unites favorable attributes of adenoassociated virus (AAV) and adenovirus (Ad) vectors in a single particle. This was achieved by inclusion of Ad packaging elements i n different sized recombinant AAV genomes. In the presence of AAV replicati ve functions and a recombinant helper Ad, AAV/Ad hybrid particles were gene rated via encapsidation of AAV-dependent replicative intermediates into Ad capsids. In stringent in vitro models based on transduction of proliferatin g cells we show that AAV/Ad, hybrid vectors are superior to Ad vectors in e stablishing prolonged transgene expression and can be used to deliver DNA f ragments of at least 27 kb. (C) 2001 Academic Press.