Adeno-associated virus-based vectors and their application for gene therapy

Adeno-associated virus (AAV)-based vectors are one of the most promising tools for the delivery of exogenous genes into mammalian cells. Their use has to be considered for most gene therapy applications, given the advantages that they potentially offer compared to other more widely used vectors for gene transfer (adenoviruses, retroviruses), We have developed an AAV-based procedure for gene therapy of X-linked chronic granulomatous disease (X-CGD), a rare inheritable disease due to the lack of production of superoxide anion (O-2(-)) by the NADPH oxidase of phagocytic cells, The defect is caused by mutations of the gp91-phox gene, located on the X chromosome. The wild type gp91-phox cDNA was cloned within the AAV genome in a plasmid backbone, and recombinant infectious virus was obtained by transfection of this plasmid in a human epithelial cell Line together with another plasmid providing helper packaging functions and upon infection with adenovirus. High titer recombinant AAV preparations were used for the transduction of an EBV-transformed B lymphoblastoid cell line obtained from a patient with X-CGD. Functional correction of the NADPH oxidase defect was obtained in this cell line, as monitored by O-2(-) production by a chemiluminescence assay, These results show the feasibility of a gene therapy protocol for X-CGD using AAV-based vectors.