Recombinant adeno-associated virus (AAV) gene therapy vectors for the monogenic lung diseases, cystic fibrosis (CF) and alpha-1-antitrypsin deficiency (AAT)
AAV is a non-pathogenic human parvovirus which is commonly isolated from the respiratory tract of humans. AAV’s life cycle includes a unique mechanism for persistence in human cells by means of site-specific integration into a region of chromosome 19, the AAVS1 site. In 1993, our group published the results of the first successful in vivo gene transfer with AAV. In that study, AAV vectors carrying the human CF transmembrane conductance regulator (CFTR) gene were delivered to the bronchial epithelium of rabbits. Efficient gene transfer was observed which persisted for over 6 months without any detectable toxicity. Subsequently, we studied AAV-CFTR gene transfer in rhesus macaques.
The rhesus model offers the advantage of being another natural host for AAV infection. Furthermore, the rhesus genome contains an AAVS1 site homologue, which we have recently cloned and sequenced and found to be very similar to the human sequence. Our studies in rhesus served two purposes: 1. We performed the primary toxicology study to justify beginning our phase I trial of AAV-CFTR administration in humans, and 2. We studied vector integration and persistence in vivo for the first time.
Currently there are three NIH-funded projects underway in my laboratory:
Adeno-associated Virus (AAV) Vectors for CF Gene Therapy (HL51811): This includes the continuing preclinical and phase I clinical studies of the current AAV-CFTR vectors and newer AAV-CFTR vectors containing larger, more active promoters.
Strategies to Improve AAV vector Persistence and Expression (DK51809): In this project, AAV vectors with transient or conditional Rep expression are being studied in human cell lines and in rhesus macaques in an attempt to restore site-specific integration to the vectors.
AAV Transduction of Skeletal Muscle as a Platform for Therapeutic Protein Delivery (HL59412): In this project, skeletal muscle is being used as a site for ectopic secretion of alpha-1-antitrypsin (AAT) in mice and rhesus macaques. We are seeking to exploit the very high efficiency and duration of AAV vector expression in skeletal muscle and to use AAV-AAT to study immune responses to AAV vectors. Alternative routes of delivery, including liver-directed (portal vein injection) and lung-directed (intratracheal injection) are also being studied in detail.
