Expression of a truncated cystic fibrosis transmembrane conductance regulator with an AAVS-pseudotyped vector in primates

Gene therapy using recombinant adeno-associated virus (rAAV2) vectors for cystic fibrosis has shown gene transfer and remarkable safety, yet indeterminate expression. A new construct has been characterized with a powerful exogenous promoter, the cytomegalovirus enhancer/chicken beta-actin promoter, driving a truncated CF transmembrane conductance regulator (CFTR), pseudotyped in an AAV5 viral coat. Our goal is to demonstrate that airway delivery of a pseudotyped rAAV5 vector results in gene transfer as well as expression in non-human primates. Aerosolized pseudotyped rAAV5-Delta CFTR or rAAV5-GFP (green fluorescent protein) genes were delivered to four and six lungs, respectively. The pseudotyped rAAV5 vector did result in GFP gene transfer (1.005 x 10(6) copies/mu g DNA on average) and quantifiable gene expression. Microscopy confirmed protein expression in airway epithelium. Similarly, the vector also resulted in vector-specific CFTR DNA (1.24 x 10(5) copies/mu g) and mRNA expression. Immunoprecipitation and P-32 phosphoimaging were used to demonstrate CFTR protein expression, as qualitatively enhanced beyond the barely detectable endogenous expression in untreated animals. Based on these promising studies, this CFTR minigene construct is a therapeutic candidate.