CMV-beta-actin promoter directs higher expression from an adeno-associatedviral vector in the liver than the cytomegalovirus or elongation factor 1 alpha promoter and results in therapeutic levels of human factor X in mice

Although AAV vectors show promise for hepatic gene therapy, the optimal tra nscriptional regulatory elements have not yet been identified. In this stud y, we show that an AAV vector with the CMV enhancer/chicken beta -actin pro moter results in 9.5-fold higher expression after portal vein injection tha n an AAV vector with the EF1 alpha promoter, and 137-fold higher expression than an AAV vector with the CMV promoter/enhancer. Although induction of t he acute-phase response with the administration of lipopolysaccharide (LPS) activated the CMV promoter/enhancer from the context of an adenoviral vect or in a previous study, LPS resulted in only a modest induction of this pro moter from an AAV vector in vivo, An AAV vector with the CMV-beta -actin pr omoter upstream of the coagulation protein human factor X (hFX) was injecte d intravenously into neonatal mice. This resulted in expression of hFX at 5 48 ng/ml (6.8% of normal) for up to 1.2 years, and 0.6 copies of AAV vector per diploid genome in the liver at the time of sacrifice. Neonatal intramu scular injection resulted in expression of hFX at 248 ng/ml (3.1% of normal ), which derived from both liver and muscle, We conclude that neonatal gene therapy with an AAV vector with the CMV-beta -actin promoter might correct hemophilia due to hFX deficiency.