Phenotype correction of hemophilia A mice with adeno-associated virus vectors carrying the B domain-deleted canine factor VIII gene

Adeno-associated virus (AAV) vectors carrying the B domain-deleted canine FVIII (BDD cFVIII) gene utilizing the β-actin minimum promoter (167b) pseudotyped with serotype 1 (AAV1-β-actin-cFVIII) and serotype 8 (AAV8-β-actin-cFVIII) were developed to express cFVIII in hemophilia A mice. FVIII clotting activities measured by the APTT method increased in hemophilia A mice with intramuscular injection of AAV1-β-actin-cFVIII in a dose-dependent manner. Therapeutic FVIII levels (2.9 ± 1.0%) in hemophilia A mice with the AAV1-β-actin-cFVIII dose of 1 × 1012 gc/body were achieved, suggesting partial correction of the phenotype with AAV1-β-actin-cFVIII vectors. FVIII clotting activity levels in hemophilia A mice with intravenous injection of AAV8-β-actin-cFVIII also were increased dose-dependently, achieving therapeutic FVIII levels (5–90%) in hemophilia A mice with the AAV8-β-actin-cFVIII doses of 1–3 × 1011 gc/body and supernormal FVIII levels (180–670%) in hemophilia A mice with the AAV8-β-actin-cFVIII dose of 1 × 1012 gc/body. Transduction of the liver with AAV8-β-actin-cFVIII is superior to transduction of skeletal muscles with AAV1cFVIII regarding the FVIII production and antibody formation. These data suggested that both AAV1 and AAV8 vectors carrying the FVIII gene utilizing a minimum promoter have a potential for hemophilia A gene therapy.