cFVIII expression and anti-cFVIII antibody response in a high-responding hemophilia A dog after AAV-mediated liver expression of cFVIII. A high-responding hemophilia A dog from the Queen's University colony (Wembley) was administered 2.5 × 10¹³ vg/kg of AAV8-TBG-cFVIII-HC and AAV8-TBG-cFVIII-LC by peripheral venous injection. (A) cFVIII antigen levels were assayed by a cFVIII-LC-specific ELISA, and activity was monitored by FVIII assay. (B) Anti-cFVIII antibody responses were measured by anti-cFVIII IgG2 ELISA and Bethesda assays.