Constructs used in vector preparation. (A) Helper plasmids contain rep gene sequences from AAV-2 and cap gene sequences from AAV-2, AAV-1, and AAV-6 respectively. (B) The canine transgene cassette contains the cF.IX cDNA, the human β-globin intron 1, the CMV enhancer/promoter, and the human growth hormone polyadenylation signal, flanked by the AAV-2 inverted terminal repeats. The human transgene cassette contains the human F.IX cDNA interrupted by a 1.4-kb fragment of hF.IX intron 1, the CMV enhancer/promoter, and the SV40 polyadenylation signal, also flanked by the AAV-2 inverted terminal repeats.