Comparison of human FVIII expression in exon 16 and exon 17–disrupted hemophiliac mice. The adenoviral vector, Av3H8101 (6 × 10¹⁰ particles/mouse) was administered via tail vein injection to groups of 12 exon 16– or 11 exon 17–disrupted hemophiliac mice. At the indicated time points, plasma samples were collected and FVIII biological activity was quantitated. Mice that were expressing below less than 1% of normal FVIII levels (<25 mU/mL) were killed at 24 weeks. The FVIII levels in the remaining mice were assayed for an additional 16 weeks. (A) Mean plasma levels of biologically active FVIII. (•) Exon 16-disrupted mice. (▴) Exon 17–disrupted mice. Data are plotted as a mean value and the standard error of the mean at each time point. The dotted line represents the human therapeutic level of FVIII, 50 mU/mL.33