Serotype and dose comparison in canine 2-chain intraportal delivery. AAV serotypes 2, 5, 7, and 8 expressing canine FVIII in 2 separate AAV vectors (heavy and light chains) were evaluated in FVIII KO mice at different vector doses. Because the vector injections were staggered for experimental convenience, data on some mice are available beyond 12 months, whereas the data on others end at 9 months. (A) Mice injected with 8 × 10¹¹ gc/vector/mouse have long-term normal levels of FVIII expression when measured on the canine standard curve and supraphysiologic levels based on the murine standard curve. (B) Evaluation of the 4 serotypes at 1 × 10¹¹ gc/vector/mouse. At this dose, both AAV8 and AAV7 express normal levels of FVIII when determined on the canine standard curve and supraphysiologic levels for AAV8 based on the murine standard curve. FVIII expression with AAV5 and AAV2 were at much lower levels. (C) The FVIII levels at a dose of 3 × 10¹⁰ gc/vector/mouse. AAV8 is clearly superior, expressing normal levels of FVIII over the long-term, whereas AAV7, 5, and 2 express at a much lower level that diminishes over time. This panel shows absence of activity at the lowest dose (1 × 10¹⁰ gc/vector/mouse) from AAV7, 5, and 2. On the other hand, AAV8 maintains a low, but respectable, level of FVIII activity. Error bars represent the mean ± SD.