Dose comparison of AAV8 and AAV2 in canine single-chain intraportal delivery. AAV serotypes 8 and 2 were evaluated at 3 different doses, 1 × 10¹¹, 3 × 10¹⁰, and 1 × 10¹⁰ gc/mouse. At the high and mid doses, AAV8 expresses normal levels of FVIII activity as measured against the canine standard curve and supraphysiologic levels based on the murine standard curve. Interestingly, AAV2 shows improved levels of expression when delivered as a single vector compared to the 2-vector approach at the same doses and time points.