Comparison of FVIII activity and inhibitor development following gene transfer of AAV carrying WT-BDD-FVIII or the mutated BDD-FVIII N2118Q variant. HA mice were intravenously injected with 1 × 10¹² vg of AAV carrying WT-BDD-FVIII or the mutated FVIII N2118Q variant, respectively. (A) Schematic of the treatment and blood collection schedule. (B) The plasma was collected at marked timepoints for the detection of FVIII activity. Mice were subsequently challenged intravenously with 5 U of FVIII weekly for 6 weeks from weeks 16 to 21. (C) The prevalence of inhibitor development was calculated 1 week after final FVIII challenge. Mice with >0.6 BU inhibitor titer were considered inhibitor positive. The data are presented as means with standard deviation from 3 separate experiments.