Inhibitory antibodies to hF.IX (measured as Bethesda units [BUs]) as a function of time after hepatic AAV-hF.IX gene transfer in hemophilia B C3H/HeJ mice. (A) Four weeks. (B) Twelve weeks. (C) Twenty weeks. Mice had received repeated intranasal administration of ova peptide (♦), hF.IX-derived peptide 2A-54 (▴), or saline control (•). Each data point represents an individual animal. Horizontal bars show average antibody titers. P values are indicated. Numbers of mice are indicated for each cohort and time point.