Subclasses of anti-hF.IX immunoglobulin after intramuscular injection of AAV-2-CMV-hF.IX. Hemophilia B knockout mice on C57Bl/6 background (n=4), or hemophilic mice carrying an hF.IX (wild-type or mutant) transgene (n=2-3 per group), were injected with AAV-2-CMV-hF.IX at a dose of 1.0 × 10¹¹ vg/animal (4 × 10¹² vg/kg). Each panel shows antibody titer in ng IgG/mL for IgG subclass-specific ELISA. Each line represents an individual animal. Bethesda titers were determined at 4 weeks, and were 2.0 BU ± 0.9 BU in hemophilia B knockout mice, approximately the same for the ES and LS mutation mice, and undetectable in the wild-type, missense (MS), and cCH mutation mice.