Mouse IgG anti–human factor IX following AVC3FIX5 as a function of RI mouse strain. (Top) AXB RI mouse strains. (Bottom) BXA RI mouse strains. Mean IgG anti–human factor IX levels are shown with 95% CIs indicated by vertical lines for each panel. M indicates male; F, female. A/J and C57BL/6J antibody levels (from Figure 1) are also shown in each panel for reference purposes.