Dysbiosis enhances the immune response to FVIII. (A) Plasma was assessed at the study end point (10 weeks of age) for FVIII-specific IgG and was quantified by the highest titer or dilution at which the ELISA was positive. (B) The magnitude of inhibitory activity was assessed by Bethesda assay. (C) FVIII-specific IgG was quantified based on IgG subclass using a mouse reference serum standard curve. The means and standard deviations were compared using Mann-Whitney U test for total FVIII-specific IgG and an unpaired, 2-tailed Student t test for all other analyses (n = 10). **P < .01; ***P < .001; ****P < .0001.