FVIII activity levels in vivo in plasma taken from mice injected with vector expressing FVIII from codon-optimized cDNA sequences. Activity of human FVIII in blood plasma taken from mice injected with LV expressing SQ FVIII (co) (gray circles), SQ FVIII Fugu B (co) (◇), and SQ FVIII N6 (co) (▴) collated. Points on graphs represent the mean; error bars represent the SD. No significant difference in expression is noted between constructs expressing different B domains (P > .5, Bonferroni simultaneous test).