Inhibition of human/porcine hybrid factor VIII proteins by inhibitory patient's plasma. Inhibition of factor VIII clotting activities of recombinant human factor VIII des-Ser⁷⁴¹-Arg¹⁶⁴⁸ (⋄)15 was compared to inhibition of six hybrid proteins with substitutions of porcine sequence in the A2 domain using dilutions of inhibitor patient plasma from the 3-month (peak titer) sample. The homologous substitutions were of human residues 387-740 (▪), 387-604 (□), 387-508 (•), 484-508 (○), 489-508 (▴), and 484-488 (▵) as described by Healey et al.16