Epitope mapping of anti-A2 mAbs by homolog-scanning mutagenesis. (A) BDD hybrid human/porcine fVIII constructs. Shaded areas represent porcine fVIII substitutions. (B) Binding of anti-A2 mAbs to human/porcine fVIII. fVIII was captured on a microtiter plate using immobilized anti-C2 mAb, followed by addition of biotinylated anti-A2 mAb and detection using streptavidin–alkaline phosphatase. Bars represent the range of duplicate determinations.