Time course of canine FIX expression and coagulation activity in naive hemophilia B dogs after ATRVX delivery of an AAV6-cFIX vector. (A) Canine FIX antigen levels measured by ELISA. (B) Whole blood clotting time (WBCT); m indicates minutes. (C) Activated partial thromboplastin time (aPTT); s indicates seconds. x axis represents time in days.