Time course of circulating canine FIX and coagulation activity in naive hemophilia B dogs after ATVRX vector delivery. (A) Canine FIX (cFIX) antigen levels measured by ELISA. (B) Activated partial thromboplastin time (aPTT); s indicates seconds. (C) Whole blood clotting time (WBCT); m indicates minutes. (D) Creatinine phosphokinase (CPK) levels. Each line represents an individual dog: red indicates dogs from the low-dose cohort (1 × 10¹² vg/kg); black, dogs from the mid-dose cohort (3 × 10¹² vg/kg). Shaded gray areas represent indicate range of values for hemostatically normal animals. x axis represents time in days.