The FV2-specific IgG from both rats and rabbit's sera were affinity purified on HiTRap TM NHS-activated HP columns (GE Healthcare), according to the manufacturer's instructions. Briefly, each column was coated with 0.5 mg/ml of a DBL-domain resulting in six different columns for the individual six DBLdomains. The affinity purified IgG was verified using ELISA as previously described in this material and methods section. The assay was performed twice with similar results.