Immunoglobulin responses in treated SCID-X1 canines. (A) Bacteriophage immunoglobulin response in serum of FV-treated SCID-X1 dogs (mobilized, green; nonmobilized, blue) and in a normal control (red) ±2 standard deviations (dashed lines). Animals were injected with a first dose of bacteriophage φX174 at 8 to 12 months post–FV vector treatment and with a second dose 6 weeks later. Primary and secondary immune responses to injection were assessed at 1, 2, and 4 weeks, compared with preinjection levels, and expressed as the rate of phage inactivation or K value (Kv; described in Methods). (B) Quantitative measurement of the 3 main classes of immunoglobulin in serum of mobilized animals at 14 and 15 months posttreatment as compared with a normal control. Standard range is based on normal dog age 1 year.