FIG. 5.

Enzyme activity in harvested mouse serum on days 9, 30, and 45 following administration of rAAV1-hADA or lactated Ringer's PBS to ADA-SCID KO mice. (A) Serum hADA activity on day 9 post-vector injection is low relative to that of negative control mice, indicating either a lack of vector-driven enzyme activity or a relatively high degree of background enzyme activity. (B) Observed serum enzyme activity on day 30. At this time point, the average level of serum enzyme activity increases approximately threefold for vector-treated mice, whereas background ADA activity from PBS-injected mice remains relatively stable. (C) hADA activity found in mouse serum on day 45. At this final time point, enzyme activity in serum of treated animals decreases, whereas enzyme activity for the untreated animals remains stable at approximately 4 units. Overall, this time-course study suggests a trend of increasing and decreasing levels of serum ADA activity in treated versus untreated KO mice, which may parallel cycles of enzyme synthesis and degradation in the treated mice. However, given the large SDs, the observed trend is not statistically significant. Post-IM, post-intramuscular.