Fig. 1a, b.

PPT1 activity and secondary lysosomal enzyme elevations in the brain at 7 months of age. a PPT1 activity in the treated and untreated brains. Ppt1-/- mice treated with either AAV only or AAV+ phosphocysteamine resulted in a twofold increase in PPT1 enzyme activity compared to WT brains. Untreated Ppt1-/- brains or those treated with only phosphocysteamine had undetectable levels of PPT1 activity in the brain. b Secondary lysosomal enzyme elevations in the treated and untreated brains. To ascertain whether secondary elevations in lysosomal enzyme activity were decreased in response to therapy, we performed β-glucoronidase activities on the brains from treated and untreated mice. There was a six fold increase in β-glucoronidase activity in the brains of untreated Ppt1-/- mice compared to normal. A similar increase in β-glucoronidase activity was observed in the phosphocysteamine only group. Following either AAV only or AAV+phosphocysteamine treatment, there was a decrease in secondary enzyme elevation, returning β-glucoronidase activity to WT levels. (*p<0.05, ***p<0.001)