SUMMARY
# AAV Serotype Comparison for LRRK2 Knockdown in PD Gene Therapy
## Background and Rationale
Parkinson's disease (PD) is characterized by progressive neurodegeneration of dopaminergic neurons in the substantia nigra, with mutations in LRRK2 (leucine-rich repeat kinase 2) being the most common genetic cause of familial PD. LRRK2 G2019S mutation leads to increased kinase activity and enhanced neuronal toxicity, making it an attractive therapeutic target. Gene therapy approaches using adeno-associa
METHODOLOGY NOTES
Phase 1 (Days 1-3): Prepare AAV vectors - AAV2, AAV5, AAV9, and AAV-PHP.eB serotypes carrying identical LRRK2 shRNA constructs under U6 promoter with GFP reporter (1×10^12 vg/ml titer). House 8-week-old LRRK2 G2019S transgenic mice (n=60, equal male/female) under standard conditions. Phase 2 (Day 4): Perform stereotactic surgery under isoflurane anesthesia. Inject 2μl AAV suspension bilaterally into substantia nigra (coordinates: AP -3.1, ML ±1.2, DV -4.6 mm from bregma) using Hamilton syringe at 0.2μl/min rate. Groups: AAV2 (n=12), AAV5 (n=12), AAV9 (n=12), PHP.eB (n=12), PBS control (n=12). Phase 3 (Weeks 2-8): Conduct weekly behavioral assessments including rotarod test, cylinder test, and open field analysis. Phase 4 (Week 4): Sacrifice subset (n=6/group) for biodistribution analysis via qPCR of liver, heart, kidney, spleen tissues. Phase 5 (Week 8): Terminal sacrifice remaining mice. Perfuse with 4% PFA, collect brains for immunohistochemistry (TH, GFP, LRRK2 staining) and qRT-PCR