SUMMARY
# AAV Serotype Comparison for LRRK2 Knockdown in PD
## Background and Rationale
Leucine-rich repeat kinase 2 (LRRK2) mutations are the most common genetic cause of Parkinson's disease (PD), with G2019S being the most prevalent pathogenic variant. LRRK2 gain-of-function mutations lead to increased kinase activity, resulting in neuronal dysfunction and degeneration. Adeno-associated virus (AAV)-mediated gene therapy represents a promising therapeutic approach, but optimal serotype selection is cri
METHODOLOGY NOTES
Phase 1 (Week 0): Prepare AAV vectors encoding LRRK2 shRNA in serotypes AAV1, AAV2, AAV5, AAV9, and AAVrh10 (1×10^12 vg/ml). Acclimate 60 male C57BL/6 mice (8-10 weeks) for one week. Phase 2 (Week 1): Perform stereotactic surgery under isoflurane anesthesia. Inject 2μl of AAV vectors bilaterally into substantia nigra (coordinates: AP -3.1mm, ML ±1.2mm, DV -4.2mm) using Hamilton syringe (n=10 per serotype). Include control group with saline injection. Phase 3 (Weeks 2-8): Monitor animals weekly for weight and general health. Perform behavioral assessments at weeks 4, 6, and 8 including rotarod performance (5 trials, 4-40 rpm acceleration) and cylinder test for forepaw asymmetry. Phase 4 (Week 8): Sacrifice animals via transcardial perfusion with 4% paraformaldehyde. Collect brain tissue for immunohistochemistry and separate cohort for biochemical analysis. Phase 5 (Weeks 9-12): Process tissue sections for tyrosine hydroxylase and LRRK2 immunostaining. Perform stereological counting of d