Striatal delivery of rAAV-hAADC to rats with preexisting immunity to AAV

Mol Ther. 2004 Mar;9(3):403-9. doi: 10.1016/j.ymthe.2003.12.005.


We tested the hypotheses that initial immunization of rats with rAAV might limit subsequent transduction by rAAV-hAADC when stereotaxically infused into the striatum and that the level of inhibition would correlate with AAV neutralizing antibody titers. Immunohistochemical detection of AADC and analysis by stereology revealed that the control group (no immunization) had the greatest volume of distribution of AADC (20.32 +/- 2.03 mm3) (+/-SD). There was a 58% decrease in spread (8.46 +/- 3.67 mm3, P < 0.008) in the high-dose immunization group (5 x 10(10) vg rAAV-null). Transduction weakly correlated with preexisting titer levels of neutralizing antibody at the time of intrastriatal rAAV-hAADC infusion. Only rats with neutralizing antibody titers of 1:1208 +/- 332 had significantly decreased AADC transgene expression compared to the unimmunized control group. Immunohistochemistry on serial sections for inflammatory markers including GFAP, CD11b, CD4, and CD8a revealed normal morphology and no cellular infiltration, suggesting little immune reaction in the CNS. We conclude that rAAV vectors can transduce brain tissue in the context of preexisting immunity, but that efficiency of transduction declines significantly in the presence of very high titers of neutralizing antibodies. These results have important implications for gene therapy for CNS disorders.

MeSH terms

  • Animals
  • Aromatic-L-Amino-Acid Decarboxylases / genetics*
  • Biotinylation
  • Brain / metabolism
  • CD11b Antigen / biosynthesis
  • CD4 Antigens / biosynthesis
  • CD8 Antigens / biosynthesis
  • Cell Line
  • Central Nervous System / metabolism
  • Central Nervous System Diseases / therapy
  • Dependovirus / genetics*
  • Gene Transfer Techniques*
  • Genetic Therapy / methods
  • Genetic Vectors*
  • Glial Fibrillary Acidic Protein / biosynthesis
  • Humans
  • Immunohistochemistry
  • Inflammation
  • Models, Genetic
  • Parkinson Disease / therapy
  • Rats
  • Rats, Sprague-Dawley
  • T-Lymphocytes / metabolism
  • Transgenes


  • CD11b Antigen
  • CD4 Antigens
  • CD8 Antigens
  • Glial Fibrillary Acidic Protein
  • Aromatic-L-Amino-Acid Decarboxylases