Sustained AAV9-mediated expression of a non-self protein in the CNS of non-human primates after immunomodulation

PLoS One. 2018 Jun 6;13(6):e0198154. doi: 10.1371/journal.pone.0198154. eCollection 2018.


A critical issue in transgene delivery studies is immune reactivity to the transgene- encoded protein and its impact on sustained gene expression. Here, we test the hypothesis that immunomodulation by rapamycin can decrease immune reactivity after intrathecal AAV9 delivery of a transgene (GFP) in non-human primates, resulting in sustained GFP expression in the CNS. We show that rapamycin treatment clearly reduced the overall immunogenicity of the AAV9/GFP vector by lowering GFP- and AAV9-specific antibody responses, and decreasing T cell responses including cytokine and cytolytic effector responses. Spinal cord GFP protein expression was sustained for twelve weeks, with no toxicity. Immune correlates of robust transgene expression include negligible GFP-specific CD4 and CD8 T cell responses, absence of GFP-specific IFN-γ producing T cells, and absence of GFP-specific cytotoxic T cells, which support the hypothesis that decreased T cell reactivity results in sustained transgene expression. These data strongly support the use of modest doses of rapamycin to modulate immune responses for intrathecal gene therapies, and potentially a much wider range of viral vector-based therapeutics.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Autoantigens / immunology
  • Central Nervous System / immunology
  • Central Nervous System / metabolism*
  • Dependovirus / genetics*
  • Dependovirus / immunology
  • Gene Expression
  • Gene Transfer Techniques
  • Genetic Vectors* / immunology
  • Green Fluorescent Proteins / genetics*
  • Green Fluorescent Proteins / immunology*
  • Immunomodulation / physiology*
  • Macaca fascicularis
  • Primates / genetics*
  • Primates / immunology*
  • Random Allocation
  • Transduction, Genetic
  • Transgenes / immunology


  • Autoantigens
  • Green Fluorescent Proteins