Transgene regulation using the tetracycline-inducible TetR-KRAB system after AAV-mediated gene transfer in rodents and nonhuman primates

PLoS One. 2014 Sep 23;9(9):e102538. doi: 10.1371/journal.pone.0102538. eCollection 2014.


Numerous studies have demonstrated the efficacy of the Adeno-Associated Virus (AAV)-based gene delivery platform in vivo. The control of transgene expression in many protocols is highly desirable for therapeutic applications and/or safety reasons. To date, the tetracycline and the rapamycin dependent regulatory systems have been the most widely evaluated. While the long-term regulation of the transgene has been obtained in rodent models, the translation of these studies to larger animals, especially to nonhuman primates (NHP), has often resulted in an immune response against the recombinant regulator protein involved in transgene expression regulation. These immune responses were dependent on the target tissue and vector delivery route. Here, using AAV vectors, we evaluated a doxycyclin-inducible system in rodents and macaques in which the TetR protein is fused to the human Krüppel associated box (KRAB) protein. We demonstrated long term gene regulation efficiency in rodents after subretinal and intramuscular administration of AAV5 and AAV1 vectors, respectively. However, as previously described for other chimeric transactivators, the TetR-KRAB-based system failed to achieve long term regulation in the macaque after intramuscular vector delivery because of the development of an immune response. Thus, immunity against the chimeric transactivator TetR-KRAB emerged as the primary limitation for the clinical translation of the system when targeting the skeletal muscle, as previously described for other regulatory proteins. New developments in the field of chimeric drug-sensitive transactivators with the potential to not trigger the host immune system are still needed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Dependovirus / classification
  • Dependovirus / genetics*
  • Dependovirus / immunology
  • Doxycycline
  • Gene Expression Regulation / drug effects
  • Gene Transfer Techniques
  • Genetic Vectors / administration & dosage*
  • Genetic Vectors / drug effects
  • Humans
  • Immunity, Cellular
  • Kruppel-Like Transcription Factors / genetics
  • Kruppel-Like Transcription Factors / metabolism*
  • Macaca
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Muscle, Skeletal / immunology
  • Muscle, Skeletal / metabolism*
  • Muscle, Skeletal / virology
  • Rats
  • Rats, Wistar
  • Retina / metabolism*
  • Retina / virology
  • Tetracycline / metabolism
  • Tetracycline / pharmacology*
  • Transgenes


  • Kruppel-Like Transcription Factors
  • Tetracycline
  • Doxycycline

Grants and funding

Financial supports came from the INSERM, the INRA, the University Hospital of Nantes, the Fondation pour la Thérapie Génique en Pays de Loire, The Région Pays de La Loire (IMBIO-CD network) and the AFM-Telethon (Association Française contre les Myopathies). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.