Evaluation of the expression pattern of rAAV2/1, 2/5, 2/7, 2/8, and 2/9 serotypes with different promoters in the mouse visual cortex

J Comp Neurol. 2015 Oct 1;523(14):2019-42. doi: 10.1002/cne.23819. Epub 2015 Jun 19.


This study compared the expression pattern, laminar distribution, and cell specificity of several rAAV serotypes (2/1, 2/5, 2/7, 2/8, and 2/9) injected in the primary visual cortex (V1) of adult C57Bl/6J mice. In order to obtain specific expression in certain neuron subtypes, different promoter sequences were evaluated for excitatory cell specificity: a universal cytomegalovirus (CMV) promoter, and two versions of the excitatory neuron-specific Ca(2+) /calmodulin-dependent kinase subunit α (CaMKIIα) promoter, CaMKIIα 0.4 and CaMKIIα 1.3. The spatial distribution as well as the cell type specificity was immunohistochemically verified. Depending on the rAAV serotype used, the transduced volume expressing reporter protein differed substantially (rAAV2/5 ≫ 2/7 ≈ 2/9 ≈ 2/8 ≫ 2/1). Excitatory neuron-specific targeting was promoter-dependent, with a surprising difference between the 1.3 kb and 0.4 kb CaMKIIα promoters. While CaMKIIα 1.3 and CMV carrying vectors were comparable, with 78% of the transduced neurons being excitatory for CMV and 82% for CaMKIIα 1.3, the shorter CaMKIIα 0.4 version resulted in 95% excitatory specificity. This study therefore puts forward the CaMKIIα 0.4 promoter as the best choice to target excitatory neurons with rAAVs. Together, these results can be used as an aid to select the most optimal vector system to deliver transgenes into specific rodent neocortical circuits, allowing further elucidation of their functions.

Keywords: CMV; CaMKIIα; GABA; connectivity; optogenetic; viral vector.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2 / genetics
  • Cell Count
  • Cytomegalovirus / genetics
  • Dependovirus / classification
  • Dependovirus / genetics*
  • Dependovirus / metabolism*
  • Gene Expression
  • Gene Transfer Techniques*
  • Genetic Vectors*
  • HEK293 Cells
  • Humans
  • Immunohistochemistry
  • Mice, Inbred C57BL
  • Neuroanatomical Tract-Tracing Techniques / methods
  • Neurons / metabolism
  • Neurons / virology
  • Promoter Regions, Genetic*
  • Serogroup
  • Serotyping
  • Visual Cortex / metabolism*
  • Visual Cortex / virology
  • gamma-Aminobutyric Acid / metabolism


  • gamma-Aminobutyric Acid
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • Camk2a protein, mouse