A novel viral tool designed with enhancer-driven gene expression (EDGE) technology allows specific labelling of cell types in wild type rodents

The mammalian brain contains an unimaginable number of neurons, who are all intricately connected to form complex neuronal circuits. Neurons that exhibit similar properties are often defined as belonging to the same cell-type, which can be determined for example by analysing the genetic profile of the cells. A key aspect of studying brain function on a circuit level is the ability to target specific cell types, but this necessitates sophisticated molecular and genetic tools. Here, we contribute to the ever-expanding toolkit of genetic targeting approaches, by utilizing Enhancer-Driven Gene Expression (EDGE) technology to create viral tools that allow specific targeting of cell populations in the hippocampus and parahippocampus of wild type mice. We also demonstrate the applicability of our tool in wild type rats, emphasising the versatility of this technology in cross-species studies. Cell-type specific targeting in wild type animals is something that could be of great benefit to the field, also in other species than mice where transgenic lines are not common. Overall design: Bulk ChIP-seq against H3K27Ac for several brain regions, analyzed to find region specific putative enhancers