Rapid, reproducible transduction of select forebrain regions by targeted recombinant virus injection into the neonatal mouse brain.

Viral vectors can mediate long-term gene expression in different regions of the brain. Recombinant adeno-associated virus (rAAV) and Lenti virus (LV) have both gained prominence due to their ability to achieve specific transduction of various neuronal populations. Whilst widespread gene delivery has been obtained by targeted injection of rAAV in various brain structures, LV has also been utilized for infection of stem cell populations for cell lineage tracing. Both viral vector systems are most commonly used for gene delivery in mature brains, but the great potential of somatic gene delivery into the neonate brain has not been systematically exploited. Here we provide a systematic guideline for efficient stereotaxic virus delivery into different neuronal populations of the neonate brain. We demonstrate region specific recombination of a 'stop-floxed' Rosa26 reporter allele upon targeted injection of rAAV vectors expressing Cre-recombinase at postnatal day zero (P0). In addition, utilizing LV, we show efficient transduction of P0 subventricular zone stem cells with subsequent labeling of approximately 20% of migrating neuroblasts along the rostral migratory stream (RMS) into the olfactory bulb. In summary, we report on an optimized protocol for facile, reproducible, high-throughput virus-based gene transfer into neonatal brains of wild-type and genetically altered mice, which allows targeted transduction of different brain regions and distinct neuronal populations.