OMP PROMOTER-DRIVEN VIRAL LABELING REVEALS FUNCTIONAL ORGANIZATION OF OLFACTORY SENSORY NEURON PROJECTIONS

Olfactory receptor neurons (ORNs) continuously convey sensory information from the olfactory epithelium (OE) to the olfactory bulb (OB). Accurate tools for labeling these neurons are essential for investigating the organization of olfactory circuits. In this study, we developed and adeno-associated virus (AAV) vector driven by the mouse olfactory marker protein (OMP) promoter to enable selective labeling of mature ORNs. Following intranasal administration, AAV-mOMP-EGFP produced strong EGFP expression restricted to OMP-positive ORNs in vivo, confirming cell-type specificity. Consistently, primary olfactory cultures also showed EGFP signals co-localized with OMP, validating the selective targeting of mature ORNs in vitro. In sagittal sections, EGFP-positive signals extended from the OE to the glomeruli of the OB, reliably reflecting the canonical trajectory and termination of ORN axons. Furthermore, stereotaxic injection into the OB enabled spatially precise viral delivery and localized labeling within defined OB subregions. Together, these findings demonstrated that AAV-mOMP-EGFP is a reliable and versatile tool for selective labeling of mature ORNs and their projections, providing a foundation for future studies of olfactory circuit development and dysfunction.