Molecular and functional characterization of olfactory pathways in the arbovirus vector mosquito Aedes aegypti

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Project Summary Abstract Mosquitoes infect hundreds of millions of people with deadly pathogens every year. Since mosquitoes identify humans and other important resources primarily via their sense of smell, the disruption of mosquito olfactory systems has long been recognized as a potential strategy for controlling these pathogens. For example, repellants that scramble or block the detection of odors may be used to push mosquitoes away from humans and the areas where we live and work. Conversely, irresistibly attractive blends of volatile chemicals may be deployed to pull mosquitoes into lethal traps. Despite some advances in this area over the past decade, progress has been limited by the fact that the olfactory systems of our most important vector mosquitoes remain largely uncharacterized. We know that mosquitoes detect odors using tens to hundreds of ligand-specific olfactory receptors expressed in approximately 60 different types of olfactory sensory neurons (OSNs) found on their antennae and maxillary palps. But we don’t yet know exactly which neurons mosquitoes rely on for detecting humans, flowers, and oviposition sites, nor which receptors are expressed in those neurons. Moreover, exciting preliminary data from our lab and others indicates that the 1-to-1 matching between receptors and sensory neurons observed in Drosophila vinegar flies does not apply in mosquitoes. Instead, mosquito sensory neurons appear to express multiple, ligand-specific receptors. This means that the tuning of the neurons that drive behavior cannot be equated to the tuning of individual receptors and thus helps to explain why previous receptor-focused studies have largely failed to unlock the logic of mosquito host attraction. Here, we propose to characterize the molecular and functional properties of all major OSN cell types on the antennae of the arbovirus vector mosquito Aedes aegypti. In Aim 1, we will conduct single- nucleus RNA sequencing of antennal neurons to identify putative OSN cell types and the receptors expressed therein. In Aim 2, we will use CRISPR/Cas9 genome editing to generate OSN type-specific expression drivers that can be used to match OSN types to their target glomeruli in the antennal lobe of the brain. In Aim 3, we will use in vivo antennal lobe imaging to characterize the tuning of a subset of OSN types to a panel of 200-300 biologically relevant odorants and natural blends. Taken together we expect to generate a receptor-neuron-glomerulus map for this important disease vector and a library of genetic tools with which to manipulate it—facilitating the identification of the neurons that drive behavior and opening the door to the efficient and rational design of chemical repellants and attractants for use in vector control.