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

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 hundreds of ligand-specific olfactory receptors expressed in ~60 different types of odor-sensing neurons scattered across their antennae and maxillary palps. But we don't yet know exactly which of these neurons mosquitoes use to detect humans nor which receptors are expressed in those neurons. The parent award of this administrative supplement aims to characterize the molecular and functional properties of all major odor-sensing cell types on the antennae of biting females of the dengue, yellow fever, and zika vector mosquito Aedes aegypti. In Aim 1, we proposed to identify the molecular receptors expressed in each of the ~60 types of odor-sensing neurons using single- nucleus RNA sequencing. This work has been completed successfully and is currently being prepared for publication. In Aim 2, we proposed to generate the genetic tools necessary to manipulate each type of odor-sensing neuron using CRISPR/Cas9 genome editing. This work is in progress. In Aim 3, we proposed to use the genetic tools from Aim 2 to identify the chemical odorants detected by each odor- sensing neuron type. This third aim represents a critical final step in our overarching goal to determine exactly which odor-sensing neurons mosquitoes use to detect humans. However, it requires the use of a sophisticated two-photon microscope for imaging neural responses in odor-sensing neurons, and this microscope recently malfunctioned. In this application, we are requesting an administrative supplement to cover the cost of the unexpected repair to this microscope. Without these funds, we will not be able to complete the goals of the parent award. Taken together we expect to generate a receptor-neuron-ligand map for Aedes aegypti vector mosquitoes and a library of genetic tools with which to manipulate them- opening the door to the efficient and rational design of chemical repellants and attractants for use in vector control.