A neurogenetic toolkit to decode Anopheles gambiae olfaction

Abstract

The African malaria mosquito Anopheles gambiae exhibits a strong innate sensory drive to seek out human scent. To detect human odorants, An. gambiae uses olfactory sensory neurons (OSNs) that can be divided into different classes by unique repertoires of chemoreceptor gene expression. We applied CRISPR-Cas9-mediated T2A-In Frame Fusions and the QF2/QUAS system to gain genetic access to specific OSN subsets in An. gambiae expressing the chemoreceptor genes Ir25a, Ir76b, Gr22 and orco. We first optimized methods to generate cell-type specific QF2 driver and QUAS responder lines to map expression patterns of these chemoreceptors across mosquito sensory appendages. We next applied transcuticular calcium imaging to record neurophysiological responses to select human-related odorants for each OSN class. This neurogenetic toolkit tiling OSN subsets in An. gambiae, including those responsive to CO2, stands to support systematic efforts to decode olfaction in this prolific disease vector at high-resolution to combat malaria.