Antennal RNAseq reveals candidate genes associated with host preference in the Northern house mosquito, Culex pipiens

Culex pipiens, the Northern house mosquito, is the primary vector for West Nile virus (WNv) in North America. Its two distinct bioforms, Cx. p. pipiens and molestus, have divergent host preferences—pipiens prefers avian hosts, while molestus prefers mammals. However, hybrid offspring display indiscriminate host choice. Host preference dynamics critically impact spillover of WNv to humans and other mammals, causing severe neurological disease. Hence, it is therefore crucial to identify the genetic underpinnings of this trait in Culex. We used a host landing assay to characterize blood host preferences of individual females from three field-isolated strains of pipiens and molestus. Antennae were dissected from assayed females and pooled according to strain and host preference for RNA sequencing. Our analysis revealed differences in gene expression for human- and chick-seeking antennal transcriptomes, including genes from four families known to play important roles in chemosensation: odorant-binding proteins (OBPs), odorant receptors (ORs), ionotropic receptors (IRs), and gustatory receptors (GRs). Through a series of comparative analyses between the antennal transcriptomes of human- and chick-seeking pools of Culex, we have identified at least eight chemosensory genes as strong candidate genes associated with host preference. These results contribute to a deeper understanding of host preference genomics in Culex and lay the groundwork for future functional studies, which could reveal novel targets for management of vector-borne disease transmission.