Identification and characterization of an odorant receptor from the West Nile Virus mosquito, Culex quinquefasciatus

Members of the Culex pipens mosquito group including C. quinquefasciatus are responsible for the transmission of Bancroftian filarisis as well as West Nile Virus (WNV) in the United States. As is the case for other mosquitoes, the host preference of this disease vector relies on olfaction and accordingly mediated via G-protein coupled signal transduction pathways. Here, we identify and characterize CqOR7, the first candidate member of the odorant receptor gene family from C. quinquefasciatus. CqOR7 displays extremely high primary amino acid conservation with other apparent orthologs including AaOR7, from the Dengue virus vector mosquito Aedes aegypti, AgOR7 from the malaria vector Anopheles gambiae and DOr83b from the fruit fly Drosophila melanogaster that form an essential non-conventional odorant receptor sub-family. CqOR7 transcripts can be detected in adult chemosensory tissues and during several pre-adult stages of C. quinquefasciatus, and the CqOR7 protein is localized to characteristic olfactory tissues such as the antennae and maxillary palps as well as the proboscis, a typically gustatory appendage. These results suggest that CqOR7 and its orthologs are likely to play a role in the chemosensory processes of Culicine and other mosquitoes that underlie their vectorial capacity.