Abstract
BackgroundAedes albopictus is a globally invasive mosquito and a major vector of arboviruses, including dengue, Zika and Chikungunya. Olfactory-related behaviors, particularly host-seeking, offer opportunities to disrupt the disease-transmission process. A better understanding of odorant receptors (ORs) may assist in explaining host selection and location, and contribute to novel strategy of vector control.MethodsBased on previous prediction of 158 putative odorant receptors by Ae. albopictus genome analysis, 29 AalORs were selected for tissue-specific expression profiles in the present study. AalOrco (AalOR7), AalOR10 and AalOR88, highly expressed in female olfactory tissues, were chosen for further structure predictions as well as functional validation including calcium imaging assay in human embryonic kidney (HEK293) cells and RNA interference assay in Ae. albopictus. We also conducted electrophysiological and behavioral assays in mosquitoes after RNA interference of the three genes to determine their roles in host-seeking.ResultsThe results support previous conclusions that individual conventional (ORXs) and Orco can form heteromeric complexes to recognize odorants and respond to components of human volatiles in HEK293 cells. The reduction of AalOrco transcript levels led to a significant decrease in host-seeking and confusion in host preference. In contrast, AalOR10 and AalOR88 knockdown mosquitoes showed no significant behavioral differences compared with controls. The functions of conventional ORs at least AalOR10 and AalOR88 are abolished with inhibited expression of the Orco gene orthologs, along with the concomitant relevant olfactory behavior.ConclusionsCombining structural and functional data, we conclude that the product of the Orco gene in this mosquito is crucial for transmitting olfactory signaling and conventional ORs contribute directly to odorant recognition. Our results provide insight into the linkage between odorant receptors and host-seeking in this important vector species.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1644-9) contains supplementary material, which is available to authorized users.
Highlights
Aedes albopictus is a globally invasive mosquito and a major vector of arboviruses, including dengue, Zika and Chikungunya
Identification and expression profiles of AalORs In order to search for highly expressed AalOR genes in the female antennae, twenty-nine AalORs were selected for tissue-specific expression profile
Here we reported the high expression of AalOrco, the Ae. albopictus Orco ortholog, AalOR10 and AalOR88 in adult female antennae and their involvement in olfactory functions
Summary
Aedes albopictus is a globally invasive mosquito and a major vector of arboviruses, including dengue, Zika and Chikungunya. Aedes albopictus (Skuse) (Diptera: Culicidae), the Asian tiger mosquito, is an important vector of arboviruses including dengue, Chikungunya [1], Zika [2] and yellow fever [3, 4]. Odorant receptors (ORs) play key roles in olfactory behaviors including a co-receptor, designated Orco (OR7), and conventional ligand-binding odorant receptors [10] (ORX). The conservation of its structure and expression in mosquitoes support the conclusion that Orco plays an important role in olfactory functions. The spatial and temporal expression profiles and functions of conventional odorant receptors, which are highly divergent and species-specific, correlate with some olfactory-mediated behavioral roles [12]. AaOR4 which is significantly associated with preference for humans, is highly expressed in the antennae [13] whereas 11 conventional ORs may perceive contacting pheromones are expressed highly in non-olfactory tissues, wings and legs, in the migratory locust [14]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
