title: Functional analysis of Orco and odorant receptors in odor recognition in Aedes albopictus.
abstract: Aedes 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.
  
  
  
  Based 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.
  
  
  
  The 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.
  
  
  
  Combining 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.
authors.affiliation: Department of Pathogen Biology, Key Laboratory of Prevention and Control of Emerging Infectious Diseases of Guangdong Higher Education Institutes, School of Public Health, Southern Medical University, Guangzhou, Guangdong, People's Republic of China.
authors.forename: Hongmei
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Pathogen Biology, Key Laboratory of Prevention and Control of Emerging Infectious Diseases of Guangdong Higher Education Institutes, School of Public Health, Southern Medical University, Guangzhou, Guangdong, People's Republic of China.
authors.forename: Tong
authors.initials: T
authors.lastname: Liu
authors.affiliation: Department of Pathogen Biology, Key Laboratory of Prevention and Control of Emerging Infectious Diseases of Guangdong Higher Education Institutes, School of Public Health, Southern Medical University, Guangzhou, Guangdong, People's Republic of China.
authors.forename: Lihua
authors.initials: L
authors.lastname: Xie
authors.affiliation: Department of Pathogen Biology, Key Laboratory of Prevention and Control of Emerging Infectious Diseases of Guangdong Higher Education Institutes, School of Public Health, Southern Medical University, Guangzhou, Guangdong, People's Republic of China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Pathogen Biology, Key Laboratory of Prevention and Control of Emerging Infectious Diseases of Guangdong Higher Education Institutes, School of Public Health, Southern Medical University, Guangzhou, Guangdong, People's Republic of China.
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Deng
authors.affiliation: Institute of Molecular and Genomic Medicine, National Health Research Institutes, Miaoli, Taiwan.
authors.forename: Chun-Hong
authors.initials: CH
authors.lastname: Chen
authors.affiliation: Departments of Microbiology and Molecular Genetics, and Molecular Biology and Biochemistry, 3205 McGaugh Hall, University of California, Irvine, CA, 92697-3900, USA.
authors.forename: Anthony A
authors.initials: AA
authors.lastname: James
authors.affiliation: Department of Pathogen Biology, Key Laboratory of Prevention and Control of Emerging Infectious Diseases of Guangdong Higher Education Institutes, School of Public Health, Southern Medical University, Guangzhou, Guangdong, People's Republic of China. xgchen2001@hotmail.com.
authors.forename: Xiao-Guang
authors.initials: XG
authors.lastname: Chen
mesh_terms: D000330:Aedes / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal; D055724:Electrophysiological Phenomena; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D057809:HEK293 Cells; D006801:Humans; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D009812:Odorants; D010802:Phylogeny; D034622:RNA Interference; D018035:Receptors, Odorant / Q000235:genetics / Q000378:metabolism*
chemical_list: D019476:Insect Proteins; D018035:Receptors, Odorant
keywords: HEK293 cells; Heterologous expression; Mosquito; Olfactory