Abstract: 【Aim】 Olfactory cues play a critical role in mediating a variety of important behaviors in mosquitoes including host seeking, and oviposition. Anopheles sinensis is the major malaria vector in China. However, little is known about the olfactory signal transmission of An. sinensis. Our study aims to clone an odorant binding protein (OBP) gene from An. sinensis and analyze its expression patterns in different tissues and in response to blood-meal feeding, so as to provide the foundation for further research of the molecular mechanism of An. sinensis olfactory transmission. 【Methods】 A transcriptome database for An. sinensis was mined through bioinformatic analysis. Gene expression levels were analyzed in different tissues of An. sinensis adults and at different time post blood-meal feeding using reverse transcription PCR (RT-PCR) or real-time PCR. 【Results】 An odorant binding protein gene was identified and named AsinOBP1, with the Genbank accession number of KJ958382. AsinOBP1 contains a 453-bp open reading frame encoding 144-amino-acid residues including an N-terminal signal peptide. The mature protein of AsinOBP1 contains six conserved cysteine residues, which are the hallmark of insect OBPs. Tissue expression profile analysis showed that AsinOBP1 was expressed in all tested tissues of antennae, maxillary palps, proboscis and head in adults, but not in tissues of legs and body (head removed). The expression level of AsinOBP1 in antennae of female adults was strongly downregulated after blood-meal feeding. Similarly, AsinOBP1 expression in antennae of female adults was also decreased significantly in response to mouse odor. 【Conclusion】 These findings strongly suggest that AsinOBP1 might be expressed specifically in olfactory tissues and involved in host seeking. Further functional analysis is required to clarify the roles of AsinOBP1 in An. sinensis.

Key words:  Anopheles sinensis, odorant binding protein, tissue expression pattern, quantitative real-time PCR, blood-meal feeding