【目的】 通过对小菜蛾Plutella xylostella化学感受蛋白基因PxylCSP5进行基因克隆、生物信息学分析、时空表达谱分析和体外原核表达，推测PxylCSP5基因在小菜蛾体内的功能，为探究小菜蛾化学感受蛋白基因的功能奠定基础。【方法】 采用RT-PCR法克隆了小菜蛾化学感受蛋白基因PxylCSP5，对该序列进行生物信息学分析。利用RT-qPCR对PxylCSP5基因在小菜蛾不同发育时期和成虫不同组织中的表达量进行分析。构建了小菜蛾PxylCSP5原核表达载体，并在大肠杆菌BL21（DE3）感受态细胞中诱导表达该蛋白。【结果】 小菜蛾化学感受蛋白基因PxylCSP5完整的开放阅读框为393 bp，编码了130个氨基酸残基，预测氨基酸序列的末端含有18个氨基酸长度的信号肽序列，同时含有4个保守的半胱氨酸位点。氨基酸同源比对结果显示，PxylCSP5与谷实夜蛾Helicoverpa zea HzeaCSP的氨基酸序列一致性最高，达到67.91%。RT-qPCR结果表明PxylCSP5在不同发育时期中成虫期表达量最高，与其它发育时期相比较，具有显著差异性（P<0.05）；成虫期不同组织中足的表达量最高，与其它组织比较具有显著差异性（P<0.05）。成功构建了PxylCSP5的原核表达载体pET28a-PxylCSP5并在体外诱导表达。【结论】 小菜蛾PxylCSP5基因在成虫足中高表达，初步推测可能该基因功能与寄主定位有关。

[Objectives]  To investigate the function of the chemosensory protein PxylCSP5 in Plutella xylostella. [Methods]  The PxylCSP5 gene was cloned using RT-PCR, and its sequence analyzed using bioinformatics methods. RT-qPCR was used to analyze the expression of the PxylCSP5 gene in different developmental stages and tissues of adult moths. A prokaryotic expression vector for PxylCSP5 was constructed in BL21(DE3) [Results]  The complete open reading frame of PxylCSP5 is 393 bp, encodes 130 amino acid residues, contains a signal peptide sequence of 18 amino acids at the N-terminal and has four conserved cysteines. The results of amino acid sequence alignment indicate that PxylCSP5 was homologous to Helicoverpa zea HzeaCSP with 67.91% amino acid sequence identify. RT-qPCR results show that PxylCSP5 was more highly expressed in adults, and within adult tissues, in the legs. A prokaryotic expression vector for PxylCSP5 was successfully constructed allowing PxylCSP5 to be expressed in vitro. [Conclusion]  The PxylCSP5 gene is highly expressed in the legs of adults, which suggests that its function may be related to host location.