Lu Stephen, Bland David M, Dahlstrom Eric, Redekar Neelam, Guizzo Melina G, Barbian Kent, Hinnebusch B Joseph, Ribeiro José M C
Section of Vector Biology, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Room 2E-28, Twinbrook III Building, MSC 8132, Bethesda, MD, 20892-8132, USA.
Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, 59840, USA.
BMC Genomics. 2025 Jul 1;26(1):621. doi: 10.1186/s12864-025-11759-8.
The Oriental rat flea, Xenopsylla cheopis, is a main vector of plague caused by the bacterium Yersinia pestis. Transcriptomic analysis of this insect and the interaction between Yersinia and the flea digestive tract have been the subject of several studies. However, to develop more refined studies on this vector in the future, we sequence and describe a draft genome of the rat flea Xenopsylla cheopis, discuss the physiological implications of its genetic features, and compare them with the only other sequenced member of the Siphonaptera, the cat flea, Ctenocephalides felis.
Sequencing data from both long and short reads were assembled into 7,694 contigs, from which 95,638 putative coding sequences (CDSs) were extracted and functionally annotated, providing insights into various aspects of flea physiology. This includes the identification of putative salivary proteins, such as acid phosphatases and FS-H/I, associated with blood acquisition; classification of multiple serine peptidases likely representing the primary digestive enzymes of X.cheopis; and the identification of all enzymes involved in heme biosynthesis, as well as heme oxygenases and unique heme-binding proteins potentially involved in heme detoxification. Comparison of detoxification-related genes-namely those in the cytochrome P450, carboxylesterase, and glutathione S-transferase families-with homologs from the cat flea (C. felis) revealed the presence of a platelet-activating factor (PAF) acetyl hydrolase that appears to be unique to rat fleas, cat fleas, and human head and body lice, but is absent in other blood-feeding arthropods. Additionally, we identified key components of immune-related pathways known from other arthropods, including the Toll, IMD, and JAK/STAT pathways. Finally, a contig encoding a novel bacterium was discovered within the assembled flea genome. Phylogenetic analysis of the Wolbachia endosymbiont in X. cheopis suggests it is closely related to the Wolbachia strain found in Drosophila melanogaster.
The disclosure of the X. cheopis genome, together with its Wolbachia symbiont, should advance research on the biology of this vector.
印鼠客蚤（Xenopsylla cheopis）是由鼠疫耶尔森菌引起的鼠疫的主要传播媒介。对这种昆虫以及耶尔森菌与蚤类消化道之间相互作用的转录组分析已成为多项研究的主题。然而，为了未来开展对该传播媒介更精细的研究，我们对印鼠客蚤的基因组草图进行了测序和描述，讨论了其遗传特征的生理意义，并将它们与蚤目（Siphonaptera）中唯一已测序的另一个成员——猫栉首蚤（Ctenocephalides felis）进行了比较。
来自长读长和短读长的测序数据被组装成7694个重叠群，从中提取了95638个推定的编码序列（CDS）并进行了功能注释，为蚤类生理学的各个方面提供了见解。这包括鉴定推定的唾液蛋白，如与吸血相关的酸性磷酸酶和FS-H/I；对可能代表印鼠客蚤主要消化酶的多种丝氨酸蛋白酶进行分类；鉴定参与血红素生物合成的所有酶，以及可能参与血红素解毒的血红素加氧酶和独特的血红素结合蛋白。将与解毒相关的基因（即细胞色素P450、羧酸酯酶和谷胱甘肽S-转移酶家族中的基因）与其在猫蚤（C. felis）中的同源物进行比较，发现了一种血小板激活因子（PAF）乙酰水解酶，该酶似乎是印鼠客蚤、猫蚤以及人头虱和体虱所特有的，但在其他吸血节肢动物中不存在。此外，我们鉴定了其他节肢动物中已知的免疫相关途径的关键成分，包括Toll、IMD和JAK/STAT途径。最后，在组装的蚤类基因组中发现了一个编码新型细菌的重叠群。对印鼠客蚤中沃尔巴克氏体共生菌的系统发育分析表明，它与在黑腹果蝇中发现的沃尔巴克氏体菌株密切相关。
印鼠客蚤基因组及其沃尔巴克氏体共生菌的公开应该会推动对这种传播媒介生物学的研究。
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