Data from: Horizontal transmission of Rickettsia felis between cat fleas, Ctenocephalides felis

Rickettsia felis is a rickettsial pathogen primarily associated with the cat flea, Ctenocephalides felis. Although laboratory studies have confirmed that R. felis is maintained by transstadial and transovarial transmission in C. felis, distinct mechanisms of horizontal transmission of R. felis among cat fleas is undefined. Based on the inefficient vertical transmission of R. felis by cat fleas and the detection of R. felis in a variety of hematophagous arthropods, we hypothesize that R. felis is horizontally transmitted between cat fleas. Towards testing this hypothesis, flea transmission of R. felis via a bloodmeal was assessed weekly for four weeks. Rhodamine B was used to distinguish uninfected recipient and R. felis-infected donor fleas in a rickettsial horizontal transmission bioassay and quantitative real-time PCR assay was utilized to measure transmission frequency; immunofluorescence assay also confirmed transmission. Female fleas acquired R. felis-infection more readily than male fleas after feeding on a R. felis-infected bloodmeal for 24 h (69.3% and 43.3%, respectively) and both Rickettsia-uninfected recipient male and female fleas became infected with R. felis after co-feeding with R. felis-infected donor fleas (3.3-40.0%). Distinct bioassays were developed to further determine that R. felis was transmitted from R. felis-infected to uninfected fleas during co-feeding and copulation. Vertical transmission of R. felis by infected fleas was not demonstrated in this study. The demonstration of horizontal transmission of R. felis between cat fleas has broad implications for the ecology of R. felis rickettsiosis.菲克斯立克次体（Rickettsia felis）是一类立克次体病原体，主要与猫栉首蚤（Ctenocephalides felis，俗称猫蚤）相关联。尽管实验室研究已证实，菲克斯立克次体可在猫栉首蚤体内通过经变态传播（transstadial transmission）与经卵传播（transovarial transmission）完成种群维持，但猫栉首蚤间菲克斯立克次体的明确水平传播（horizontal transmission）机制仍未明确。基于猫栉首蚤对菲克斯立克次体的低效垂直传播（vertical transmission）特性，以及在多种吸血节肢动物（hematophagous arthropods）中检出菲克斯立克次体的研究结果，本研究提出假说：菲克斯立克次体可在猫栉首蚤间通过水平途径实现传播。为验证该假说，本研究连续四周每周评估猫栉首蚤通过吸血餐获取菲克斯立克次体的传播情况。本研究使用罗丹明B（Rhodamine B）区分立克次体水平传播生物测定中的未感染受体蚤与菲克斯立克次体感染供体蚤，并采用定量实时聚合酶链反应（quantitative real-time PCR）测定传播频率；同时通过免疫荧光试验（immunofluorescence assay）验证了传播现象。实验结果显示：取食感染菲克斯立克次体的血液24小时后，雌性猫蚤的感染率（69.3%）显著高于雄性猫蚤（43.3%）；与感染菲克斯立克次体的供体蚤共同取食后，未感染的雌雄受体猫蚤均被菲克斯立克次体感染，感染率区间为3.3%~40.0%。本研究进一步通过专属生物测定体系证实，菲克斯立克次体可在共同取食与交配过程中，从感染个体传播至未感染的猫栉首蚤。本研究未观察到感染猫栉首蚤对菲克斯立克次体的垂直传播现象。猫栉首蚤间菲克斯立克次体水平传播的证实，对菲克斯立克次体立克次体病的生态学研究具有广泛的应用价值。