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，其主要关联宿主为猫栉首蚤（Ctenocephalides felis）。尽管实验室研究已证实，菲克斯立克次体可经猫栉首蚤的变态期传播与经卵传播完成种群维持，但猫栉首蚤间菲克斯立克次体的明确水平传播机制仍未阐明。基于猫栉首蚤对菲克斯立克次体低效的垂直传播特性，以及该病原体在多种吸血节肢动物中的检出结果，本研究提出假说：菲克斯立克次体可在猫栉首蚤间实现水平传播。为验证该假说，本研究连续四周每周评估了吸血餐介导的菲克斯立克次体蚤间传播情况。实验中采用罗丹明B（Rhodamine B）区分未感染的受体蚤与菲克斯立克次体感染的供体蚤，开展立克次体水平传播生物测定；同时利用实时荧光定量PCR（quantitative real-time PCR）检测传播频率，并通过免疫荧光测定（immunofluorescence assay）确认传播事件。结果显示，以菲克斯立克次体感染血餐饲喂24小时后，雌性猫栉首蚤的感染率（69.3%）高于雄性（43.3%）；与菲克斯立克次体感染供体蚤共饲养的未感染受体雌雄蚤，均成功感染菲克斯立克次体，感染率范围为3.3%至40.0%。通过多组独立生物测定实验，本研究进一步明确：菲克斯立克次体可在共饲养的猫栉首蚤间以及交配过程中完成传播。本研究未观测到感染蚤对菲克斯立克次体的垂直传播现象。本研究证实猫栉首蚤间存在菲克斯立克次体的水平传播，该发现对菲克斯立克次体立克次体病的生态学研究具有广泛的参考价值。