a Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy , University of Gothenburg , Göteborg , Sweden.
b Department of Clinical Microbiology , Sahlgrenska University Hospital , Göteborg , Sweden.
Emerg Microbes Infect. 2019;8(1):413-425. doi: 10.1080/22221751.2019.1584017.
Candidatus (Ca.) Neoehrlichia mikurensis is the cause of neoehrlichiosis, an emerging tick-borne infectious disease characterized by fever and vascular events. The bacterium belongs to the Anaplasmataceae, a family of obligate intracellular pathogens, but has not previously been cultivated, and it is uncertain which cell types it infects. The goals of this study were to cultivate Ca. N. mikurensis in cell lines and to identify possible target cells for human infection. Blood components derived from infected patients were inoculated into cell lines of both tick and human origin. Bacterial growth in the cell cultures was monitored by real-time PCR and imaging flow cytometry. Ca. N. mikurensis was successfully propagated from the blood of immunocompromised neoehrlichiosis patients in two Ixodes spp. tick cell lines following incubation periods of 7-20 weeks. Human primary endothelial cells derived from skin microvasculature as well as pulmonary artery were also susceptible to infection with tick cell-derived bacteria. Finally, Ca. N. mikurensis was visualized within circulating endothelial cells of two neoehrlichiosis patients. To conclude, we report the first successful isolation and propagation of Ca. N. mikurensis from clinical isolates and identify human vascular endothelial cells as a target of infection.
候选新立克次体（Ca.）是新立克次体病的病原体，这是一种新出现的蜱传传染病，以发热和血管事件为特征。该细菌属于立克次体科，是一种专性细胞内病原体，但以前未被培养，也不确定它感染哪些细胞类型。本研究的目的是在细胞系中培养候选新立克次体（Ca.）并确定人类感染的可能靶细胞。从感染患者的血液成分接种到源自蜱和人类的细胞系中。通过实时 PCR 和成像流式细胞术监测细胞培养物中的细菌生长。在两周至 20 周的孵育期后，候选新立克次体（Ca.）从免疫功能低下的新立克次体病患者的血液中成功地在两种硬蜱细胞系中增殖。源自皮肤微血管和肺动脉的人原代内皮细胞也容易受到来自蜱细胞的细菌感染。最后，在两名新立克次体病患者的循环内皮细胞中观察到候选新立克次体（Ca.）。总之，我们报告了首例从临床分离株中成功分离和培养候选新立克次体（Ca.），并确定人血管内皮细胞为感染靶细胞。
