Schwan Tom G, Raffel Sandra J
Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South 4th Street, Hamilton, MT 59840, USA.
Microorganisms. 2021 Sep 17;9(9):1978. doi: 10.3390/microorganisms9091978.
Transovarial passage of relapsing fever spirochetes ( species) by infected female argasid ticks to their progeny is a widespread phenomenon. Yet this form of vertical inheritance has been considered rare for the North American tick infected with . A laboratory colony of was established from a single infected female and two infected males that produced a population of ticks with a high prevalence of transovarial transmission based on infection assays of single and pooled ticks feeding on mice and immunofluorescence microscopy of eggs and larvae. Thirty-eight of forty-five (84.4%) larval cohorts (groups of larvae originating from the same egg clutch) transmitted to mice over four and a half years, and one hundred and three single and one hundred and fifty-three pooled nymphal and adult ticks transmitted spirochetes during two hundred and fourteen of two hundred and fifty-six (83.6%) feedings on mice over seven and a half years. The perpetuation of for many years by infected ticks only (without acquisition of spirochetes from vertebrate hosts) demonstrates the reservoir competence of . produced the variable tick protein in eggs and unfed larvae infected by transovarial transmission, leading to speculation of the possible steps in the evolution of borreliae from a tick-borne symbiont to a tick-transmitted parasite of vertebrates.
感染的雌性钝缘蜱将回归热螺旋体（种）经卵传递给后代是一种普遍现象。然而，对于感染了[病原体名称未给出]的北美蜱而言，这种垂直遗传形式被认为很罕见。从一只感染的雌性蜱和两只感染的雄性蜱建立了一个[蜱种名称未给出]实验室种群，根据以小鼠为食的单只蜱和混合蜱的感染检测以及对卵和幼虫的免疫荧光显微镜检查，该种群产生了经卵传递率很高的蜱群。在四年半的时间里，45个幼虫群体（来自同一批卵的幼虫组）中的38个（84.4%）将[病原体名称未给出]传播给了小鼠，在七年半的时间里，103只单只以及153只混合若虫和成虫蜱在对小鼠的256次取食中有214次（83.6%）传播了螺旋体。仅由感染的蜱（无需从脊椎动物宿主获取螺旋体）将[病原体名称未给出]持续传播多年，证明了[蜱种名称未给出]作为储存宿主的能力。[病原体名称未给出]在经卵传递感染的卵和未进食的幼虫中产生了可变的蜱蛋白，这引发了对疏螺旋体从蜱传播的共生体演变为蜱传播的脊椎动物寄生虫可能步骤的推测。
