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biology of francisella tularensis subspecies holarctica live vaccine strain in the tick vector dermacentor variabilis土拉杆菌内生物学亚种holarctica疫苗株活在向量变异革蜱蜱虫.pdf

发布:2017-09-11约字共10页下载文档
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Biology of Francisella tularensis Subspecies holarctica Live Vaccine Strain in the Tick Vector Dermacentor variabilis Rinosh J. Mani, Mason V. Reichard, Rebecca J. Morton, Katherine M. Kocan, Kenneth D. Clinkenbeard* Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, Oklahoma, United States of America Abstract Background: The c-proteobacterium Francisella tularensis is the etiologic agent of seasonal tick-transmitted tularemia epizootics in rodents and rabbits and of incidental infections in humans. The biology of F. tularensis in its tick vectors has not been fully described, particularly with respect to its quanta and duration of colonization, tissue dissemination, and transovarial transmission. A systematic study of the colonization of Dermacentor variabilis by the F. tularensis subsp. holarctica live vaccine strain (LVS) was undertaken to better understand whether D. variabilis may serve as an inter-epizootic reservoir for F. tularensis. Methodology/Principal Findings: Colony-reared larva, nymph, and adult D. variabilis were artificially fed LVS via glass capillary tubes fitted over the tick mouthparts, and the level of colonization determined by microbial culture. Larvae and nymphs were initially colonized with 8.860.8 6101 and 1.1 60.03 6103 CFU/tick, respectively. Post-molting, a significant increase in colonization of both molted nymphs and adults occurred, and LVS persisted in 42% of molted adult ticks at 126 days post-capillary tube feeding. In adult ticks, LVS initially colonized the gut, disseminated to hemolymph and salivary glands by 21 days, and persisted up to 165 days. LVS was detected in the salivary secretions of adult ticks after four days post intra-hemocoelic inoculati
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