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
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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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