Biology of Francisella tularensis Subspecies holarctica Live Vaccine Strain in the Tick Vector Dermacentor variabilis

Mani, Rinosh; Reichard, Mason V.; Morton, Robert; Kocan, Katherine M.; Clinkenbeard, Kenneth D.

doi:10.1371/journal.pone.0035441

Cited by 20 publications

(39 citation statements)

References 41 publications

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“…Microscopic (25), epidemiological (5,26), and relatively recent experimental (9,10,16) evidence implicates several tick species as major natural reservoirs for F. tularensis. A goal of these studies was to establish a quantitative tick infection model to determine if replication occurs and to follow its kinetics.…”

Section: Discussionmentioning

confidence: 99%

“…Previously it has been shown that transmission for type A and B strains from adult D. variabilis females to mice occurs shortly after attachment (10), possibly supporting a mechanism of transmission from tick salivary glands directly into the skin. Using a capillary feeding model of D. variabilis infection, F. tularensis was found to initially colonize the tick midgut and then disseminate to the hemolymph and salivary glands (16). To determine the localization of bacteria in tick tissues and to quantify the relative number of bacteria in each tissue, we infected nymphal D. variabilis ticks with LVS or LVS strains containing pFNLTP6 gro-GFP or gro-TURBO red and performed fluorescence microscopy on harvested midgut or salivary gland tissues.…”

Section: Figmentioning

confidence: 99%

“…This technique requires considerable skill and is unlikely to be useful in a setting of large-scale genetic screens. Additionally, this procedure results in a low infection rate and variation in the number of bacteria/tick by several orders of magnitude (16). A goal of the current work was to develop a reproducible method of tick inoculation to quantitatively assess bacterial replication.…”

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confidence: 99%

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Reproducible and Quantitative Model of Infection of Dermacentor variabilis with the Live Vaccine Strain of Francisella tularensis

Coburn

Maier

Casey

et al. 2015

Appl Environ Microbiol

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Pathogen life cycles in mammalian hosts have been studied extensively, but studies with arthropod vectors represent considerable challenges. In part this is due to the difficulty of delivering a reproducible dose of bacteria to follow arthropod-associated replication. We have established reproducible techniques to introduce known numbers of Francisella tularensis strain LVS from mice into Dermacentor variabilis nymphs. Using this model infection system, we performed dose-response infection experiments and followed bacterial replication through the molt to adults and at later time points. During development to adults, bacteria replicate to high numbers and can be found associated with the gut tissues, salivary glands, and hemolymph of adult ticks. Further, we can transmit a mutant of LVS (LVS ⌬purMCD) that cannot replicate in macrophages in vitro or in mice to nymphs. Our data show that the LVS ⌬purMCD mutant cannot be transstadially transmitted from nymphs to adult ticks. We then show that a plasmid-complemented strain of this mutant is recoverable in adult ticks and necessary for bacterial replication during the molt. In a mixed-infection assay (⌬purMCD mutant versus ⌬purMCD complement), 98% of the recovered bacteria retained the plasmid marker. These data suggest that the ⌬purMCD mutation cannot be rescued by the presence a complemented strain in a mixed infection. Importantly, our infection model provides a platform to test specific mutants for their replication in ticks, perform competition studies, and use other genetic techniques to identify F. tularensis genes that are expressed or required in this unique environment.F rancisella tularensis, a highly infectious zoonotic pathogen, causes a variety of syndromes collectively known as tularemia (1). Transmission of the organism to humans occurs by several routes, including contact with infected animal tissues, ingestion of contaminated food or water, exposure to biting flies, mosquitos, and ticks, or through aerosols (1-5). In the United States, acquisition of the bacterium is most often mediated by contact with infected rabbits or through the bite of an infected tick (6, 7). Since small mammals succumb to F. tularensis infection rapidly, a critical reservoir for maintenance of the organism in enzootic infection is the tick (8).The American dog tick, Dermacentor variabilis, appears to play a major role as a bridging vector to humans (9, 10). The highest incidence of F. tularensis human infections and D. variabilis habitat overlap in geographic distribution (9,11,12). F. tularensis has been identified in adult D. variabilis ticks collected from the environment (11). Moreover, experimental work has shown that type A (A1a, A1b, and A2) as well as virulent type B strains of F. tularensis can be transmitted from infected mice to larval ticks and that these ticks develop to the nymphal stage and can transmit the infection to naive animals (9). Transmission was, however, inefficient, as the bacterial infection affected tick fitness and mortality (9). In more recent ...

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Section: Discussionmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

mentioning

confidence: 99%

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Reproducible and Quantitative Model of Infection of Dermacentor variabilis with the Live Vaccine Strain of Francisella tularensis

Coburn

Maier

Casey

et al. 2015

Appl Environ Microbiol

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“…Our results confirm those of a previous report in which F. tularensis LVS colonized capillary‐fed Dermacentor variabilis (Mani et al . ). To investigate the bacterial factors associated with bacterial growth in ticks, a hlyD mutant was constructed in F. tularensis LVS and microinjected into ticks.…”

Section: Resultsmentioning

confidence: 97%

Detection of Francisella tularensis and analysis of bacterial growth in ticks in Japan

Suzuki

Hashino

Matsumoto

et al. 2016

Lett Appl Microbiol

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Francisella tularensis has been detected in ticks, suggesting that it is a tick-borne pathogen. However, F. tularensis has not been detected in ticks in Japan since 1991. In this study, we performed a large-scale analysis of DNA isolated from ticks in Japan and detected F. tularensis by real-time polymerase chain reaction (PCR) and nested PCR. We found that F. tularensis could survive in ticks based on an experimental tick-infection model. We also identified a bacterial factor that contributes to survival in ticks. Our results suggest that ticks are candidate vectors that mediate F. tularensis infection in Japan.

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“…Vector Control-Development and Improvement of the Modern Chemical Insecticides 2 obtained by microscopic, immunofluorescent, biochemical techniques and other methods, through which the knowledge about the mode of transmission of various infections is becoming objective and specified [6,7].…”

Section: David Publishingmentioning

confidence: 99%

Vector Control—Development and Improvement of the Modern Chemical Insecticides

Popivanov¹,

Petkova²,

Doycheva³

et al. 2015

JPP

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Abstract:The transition from empirical and applied approach toward a scientific approach in modern medical disinsection is a result of the discoveries of the organic chemistry. The most intensive used substance in this field-DDT (dichlorodiphenyltrichloroethane) is introduced during World War II and contributes to world practical epidemiology just as antibiotics in clinical medicine. However, after the 70s, this substance was placed under a ban, because of the accumulated evidence of many adverse health and environmental impacts globally. Improvement of the insecticides after "DDT-era" is represented by the introduction of organophosphate and carbamate insecticides in the 1960s. Their broad application is determined by better ecotoxicological characteristics. The advance in biotechnology after the 1980s establishes the new class of insecticides-synthetic pyrethroids. Nowadays they are basic for the insect control. Pyrethroids are characterized by selective impact on insects with much less impact on warm-blooded animals and the environment. Insecticides from the newest class insect growth regulators realize their mode of activity by interfering with chitin metabolism and thus prevent an insect from reaching maturity. These substances have extremely low toxicity, which makes them very promising for the treatment of civilian and military facilities.

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Biology of Francisella tularensis Subspecies holarctica Live Vaccine Strain in the Tick Vector Dermacentor variabilis

Cited by 20 publications

References 41 publications

Reproducible and Quantitative Model of Infection of Dermacentor variabilis with the Live Vaccine Strain of Francisella tularensis

Reproducible and Quantitative Model of Infection of Dermacentor variabilis with the Live Vaccine Strain of Francisella tularensis

Detection of Francisella tularensis and analysis of bacterial growth in ticks in Japan

Vector Control—Development and Improvement of the Modern Chemical Insecticides

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