scholarly journals A Francisella tularensis Chitinase Contributes to Bacterial Persistence and Replication in Two Major U.S. Tick Vectors

Pathogens ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1037
Author(s):  
Brenden G. Tully ◽  
Jason F. Huntley
Keyword(s):  
Francisella Tularensis ◽  
Alternative Energy ◽  
Vector Competence ◽  
Chitinase Activity ◽  
Dermacentor Variabilis ◽  
Amblyomma Americanum ◽  
Haemaphysalis Longicornis ◽  
Order Of Magnitude ◽  
Transmission Studies

Nearly 100 years after the first report of tick-borne tularemia, questions remain about the tick vector(s) that pose the greatest risk for transmitting Francisella tularensis (Ft), the causative agent of tularemia. Additionally, few studies have identified genes/proteins required for Ft to infect, persist, and replicate in ticks. To answer questions about vector competence and Ft transmission by ticks, we infected Dermacentor variabilis (Dv),Amblyomma americanum (Aa), and Haemaphysalis longicornis (Hl; invasive species from Asia) ticks with Ft, finding that although Aa ticks initially become infected with 1 order of magnitude higher Ft, Ft replicated more robustly in Dv ticks, and did not persist in Hl ticks. In transmission studies, both Dv and Aa ticks efficiently transmitted Ft to naïve mice, causing disease in 57% and 46% of mice, respectively. Of four putative Ft chitinases, FTL1793 is the most conserved among Francisella sp. We generated a ΔFTL1793 mutant and found that ΔFTL1793 was deficient for infection, persistence, and replication in ticks. Recombinant FTL1793 exhibited chitinase activity in vitro, suggesting that FTL1793 may provide an alternative energy source for Ft in ticks. Taken together, Dv ticks appear to pose a greater risk for harboring and transmitting tularemia and FTL1793 plays a major role in promoting tick infections by Ft.

scholarly journals A Francisella tularensis Chitinase Contributes to Bacterial Persistence and Replication in Two Major U.S. Tick Vectors

2020 ◽  
Author(s):  
Jason F. Huntley ◽  
Brenden Tully
Keyword(s):  
Francisella Tularensis ◽  
Alternative Energy ◽  
Vector Competence ◽  
Chitinase Activity ◽  
Dermacentor Variabilis ◽  
Amblyomma Americanum ◽  
Haemaphysalis Longicornis ◽  
Tick Infection ◽  
Transmission Studies

Tick-borne tularemia was first described in 1924. Nearly 100 years later, questions remain about the tick vector(s) that pose(s) the greatest risk for transmitting Francisella tularensis (Ft), the causative agent of tularemia. Additionally, few studies have identified genes/proteins required for Ft to infect, persist, and replicate in ticks. To answer questions about vector competence and Ft transmission by ticks, we infected Dermacentor variabilis (Dv), Amblyomma americanum (Aa), and Haemaphysalis longicornis (Hl; invasive species from Asia) ticks with Ft, finding that although Aa ticks initially become infected with 1-log higher Ft, Ft replicated more robustly in Dv ticks, and did not persist in Hl ticks. In transmission studies, both Dv and Aa ticks efficiently infected naïve mice, causing disease in 57% and 46% of those mice, respectively. We identified a putative Ft chitinase, FTL1793, generated a FTL1793 mutant, and found that FTL1793 was deficient in tick infection, persistence, and replication in ticks. Recombinant FTL1793 exhibited chitinase activity in vitro, suggesting that this chitinase may provide an alternative energy source for Ft in ticks. Taken together, Dv ticks appear to pose a greater risk for harboring and transmitting tularemia and FTL1793 plays a major role in promoting tick infections by Ft.

scholarly journals Association of the invasive Haemaphysalis longicornis tick with vertebrate hosts, other native tick vectors, and tick-borne pathogens in New York City

2020 ◽  
Author(s):  
Danielle M. Tufts ◽  
Laura B. Goodman ◽  
Meghan C. Benedict ◽  
April D. Davis ◽  
Meredith C. VanAcker ◽  
...  
Keyword(s):  
United States ◽  
New York ◽  
Vector Potential ◽  
The United States ◽  
Dermacentor Variabilis ◽  
Amblyomma Americanum ◽  
Invasive Pest ◽  
Haemaphysalis Longicornis ◽  
Tick Vectors ◽  
Host Associations

AbstractHaemaphysalis longicornis, the Asian longhorned tick, is an invasive ixodid tick that has rapidly spread across the northeastern and southeastern regions of the United States since first reported in 2017. The emergence of H. longicornis presents a potential threat for livestock, wildlife, and human health as the host associations and vector potential of this invasive pest in the United States are poorly understood. Previous field data from the United States has shown that H. longicornis was not associated with natural populations of small mammals or birds, but they show a preference for medium sized mammals in laboratory experiments. Therefore, medium and large sized mammals were sampled on Staten Island, New York to determine H. longicornis host associations and vector potential for a range of human and veterinary pathogens. A total of 97 hosts were sampled and five species of tick (Amblyomma americanum, Dermacentor variabilis, H. longicornis, Ixodes scapularis, Ixodes cookei) were found feeding concurrently on these hosts. Haemaphysalis longicornis was found in the highest proportions compared to other native tick species on raccoons (55.4%), Virginia opossums (28.9%), and white-tailed deer (11.5%). Tissue, blood, and engorged larvae were tested for 17 different pathogens using a nanoscale PCR platform. Infection with five pathogens (Borrelia burgdorferi, Anaplasma phagocytophilum, Rickettsia spp., Mycoplasma haemocanis, and Bartonella spp.) was detected in host samples, but no pathogens were found in any larval samples. These results suggest that although large and medium sized mammals feed large numbers of H. longicornis ticks in the environment there is presently a low potential for H. longicornis to acquire pathogens from these wildlife hosts.HighlightsH. longicornis were sampled from seven genera of large and medium-sized mammalsRaccoons, opossums, and white-tailed deer fed a large proportion of H. longicornisH. longicornis did not acquire pathogens through co-feeding with native tick vectorsHost species were infected with a range of pathogens of human and veterinary concernHost-derived H. longicornis engorged larvae were not infected with any pathogens

scholarly journals Effect of Vegetation on the Abundance of Tick Vectors in the Northeastern United States: A Review of the Literature

2021 ◽  
Author(s):  
Daniel C Mathisson ◽  
Sara M Kross ◽  
Matthew I Palmer ◽  
Maria A Diuk-Wasser
Keyword(s):  
United States ◽  
Ixodes Scapularis ◽  
The United States ◽  
Dermacentor Variabilis ◽  
Amblyomma Americanum ◽  
Habitat Associations ◽  
Haemaphysalis Longicornis ◽  
Northeastern United States ◽  
Tick Abundance ◽  
Open Canopy

Abstract Tick-borne illnesses have been on the rise in the United States, with reported cases up sharply in the past two decades. In this literature review, we synthesize the available research on the relationship between vegetation and tick abundance for four tick species in the northeastern United States that are of potential medical importance to humans. The blacklegged tick (Ixodes scapularis) (Say; Acari: Ixodidae) is found to be positively associated with closed canopy forests and dense vegetation thickets, and negatively associated with open canopy environments, such as grasslands or old agricultural fields. The American dog tick (Dermacentor variabilis) (Say; Acari: Ixodidae) has little habitat overlap with I. scapularis, with abundance highest in grasses and open-canopy fields. The lone star tick (Amblyomma americanum) (Linnaeus; Acari: Ixodidae) is a habitat generalist without consistent associations with particular types of vegetation. The habitat associations of the recently introduced Asian longhorned tick (Haemaphysalis longicornis) (Neumann; Acari: Ixodidae) in the northeastern United States, and in other regions where it has invaded, are still unknown, although based on studies in its native range, it is likely to be found in grasslands and open-canopy habitats.

scholarly journals A 4-Yr Survey of the Range of Ticks and Tick-Borne Pathogens in the Lehigh Valley Region of Eastern Pennsylvania

2019 ◽  
Vol 56 (4) ◽  
pp. 1122-1134 ◽  
Author(s):  
Marten J Edwards ◽  
James C Russell ◽  
Emily N Davidson ◽  
Thomas J Yanushefski ◽  
Bess L Fleischman ◽  
...  
Keyword(s):  
New York ◽  
Dermacentor Variabilis ◽  
Amblyomma Americanum ◽  
Babesia Microti ◽  
Infection Prevalence ◽  
Haemaphysalis Longicornis ◽  
Borrelia Miyamotoi ◽  
Lehigh Valley ◽  
Eastern Pennsylvania ◽  
Pathogen Surveillance

AbstractQuesting ticks were surveyed by dragging in forested habitats within the Lehigh Valley region of eastern Pennsylvania for four consecutive summers (2015–2018). A high level of inter-annual variation was found in the density of blacklegged tick nymphs, Ixodes scapularis Say, with a high density of host-seeking nymphs (DON) in summer 2015 and 2017 and a relatively low DON in summer 2016 and 2018. Very few American dog ticks (Dermacentor variabilis Say) and Ixodes cookei Packard were collected. Lone star ticks (Amblyomma americanum L.) and longhorned ticks (Haemaphysalis longicornis Neumann) were not represented among the 6,398 ticks collected. For tick-borne pathogen surveillance, DNA samples from 1,721 I. scapularis nymphs were prepared from specimens collected in summers 2015–2017 and screened using qPCR, high resolution melting analysis, and DNA sequencing when necessary. The overall 3-yr nymphal infection prevalence of Borrelia burgdorferi was 24.8%, Borrelia miyamotoi was 0.3%, Anaplasma phagocytophilum variant-ha was 0.8%, and Babesia microti was 2.8%. Prevalence of coinfection with B. burgdorferi and B. microti as well as B. burgdorferi and A. phagocytophilum variant-ha were significantly higher than would be expected by independent infection. B. burgdorferi nymphal infection prevalence is similar to what other studies have found in the Hudson Valley region of New York, but levels of B. microti and A. phagocytophilum variant-ha nymphal infection prevalence are relatively lower. This study reinforces the urgent need for continued tick and pathogen surveillance in the Lehigh Valley region.

scholarly journals Vector competence of human-biting ticks Ixodes scapularis, Amblyomma americanum and Dermacentor variabilis for Powassan virus

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Rohit Sharma ◽  
Duncan W. Cozens ◽  
Philip M. Armstrong ◽  
Douglas E. Brackney
Keyword(s):  
Tick Species ◽  
Ixodes Scapularis ◽  
Vector Competence ◽  
Dermacentor Variabilis ◽  
Amblyomma Americanum ◽  
Hard Tick ◽  
Nymphal Stage ◽  
Tick Borne Encephalitis ◽  
Powassan Virus ◽  
The Usa

Abstract Background Powassan virus (POWV; genus Flavivirus) is the sole North American member of the tick-borne encephalitis sero-complex and an increasing public health threat in the USA. Maintained in nature by Ixodes spp. ticks, POWV has also been isolated from species of other hard tick genera, yet it is unclear if these species can serve as vectors. Dermacentor variabilis and Amblyomma americanum share geographic and ecologic overlap with Ixodes spp. ticks and POWV transmission foci, raising the possibility that POWV could become established in these tick species and leading to range expansion and increased human risk. Therefore, we assessed the competency of Ixodes scapularis, D. variabilis and A. americanum for POWV lineage II (POWV II). Methods Larvae from all three species were co-infested on POWV-infected Balb/c mice. The engorged larvae were allowed to molt to nymphs and screened for the presence of POWV II RNA by reverse transcription-qPCR. Eight infected nymphs from each species were allowed to individually feed on a naïve mouse. Mice were screened for the presence of POWV II RNA to determine infection status. Results The results demonstrated that larvae from all three tick species were able to efficiently acquire POWV II via feeding on viremic mice, maintain infection through molting and successively transmit POWV to naïve mice at the nymphal stage at comparable rates across all three species. Conclusions Our findings reveal that non-Ixodes tick species can serve as competent vectors for POWV and highlight the potential role of these species in the ecology and epidemiology of POWV. Future studies examining the possible implications of these findings on POWV epidemiology and the adaptability of POWV in these new vectors are warranted. Graphical abstract

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

2014 ◽  
Vol 81 (1) ◽  
pp. 386-395 ◽  
Author(s):  
Jenifer Coburn ◽  
Tamara Maier ◽  
Monika Casey ◽  
Lavinia Padmore ◽  
Hiromi Sato ◽  
...  
Keyword(s):  
Francisella Tularensis ◽  
Mixed Infection ◽  
Dermacentor Variabilis ◽  
Quantitative Model ◽  
Life Cycles ◽  
Infection Model ◽  
Content Type ◽  
Genetic Techniques ◽  
Bacterial Replication

ABSTRACTPathogen 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 ofFrancisella tularensisstrain LVS from mice intoDermacentor variabilisnymphs. 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 ΔpurMCD) that cannot replicate in macrophagesin vitroor in mice to nymphs. Our data show that the LVS ΔpurMCDmutant 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 (ΔpurMCDmutant versus ΔpurMCDcomplement), 98% of the recovered bacteria retained the plasmid marker. These data suggest that the ΔpurMCDmutation 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 identifyF. tularensisgenes that are expressed or required in this unique environment.

scholarly journals Show us your ticks: a survey of ticks infesting dogs and cats across the USA

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Meriam N. Saleh ◽  
Kellee D. Sundstrom ◽  
Kathryn T. Duncan ◽  
Michelle M. Ientile ◽  
Julia Jordy ◽  
...  
Keyword(s):  
Tick Species ◽  
Large Scale ◽  
Attachment Site ◽  
Rhipicephalus Sanguineus ◽  
Dermacentor Variabilis ◽  
Amblyomma Americanum ◽  
Haemaphysalis Longicornis ◽  
Attachment Sites ◽  
The Usa ◽  
Head Neck

Abstract Background A variety of tick species infest dogs and cats in North America. Although most of these species also readily feed on people, national data regarding the species and abundance of ticks on dogs and cats are lacking. Here we report a large-scale study of ticks from dogs and cats in the USA over a 12-month period. Methods Tick submissions were invited from veterinary practices in all 50 states. Ticks were submitted with information about the pet and the attachment sites of each tick marked on a biopsy chart. Upon receipt, ticks were identified to species and stage using morphologic keys; when necessary, species identification was confirmed molecularly. Results From February 2018 through January 2019, 10,978 ticks were submitted from 1494 dogs and 336 cats in 49 states and ticks were collected in every month. Dog and cat infestation intensities ranged from 1 to 4765 and from 1 to 38 (median = 1, mean = 6.7 and 2.6), respectively. Dogs were primarily infested with Dermacentor variabilis (532/1494; 35.6%), Ixodes scapularis (409/1494; 27.4%), Amblyomma americanum (345/1494; 23.1%) and Rhipicephalus sanguineus (172/1494; 11.5%). Cats were primarily infested with I. scapularis (156/336; 46.4%), A. americanum (99/336; 29.5%) and D. variabilis (60/336; 17.9%). Other submitted ticks included A. maculatum, Haemaphysalis longicornis, Otobius megnini, and less common Dermacentor spp. and Ixodes spp. Co-infestations were documented in 93 dogs and 14 cats. Reported attachment sites of common tick species differed. In dogs, A. americanum was most commonly attached to the abdomen, axillary, and inguinal regions; D. variabilis and I. scapularis to the head, neck, and back; and R. sanguineus to the head, neck, abdomen, legs, and feet. In cats, I. scapularis was most commonly attached to the head and A. americanum was most commonly attached to the tail and perianal region. Conclusions These data confirm that dogs and cats in the USA are at risk of tick infestation throughout the year and that tick species present in the region have apparent attachment site preferences.

scholarly journals The Influence of Southwestern Virginia Environmental Conditions on the Potential Ability of Haemaphysalis longicornis, Amblyomma americanum, and Amblyomma maculatum to Overwinter in the Region

Insects ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1000
Author(s):  
Amanda Marie Whitlow ◽  
Roger Schürch ◽  
Donald Mullins ◽  
Gillian Eastwood
Keyword(s):  
Environmental Conditions ◽  
Life Stage ◽  
Dermacentor Variabilis ◽  
Amblyomma Americanum ◽  
Haemaphysalis Longicornis ◽  
Amblyomma Maculatum ◽  
Behavioral Adaptations ◽  
Key Factor ◽  
Overwintering Survival ◽  
Established Species

Ticks are susceptible to environmental conditions and, to ensure survival during winter conditions, they adopt a wide variety of physiological and behavioral adaptations including utilization of a suitable niche with insulation (e.g., leaf coverage). To investigate the potential overwintering survival of three tick populations emerging within Appalachian Virginia (Haemaphysalis longicornis, Amblyomma americanum, and Amblyomma maculatum), both a laboratory experiment assessing super-cooling points and a two-factor (elevation and insulation coverage) field experiment assessing overwintering survivability were conducted across a natural southwestern Virginian winter (2020–2021). Dermacentor variabilis adults were included in this study as an example of a well-established species in this region known to overwinter in these conditions. Our study indicated that A. americanum and H. longicornis wintering tolerance is based on life stage rather than external factors such as insulation (e.g., leaf litter) and elevation. Amblyomma maculatum was more likely to survive without insulation. The ability to withstand the extreme temperatures of new regions is a key factor determining the survivability of novel tick species and is useful in assessing the invasion potential of arthropod vectors.

The Effect of Adrenaline Infusions on Blood Coagulation in Normal and Haemophilia B Dogs

1966 ◽  
Vol 15 (03/04) ◽  
pp. 349-364 ◽  
Author(s):  
A.H Özge ◽  
H.C Rowsell ◽  
H.G Downie ◽  
J.F Mustard
Keyword(s):  
Body Weight ◽  
Factor Viii ◽  
Factor Ix ◽  
Clotting Factor ◽  
Blood Ph ◽  
Order Of Magnitude ◽  
Dose Dependent ◽  
Generation Test ◽  
Plasma Activity

SummaryThe addition of trace amounts of adrenaline to whole blood in plasma in vitro increased factor VIII, factor IX and whole plasma activity in the thromboplastin generation test. This was dose dependent.Adrenaline infusions less than 22 (μg/kg body weight in normal dogs accelerated clotting, increased factor IX, factor VIII and whole plasma activity in the thromboplastin generation test and caused a fall in blood pH. In a factor IX deficient dog, there was no increase in factor IX activity. After adrenaline infusions, however, the other changes occurred and were of the same order of magnitude as in the normal. Adrenaline in doses greater than 22 μg/kg body weight did not produce as great an effect on clotting in normal or factor IX deficient dogs. The platelet count in the peripheral blood was increased following the infusion of all doses of adrenaline. These observations suggest that the accelerating effect of adrenaline on clotting is not mediated through increase in activity of a specific clotting factor.

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