Ticks (Family Ixodidae) spend most of their life cycle as immature stages in the soil and litter, and as any other soil invertebrates, are likely to be controlled top-down by soil-dwelling predators. To date, the ability of soil invertebrate predators to control ixodid tick population remains little known, partly due to methodological difficulties. In the current study, we developed and successfully tested a novel method of labeling live Ixodes ricinus (L., 1758) (Ixodida: Ixodidae) nymphs with a 15N isotope label. Labeled ticks were used in a small-scale 8-day-long microcosm experiment to reveal soil predators attacking nymphs. Only a small fraction (4.1% of all samples) of soil generalist predators preyed upon nymphs. A strong 15N label was found in 5 predator species, namely 2 spiders (Pachygnatha listeri Sundevall, 1830, Tetragnathidae and Ozyptila sp., Theridiidae), 2 gamasid mites (Pergamasus beklemischevi Sellnick, 1929 and Pergamasus quisquiliarum [Canestrini, 1882], Parasitidae), and 1 staphylinid beetle (Geostiba circellaris [Gravenhorst, 1806], Staphylinidae). The isotopic labeling can be a useful tool in revealing a range of invertebrate predators that can control tick populations in soil.
Tick saliva injected into the vertebrate host contains bioactive anti-proteolytic proteins from the cystatin family; however, the molecular basis of their unusual biochemical and physiological properties, distinct from those of host homologs, is unknown. Here, we present Ricistatin, a novel secreted cystatin identified in the salivary gland transcriptome of Ixodes ricinus ticks. Recombinant Ricistatin inhibited host-derived cysteine cathepsins and preferentially targeted endopeptidases, while having only limited impact on proteolysis driven by exopeptidases. Determination of the crystal structure of Ricistatin in complex with a cysteine cathepsin together with characterization of structural determinants in the Ricistatin binding site explained its restricted specificity. Furthermore, Ricistatin was potently immunosuppressive and anti-inflammatory, reducing levels of pro-inflammatory cytokines IL-6, IL-1β, and TNF-α and nitric oxide in macrophages; IL-2 and IL-9 levels in Th9 cells; and OVA antigen-induced CD4+ T cell proliferation and neutrophil migration. This work highlights the immunotherapeutic potential of Ricistatin and, for the first time, provides structural insights into the unique narrow selectivity of tick salivary cystatins determining their bioactivity.
- MeSH
- cystatiny * farmakologie MeSH
- cystein metabolismus MeSH
- endopeptidasy metabolismus MeSH
- kathepsiny metabolismus MeSH
- klíště * chemie MeSH
- obratlovci MeSH
- proteasy metabolismus MeSH
- slinné cystatiny chemie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Babesióza patří mezi méně běžné, ale významné infekční onemocnění přenášené klíšťaty. Během posledních 50 let byl zaznamenán zvyšující se počet případů po celém světě, zvláště v USA. Severní část USA je endemickou oblastí, kde počet případů za poslední dekádu stoupl na 2 000 ročně. Původcem většiny těchto nákaz je v tomto regionu Babesia microti, parazit drobných hlodavců. V Evropě bylo od roku 1957 zaznamenáno 56 autochtonních případů lidské babesiózy. Většina těchto onemocnění byla způsobena druhem Babesia divergens, parazitem hovězího dobytka. Od roku 1992 bylo 13 případů nákazy B. microti importováno ze Severní Ameriky do Evropy. Onemocnění je závažné zejména pro splenektomované a imunokomprimované pacienty. Ačkoli nejvýznamnějším přenašečem infekce babesií v Evropě je klíště Ixodes ricinus, byl přenos infekce u řady pacientů způsoben krevní transfuzí, která pro oslabené jedince může končit fatálně. Diagnóza babesiózy se opírá o identifikaci intraerytrocytárních parazitů v krevním roztěru, detekcí DNA babesie testy PCR a stanovením protilátek sérologickými metodami a imunofluorescencí. Onemocnění se léčí antibiotiky (azithromycin, při těžkém průběhu clindamycin) a chininem. Zvýšený nárůst humánní babesiózy je dán nejen změnami klimatu a aktivity klíšťat, pobytem lidí v přírodě a zvýšenou migrací lidí, ale významnou úlohu zde hraje i rozvoj molekulárních metod a rostoucí povědomí o tomto onemocnění.
Babesiosis is a less common but important tick-borne infectious disease. Over the last 50 years, an increasing number of cases have been reported worldwide, especially in the USA. The northern part of the US is an endemic area where the incidence has risen to 2,000 cases per year in the last decade. Babesia microti, a parasite of small rodents, is the cause of most of these infections in that region. In Europe, 56 autochthonous cases of human babesiosis have been reported since 1957. Most of them were caused by the species Babesia divergens, a parasite of cattle. Since 1992, 13 cases of B. microti infection have been imported from North America into Europe. The disease is serious especially for splenectomised and immunocompromised patients. Although the most important vector of babesiosis in Europe is the tick Ixodes ricinus, infection was transmitted through blood transfusion in number of patients, which can be fatal for immunosuppressed patients. The diagnosis of babesiosis is based on the identification of intraerythrocytic parasites in a blood smear, PCR detection of Babesia DNA, and determination of antibodies by serology and immunofluorescence assays. The disease is treated with antibiotics (azithromycin or clindamycin in a severe course of the disease) and quinine. The increase in human babesiosis is not only due to climate change and tick activity, outdoor leisure activities, and increased human migration, but an important role is also played by improved molecular methods and growing awareness of the disease.
- MeSH
- Babesia microti mikrobiologie patogenita MeSH
- Babesia klasifikace mikrobiologie patogenita MeSH
- babezióza * diagnóza epidemiologie farmakoterapie mikrobiologie přenos MeSH
- incidence MeSH
- infekce přenášené vektorem MeSH
- klíště mikrobiologie parazitologie MeSH
- lidé MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
- Geografické názvy
- Česká republika MeSH
- Spojené státy americké MeSH
Ticks are hematophagous arthropods that use a complex mixture of salivary proteins to evade host defenses while taking a blood meal. Little is known about the immunological and physiological consequences of tick feeding on humans. Here, we performed the first bulk and single-nucleus RNA sequencing (snRNA-seq) of skin and blood of four persons presenting with naturally acquired, attached Ixodes scapularis ticks. Pathways and individual genes associated with innate and adaptive immunity were identified based on bulk RNA sequencing, including interleukin-17 signaling and platelet activation pathways at the site of tick attachment or in peripheral blood. snRNA-seq further revealed that the Hippo signaling, cell adhesion, and axon guidance pathways were involved in the response to an I. scapularis bite in humans. Features of the host response in these individuals also overlapped with that of laboratory guinea pigs exposed to I. scapularis and which acquired resistance to ticks. These findings offer novel insights for the development of new biomarkers for I. scapularis exposure and anti-tick vaccines for human use.
- MeSH
- klíště * genetika MeSH
- kousnutí klíštětem * MeSH
- lidé MeSH
- morčata MeSH
- RNA malá jaderná MeSH
- sekvence nukleotidů MeSH
- stravovací zvyklosti fyziologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- morčata MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Vector-borne zoonotic diseases are a concerning issue in Europe. Lyme disease and tick-borne encephalitis virus (TBEV) have been reported in several countries with a large impact on public health; other emerging pathogens, such as Rickettsiales, and mosquito-borne flaviviruses have been increasingly reported. All these pathogens are linked to wild ungulates playing roles as tick feeders, spreaders, and sentinels for pathogen circulation. This study evaluated the prevalence of TBEV, Borrelia burgdorferi sensu lato, Rickettsia spp., Ehrlichia spp., and Coxiella spp. by biomolecular screening of blood samples and ticks collected from wild ungulates. Ungulates were also screened by ELISA and virus neutralization tests for flaviviral antibody detection. RESULTS: A total of 274 blood samples were collected from several wild ungulate species, as well as 406 Ixodes ricinus, which were feeding on them. Blood samples tested positive for B. burgdorferi s.l. (1.1%; 0-2.3%) and Rickettsia spp. (1.1%; 0-2.3%) and showed an overall flaviviral seroprevalence of 30.6% (22.1-39.2%): 26.1% (17.9-34.3%) for TBEV, 3.6% (0.1-7.1%) for Usutu virus and 0.9% (0-2.7%) for West Nile virus. Ticks were pooled when possible and yielded 331 tick samples that tested positive for B. burgdorferi s.l. (8.8%; 5.8-11.8%), Rickettsia spp. (26.6%; 21.8-31.2%) and Neoehrlichia mikurensis (1.2%; 0-2.4%). TBEV and Coxiella spp. were not detected in either blood or tick samples. CONCLUSIONS: This research highlighted a high prevalence of several tick-borne zoonotic pathogens and high seroprevalence for flaviviruses in both hilly and alpine areas. For the first time, an alpine chamois tested positive for anti-TBEV antibodies. Ungulate species are of particular interest due to their sentinel role in flavivirus circulation and their indirect role in tick-borne diseases and maintenance as Ixodes feeders and spreaders.
- MeSH
- Coxiella MeSH
- klíště * MeSH
- komáří přenašeči MeSH
- Rickettsia * MeSH
- savci MeSH
- séroepidemiologické studie MeSH
- viry klíšťové encefalitidy * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Evropa MeSH
Pathogen life history theory assumes a positive relationship between pathogen load in host tissues and pathogen transmission. Empirical evidence for this relationship is surprisingly rare due to the difficulty of measuring transmission for many pathogens. The comparative method, where a common host is experimentally infected with a set of pathogen strains, is a powerful approach for investigating the relationships between pathogen load and transmission. The validity of such experimental estimates of strain-specific transmission is greatly enhanced if they can predict the pathogen population strain structure in nature. Borrelia burgdorferi is a multi-strain, tick-borne spirochete that causes Lyme disease in North America. This study used 11 field-collected strains of B. burgdorferi, a rodent host (Mus musculus, C3H/HeJ) and its tick vector (Ixodes scapularis) to determine the relationship between pathogen load in host tissues and lifetime host-to-tick transmission (HTT). Mice were experimentally infected via tick bite with 1 of 11 strains. Lifetime HTT was measured by infesting mice with I. scapularis larval ticks on 3 separate occasions. The prevalence and abundance of the strains in the mouse tissues and the ticks were determined by qPCR. We used published databases to obtain estimates of the frequencies of these strains in wild I. scapularis tick populations. Spirochete loads in ticks and lifetime HTT varied significantly among the 11 strains of B. burgdorferi. Strains with higher spirochete loads in the host tissues were more likely to infect feeding larval ticks, which molted into nymphal ticks that had a higher probability of B. burgdorferi infection (i.e., higher HTT). Our laboratory-based estimates of lifetime HTT were predictive of the frequencies of these strains in wild I. scapularis populations. For B. burgdorferi, the strains that establish high abundance in host tissues and that have high lifetime transmission are the strains that are most common in nature.
- MeSH
- Borrelia burgdorferi * MeSH
- klíště * MeSH
- larva MeSH
- lymeská nemoc * MeSH
- myši inbrední C3H MeSH
- myši MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Cíl: Cílem této práce bylo analyzovat vztah mezi novými případy klinické formy klíšťové encefalitidy a různými meteorologickými a sezonními prediktory. Materiál a metodika: Modelování vychází z národních dat České republiky za období 2001–2016 v denním rozlišení, a to z hodnot průměrné teploty, průměrné relativní vlhkosti vzduchu a počtu případů klíšťové encefalitidy klasifikovaných podle data prvních příznaků. Používají se čtyři varianty negativně binomického modelu z třídy zobecněných aditivních modelů. Základní model dává výskyt klíšťové encefalitidy do souvislosti se zpožděnou průměrnou denní teplotou okolí a denní průměrnou relativní vlhkostí vzduchu a jejich interakcí se zpožděním odrážejícím inkubační dobu a další faktory. Hodnota zpoždění byla odhadnuta optimalizačním postupem založeným na Akaikeho informačním kritériu. Model také zahrnuje vliv sezony a vliv dne v týdnu. Pro zvýšení biologické věrohodnosti byl základní model rozšířen a byl použit distributed lag model, který zohledňuje možné časově proměnlivé účinky meteorologických proměnných a zahrnuje více zpoždění. Výsledky: Statisticky nejvýznamnějším efektem je sezonnost v rámci roku a pak interakce teploty a relativní vlhkosti vzduchu. Vztah obou meteorologických faktorů a jejich interakce se mění v průběhu sezony aktivity hladových klíšťat Ixodes ricinus. To také mění podmínky výskytu nových klinických případů klíšťové encefalitidy. Časově proměnlivý vliv meteorologických faktorů na výskyt klíšťové encefalitidy vykazuje netriviální změny v průběhu roku. V období před polovinou kalendářního roku (kolem 22. týdne) je efekt nižší, poté následuje zvýšení až do 35. týdne. Závěr: Byly vyvinuty flexibilní modely s kvantitativně charakterizovanými vlivy teploty, vlhkosti vzduchu a jejich interakce, se zpožděním efektu odhadnutým optimalizačním procesem. Výkonnost finálního modelu byla zkontrolována pomocí nezávislých dat, aby se ověřila možnost využití výsledků ke zlepšení predikce rizika nárůstu klinických případů klíšťové encefalitidy.
Objectives: The aim of this work was to analyze the relationship between new cases of clinical tick-borne encephalitis (TBE) and various meteorological and seasonal predictors. Material and Methods: The modelling is based on national data from the Czech Republic for the period 2001–2016 in daily resolution, namely on average temperatures, average relative air humidity and the number of TBE cases classified according to the date of the first symptoms. Four variants of a negative binomial model from the generalized additive model class are used. The basic model relates the occurrence of TBE to the lagged ambient daily average temperature and daily average relative air humidity and their interaction with the lag reflecting the incubation period and other factors. The lag value was estimated via the optimization procedure based on Akaike information criterion. The model also includes the effect of the season and the effect of the day of the week. To increase the biological plausibility, the basic model has been expanded to account for possible time-varying effects of meteorological variables and to incorporate multiple lags. Results: The most statistically significant effect is the within-year seasonality and then the interaction of the temperature and relative air humidity. The relationship of both meteorological factors and their interactions vary throughout the activities season of the hostquesting Ixodes ricinus. This also changes the conditions of occurrence of the new clinical cases of TBE. The time-varying effect of meteorological factors on the incidence of TBE shows non-trivial changes within a year. In the period before the middle of the calendar year (around the week 22) the effect decreases, then it is followed by an increase until the week 35. Conclusion: Flexible models were developed with quantitatively characterized effects of temperature, air humidity and their interaction, with the delay of the effect estimated through the optimization process. Performance of the model with multiple lags was checked using independent data to verify the possibility of using the results to improve the prediction of the risk of clinical cases of TBE uprise.
- MeSH
- incidence MeSH
- klíště patogenita MeSH
- klíšťová encefalitida * epidemiologie MeSH
- lidé MeSH
- meteorologické pojmy * MeSH
- roční období MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
Salivary glands are vital to tick feeding success and also play a crucial role in tick-borne pathogen transmission. In previous studies of Ixodes scapularis salivary glands, we demonstrated that saliva-producing type II and III acini are innervated by neuropeptidergic axons which release different classes of neuropeptides via their terminals (Šimo et al., 2009b, 2013). Among these, the neuropeptide SIFamide-along with its cognate receptor-were postulated to control the basally located acinar valve via basal epithelial and myoepithelial cells (Vancová et al., 2019). Here, we functionally characterized a second SIFamide receptor (SIFa_R2) from the I. scapularis genome and proved that it senses a low nanomolar level of its corresponding ligand. Insect SIFamide paralogs, SMYamides, also activated the receptor but less effectively compared to SIFamide. Bioinformatic and molecular dynamic analyses suggested that I. scapularis SIFamide receptors are class A GPCRs where the peptide amidated carboxy-terminus is oriented within the receptor binding cavity. The receptor was found to be expressed in Ixodes ricinus salivary glands, synganglia, midguts, trachea, and ovaries, but not in Malpighian tubules. Investigation of the temporal expression patterns suggests that the receptor transcript is highly expressed in unfed I. ricinus female salivary glands and then decreases during feeding. In synganglia, a significant transcript increase was detected in replete ticks. In salivary gland acini, an antibody targeting the SIFa_R2 recognized basal epithelial cells, myoepithelial cells, and basal granular cells in close proximity to the SIFamide-releasing axon terminals. Immunoreactivity was also detected in specific neurons distributed throughout various I. ricinus synganglion locations. The current findings, alongside previous reports from our group, indicate that the neuropeptide SIFamide acts via two different receptors that regulate distinct or common cell types in the basal region of type II and III acini in I. ricinus salivary glands. Our study investigates the peptidergic regulation of the I. ricinus salivary gland in detail, emphasizing the complexity of this system.
- MeSH
- klíště * genetika metabolismus MeSH
- neurony metabolismus MeSH
- neuropeptidy * genetika metabolismus MeSH
- slinné žlázy metabolismus MeSH
- sliny MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Tick-borne encephalitis (TBE) is a viral disease endemic in Eurasia. The virus is mainly transmitted to humans via ticks and occasionally via the consumption of unpasteurized milk products. The European Centre for Disease Prevention and Control reported an increase in TBE incidence over the past years in Europe as well as the emergence of the disease in new areas. To better understand this phenomenon, we investigated the drivers of TBE emergence and increase in incidence in humans through an expert knowledge elicitation. We listed 59 possible drivers grouped in eight domains and elicited forty European experts to: (i) allocate a score per driver, (ii) weight this score within each domain, and (iii) weight the different domains and attribute an uncertainty level per domain. An overall weighted score per driver was calculated, and drivers with comparable scores were grouped into three terminal nodes using a regression tree analysis. The drivers with the highest scores were: (i) changes in human behavior/activities; (ii) changes in eating habits or consumer demand; (iii) changes in the landscape; (iv) influence of humidity on the survival and transmission of the pathogen; (v) difficulty to control reservoir(s) and/or vector(s); (vi) influence of temperature on virus survival and transmission; (vii) number of wildlife compartments/groups acting as reservoirs or amplifying hosts; (viii) increase of autochthonous wild mammals; and (ix) number of tick species vectors and their distribution. Our results support researchers in prioritizing studies targeting the most relevant drivers of emergence and increasing TBE incidence.
INTRODUCTION: Borrelia burgdorferi sensu lato, the causative agents of Lyme borreliosis, are transmitted by Ixodes ticks. Tick saliva proteins are instrumental for survival of both the vector and spirochete and have been investigated as targets for vaccine targeting the vector. In Europe, the main vector for Lyme borreliosis is Ixodes ricinus, which predominantly transmits Borrelia afzelii. We here investigated the differential production of I. ricinus tick saliva proteins in response to feeding and B. afzelii infection. METHOD: Label-free Quantitative Proteomics and Progenesis QI software was used to identify, compare, and select tick salivary gland proteins differentially produced during tick feeding and in response to B. afzelii infection. Tick saliva proteins were selected for validation, recombinantly expressed and used in both mouse and guinea pig vaccination and tick-challenge studies. RESULTS: We identified 870 I. ricinus proteins from which 68 were overrepresented upon 24-hours of feeding and B. afzelii infection. Selected tick proteins were successfully validated by confirming their expression at the RNA and native protein level in independent tick pools. When used in a recombinant vaccine formulation, these tick proteins significantly reduced the post-engorgement weights of I. ricinus nymphs in two experimental animal models. Despite the reduced ability of ticks to feed on vaccinated animals, we observed efficient transmission of B. afzelii to the murine host. CONCLUSION: Using quantitative proteomics, we identified differential protein production in I. ricinus salivary glands in response to B. afzelii infection and different feeding conditions. These results provide novel insights into the process of I. ricinus feeding and B. afzelii transmission and revealed novel candidates for an anti-tick vaccine.
- MeSH
- arachnida jako vektory MeSH
- klíště * MeSH
- lymeská nemoc * prevence a kontrola MeSH
- morčata MeSH
- myši MeSH
- proteiny členovců MeSH
- proteom MeSH
- slinné žlázy MeSH
- vakcíny * MeSH
- zvířata MeSH
- Check Tag
- morčata MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
