Ticks are parasites that feed on the blood of humans and animals, using it as their sole source of food. Due to their lifestyle, ticks at each life stage transmit various tick-borne pathogens while feeding on their hosts. Unlike mosquitoes - another important group of pathogen-transmitting arthropods - ticks can feed on the same host for prolonged periods, which underscores the importance of tick mechanisms that inhibit or reduce the host's defence mechanisms and, consequently, allow the transmission of pathogens. This unique tick-host-pathogen triangle requires the involvement of various tick molecules to mediate interactions with both host and pathogen molecules at multiple levels. This review highlights the glycan molecules identified in various tick species that can trigger an immune response and thus primarily affect the interaction with the host. As the enzymes involved in Golgi-mediated glycan maturation differ between ticks, insects, and their vertebrate hosts, these differences contribute to the glycan profiles observed in ticks. These differences in glycan structures influence the interactions ticks have with their hosts and pathogens. On one hand, they may participate in molecular mimicry and mechanisms that lower the host's immune reaction, blood clotting, and other defence mechanisms due to their different structures, but on the other hand they may also trigger the host's defence mechanisms, such as participating in delayed red meat allergy and facilitating the transmission of pathogens. Tick glycobiology remains largely unexplored and deserves more attention, especially considering the potential of glycans and glycoproteins as targets for anti-tick vaccines.

Ixodes ricinus ticks are widely distributed throughout Europe and represent major vectors of tick-borne encephalitis virus and the Lyme borreliosis agent Borrelia burgdorferi sensu lato. In invertebrates, C-type lectins are commonly associated with innate immune functions, and several such lectins have been predicted in I. ricinus. Given the limited knowledge of lectin function in ticks, we characterized three carbohydrate-recognition domains (CRDs) of a novel C-type lectin identified in the I. ricinus transcriptome (IrCLec).The tertiary structures of CRD1, CRD2, and CRD3, predicted using the AlphaFold 3 program, corresponded to the typical structure of C-type lectins. Conserved carbohydrate-binding motifs were identified in CRD3, whereas non-canonical motifs were present in CRD1 and CRD2. Recombinant His-tagged CRDs were produced and analyzed for carbohydrate-binding activity. Glycan array analysis revealed binding of all three domains to selected glycans, while haemagglutination assays demonstrated pronounced binding activity of CRD1 and CRD2 toward human erythrocyte antigens of blood groups A, B, and O.IrCLec expression was highest in the tick midgut and also detected in haemocytes, with expression levels increasing after blood feeding. RNAi-mediated silencing of IrCLec impaired blood feeding efficiency in tick nymphs. Together, these findings identify IrCLec as a novel multidomain lectin localized predominantly in the tick midgut, with individual CRDs displaying different carbohydrate-binding preferences and a potential role during feeding.

Tick-borne encephalitis virus (TBEV) is a medically important flavivirus that causes severe neurological diseases in humans. The assembly of flaviviruses is initiated by the interaction between capsid (C) proteins and viral genomic RNA, yet the molecular determinants that govern RNA encapsidation remain unclear. In this study, we established a TBEV virus-like particle (VLP) system to analyse viral factors that influence viral RNA incorporation independently of productive infection. Using a reporter-containing TBEV minigenome, we investigated the contribution of UTRs to the incorporation of RNA into extracellular particles. Truncation of the 5' UTR, 3' UTR or both did not significantly affect the levels of minigenome RNA detected in pelleted extracellular fractions, indicating that RNA incorporation occurs largely in a non-specific manner. We further examined the role of C protein dimerization by introducing alanine substitutions into residues that form the α2-α2' and α4-α4' dimer interfaces. Paradoxically, these substitutions increased the levels of minigenome RNA detected in pelleted extracellular particles without altering intracellular RNA expression, indicating a complex relationship between the integrity of the C protein dimer interface and levels of extracellular viral RNA. Finally, we showed that TBEV proteins and minigenome RNA can be detected in extracellular vesicle (EV)-associated fractions under VLP-producing conditions. Using immunoaffinity purification, we demonstrate the presence of viral components in EVs, underscoring EV-associated release as a factor that complicates the analysis of flaviviral particle assembly.

Sialic acid commonly decorates the surface of cells and secreted proteins of Eukaryotes. It plays roles in cell signalling and adhesion, affects immune reactions and alternative complement pathways, and neurogenesis. While sialic acid is a saccharide present in high abundance in vertebrates, its minor representation was reported in arthropods and among medically necessary parasites.Ixodes ricinus tick is a significant vector of pathogens causing severe infections in humans and livestock. It has been known mainly through indirect evidence that sialylated glycoproteins are present in tick tissues. As a blood-feeding parasite, the host's blood, full of sialylated molecules, could be the source of such glycoproteins within the tick's body. To detect solely the tick sialylated glycoproteins, we used an azide-modified precursor of sialic acid to be metabolically incorporated by the tick cell line IRE/CTVM20 originating in this tick or by ticks if the corresponding biosynthetic pathway is present and active.Our I. ricinus genome screen revealed two sialyltransferase genes, which were expressed in all ticks' life stages, and we confirmed sialyltransferase activity in tick cells. We combined in vitro feeding along with Click chemistry to track the presence of sialylated glycoproteins from fed female ticks through their eggs to the larvae. Similarly, sialylated glycoproteins were produced by the IRE/CTVM20 cell line. Thus, we confirmed the ability of ticks to produce their own sialylated glycoproteins in addition to those originating from the host blood.

Background: While the influence of landscape and microclimatic conditions on tick populations is well-documented, there remains a gap in more specific data regarding their relationship to rewilding efforts with large herbivore activity. Objective: This pilot study, spanning from 2019 to 2021, explores the effects of naturalistic grazing by large semi-wild ungulates on tick abundance in the Milovice Reserve, Czechia. Methods: Tick collection was observed using flagging techniques at two distinct sites of rewilding area: one grazed, actively utilized by animals involved in the rewilding project, and one ungrazed, left fallow in neighboring areas utilized only by wild animals. Transects, each measuring 150 m in length and 5 m in width (750 m2), were established at these two sampling locations from March to September between 2019 and 2021. To minimize potential bias resulting from tick movement, a 300 m buffer zone separated the two sites. Data analysis employed a generalized estimating equations (GEE) model with negative binomial regression. The study assessed potential variations in tick abundance between selected transects, considering factors such as plant cover seasonality, temperature, and humidity. Results: During the collection periods, we gathered 586 live ticks, with 20% found in grazed areas and 80% in ungrazed areas. Notably, tick abundance was significantly higher in ungrazed areas. Peaks in tick abundance occurred in both grazed and ungrazed areas during spring, particularly in April. However, tick numbers declined more rapidly in grazed areas. Microclimatic variables like temperature and humidity did not significantly impact tick abundance compared to landscape management and seasonal factors. Conclusion: Rewilding efforts, particularly natural grazing by large ungulates, influence tick abundance and distribution. This study provides empirical data on tick ecology in rewilded areas, highlighting the importance of landscape management and environmental factors in tick management and conservation. Trophic rewilding plays a crucial role in shaping ecosystems and tick population dynamics in transformed landscapes.

Ticks attaching to ear canals of humans and animals are the cause of otoacariasis, common in rural areas of Nepal. The plant Clerodendrum viscosum is used in multiple indigenous systems of medicine by ethnic communities in the Indo-Nepali-Malaysian region. Visiting the Chitwan National Park, we learned that in indigenous medicine, flower extract of C. viscosum is utilized to treat digestive disorders and extracts from leaves as tick repellent to prevent ticks from invading or to remove them from the ear canal. The objective of our study was to provide support to indigenous medicine by characterizing the in vivo effect of leave extracts on ticks under laboratory conditions and its phytochemical composition. We collected plant parts of C. viscosum (leaves and flowers) and mango (Mangifera indica) leaves at the Chitwan National Park, previously associated with repellent activity to characterize their effect on Ixodes ricinus ticks by in vivo bioassays. A Q-ToF high-resolution analysis (HPLC-ESI-QToF) was conducted to elucidate phenolic compounds with potential repellent activity. Clerodendrum viscosum and M. indica leaf extracts had the highest tick repellent efficacy (%E = 80-100%) with significant differences when compared to C. viscosum flowers extracts (%E = 20-60%) and phosphate-buffered saline. Phytochemicals with tick repellent function as caffeic acid, fumaric acid and p-coumaric acid glucoside were identified in C. viscosum leaf extracts by HPLC-ESI-QToF, but not in non-repellent flower extracts. These results support the Nepali indigenous medicine application of C. viscosum leaf extracts to repel ticks. Additional research is needed for the development of natural and green repellent formulations to reduce the risks associated with ticks resistant to acaricides.

Lyme disease is a multisystem disorder primarily caused by Borrelia burgdorferi sensu lato. However, B. garinii, which has been identified on islands off the coast of Newfoundland and Labrador, Canada, is a cause of Lyme disease in Eurasia. We report isolation and whole-genome nucleotide sequencing of a B. garinii isolate from a cotton mouse (Peromyscus gossypinus) in South Carolina, USA. We identified a second B. garinii isolate from the same repository. Phylogenetic analysis does not associate these isolates with the previously described isolates of B. garinii from Canada.

Borrelia garinii , is a cause of Lyme disease in Europe and Asia. For the first time, we report it in the southeastern United States in rodents. Whole genome sequencing and phylogenetic analysis revealed that USA-located B. garinii is part of a clade consisting primarily of few European and majority of Far Eastern strains. Continued surveillance of wildlife hosts and ticks is necessary to assess the ecological status and public health risks of B. garinii in southeastern US.

Tick-borne encephalitis virus (TBEV) is the most medically relevant tick-transmitted Flavivirus in Eurasia, targeting the host central nervous system and frequently causing severe encepha-litis. The primary function of its capsid protein (TBEVC) is to Tick-borne pathogen idae family, (TBFVs),

Ticks transmit a broad spectrum of pathogens, threatening both animal and human health. Tick survival and proliferation are strongly dependent on host selection and suitability. The hard tick Ixodes ricinus, which is widespread throughout most of Europe, is a host generalist capable of feeding on many different vertebrate species. Pasture-kept exotic farm animals may be at a high risk for tick and tick-borne pathogens infestations but research characterizing this is currently lacking. This study focused on the detection of Borrelia spirochetes (including Borrelia miyamotoi) in exotic farm animals. Using nested-PCR with Borrelia-specific primers, 121 serum samples from 54 exotic farm animals of several species bred in four different farms in Bohemia and Moravia (Czechia) were tested. Positive samples were sequenced for the identification of Borrelia species. The prevalence of Borrelia DNA in the samples ranged from 13 to 67%, depending on the sampling site. The sequencing results confirmed the DNA presence of multiple spirochete species from the Borrelia burgdorferi sensu lato complex. Only one sample from an ostrich (Struthio camelus) was found to be positive for Borrelia myiamotoi. The results show that exotic farm animals can serve as hosts for hard ticks and can be infected by Borrelia spirochetes, transmitted by hard ticks. Therefore, these animals could play a relevant role in maintaining Borrelia spirochetes in nature.

Tick-borne encephalitis virus (TBEV), the most medically relevant tick-transmitted flavivirus in Eurasia, targets the host central nervous system and frequently causes severe encephalitis. The severity of TBEV-induced neuropathogenesis is highly cell-type specific and the exact mechanism responsible for such differences has not been fully described yet. Thus, we performed a comprehensive analysis of alterations in host poly-(A)/miRNA/lncRNA expression upon TBEV infection in vitro in human primary neurons (high cytopathic effect) and astrocytes (low cytopathic effect). Infection with severe but not mild TBEV strain resulted in a high neuronal death rate. In comparison, infection with either of TBEV strains in human astrocytes did not. Differential expression and splicing analyses with an in silico prediction of miRNA/mRNA/lncRNA/vd-sRNA networks found significant changes in inflammatory and immune response pathways, nervous system development and regulation of mitosis in TBEV Hypr-infected neurons. Candidate mechanisms responsible for the aforementioned phenomena include specific regulation of host mRNA levels via differentially expressed miRNAs/lncRNAs or vd-sRNAs mimicking endogenous miRNAs and virus-driven modulation of host pre-mRNA splicing. We suggest that these factors are responsible for the observed differences in the virulence manifestation of both TBEV strains in different cell lines. This work brings the first complex overview of alterations in the transcriptome of human astrocytes and neurons during the infection by two TBEV strains of different virulence. The resulting data could serve as a starting point for further studies dealing with the mechanism of TBEV-host interactions and the related processes of TBEV pathogenesis.

Lyme borreliosis (LB) is a multisystem disorder with a diverse spectrum of clinical manifestations. It is one of the most frequently recorded tick-borne diseases in the northern hemisphere, caused by selected species of spirochaetes from the Borrelia burgdorferi sensu lato complex. This expert opinion discusses the impact of global warming and climate change on the abundance and distribution of LB and its causative agents.

In vitro models are often used for studying macrophage functions, including the process of phagocytosis. The application of primary macrophages has limitations associated with the individual characteristics of animals, which can lead to insufficient standardization and higher variability of the obtained results. Immortalized cell lines do not have these disadvantages, but their responses to various signals can differ from those of the living organism. In the present study, a comparative proteomic analysis of immortalized PMJ2-R cell line and primary peritoneal macrophages isolated from C57BL/6 mice was performed. A total of 4005 proteins were identified, of which 797 were quantified. Obtained results indicate significant differences in the abundances of many proteins, including essential proteins associated with the process of phagocytosis, such as Elmo1, Gsn, Hspa8, Itgb1, Ncf2, Rac2, Rack1, Sirpa, Sod1, C3, and Msr1. These findings indicate that outcomes of studies utilizing PMJ2-R cells as a model of peritoneal macrophages should be carefully validated. All MS data are deposited in ProteomeXchange with the identifier PXD022133.