Ticks are important vectors of disease, particularly in the context of One Health, where tick-borne diseases (TBDs) are increasingly prevalent worldwide. TBDs often involve co-infections, where multiple pathogens co-exist in a single host. Patients with chronic Lyme disease often have co-infections with other bacteria or parasites. This study aimed to create a co-infection model with Borrelia afzelii and tick-borne encephalitis virus (TBEV) in C3H mice and to evaluate symptoms, mortality, and pathogen level compared to single infections. Successful co-infection of C3H mice with B. afzelii and TBEV was achieved. Outcomes varied, depending on the timing of infection. When TBEV infection followed B. afzelii infection by 9 days, TBEV symptoms worsened and virus levels increased. Conversely, mice infected 21 days apart with TBEV showed milder symptoms and lower mortality. Simultaneous infection resulted in mild symptoms and no deaths. However, our model did not effectively infect ticks with TBEV, possibly due to suboptimal dosing, highlighting the challenges of replicating natural conditions. Understanding the consequences of co-infection is crucial, given the increasing prevalence of TBD. Co-infected individuals may experience exacerbated symptoms, highlighting the need for a comprehensive understanding through refined animal models. This study advances knowledge of TBD and highlights the importance of exploring co-infection dynamics in host-pathogen interactions.
- Klíčová slova
- C3H mice, co-infection, pathogen fitness, pathogen invasiveness, tick-borne pathogens,
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Ticks can transmit a broad variety of pathogens of medical importance, including Borrelia afzelii, the causative agent of Lyme borreliosis in Europe. Tick microbiota is an important factor modulating, not only vector physiology, but also the vector competence. Anti-microbiota vaccines targeting keystone taxa of tick microbiota can alter tick feeding and modulate the taxonomic and functional profiles of bacterial communities in the vector. However, the impact of anti-microbiota vaccine on tick-borne pathogen development within the vector has not been tested. RESULTS: Here, we characterized the Ixodes ricinus microbiota modulation in response to B. afzelii infection and found that the pathogen induces changes in the microbiota composition, its beta diversity and structure of bacterial community assembly. Tick microbiota perturbation by anti-microbiota antibodies or addition of novel commensal bacteria into tick midguts causes departures from the B. afzelii-induced modulation of tick microbiota which resulted in a lower load of the pathogen in I. ricinus. Co-occurrence networks allowed the identification of emergent properties of the bacterial communities which better defined the Borrelia infection-refractory states of the tick microbiota. CONCLUSIONS: These findings suggest that Borrelia is highly sensitive to tick microbiota perturbations and that departure from the modulation induced by the pathogen in the vector microbiota pose a high cost to the spirochete. Network analysis emerges as a suitable tool to identify emergent properties of the vector microbiota associated with infection-refractory states. Anti-microbiota vaccines can be used as a tool for microbiota perturbation and control of important vector-borne pathogens. Video Abstract.
- Klíčová slova
- Anti-microbiota vaccine, Borrelia afzelii, Ixodes ricinus, Lyme borreliosis, Vector microbiota,
- MeSH
- Bacteria MeSH
- Borrelia burgdorferi komplex * fyziologie MeSH
- klíště * mikrobiologie fyziologie MeSH
- lymeská nemoc * mikrobiologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- audiovizuální média MeSH
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Evropa 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.
- Klíčová slova
- SIFamide, SIFamide receptors, Salivary gland acini, Synganglion, Ticks,
- 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
- Názvy látek
- neuropeptidy * MeSH
Neuropeptides are small signaling molecules expressed in the tick central nervous system, i.e., the synganglion. The neuronal-like Ixodes scapularis embryonic cell line, ISE6, is an effective tool frequently used for examining tick-pathogen interactions. We detected 37 neuropeptide transcripts in the I. scapularis ISE6 cell line using in silico methods, and six of these neuropeptide genes were used for experimental validation. Among these six neuropeptide genes, the tachykinin-related peptide (TRP) of ISE6 cells varied in transcript expression depending on the infection strain of the tick-borne pathogen, Anaplasma phagocytophilum. The immunocytochemistry of TRP revealed cytoplasmic expression in a prominent ISE6 cell subpopulation. The presence of TRP was also confirmed in A. phagocytophilum-infected ISE6 cells. The in situ hybridization and immunohistochemistry of TRP of I. scapularis synganglion revealed expression in distinct neuronal cells. In addition, TRP immunoreaction was detected in axons exiting the synganglion via peripheral nerves as well as in hemal nerve-associated lateral segmental organs. The characterization of a complete Ixodes neuropeptidome in ISE6 cells may serve as an effective in vitro tool to study how tick-borne pathogens interact with synganglion components that are vital to tick physiology. Therefore, our current study is a potential stepping stone for in vivo experiments to further examine the neuronal basis of tick-pathogen interactions.
- Klíčová slova
- Anaplasma phagocytophilum, Ixodes scapularis ISE6 cell line, neuropeptides, synganglion,
- Publikační typ
- časopisecké články MeSH
Regulatory factors controlling tick salivary glands (SGs) are direct upstream neural signaling pathways arising from the tick's central nervous system. Here we investigated the cholinergic signaling pathway in the SG of two hard tick species. We reconstructed the organization of the cholinergic gene locus, and then used in situ hybridization to localize mRNA encoding choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT) in specific neural cells in the Ixodes synganglion. Immunohistochemical staining revealed that cholinergic axonal projections exclusively reached type I acini in the SG of both Ixodes species. In type I acini, the rich network of cholinergic axons terminate within the basolateral infoldings of the lamellate cells. We also characterized two types (A and B) of muscarinic acetylcholine receptors (mAChRs), which were expressed in Ixodes SG. We pharmacologically assessed mAChR-A to monitor intracellular calcium mobilization upon receptor activation. In vivo injection of vesamicol-a VAChT blocker-at the cholinergic synapse, suppressed forced water uptake by desiccated ticks, while injection of atropine, an mAChR-A antagonist, did not show any effect on water volume uptake. This study has uncovered a novel neurotransmitter signaling pathway in Ixodes SG, and suggests its role in water uptake by type I acini in desiccated ticks.
- MeSH
- acinární buňky metabolismus fyziologie MeSH
- axony metabolismus MeSH
- centrální nervový systém metabolismus MeSH
- cholin-O-acetyltransferasa genetika metabolismus MeSH
- cholinergní látky metabolismus MeSH
- klíště metabolismus MeSH
- messenger RNA metabolismus MeSH
- neurony cholinergní metabolismus fyziologie MeSH
- neurony metabolismus MeSH
- signální transdukce genetika MeSH
- slinné žlázy metabolismus fyziologie MeSH
- vezikulární transportní proteiny acetylcholinu genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- cholin-O-acetyltransferasa MeSH
- cholinergní látky MeSH
- messenger RNA MeSH
- vezikulární transportní proteiny acetylcholinu MeSH
The different components of the mouthparts of hard ticks (Ixodidae) enable these parasites to penetrate host skin, secrete saliva, embed, and suck blood. Moreover, the tick's mouthparts represent a key route for saliva-assisted pathogen transmission as well as pathogen acquisition from blood meal during the tick feeding process. Much has been learned about the basic anatomy of the tick's mouthparts and in the broad outlines of how they function in previous studies. However, the precise mechanics of these functions are little understood. Here, we propose for the first time an animated model of the orchestration of the tick mouthparts and associated structures during blood meal acquisition and salivation. These two actions are known to alternate during tick engorgement. Specifically, our attention has been paid to the mechanism underlining the blood meal uptake into the pharynx through the mouth and how ticks prevent mixing the uptaken blood with secreted saliva. We animated function of muscles attached to the salivarium and their possible opening /closing of the salivarium, with a plausible explanation of the movement of saliva within the salivarium and massive outpouring of saliva.
- MeSH
- infestace klíšťaty parazitologie MeSH
- klíště anatomie a histologie MeSH
- mikroskopie elektronová rastrovací MeSH
- myši MeSH
- nymfa anatomie a histologie parazitologie MeSH
- salivace * MeSH
- stravovací zvyklosti * MeSH
- ústa anatomie a histologie parazitologie MeSH
- zobrazování trojrozměrné MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Ticks can survive in harsh and fluctuating vegetated environments for long durations between blood feedings with highly developed osmoregulatory mechanisms. Like the unique life history of hematophagous ticks, osmoregulatory organs and their regulatory mechanisms are significantly different from those in the closely related insect taxa. Over the last ten years, research has uncovered several neuropeptidergic innervations of the primary osmoregulatory organ, the salivary glands: myoinhibitory peptide (MIP), SIFamide, and elevenin. These neuropeptides are thought to be modulators of dopamine's autocrine or paracrine actions controlling the salivary glands, including the activation of fluid transport into the lumen of salivary acini and the pumping and gating action of salivary acini for expelling fluids out into salivary ducts. These actions are through two different dopamine receptors, D1 receptor and invertebrate D1-like dopamine receptor, respectively. Interestingly, MIP and SIFamide are also involved in the control of another important excretory/osmoregulatory organ, the hindgut, where SIFamide is myostimulatory, with MIP having antagonistic effects. FGLamide related allatostatin is also found to have axonal projections located on the surface of the rectum. Investigations of the osmoregulatory mechanisms of these critical vector species will potentially lead to the development of a measure to control tick species.
- Klíčová slova
- Dopamine, Neuropeptides, Osmoregulation, Receptors, Tick hindgut, Tick salivary secretion,
- MeSH
- axony metabolismus ultrastruktura MeSH
- biologické modely MeSH
- dopamin metabolismus MeSH
- endokrinní systém metabolismus MeSH
- fluorescenční barviva metabolismus MeSH
- klíště metabolismus MeSH
- neurony metabolismus MeSH
- orgánová specificita * MeSH
- osmoregulace * MeSH
- slinné žlázy metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Research Support, N.I.H., Extramural MeSH
- Názvy látek
- dopamin MeSH
- fluorescenční barviva MeSH
The salivary gland of hard ticks is a highly innervated tissue where multiple intertwined axonal projections enter each individual acini. In the present study, we investigated the ultrastructural architecture of axonal projections within granular salivary gland type II and III acini of Ixodes ricinus female. Using immunogold labeling, we specifically examined the associations of SIFamide neuropeptide, SIFamide receptor (SIFa_R), neuropeptide pigment dispersing factor (PDF), and the invertebrate-specific D1-like dopamine receptor (InvD1L), with acinar cells. In both acini types, SIFamide-positive axons were found to be in direct contact with either basal epithelial cells or a single adlumenal myoepithelial cell in close proximity to the either the acinar duct or its valve, respectively. Accordingly, SIFa_R staining correlated with SIFamide-positive axons in both basal epithelial and myoepithelial cells. Immunoreactivity for both InvD1L and PDF (type II acini exclusively) revealed positive axons radiating along the acinar lumen. These axons were primarily enclosed by the adlumenal myoepithelial cell plasma membrane and interstitial projections of ablumenal epithelial cells. Our study has revealed the detailed ultrastructure of I. ricinus salivary glands, and provides a solid baseline for a comprehensive understanding of the cell-axon interactions and their functions in this essential tick organ.
- MeSH
- axony metabolismus ultrastruktura MeSH
- Ixodidae MeSH
- klíště ultrastruktura MeSH
- receptory dopaminové metabolismus MeSH
- slinné žlázy inervace metabolismus ultrastruktura MeSH
- transmisní elektronová mikroskopie MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- receptory dopaminové MeSH
The carbohydrate Galα1-3Galβ1-(3)4GlcNAc-R (α-Gal) is produced in all mammals except for humans, apes and old world monkeys that lost the ability to synthetize this carbohydrate. Therefore, humans can produce high antibody titers against α-Gal. Anti-α-Gal IgE antibodies have been associated with tick-induced allergy (i.e. α-Gal syndrome) and anti-α-Gal IgG/IgM antibodies may be involved in protection against malaria, leishmaniasis and Chagas disease. The α-Gal on tick salivary proteins plays an important role in the etiology of the α-Gal syndrome. However, whether ticks are able to produce endogenous α-Gal remains currently unknown. In this study, the Ixodes scapularis genome was searched for galactosyltransferases and three genes were identified as potentially involved in the synthesis of α-Gal. Heterologous gene expression in α-Gal-negative cells and gene knockdown in ticks confirmed that these genes were involved in α-Gal synthesis and are essential for tick feeding. Furthermore, these genes were shown to play an important role in tick-pathogen interactions. Results suggested that tick cells increased α-Gal levels in response to Anaplasma phagocytophilum infection to control bacterial infection. These results provided the molecular basis of endogenous α-Gal production in ticks and suggested that tick galactosyltransferases are involved in vector development, tick-pathogen interactions and possibly the etiology of α-Gal syndrome in humans.
- MeSH
- alfa-galaktosidasa genetika metabolismus MeSH
- Anaplasma phagocytophilum patogenita MeSH
- ehrlichióza genetika metabolismus MeSH
- galaktosyltransferasy metabolismus MeSH
- genom genetika MeSH
- HL-60 buňky MeSH
- infekce přenášené vektorem MeSH
- interakce hostitele a patogenu genetika MeSH
- klíště mikrobiologie MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- proteiny členovců metabolismus MeSH
- sekvence aminokyselin MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- alfa-galaktosidasa MeSH
- galaktosyltransferasy MeSH
- GLA protein, human MeSH Prohlížeč
- proteiny členovců MeSH