Search Results (42)

Ticks transmit diverse pathogens, posing significant public health threats in northeastern China; clarifying human-biting tick species and their carried pathogens is crucial for risk assessment and prevention. This study was designed as a pathogen detection and molecular epidemiological investigation. During the May-August period of each of 2023 and 2024, 232 ticks that had bitten humans were collected from a local sentinel hospital. Ticks were morphologically identified, followed by DNA extraction, semi-nested/nested PCR targeting specific genetic markers, and Sanger sequencing to detect bacterial pathogens. Four tick species were found, with Ixodes persulcatus dominant (87.9%), followed by Dermacentor silvarum (6.9%), Haemaphysalis concinna (3.5%), and Haemaphysalis japonica (1.7%). Seven bacterial pathogens were detected, including Candidatus Rickettsia tarasevichiae (35.3%) and Borreliella garinii (17.2%); 49.6% of ticks were pathogen-positive. The coinfection rate was 13.8%, most commonly Candidatus R. tarasevichiae plus B. garinii, and I. persulcatus carried all pathogens. These findings provide basic data on human-biting tick species and their bacterial pathogen spectrum in the region, serving as a reference for subsequent tick-borne disease research and targeted prevention. Full article

The genetic diversity of the ospA gene of the Borrelia burgdorferi sensu lato species complex encoding outer surface protein A has been widely investigated. However, the information on the genetic variability of Borrelia isolates from Siberia for this gene is limited. In this study, we analyzed complete ospA gene sequences from 36 Borrelia isolates from Western Siberia, comprising 6 Borrelia afzelii, 16 Borrelia bavariensis, 1 Borrelia garinii, and 13 “Candidatus Borrelia sibirica” isolates. The obtained ospA gene sequences of B. afzelii were conserved and formed a single clade. In contrast, B. bavariensis sequences were highly variable, segregating into two distinct clades consistent with the phylogeography of Asian isolates. Notably, the B. bavariensis samples identified in molted Ixodes trianguliceps and Ixodes apronophorus were first characterized for the ospA gene; the obtained sequences corresponded to those from I. persulcatus. This study provides the first characterization of the ospA gene in “Candidatus B. sibirica”, revealing highly conserved sequences (99.8–100% intraspecific identity). The ospA gene sequences of “Candidatus B. sibirica” shared less than 88.7% identity with those of other Borrelia genospecies. Phylogenetic analysis placed “Candidatus B. sibirica” in a unique, well-supported clade, confirming its distinct phylogenetic status and suggesting potential ecological specialization in nidicolous Ixodes species. Full article

Borrelia burgdorferi sensu lato (s.l.) persistence in reservoir hosts is essential for the maintenance of the spirochaetes in the enzootic cycle. In this study, we investigated the persistence of Siberian B. burgdorferi s.l. strains in naturally infected voles and their transmission to Ixodes ticks. A long-term study conducted in 2013–2024 demonstrated the presence of Borrelia afzelii, Borrelia bavariensis, and, rarely, “Candidatus Borrelia sibirica” DNA in blood samples of small mammals. Among these, B. bavariensis exhibited the highest genetic diversity. All identified Borrelia species persisted in naturally infected Clethrionomys spp. voles throughout their lifespan (up to 50 weeks), providing the first evidence of long-term persistence of B. bavariensis and “Candidatus B. sibirica” in these hosts. Notably, the persistence of two Borrelia genospecies or several genovariants of a single genospecies within the same vole was common. Xenodiagnosis with laboratory-reared Ixodes spp. confirmed efficient transmission of all identified Borrelia genospecies to Ixodes persulcatus after 35–42 weeks of B. burgdorferi s.l. persistence. Moreover, B. bavariensis was transmitted to Ixodes pavlovskyi and I. persulcatus/I. pavlovskyi interspecies hybrids after at least 23 weeks of pathogen persistence. These findings demonstrate the reservoir competence of Clethrionomys spp. for B. afzelii, B. bavariensis, and “Candidatus B. sibirica”. Full article

A novel flavi-like virus with a segmented genome—Alongshan virus (ALSV)—has been isolated from Ixodes ticks in Russia. In this study, 4458 ixodid ticks collected in 22 regions of Russia were tested for genetic markers of ALSV by RT PCR. The highest rates of ALSV infection in ticks were detected in the Republic of Khakassia (3.3%) and in Kemerovo Oblast (2.4%), while low infection rates were more typical in the European part of Russia (0.4–0.7%). Complete four-segment genomes of 20 ALSV isolates derived from 22 PCR-positive Ixodes persulcatus ticks were sequenced using a high-throughput approach. The nucleotide sequences for Asian ALSV isolates have a 94.5–96.5% identity to ALSV isolates previously found in China, with this range for the European isolates being 89–93%. This data, together with phylogenetic analysis, indicates the existence of Asian and European subtypes of ALSV, and these may be associated with I. persulcatus and I ricinus ticks. The obtained results express the spread of ALSV in Russia and also may be useful for the diagnosis, prophylactics, and treatment of this infection. Full article

Ixodid ticks are blood-sucking ectoparasites of vertebrates. They constitute an integral part of natural foci and are responsible for the worldwide transmission of infections to humans, which can result in severe symptoms. For instance, the Tomsk region, where three abundant tick species (Dermacentor reticulatus, Ixodes pavlovskyi, I. persulcatus) occur, is an endemic area for tick-borne encephalitis virus (TBEV). An increasing number of novel infectious agents carried by ticks have been identified using metagenomic sequencing. A notable example is the Yezo virus (Orthonairovirus yezoense, YEZV), which was discovered in patients with fever after tick bites in Japan and China between 2014 and 2025. For the first time, we have performed metagenomic sequencing of the virome of ticks collected in the Tomsk region. In a sample obtained from a pool of I. pavlovskyi ticks, all three segments of the YEZV genome were detected. The phylogenetic analysis showed that the newly identified isolate formed a sister group to previously described virus isolates, indicating the presence of a new genetic variant. This study presents the first report of YEZV detection in I. pavlovskyi ticks in the Tomsk region, thereby expanding the geographical range and number of vector species for YEZV and highlighting the importance of monitoring viral agents circulating among ticks in Western Siberia. Full article

The habitats of shrews substantially overlap with those of rodents, which are well known as reservoirs for many tick-borne diseases. However, the ecological role of shrews (Mammalia: Eulipotyphla: Soricidae) remains poorly understood. We examined 103 Sorex spp. (S. unguiculatus, S. gracillimus, S. caecutiens) from Kushiro, Hokkaido, Japan, to investigate their relationships with ticks and tick-borne microorganisms, including Piroplasmida and Anaplasmataceae. Pathogen screening revealed Babesia microti Hobetsu lineage (9.7%), Neoehrlichia mikurensis (26.2%), Ehrlichia japonica (13.6%), and E. muris (0.97%). These intracellular protozoa and bacteria, typically associated with rodents, are recognized zoonotic agents or have zoonotic potential. Detection rates were highest in S. caecutiens (62.5%, 10/16), followed by S. unguiculatus (45.3%, 24/53) and S. gracillimus (23.5%, 8/34). Co-infections were observed between N. mikurensis and B. microti (n = 3) and between N. mikurensis and E. japonica (n = 4). Immature stages of Ixodes ovatus and I. persulcatus were collected from the body surface of shrews, and transstadial transmission of N. mikurensis was suggested by its detection in a molted I. ovatus nymph. These results indicate that shrews act as feeding hosts for immature ticks and reservoirs for multiple tick-borne pathogens. Shrews should be considered important reservoirs for tick-borne diseases. Full article

Ticks are important parasites of economic and public health because of their ability to transmit zoonotic diseases. Tick-borne encephalitis virus (TBEV), now officially Orthoflavivirus encephalitidis, is a Flavivirus with five main subtypes of which three, the European (TBEV-EU), the Siberian (TBEV-Sib), and the Far-Eastern subtypes (TBEV-FE), are supposedly circulate in Latvia. Several hard tick species are involved in TBEV circulation and transmission in nature. This study set out to describe the genetic landscape of TBEV subtypes in Latvian tick populations. In 2019 and 2021 to 2023, a total of 3026 ticks were collected in three Latvian regions, with Ixodes ricinus as the dominant species (2822 specimens), followed by Ixodes persulcatus (200 specimens) and Dermacentor reticulatus (4 specimens). Ticks were morphologically identified, pooled, and screened for TBEV RNA by RT-qPCR. TBEV of positive tick pools were isolated and genetically characterized by genome sequencing. Our study demonstrates the prevalence of two TBEV subtypes in Latvia with specific spatial patterning. In the sympatric Vidzeme region, these subtypes display a preferential species association of TBEV-EU with Ixodes ricinus and TBEV-Sib with Ixodes persulcatus. Phylogeographic analysis suggests independent introductions of multiple genotypes from both subtypes. Further investigations are necessary to better understand the natural transmission and the medical importance of these TBEVs. Full article

The recent discovery of the Yezo virus (YEZV) in Japan and China has raised particular concern due to its potential to cause human diseases ranging from mild febrile illnesses to severe neurological disorders. We report, for the first time, the detection of five YEZV isolates in I. persulcatus ticks from three regions of Russia. The analysis was performed using 5318 ticks of two Ixodes genus collected in 2024 from 23 regions of Russia. The minimum infection rate of YEZV in Russia among I. persulcatus ticks was 0.12% (95% CI: 0.05–0.28). The westernmost and northernmost YEZV detection points have been recorded. YEZV isolates circulating in Russia are genetically diverse. Protein domains of Russian YEZV isolates’ genomes were characterized using HMMER, AlphaFold 3, and InterProScan. The YEZV nucleoprotein (N) of Russian isolates has a racket-shaped structure with “head” and “stalk” domains similar to those of Orthonairovirus haemorrhagiae. The Lys261–Arg261 substitution in the YEZV N Chita 2024-1 isolate occurs in the α11 structure in the region of interaction with viral RNA. Our results show that the distribution area of YEZV is much wider than previously known, provide new data on complete YEZV genomes, extend our structural insight into YEZV N, and suggest a potential target for antiviral drug development to treat YEZV infection. Full article

The spectrum of ixodid ticks that bite humans in Western Siberia has significantly changed over the past two decades. In this study, we determined tick species attacking people in the vicinity of Novosibirsk and the range of bacterial agents they were infected with. This study included 301 ticks taken from people and 46% were Ixodes pavlovskyi, followed by Ixodes persulcatus (19.6%), I. persulcatus/I. pavlovskyi interspecies hybrids (19.6%), Dermacentor reticulatus (12.8%), and single Dermacentor marginatus and Dermacentor nuttalli/Dermacentor silvarum. Human DNA was determined in ticks, first demonstrating that all Ixodes spp., including hybrids, can effectively feed on humans. The DNA of Borrelia spp., Rickettsia spp., and Anaplasmataceae bacteria was detected in different tick species. Borrelia garinii prevailed in Ixodes species, being found in 8.8% of ticks, whereas B. afzelii and B. bavariensis were found in single ticks. Borrelia miyamotoi was revealed in 3.7% of ticks. “Candidatus Rickettsia tarasevichiae” and R. raoultii were identified mainly in I. persulcatus and D. reticulatus (44.8% and 26.3%, respectively), while Rickettsia helvetica was found only in 2.2% I. pavlovskyi. The prevalence of Anaplasma phagocytophilum, Ehrlichia muris, and Neoehrlichia mikurensis did not exceed 2%. The obtained results indicate a high risk for humans to be infected with agents of Lyme borreliosis, primarily B. garinii. Full article

Ticks are the second most significant vector of pathogens worldwide. Ixodes persulcatus is one of the dominant tick species in Inner Mongolia that can carry and transmit various pathogenic microorganisms. However, only one specific pathogen has been detected in a particular developmental stage of I. persulcatus, moreover metagenomic analysis has been conducted only in the adult tick stage. In this study, we used I. persulcatus at different developmental stages (first-generation female adult ticks, eggs, larval ticks, engorged larval ticks, nymphal ticks, engorged nymphal ticks, and second-generation adult ticks) from Inner Mongolia as materials for nucleic acid extraction. Subsequently, we constructed Illumina PE250 and Illumina PE150 libraries and sequenced them on the Illumina NovaSeq 6000 platform. Finally, we used molecular biology software and sequence analysis platform to analyze microbial community structures. Illumina PE250 sequencing revealed that the seven developmental stages of I. persulcatus were annotated to 21 phyla, 43 classes, 104 orders, 188 families, 391 genera, and 556 species of bacteria. Among them, 4 phyla and 14 genera were present at all developmental stages, with Proteobacteria being the dominant phylum and Rickettsia spp. being the dominant genus. In addition, Rickettsia had the highest relative abundance in the seven developmental stages. All developmental stages were annotated to a certain abundance of Brucella spp. Illumina PE150 sequencing revealed that the three samples (X-I-YDCP: first-generation adult ticks; X-I-MIX: mixed samples of eggs, larval ticks, and nymphal ticks; X-I-EDCP: second-generation adult ticks) of I. persulcatus were annotated to six orders, 28 families, 72 genera, and 158 species of viruses, of which 46 genera and 80 species were found in all three sample species. To the best of our knowledge, this is the first study that comprehensively analyzed the microbial community composition of I. persulcatus at different developmental stages. Based on the study outcomes, certain abundance of Rickettsia japonica, bovine viral diarrhea virus, and African swine fever virus were annotated to I. persulcatus. Full article

Tick-borne encephalitis virus (TBEV) causes neurological disease in humans, with varied clinical severity influenced by the viral subtype. TBEV is endemic to Mongolia, where both Siberian and Far-Eastern subtypes are present. Ixodes persulcatus is considered the main vector of TBEV in Mongolia; although, the virus has also been detected in Dermacentor species. To further characterize the disease ecology of TBEV within the endemic Selenge province of Mongolia, 1300 Ixodes persulcatus ticks were collected in May 2020 from regions outside Ulaanbaatar. Pooled tick samples (n = 20–50) were homogenized and the supernatant was inoculated into Vero cells. Two RT-PCR assays were conducted on the cell supernatant following an observed cytopathic effect: one for TBEV detection and the second for viral subtyping. Lysed cell cultures were processed for next-generation sequencing (NGS) using Illumina technology. TBEV was detected in 10.7% of tick pools (3/28), and isolates were identified as the Siberian subtype. Phylogenetic analysis showed PQ479142 clustering within the Siberian subtype and sharing high similarity with published isolates collected in Selenge in 2012 from Ixodes persulcatus. Subtype analysis of circulating TBEV isolates and sequencing analytics to track viral evolution in ticks are vital to continued understanding of the risk to local populations. Full article

Lyme borreliosis (LB) is more common in the Northern Hemisphere. It is endemic mainly in North America, where the vectors are Ixodes scapularis and Ixodes pacificus, and in Eurasia, where the vectors are Ixodes ricinus and Ixodes persulcatus. Both tick-borne diseases and LB are influenced by climate change. Africa and South America are crossed by the equator and are situated in both the Northern and Southern Hemispheres. In Africa, the LB is present on the Mediterranean and the Indian Ocean coasts. Borrelia lusitaniae is prevalent in countries bordering the Mediterranean Sea, such as Tunisia, Morocco, Algeria, and Egypt. Ticks were detected in the Ixodes Ricinus, which are carried by migratory birds and the Ixodes inopinatus and captured by the Psammodromus algirus lizards. The Borreliae Lyme Group (LG) and, in particular, Borrelia garinii, have been reported in countries bordering the Indian Ocean, such as Kenya, Tanzania, and Mozambique, transported by migratory birds from North African countries, where the vector was identified as Hyalomma rufipes ticks. This review aims to document the presence of Borreliae LG and LB in Africa. Full article

A novel tick-borne orthonairovirus called the Yezo virus (YEZV), primarily transmitted by the Ixodes persulcatus tick, has been recently discovered and poses significant threats to human health. The YEZV is considered endemic in Japan and China. Clinical symptoms associated with this virus include thrombocytopenia, fatigue, headache, leukopenia, fever, depression, and neurological complications ranging from mild febrile illness to severe outcomes like meningitis and encephalitis. At present, there is no treatment or vaccine readily accessible for this pathogenic virus. Therefore, this research employed an immunoinformatics approach to pinpoint potential vaccine targets within the YEZV through an extensive examination of its structural proteins. Three structural proteins were chosen using specific criteria to pinpoint T-cell and B-cell epitopes, which were subsequently validated through interferon-gamma induction. Six overlapping epitopes for cytotoxic T-lymphocytes (CTL), helper T-lymphocytes (HTL), and linear B-lymphocytes (LBL) were selected to construct a multi-epitope vaccine, achieving a 92.29% coverage of the global population. These epitopes were then fused with the 50S ribosomal protein L7/L12 adjuvant to improve protection against international strains. The three-dimensional structure of the designed vaccine construct underwent an extensive evaluation through structural analysis. Following molecular docking studies, the YEZV vaccine construct emerged as a candidate for further investigation, showing the lowest binding energy (−78.7 kcal/mol) along with favorable physiochemical and immunological properties. Immune simulation and molecular dynamics studies demonstrated its stability and potential to induce a strong immune response within the host cells. This comprehensive analysis indicates that the designed vaccine construct could offer protection against the YEZV. It is crucial to conduct additional in vitro and in vivo experiments to verify its safety and effectiveness. Full article

Background: California hare coltivirus (CHCV) was isolated in California in 1976 from a hare. Despite its long history, it remained unclear whether CHCV was exclusively distributed in California with limited host ranges. Main body: By next-generation sequencing (NGS), we obtained a complete sequence of CHCV from Ixodes persulcatus collected in 2019 in northeast China. An expanded epidemiological investigation was subsequently performed on ticks belonging to four species (Ix. persulcatus, Haemaphysalis concinna, Devmacentor silvarum, Haemaphysalis longicornis) collected in northeastern China by applying CHCV-specific RT-PCR and sequencing. CHCV RNA-positive results were found in 1.56% of the tick samples. Positive ticks were obtained in three of four sampled locations, with the highest rate observed in Inner Mongolia (2.69%), followed by Heilongjiang (1.94%) and Jilin provinces (0.55%). All positive results were derived from Ix. persulcatus ticks (2.33%), while no positive detection was found in the other tick species, even at the same location. Sequence analysis revealed that the current CHCV showed a high genetic identity (>80% amino acid identity) with the previously reported CHCV in all segments except segment seven (64.59% amino acid identity). Phylogenetic analysis based on RNA-dependent RNA polymerase (RdRp) amino acid sequences demonstrated that both the current and previously reported CHCV strains were grouped phylogenetically into the genus Coltivirus. Both CHCV strains formed a distinct clade, clustering with three human pathogenic coltiviruses (Colorado tick fever virus, Salmon River virus, and Eyach virus), and were distant from the other coltiviruses. Conclusions: We report the identification and characterization of CHCV for the first time in Ix. persulcatus ticks, expanding the currently known geographic scope, host, and genetic heterogeneity in CHCV. Full article

Antimicrobial peptides (AMPs) are present in a wide range of plants, animals, and microorganisms. Since AMPs are characterized by their effectiveness against emergent antibiotic-resistant bacteria, they are attracting attention as next-generation antimicrobial compounds that could solve the problem of drug-resistant bacteria. Persulcatusin (IP), an antibacterial peptide derived from the hard tick Ixodes persulcatus, shows high antibacterial activity against various Gram- positive bacteria as well as multidrug-resistant bacteria. However, reports on the antibacterial action and resistance mechanisms of IP are scarce. In this study, we spontaneously generated mutants showing increased a minimum inhibitory concentration (MIC) of IP and analyzed their cross-resistance to other AMPs and antibiotics. We also used fluorescent probes to investigate the target of IP activity by evaluating IP-induced damage to the bacterial cytoplasmic membrane. Our findings suggest that the antimicrobial activity of IP on bacterial cytoplasmic membranes occurs via a mechanism of action different from that of known AMPs. Furthermore, we screened for mutants with high susceptibility to IP using a transposon mutant library and identified 16 genes involved in IP resistance. Our results indicate that IP, like other AMPs, depolarizes the bacterial cytoplasmic membrane, but it may also alter membrane structure and inhibit cell-wall synthesis. Full article