Ixodes Persulcatus Research Articles

Study of Viral Coinfection of the Ixodes persulcatus Ticks Feeding on Humans in a Natural Focus of the South of the Far East.

The phenomenon of pathogen co-infection detected in a half-fed Ixodes persulcatus tick taken from a human in the south of the Far East was studied. Research was carried out on PEK, Vero, and Vero-E6 cell lines, outbred mice, and chicken embryos using ELISA, PCR, IMFA, plaque formation, and electron microscopy. The tick contained an antigen and a genetic marker of the tick-borne encephalitis virus (TBEV). The patient had post-vaccination antibodies in a titer of 1:200, as a result of which, obviously, an antibody-dependent elimination of TBEV occurred. The tick-borne co-isolate also contained an unknown pathogen (Kiparis-144 virus), which, in our opinion, was a trigger for the activation of chronic infection in suckling white mice. In the laboratory co-isolate, ectromelia virus was present, as evidenced by paw edema during the intradermal infection of mice, characteristic rashes on the chorioallantoic envelope of chicken embryos, and typical plaques on Vero-E6. The Kiparis-144 virus was not pathogenic for white mice and chicken embryos, but it successfully multiplied in the PEK, Vero, and Vero-E6 lines. Viral co-infection was confirmed by electron microscopy. Passaging on mice contributed to an increase in the virulence of the co-isolate, whose titer increased by 10,000 times by the fifth passage, which poses an epidemiological danger.

Applying next generation sequencing to detect tick-pathogens in Dermacentor nuttalli, Ixodes persulcatus, and Hyalomma asiaticum collected from Mongolia

Ticks and tick-borne diseases represent major threats to the public health of the Mongolian population, of which an estimated 26% live a traditional nomadic pastoralist lifestyle that puts them at increased risk for exposure. Ticks were collected by dragging and removal from livestock in Khentii, Selenge, Tuv, and Umnugovi aimags (provinces) during March-May 2020. Using next-generation sequencing (NGS) with confirmatory PCR and DNA sequencing, we sought to characterize the microbial species present in Dermacentor nuttalli (n = 98), Hyalomma asiaticum (n = 38), and Ixodes persulcatus (n = 72) tick pools. Rickettsia spp. were detected in 90.4% of tick pools, with Khentii, Selenge, and Tuv tick pools all having 100% pool positivity. Coxiella spp. were detected at an overall pool positivity rate of 60%, while Francisella spp. were detected in 20% of pools and Borrelia spp. detected in 13% of pools. Additional confirmatory testing for Rickettsia-positive pools demonstrated Rickettsia raoultii (n = 105), Candidatus Rickettsia tarasevichiae (n = 65) and R. slovaca/R. sibirica (n = 2), as well as the first report of Candidatus Rickettsia jingxinensis (n = 1) in Mongolia. For Coxiella spp. reads, most samples were identified as a Coxiella endosymbiont (n = 117), although Coxiella burnetii was detected in eight pools collected in Umnugovi. Borrelia species that were identified include Borrelia burgdorferi sensu lato (n = 3), B. garinii (n = 2), B. miyamotoi (n = 16), and B. afzelii (n = 3). All Francisella spp. reads were identified as Francisella endosymbiont species. Our findings emphasize the utility of NGS to provide baseline data across multiple tick-borne pathogen groups, which in turn can be used to inform health policy, determine regions for expanded surveillance, and guide risk mitigation strategies.

Перспективы применения энтомопатогенных грибов для сокращения численности иксодовых клещей (Ixodida: Ixodidae)

Data from 47 sources of scientific literature on the prospects for the use of biopesticides based on Metarhizium anisopliae, Beauveria bassiana and others species of entomopathogenic fungi to reduce the number of ixodid ticks Ixodes ricinus, I. scapularis, Dermacentor variabilis, D. reticulatus and Rhipicephalus sanguineus are presented. A review was made of data on the effectiveness of mycoacaricides used abroad against ixodid ticks, leading to a reduction in the number of ticks by 87–96?% after 3 weeks and by 53–74?% after 5 weeks after treatment. The use of the M. anisopliae F52 strain can become another tool for an integrated approach to the control of ticks in the residential landscape. An integrated method for controlling the number of ixodid ticks is presented, including the use of the entomopathogenic fungus M. anisopliae, the treatment of areas with acaricides, and the feeding of systemic insecticidal baits based on fipronil to rodents, which eliminate the larvae and nymphs of the tick when fed on a host. The experience of limited trials of preparative forms of mycoinsecticides that did not show high efficiency against the taiga tick Ixodes persulcatus in our country is described. Keywords: ixodid ticks, entomopathogenic fungi, Metarhizium, Beauveria, biopesticides.

TBE in China

The first TBE patients in China were reported in 1943, and the TBEV was isolated from the brain tissues of 2 patients in 1944 by Japanese military scientists, and from patients and ticks (Ixodes persulcatus and Haemaphysalis concinna) in 1952 by Chinese researchers. The Far Eastern viral subtype (TBEV-FE) is the endemic subtype that has been isolated from all 3 known natural foci (northeastern China, western China, and southwestern China). Recently a new “Himalayan subtype” of the TBEV (TBEV-HIM) was isolated from wild rodent Marmoata himalayana in the Qinghai-Tibet Plateau. The main vector of the TBEV in China is I. persulcatus. One recent report suggests that the TBEV-SIB is prevalent in the Uygur region (North West China) but epidemiological modelling indicates that the TBEV may occur even widely all over China (Figure 3). Likely, the disease is often missed by clinicians due to a lack of the availability of specific diagnostic assays.

TBE in Russia

TBE was first revealed in the Far-East Taiga Forest in the Soviet Union in springs and summers between 1933–1935 and it was further investigated as of 1937 at a large multidisciplinary expedition led by Professor Lev Zilber, the Head of the Moscow Medical Virology laboratory. The expedition demonstrated that the disease develops in humans after a tick bite, and the “Taiga Tick” Ixodes persulcatus was established as the virus carrier. The viral etiology of the disease was confirmed and the first strain of TBE virus (TBEV) was isolated. The clinical disease spectrum in humans and the respective pathology were described and the effectiveness of immunoglobulin-therapy was shown. Based on morphological studies since 1937 TBE was assigned to the group of neuro-infections as an independent nosological entity.

TBE in Mongolia

In Mongolia, TBEV was first isolated (Kraminskii V.A) from marmot liver in Dornod province in 1979, while the Ixodes persulcatus tick was identified in 1987 by M. Dash. I. persulcatus is a taiga tick distributed in coniferous forests consisting mostly of pines, spruces and larches. Much of northern Mongolia is covered in coniferous forest, and the southern edge of the Siberian taiga is located along the Khangai and Khentii mountains.

Candidatus Lariskella arthopodarum endosymbiont is the main factor differentiating the microbiome communities of female and male Borrelia-positive Ixodes persulcatus ticks

Ixodes persulcatus, a hard-bodied tick species primarily found in Asia and Eastern Europe, is a vector of pathogens to human and livestock hosts. Little research has been done on the microbiome of this species, especially using individual non-pooled samples and comparing different geographical locations. Here, we use 16S rRNA amplicon sequencing to determine the individual microbial composition of 85 Borrelia-positive I. persulcatus from the Japanese islands of Hokkaido and Honshu. The resulting data (164 unique OTUs) were further analyzed to compare the makeup and diversity of the microbiome by sex and location, as well as to determine the presence of human pathogens. We found that, while location had little influence, the diversity of I. persulcatus microbiome was predominantly dependent on sex. Males were seen to have higher microbiome diversity than females, likely due to the high presence of endosymbiotic Candidatus Lariskella arthropodarum within the female microbial communities. Furthermore, high read counts for five genera containing potentially human pathogenic species were detected among both male and female microbiomes: Ehrlichia, Borrelia, Rickettsia, Candidatus Neoehrlichia and Burkholderia and co-infections between different pathogens were frequent. We conclude that the microbiome of I. persulcatus depends mainly on sex and not geographical location and that the major difference between sexes is due to the high abundance of Ca. L. arthropodarum in females. We also stress the importance of this tick species as a vector of potential human pathogens frequently found in co-infections.

Novel Genetic Lineages of Rickettsia helvetica Associated with Ixodes apronophorus and Ixodes trianguliceps Ticks.

Ixodes apronophorus is an insufficiently studied nidicolous tick species. For the first time, the prevalence and genetic diversity of Rickettsia spp. in Ixodes apronophorus, Ixodes persulcatus, and Ixodes trianguliceps ticks from their sympatric habitats in Western Siberia were investigated. Rickettsia helvetica was first identified in I. apronophorus with a prevalence exceeding 60%. "Candidatus Rickettsia tarasevichiae" dominated in I. persulcatus, whereas I. trianguliceps were infected with "Candidatus Rickettsia uralica", R. helvetica, and "Ca. R. tarasevichiae". For larvae collected from small mammals, a strong association was observed between tick species and rickettsiae species/sequence variants, indicating that co-feeding transmission in studied habitats is absent or its impact is insignificant. Phylogenetic analysis of all available R. helvetica sequences demonstrated the presence of four distinct genetic lineages. Most sequences from I. apronophorus belong to the unique lineage III, and single sequences cluster into the lineage I alongside sequences from European I. ricinus and Siberian I. persulcatus. Rickettsia helvetica sequences from I. trianguliceps, along with sequences from I. persulcatus from northwestern Russia, form lineage II. Other known R. helvetica sequences from I. persulcatus from the Far East group into the lineage IV. The obtained results demonstrated the high genetic variability of R. helvetica.

Puutiaisten (Ixodes ricinus ja Ixodes persulcatus) levinneisyyteen ja runsauteen vaikuttavat tekijät Suomessa

Hard ticks (Acari: Ixodidae) and tick-borne diseases are considered as a threat in several parts of Europe. In Finland, both Ixodes ricinus and Ixodes persulcatus have shifted northwards in recent decades, and they have become more abundant at the same time. This is thought to be due to global climate change and its effect directly on ticks or indirectly on their host animals. This review focuses on the factors that affect both tick activity and survival, and the factors that influence the life cycle of ticks. Both presence and availability of host animals and microclimatic conditions are factors that affect tick occurrence in any given area. For example, high temperatures or low humidity force the species to seek shelter from cooler and more humid microhabitats, as ticks are sensitive to desiccation. However, tick distribution is associated with a complex combination of environmental and climatic factors.

Human Borrelia miyamotoi Infection in North America.

Borrelia miyamotoi is an emerging pathogen that causes a febrile illness and is transmitted by the same hard-bodied (ixodid) ticks that transmit several other pathogens, including Borrelia species that cause Lyme disease. B. miyamotoi was discovered in 1994 in Ixodes persulcatus ticks in Japan. It was first reported in humans in 2011 in Russia. It has subsequently been reported in North America, Europe, and Asia. B. miyamotoi infection is widespread in Ixodes ticks in the northeastern, northern Midwestern, and far western United States and in Canada. In endemic areas, human B. miyamotoi seroprevalence averages from 1 to 3% of the population, compared with 15 to 20% for B. burgdorferi. The most common clinical manifestations of B. miyamotoi infection are fever, fatigue, headache, chills, myalgia, arthralgia, and nausea. Complications include relapsing fever and rarely, meningoencephalitis. Because clinical manifestations are nonspecific, diagnosis requires laboratory confirmation by PCR or blood smear examination. Antibiotics are effective in clearing infection and are the same as those used for Lyme disease, including doxycycline, tetracycline, erythromycin, penicillin, and ceftriaxone. Preventive measures include avoiding areas where B. miyamotoi-infected ticks are found, landscape management, and personal protective strategies such as protective clothing, use of acaricides, and tick checks with rapid removal of embedded ticks.

Molecular genetic surveillance based on the identification of borrelia in ixodid ticks

Aim. To improve emergency diagnostic measures and preventive antimicrobial therapy in patients with ixodid tick bites using molecular genetic techniques for identification of Вorrelia spp.Materials and Methods. Borrelia strains were isolated by inoculation of tick suspension on the BSK-H medium. Molecular genetic screening of Вorrelia spp. was performed by real-time polymerase chain reaction (PCR) and sequencing. In total, we examined 4,276 patients including 272 bitten by Ixodes persulcatus and 3,108 bitten by Dermacentor reticulatus. In addition, we investigated blood of 896 patients for molecular signatures of Borrelia spp.Results. Borrelia spp. was detected by PCR in 30.1% of Ixodes persulcatus and 3.2% of Dermacentor reticulatus suspensions. However, detection of Borrelia spp. in blood was rare, reaching only 1.1% in those bitten by Ixodes persulcatus and two cases of Dermacentor reticulatus bites. Genotyping of Borrelia spp. in 8 tick suspensions showed the presence of Borrelia garinii in 1 sample, Borrelia afzelii in 5 samples, Borrelia bavariensis in 1 sample, and Borrelia miyamotoi in 1 sample.Conclusion. Molecular genetic screening showed the significant proportion of Ixodid ticks bearing Borrelia spp., indicating the need in specific antimicrobial therapy.

Genotyping of rickettsias circulating in the territories of the Altai Republic and Khabarovsk krai

The aim of the study was to verificate of the causative agent of Siberian tick-borne typhus (STT) upon ixodic tick mixed infection on the territory of the Altai Republic and Khabarovsk Krai using an integrated molecular biological approach. Materials and methods. The material for the study was presented as 304 imago of ixodic mites of six species. The ticks were collected on the territory of the Altai Republic and the Khabarovsk Krai in the years 20142022. Rickettsia DNA was identified by two-round PCR using genus- and species-specific primers for gltA and ompA genes, followed by sequencing and using PCR reagent kits RealBest DNA R. sibirica/R. heilongjiangensis (Vector-Best, Novosibirsk). Results. The detection of rickettsia in ticks in the Altai Republic was 82.6% (CI: 69.196.1), in the Khabarovsk Krai 53.1% (CI: 44.961.3). The species composition of rickettsias in various species of ixodic mites in these territories, endemic to Siberian tick typhus, is characterized by the presence of mixed forms. Rickettsia sibirica and R. raoultii were found in ticks Dermacentor nuttalli, Haemaphysalis concinna, D. silvarum. Only Candidatus R. tarasevichiae were detected in Ixodes persulcatus, I. pavlovsky mites and I. pavlovsky/persulcatus hybrids. The DNA of R. heilongjiangensis was found in H. mites. concinna in the Khabarovsk Krai. The DNA of Candidatus R. tarasevichiae is also present in the ticks of D. nuttalli and H. concinna from the Altai Republic. The DNA of the classic pathogenic species, R. sibirica, was detected in ticks D. nuttalli and H. concinna in the Altai Republic, ticks D. silvarum, H. concinna and H. japonica douglasi in the Khabarovsk Krai. In addition, in the Khabarovsk Krai, the DNA of R. heilongjiangensis was detected in H. concinna ticks, and a DNA fragment common to R. sibirica subsp. mongolitimonae and R. conorii was detected in H. japonica douglasi ticks, which requires further study. Candidatus R. tarasevichiae is common in Ixodes mites (I. persulcatus, I. pavlovsky and their hybrids), in the Altai Republic in D. nuttalli and H. concinna. R mites. raoultii was detected in ticks of the genus Dermacentor D. nuttalli in the Altai Republic and D. silvarum in the Khabarovsk Krai. Conclusions. During molecular biological monitoring of rickettsias in endemic territories, the detection of R. raoultii masks the presence of the etiological agent of STT R. sibirica. This phenomenon makes it possible to explain the high incidence of STT in the studied territories, with the rare detectability of R. sibirica DNA during molecular biological screening in ixodic mites.

Human pathogens in ticks removed from humans in Hebei, China

Ticks are the hosts or vectors of many human pathogens, including viruses, bacteria and protozoa, and can transmit these causative agents to humans when feeding on human bodies. In this study, 26 ticks removed from humans in Hebei, China were tested for the presence of human-pathogenic microorganisms by Polymerase Chain Reaction (PCR) or Reversed Transcript PCR (RT-PCR). As a result, 11 ticks tested positive for at least one human pathogen. Specifically, four validated human pathogens, including Rickettsia raoultii, Candidatus Rickettsia tarasevichiae, Babesia venatorum, and Borrelia garinii, as well as Anaplasma ovis with zoonotic potential, were identified in Ixodes persulcatus, Dermacentor silvarum and Haemaphysalis concinna. Importantly, this is the first report of Anaplasma and Babesia species pathogenic to humans in Hebei province. Moreover, the co-infections, including double infection and quadruple infection were observed. In addition, Candidatus R. principis with unknown pathogenicity was identified in one tick, which may be the same species as Candidatus R. hongyuanensis based on the nucleotide identity and phylogenetic analysis. Concluding, four validated tick-borne pathogens and one with zoonotic potential were identified in ticks parasitizing humans, suggesting the potential high public health risk in the local human population.

Molecular and Serological Detection of Anaplasma phagocytophilum in Dogs from Germany (2008–2020)

Anaplasma phagocytophilum is an obligate intracellular bacterium that causes granulocytic anaplasmosis in domestic animals, wildlife, and humans and is primarily transmitted by ticks of the Ixodes persulcatus complex. This retrospective study aims to determine the percentages of dogs that tested positive for A. phagocytophilum in Germany. It included the results of direct (polymerase chain reaction [PCR]) and indirect (immunofluorescence antibody test [IFAT], antibody-enzyme-linked immunosorbent assay [ELISA]) detection methods performed in the laboratory LABOKLIN on canine samples provided by German veterinarians from 2008 to 2020. Out of a total of 27,368 dogs tested by PCR, 1332 (4.9%) tested positive, while 24,720 (27.4%) of the 90,376 dogs tested by IFAT/ELISA had positive serology. High rates of positive PCR results were observed in months with known peaks in vector activity, showing that the dynamics of A. phagocytophilum infections in dogs in Germany are consistent with vector activity. In dogs with a positive PCR result, peaks in serology could be observed four weeks after initial testing. Male and senior dogs had higher rates of positive serology. A possible impact of environmental factors such as changes in climate should be investigated further. Overall, the upward trend in positive test results over the years indicates that canine granulocytic anaplasmosis will continue to become increasingly important for veterinary medicine.

Ticks and tick-borne infections in Karelia: analysis of ticks brought by citizens to be tested at the Center for hygiene and epidemiology in the Republic of Karelia (Petrozavodsk)

In 2019 and 2021, species composition of the ticks provided by citizens was studied at the Center for Hygiene and Epidemiology in the Republic of Karelia (based in Petrozavodsk). As a result, about 2 500 tick specimens were identified as belonging to the following species of the family Ixodidae: Ixodes persulcatus Schulze, 1930, I. ricinus (Linnaeus, 1758), Dermacentor marginatu s (Sulzer, 1776), D. reticulatus Fabricius, 1794, Hyalomma marginatum Koch, 1844, and Rhipicephalus sanguineus (Latreille, 1806). For 2% of the ticks, including all species not typically dwelling in Karelia, the attacks occurred outside of Karelia. For districts of Karelia, two species were identified: I. persulca tus (approx. 95% of all ticks delivered) and I. ricinus . Prevalence of pathogens in ticks as analyzed with the use of a commercial kit «AmpliSense® TBEV, B . burgdorferi sl, A . phagocytphillum , E . chaffeensis / E . muris - FL» based on real-time PCR. Prevalence of the tick-borne encephalitis virus in I. persulcatus was 1.5%. In I. ricinus ticks the virus was absent. The prevalence of the Borrelia burgdorferi s. l. and Ehrlichia spp. complex constituted 32.5 and 3.3% in I. persulcatus versus 16.3 and 0.8% in I. ricinus , respectively. A single occurrence of Anaplasma phagocytophillum was found in I. persulcatus (prevalence - 0.04%). The main determinant of the epidemiological situation in Karelia is the wide distribution and high abundance of I. persulcatus .

Geographical distribution of Ixodes persulcatus and associated pathogens: Analysis of integrated data from a China field survey and global published data

The increasing incidence and range expansion of tick-borne diseases have caused global threats to human and animal health under the background of climate and socioeconomic changes. As an efficient vector in transmission of tick-borne diseases, a growing burden caused by Ixodes persulcatus and associated pathogens could not be underestimated. This study summarized the distribution, hosts, and pathogens of I. persulcatus, and predicted the suitable habitats of this tick species worldwide. An integrated database involving a field survey, reference book, literature review, and related website was constructed. Location records of I. persulcatus and associated pathogens were incorporated into distribution maps using ArcGIS software. Positive rates for I. persulcatus-associated agents were estimated by meta-analysis. The global distribution of the tick species was predicted using Maxent model. I. persulcatus was distributed in 14 countries across the Eurasian continent, involving Russia, China, Japan, and several Baltic Sea states, which ranged between 21°N to 66°N. The tick species fed on 46 species of hosts, and 51 tick-borne agents could be harbored by I. persulcatus. The predictive model showed that I. persulcatus could be predominantly distributed in northern Europe, western Russia, and northern China. Our study fully clarified the potential public health risks posed by I. persulcatus and I. persulcatus-borne pathogens. Surveillance and control measures of tick-borne diseases should be enhanced to promote the health of humans, animals, and ecosystems.

EFFECTIVE DIAGNOSTIC TECHNIQUES IN BORRELIA BURGDORFERI INFESTATION IN DOGS

Borreliosis or Lyme disease is a disease transmitted by ixodidae ticks during feeding on blood (Ixodes pacificus and Ixodes scapularis in the USA, Ixodes persulcatus in Asia, Ixodes ricinus in Europe) and is widespread in the entire northern hemisphere. In Romania, the geographic distribution and prevalence of Borrelia burgdorferi sensu lato was 1.4% in 41 counties, with a prevalence between 0.75–18.8%. B. burgdorferi sensu lato. had a prevalence of 3.8%, being found inside ticks in 55 of 183 localities. Successful treatment and full recovery can only be achieved through early diagnosis. The clinical and serologic diagnosis of Lyme disease is particularly difficult because of the phenotypic heterogeneity within and among spirochete species. A case study is presented in this paper: an eight-year-old male Yorkshire terrier dog, which was diagnosed positive for Lyme disease, based on a test which uses a peptide called C6 and which comes from the VlsE protein of B. burgdorferi, used to detect antibodies in dogs. The results demonstrate the reliability of the commercial SNAP 4Dx Plus Test for B. burgdorferi, which uses C6 to differentiate antibodies produced by natural infection from antibodies formed after vaccination. In addition, using real-time PCR, the diagnosis was negative, confirming the results from the literature, according to which the PCR technique is only recommended for research, the positivity percentage being low, especially when the sample is blood (0.1%). We conclude that the tests for the detection of antibodies specific to Lyme disease are recommended and useful.

Evaluation of the efficacy of permethrin- and cypermethrin-based textile against taiga tick, Ixodes persulcatus

A comparison of the efficacy of permethrin- and cypermethrin-based textile against taiga ticks (Ixodes persulcatus) was carried out in a tick-borne viral encephalitis hotspot in the Irkutsk Region (Russia) using model samples of impregnated textiles. We demonstrated that permethrin- and cypermethrin-treated model samples have similar protective parameters in terms of maximum height reached by the tick when climbing up the treated textile (20.9-38.7cm for cypermethrin, 27.6-39.3cm for permethrin, depending on concentration) and knockdown time (i.e., the time until a female tick falls off the treated textile; 3.52-4.31 min for cypermethrin, 5.02-8.25 min for permethrin, depending on concentration). In contrast, when evaluating the 'biting speed' index (which is the ratio of the average attaching time of ticks contacting untreated textiles and ticks contacting treated textiles), it has been shown that permethrin-treated textiles accelerate biting. So, using permethrin-treated protective clothing against the taiga tick could be risky because it increases the likelihood of being bitten and thus getting infected. In contrast, cypermethrin-treated textiles appear to block the ability of ticks to attack warm-blooded animals and humans - after contact with cypermethrin-treated textiles none of the ticks attached to a rabbit. So cypermethrin-based textiles could be an alternative to permethrin for tick-bite protection clothing production if there is no toxic effect on humans of textile materials based on it.

Circulation of four species of Anaplasmataceae bacteria in ticks in Harbin, northeastern China

Ticks play an important role in the evolution and transmission of Anaplasmataceae bacteria which are agents of emerging infectious diseases. In this study, a total of 1286 adult ticks belonging to five species were collected from cattle, goats, horses and vegetation in Harbin area, Heilongjiang province, northeastern China. The tick-borne Anaplasmataceae bacteria were identified by amplifying and sequencing the 16S rRNA (rrs) and heat shock protein-60 encoding (groEL) genes. The results showed that Ixodes persulcatus was dominant (38.8%, 499/1283) among the five tick species, and Anaplasmataceae bacteria were detected in all tick species with an overall prevalence of 7.4%. Four species of Anaplasmataceae bacteria (Anaplasma phagocytophilum, Anaplasma ovis, Anaplasma bovis, and “Candidatus Neoehrlichia mikurensis”), which are pathogenic to humans and/or animals, were identified from tick samples by phylogenetic analyzes of the rrs and groEL gene sequences. Interestingly, the cluster 1 strains were first identified in Asian, and a novel cluster was also detected in this study. These data revealed the genetic diversity of Anaplasmataceae bacteria circulating in ticks in Harbin area, highlighting the need to investigate these tick-borne pathogens and their risks to human and animal health.

Hybrids of Ixodes ricinus and Ixodes persulcatus ticks effectively acquire and transmit tick-borne encephalitis virus.

Ixodes rici nus and Ixodes persulcatus ticks are the main vectors of tick-borne encephalitis virus (TBEV), which has three main subtypes connected with certain tick species: the European subtype, associated with I. ricinus, and the Siberian and Far-Eastern subtypes, associated with I. persulcatus. Distribution ranges of these species overlap and form large sympatric areas in the East European Plain and Baltic countries. It has previously been shown that crossing of I. ricinus and I. persulcatus is possible, with the appearance of sterile hybrids. Hybridization of ticks can affect not only the spread of ticks but also the properties of natural foci of arbovirus infections, in particular TBEV. In the present study, we analyzed the effectiveness of virus transmission from infected mice to larvae and nymphs and trans-stadial transmission (from larvae to nymph and adult) in I. ricinus, I. persulcatus, and hybrids. For this purpose, we bred a hybrid generation from the crossing of I. persulcatus females and I. ricinus males, and we used the Siberian and European subtypes of TBEV. We showed that after feeding on infected mice, virus prevalence in engorged ticks decreased over time, and after molting, the opposite was true. In hybrids we observed the highest acquisition effectiveness and RNA copy numbers during Siberian TBEV subtype transmission. The efficiency of trans-stadial transmission of both TBEV subtypes was similar in hybrids and parental species. After the second trans-stadial TBEV transmission, a significant increase in ticks' infection rates was observed only in specific subtype-tick combination. Our data demonstrate the possible features of TBEV circulation in the I. ricinus and I. persulcatus sympatry area.