Search Results (76)

The recent discovery of Orthonairovirus songlingense (SGLV) and Norwavirus beijiense (BJNV) in China has raised significant concern due to their potential to cause severe human disease. However, little is known about the structural features and function of their nucleoproteins, which play a key role in the viral life cycle. By combining small-angle X-ray scattering (SAXS) data and AlphaFold 3 simulations, we reconstructed the BJNV and SGLV nucleoprotein structures for the first time. The SGLV and BJNV nucleoproteins have structures that are broadly similar to those of Orthonairovirus haemorrhagiae (CCHFV) nucleoproteins despite low sequence similarity. Based on structural analysis, several residues located in the positively charged region of BJNV and SGLV nucleoproteins have been indicated to be important for viral RNA binding. A positively charged RNA-binding crevice runs along the interior of the SGLV and BJNV ribonucleoprotein complex (RNP), shielding the viral RNA. Despite the high structural similarity between SGLV and BJNV nucleoprotein monomers, their RNPs adopt distinct conformations. These findings provide important insights into the molecular mechanisms of viral genome packaging and replication in these emerging pathogens. Also, our work demonstrates that experimental SAXS data can validate and improve predicted AlphaFold 3 structures to reflect their solution structure and also provides the first low-resolution structures of the BJNV and SGLV nucleoproteins for the future development of POC tests, vaccines, and antiviral drugs. Full article

Kyasanur Forest Disease (KFD), first reported in 1957 in the Shimoga district of Karnataka, India, has spread significantly over the past two decades, reaching both northern and southern states, with reports of monkey deaths. Haemaphysalis spp. ticks are the primary vectors, transmitting the disease to monkeys, humans, and other mammals. This study aimed to assess the prevalence, mean abundance, and mean intensity of Ixodidae ticks, including the KFD vector, in domestic animals across selected localities of the Western Ghats. A total of 2877 domestic animals were surveyed, revealing an overall tick prevalence of 44.91% (CI: 43.10–46.73), with sheep showing the highest prevalence at 47.92% (CI: 40.96–54.95). The most abundant tick species was Rhipicephalus (Boophilus) microplus, with a mean of 2.53 ± 0.66 ticks per host, which also represented the most proportionally dominant species, accounting for 39.63% of the total ticks collected. The highest mean intensity was recorded for Haemaphysalis intermedia (7.35 ± 2.03 ticks per infested animal). Regionally, Rh. (Bo.) microplus was found in 96.15% of buffaloes examined in Tamil Nadu, Haemaphysalis bispinosa in 85.19% of cattle in Maharashtra, and in 98.46% of goats in Goa. Ha. intermedia was common in 99.11% of sheep examined in Karnataka, while Ha. bispinosa was observed in 90.82% of goats in Kerala. The proportional representation of the KFD vector Haemaphysalis spinigera was 0.97%, with a mean intensity of 2.34 ± 0.04 ticks per infested animal and an overall mean abundance of 0.06 ± 0.01 ticks per host. Adult Ha. spinigera were recorded from cattle, buffaloes, sheep, goats, and dogs; however, no nymphs were detected. This study also reports the first documented occurrence of Ixodes ceylonensis in domestic animals. These findings suggest a notable presence of tick infestations in the region and emphasize the importance of continued surveillance and targeted control measures to better understand and manage potential KFD transmission risks in the Western Ghats. Full article

Neoehrlichia mikurensis and Anaplasma phagocytophilum, both members of the Anaplasmataceae family, are pathogens that can cause diseases in animals and humans. Ixodid ticks are the primary vectors for both species. While urban green spaces offer various ecological and social benefits, there is increasing evidence suggesting potential public health risks, particularly increased exposure to vector-borne diseases. The aim of the present study was to assess the prevalence and co-occurrence of A. phagocytophilum and N. mikurensis in ticks from urban environments in Lithuania. A total of 3599 Ixodes ricinus and 29 Dermacentor reticulatus were collected from 31 urban and 21 peri-urban areas. Ticks were examined for pathogens using duplex real-time PCR. Anaplasma phagocytophilum was detected in 4.47% of tested ticks, while N. mikurensis in 6.17%. Co-infection was found in 0.42% of I. ricinus specimens. Phylogenetic analysis of the groEl gene revealed low genetic variability of N. mikurensis and the circulation of two ecotypes (I and II) of A. phagocytophilum. Additionally, Ehrlichia muris was identified in I. ricinus ticks. This study is the first report of N. mikurensis detection in ticks from Lithuania. Our findings highlight the potential risk posed by tick-borne pathogens in urban and peri-urban areas of the country. Full article

Lyme borreliosis (LB), caused by Borrelia burgdorferi sensu lato (s.l.) and babesiosis, caused by Babesia divergens and Babesia venatorum, are both transmitted by the ixodid tick Ixodes ricinus. Although these diseases coexist in Spain and other European regions, no studies have been carried out to assess the impact on the health of patients exposed to both causative pathogens. This retrospective study, conducted in Asturias in northwestern Spain between 2015 and 2017, analyzed the possible complications arising from exposure to these pathogens. To this end, the epidemiological, clinical and analytical features of two groups of a cohort of 120 LB patients exposed to one or two of the pathogens were compared. The cohort comprised 73 patients who had only been infected with Bo. burgdorferi s.l. (Bb group) and 47 patients who were seropositive for Ba. divergens/venatorum in addition to being infected with Bo. burgdorferi s.l. (BbBdv group). The results showed that LB patients who had also been exposed to infection with Babesia spp. (BbBdv group) had significantly more cardiorespiratory symptoms, in particular dyspnea and first- and second-degree atrioventricular (AV) blocks, compared to those who had been infected with Bo. burgdorferi s.l. alone (Bb group). No relevant differences in other symptoms, epidemiological factors or analytical tests were observed between the two groups. Full article

Ticks are key vectors of zoonotic pathogens, and their expanding distribution in Europe heightens public health concerns. In Bosnia and Herzegovina, while tick distribution is well documented, molecular data on tick-borne pathogens remain limited. This study aimed to illustrate the presence and diversity of these pathogens, focusing on areas with high human activity. Ticks (n = 556) were collected in April 2022 from eight diverse locations, including urban parks, private properties, and rural sites. PCR-based screening was employed to detect Anaplasmataceae, Borrelia, Francisella, Piroplasmida, Rickettsia, and tick-borne encephalitis virus (TBEV), with subsequent sequencing to confirm results. Further characterization of Borrelia burgdorferi sensu lato was achieved via reverse line blotting (RLB) hybridization and sequencing. Ixodes ricinus was the most prevalent species, followed by Dermacentor marginatus and D. reticulatus. Our analysis revealed an overall infection rate of 22.1% in questing ticks, with Rickettsia spp. and Borrelia spp. predominating. Notably, seven Borrelia species were identified in I. ricinus, alongside Anaplasma phagocytophilum, Rickettsia helvetica, and R. monacensis, with co-infections mainly observed in peri-urban areas. This study provides the first molecular evidence of multiple tick-borne pathogens in the region, underscoring the need for further surveillance and risk assessment of tick-borne diseases in the region. 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

Background/Objectives: Amblyomma sculptum is among the most dangerous ticks in South America, as it is the species most associated with humans and is the main vector of Rickettsia rickettsii. In the face of the problems related to tick control based on chemical acaricides, vaccines emerge as a promising method. In previous works, three salivary recombinant proteins (rAs8.9kDa, rAsKunitz, and rAsBasicTail) and one protein based on intestinal immunogenic regions (rAsChimera) were described with 59 to 92% vaccine efficacy against A. sculptum females. Here, we evaluate novel vaccine formulations containing binary or multiple combinations of the antigens rAs8.9kDa, rAsKunitz, rAsBasicTail, and rAsChimera against the three instars of the tick. Methods: A control group of mice was immunized with adjuvant alone (aluminum hydroxide gel) and compared to five groups immunized with formulations containing two, three, or four of the antigens. Results: The formulations were safe, with no significant alterations to host behavior and hematological or biochemical parameters. Immunizations induced a significant increase in the CD19⁺ B lymphocyte percentage in all groups, but no difference was seen for CD8⁺ and CD4⁺ T lymphocytes or CD14⁺ monocytes. The best protection was observed for the formulations containing two antigens, which reached above 98% efficacy, while the groups containing three or four antigens presented 92.7 and 94.4% efficacy, respectively. Conclusions: All antigen combinations were promising as vaccine formulations against A. sculptum. The formulation containing rAs8.9kDa and rAsChimera showed the best efficacy and should be focused on in further experiments. Full article

Currently, a large number of novel tick-borne viruses potentially pathogenic to humans are discovered. Studying many of them by classical methods of virology is difficult due to the absence of live viral particles or a sufficient amount of their genetic material. In this case, the use of modern methods of bioinformatics and synthetic and structural biology can help. Haseki tick virus (HSTV) is a recently discovered tick-borne unclassified ssRNA(+) virus. HSTV-positive patients experienced fever and an elevated temperature. However, at the moment, there is no information on the tertiary structure and functions of its proteins. In this work, we used AlphaFold 3 and other bioinformatic tools for the annotation of HSTV nonstructural proteins, based on the principle that the tertiary structure of a protein is inextricably linked with its molecular function. We were the first to obtain models of tertiary structures and describe the putative functions of HSTV nonstructural proteins (NS3 helicase, NS3 protease, NS5 RNA-dependent RNA-polymerase, and NS5 methyltransferase), which play a key role in viral genome replication. Our results may help in further taxonomic identification of HSTV and the development of direct-acting antiviral drugs, POC tests, and vaccines. Full article

Ticks are a significant threat to livestock globally, with certain species displaying distinct host preferences at various developmental stages. Accurate species-level identification is essential for studying tick populations, implementing control strategies, and understanding disease dynamics. This study evaluated ticks infesting cattle across six provinces in South Africa using morphological and molecular methods. Ticks were preserved, examined morphologically using an Olympus Digital Camera Microscope, and identified using the 16S rRNA gene. The study identified four genera, namely Amblyomma, Hyalomma, Ixodes, and Rhipicephalus, comprising 15 ixodid species. Amblyomma hebraeum was the most prevalent species, with an infestation rate of 54.4%. Molecular analysis revealed genetic relationships among tick species, with genetic distances ranging from 0.00 to 0.13, and phylogenetic analysis clustered species into distinct genera with high bootstrap support. Principal Component Analysis highlighted clear genetic relatedness among species. These findings enhance our understanding of tick diversity, morphology, and distribution in South Africa’s cattle populations, emphasizing their economic significance. The study provides critical baseline data for monitoring and developing effective strategies to manage tick-borne diseases, ensuring improved livestock health and productivity. Full article

Ticks are involved in the transmission a plethora of pathogens. To effectively control ticks and mitigate the risks associated with tick-borne diseases, it is important to implement tick control measures. These may include the use of acaricides as well as the development and implementation of an alternative, environmentally friendly tick management program that include practices such as habitat modification or establishing biological control. Ixodiphagus hookeri Howard is a tick-specific parasitoid wasp that predates on several species of ixodid ticks and could contribute to the control of the tick population. This work aimed to detect the presence of parasitoid wasps in ticks (Ixodidae) using genetic approaches. Several tick species of the genera Ixodes, Haemaphysalis, and Dermacentor, with a sympatric occurrence in the Slovak Karst National Park in southeastern Slovakia, were screened for the presence of wasps of the genus Ixodiphagus. The DNA of the parasitoids was detected in four tick species from three genera. This work presents the first molecular detection of parasitoids in two Dermacentor tick species, as well as the first molecular identification of Ixodiphagus wasps in Ixodes ricinus and Haemaphysalis concinna ticks from the Karst area. In the given area, it was observed that I. ricinus and H. concinna ticks are hyper-parasitized by wasps. Moreover, it was observed that wasps here can parasitize several tick species, some of which are of less significance for human and animal health (as they transmit fewer pathogens). Full article

Rickettsial pathogens are among the emerging and re-emerging vector-borne zoonoses of public health importance. Reports indicate human exposure to Rickettsial pathogens in Namibia through serological surveys, but there is a lack of data on infection rates in tick vectors, hindering the assessment of the relative risk to humans. Our study sought to screen Ixodid ticks collected from livestock for the presence of Rickettsia species in order to determine infection rates in ticks and to determine the Rickettsia species circulating in the country. We collected and pooled Hyalomma and Rhipicephalus ticks from two adjacent regions of Namibia (Khomas and Otjozondjupa) and observed an overall minimum Rickettsia infection rate of 8.6% (26/304), with an estimated overall pooled prevalence of 9.94% (95% CI: 6.5–14.3). There were no statistically significant differences in the estimated pooled prevalence between the two regions or tick genera. Based on the nucleotide sequence similarity and phylogenetic analysis of the outer membrane protein A (n = 9) and citrate synthase (n = 12) genes, BLAST analysis revealed similarity between Rickettsia africae (n = 2) and Rickettsia aeschlimannii (n = 11), with sequence identities ranging from 98.46 to 100%. Our initial study in Namibia indicates that both zoonotic R. africae and R. aeschlimannii are in circulation in the country, with R. aeschlimannii being the predominant species. Full article

Tick-borne diseases result from human–ixodid tick encounters, making it crucial to understand host–ixodid tick interactions and host-dependent distribution for epidemiology and prevention. This study examines water deer patterns and ixodid tick interactions in designated croplands of South Korea over two years, finding that the highest deer presence occurred in July and the lowest in May, during crop harvesting. Four tick species were identified, with Haemaphysalis longicornis being predominant (92.2%). Tick life stage analysis revealed peak nymphs and adults in July and larvae in October. Nymph abundance correlated positively with nearby water deer. MaxEnt biodiversity prediction results indicated wider water deer distribution in summer, reflecting their tendency to use multiple croplands. Areas with nymphs and adults aligned with predicted deer presence in summer, while larval areas aligned in autumn. Increased agroforestry expanded water deer habitats, enhancing tick dispersion. Prevention involved minimizing human–deer encounters by strategic land use in tick-prone areas. This comprehensive study provides insights into preventing severe fever with thrombocytopenia syndrome in agricultural workers, emphasizing the need for targeted interventions based on host behavior and tick life stages in different seasons. Full article

Following blood meals or questing bouts, hard ticks (Ixodidae) must locate moist off-host microhabitats as refuge. Soil-dwelling fungi, including entomopathogenic Beauveria bassiana (Bb), thrive in moist microhabitats. Working with six species of ixodid ticks in olfactometer bioassays, we tested the hypothesis that ticks avoid Bb. Contrary to our prediction, nearly all ticks sought, rather than avoided, Bb-inoculated substrates. In further bioassays with female black-legged ticks, Ixodes scapularis, ticks oriented towards both harmful Bb and harmless soil-dwelling fungi, implying that fungi—regardless of their pathogenicity—signal habitat suitability to ticks. Only accessible Bb-inoculated substrate appealed to ticks, indicating that they sense Bb or its metabolites by contact chemoreception. Bb-inoculated substrate required ≥24 h of incubation before it appealed to ticks, suggesting that they respond to Bb metabolites rather than to Bb itself. Similarly, ticks responded to Bb-inoculated and incubated cellulose but not to sterile cellulose, indicating that Bb detection by ticks hinges on the Bb metabolism of cellulose. 2-Methylisoborneol—a common fungal metabolite with elevated presence in disturbed soils—strongly deterred ticks. Off-host ticks that avoid disturbed soil may lower their risk of physical injury. Synthetic 2-methylisoborneol could become a commercial tick repellent, provided its repellency extends to ticks in diverse taxa. Full article

Novel segmented tick-borne RNA viruses belonging to the group of Jingmenviruses (JMVs) are widespread across Africa, Asia, Europe, and America. In this work, we obtained whole-genome sequences of two Kindia tick virus (KITV) isolates and performed modeling and the functional annotation of the secondary structure of 5′ and 3′ UTRs from JMV and KITV viruses. UTRs of various KITV segments are characterized by the following points: (1) the polyadenylated 3′ UTR; (2) 5′ DAR and 3′ DAR motifs; (3) a highly conserved 5′-CACAG-3′ pentanucleotide; (4) a binding site of the La protein; (5) multiple UAG sites providing interactions with the MSI1 protein; (6) three homologous sequences in the 5′ UTR and 3′ UTR of segment 2; (7) the segment 2 3′ UTR of a KITV/2017/1 isolate, which comprises two consecutive 40 nucleotide repeats forming a Y-3 structure; (8) a 35-nucleotide deletion in the second repeat of the segment 2 3′ UTR of KITV/2018/1 and KITV/2018/2 isolates, leading to a modification of the Y-3 structure; (9) two pseudoknots in the segment 2 3′ UTR; (10) the 5′ UTR and 3′ UTR being represented by patterns of conserved motifs; (11) the 5′-CAAGUG-3′ sequence occurring in early UTR hairpins. Thus, we identified regulatory elements in the UTRs of KITV, which are characteristic of orthoflaviviruses. This suggests that they hold functional significance for the replication of JMVs and the evolutionary similarity between orthoflaviviruses and segmented flavi-like viruses. Full article

The Korean water deer (WD), a predominant wildlife species in South Korea, is listed as vulnerable by the IUCN Red List. Despite belonging to the same family, Cervidae, WD show significantly fewer adult ixodid tick infestations compared to roe deer (RD). Ticks, which cannot fly, engage in questing behavior in natural environments to latch onto hosts. They detect signals like body temperature and host skin chemicals to navigate through the hair coat to the preferred epidermis. In light of this, we performed an extensive comparative study of the skin tissue and hair characteristics of both deer species, focusing on elements contributing to the reduced tick bite incidence in WD. Remarkably, WD exhibited more prominent blood vessels, sebaceous glands, and sweat glands, which are crucial for skin barrier functions (p < 0.005). Moreover, WD had irregular scale patterns on their hair cuticles and possessed hair that was significantly stiffer and 2.83 times thicker than that of RD (p < 0.001). These characteristics potentially impede ticks from reaching the epidermis hair in WD and RD in the context of tick bite prevention. Further investigations in this area could enhance our understanding of tick–host dynamics and contribute to developing preventive measures against tick-borne diseases in other deer species. Full article