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Duron O. Nutritional symbiosis in ticks: singularities of the genus Ixodes. Trends Parasitol 2024:S1471-4922(24)00164-8. [PMID: 38942646 DOI: 10.1016/j.pt.2024.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 06/10/2024] [Accepted: 06/10/2024] [Indexed: 06/30/2024]
Abstract
Symbiosis with intracellular bacteria is essential for the nutrition of ticks, particularly through the biosynthesis of B vitamins. Yet, ticks of the genus Ixodes, which include major vectors of human pathogens, lack the nutritional symbionts usually found in other tick genera. This paradox raises questions about the mechanisms that Ixodes ticks use to prevent nutritional deficiencies. Nonetheless, Ixodes ticks commonly harbor other symbionts belonging to the order Rickettsiales. Although these obligate intracellular bacteria are primarily known as human pathogens, Rickettsiales symbionts often dominate the Ixodes microbial community without causing diseases. They also significantly influence Ixodes physiology, synthesize key B vitamins, and are crucial for immatures. These findings underscore unique associations between Rickettsiales and Ixodes ticks distinct from other tick genera.
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Affiliation(s)
- Olivier Duron
- MIVEGEC, University of Montpellier (UM), Centre National de la Recherche Scientifique (CNRS), Institut pour la Recherche et le Développement (IRD), Montpellier, France.
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Bakker JW, Begemann HLM, Fonville M, Esser HJ, de Boer WF, Sprong H, Koenraadt CJM. Differential associations of horizontally and vertically transmitted symbionts on Ixodes ricinus behaviour and physiology. Parasit Vectors 2023; 16:443. [PMID: 38017525 PMCID: PMC10685571 DOI: 10.1186/s13071-023-06025-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 10/19/2023] [Indexed: 11/30/2023] Open
Abstract
BACKGROUND Ixodes ricinus ticks are infected with a large diversity of vertically and horizontally transmitted symbionts. While horizontally transmitted symbionts rely on a vertebrate host for their transmission, vertically transmitted symbionts rely more on the survival of their invertebrate host for transmission. We therefore hypothesized horizontally transmitted symbionts to be associated with increased tick activity to increase host contact rate and vertically transmitted symbionts to be associated with higher tick weight and lipid fraction to promote tick survival. METHODS We used a behavioural assay to record the questing activity of I. ricinus ticks. In addition, we measured weight and lipid fraction and determined the presence of ten symbiont species in these ticks using qPCR, of which six were vertically transmitted and four horizontally transmitted. RESULTS Vertically transmitted symbionts (e.g. Midichloria mitochondrii) were associated with an increase in tick weight, whereas horizontally transmitted symbionts (e.g. Borrelia burgdorferi sensu lato) were often associated with lower weight and lipid fraction of ticks. Moreover, horizontally transmitted symbionts (e.g. B. burgdorferi s.l.) were associated with increased tick activity, which may benefit pathogen transmission and increases tick-borne disease hazard. CONCLUSIONS Our study shows that horizontally and vertically transmitted symbionts differentially influence the behaviour and physiology of I. ricinus and warrants future research to study the underlying mechanisms and effects on transmission dynamics of tick-borne pathogens.
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Affiliation(s)
- Julian W Bakker
- Laboratory of Entomology, Wageningen University and Research, Wageningen, The Netherlands.
| | - Hannah L M Begemann
- Laboratory of Entomology, Wageningen University and Research, Wageningen, The Netherlands
| | - Manoj Fonville
- Centre for Infectious Disease Control, National Institute of Public Health and the Environment (RIVM), Bilthoven, The Netherlands
| | - Helen J Esser
- Wildlife Ecology and Conservation Group, Wageningen University & Research, Wageningen, The Netherlands
| | - Willem F de Boer
- Wildlife Ecology and Conservation Group, Wageningen University & Research, Wageningen, The Netherlands
| | - Hein Sprong
- Centre for Infectious Disease Control, National Institute of Public Health and the Environment (RIVM), Bilthoven, The Netherlands
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Boulanger N, Insonere JLM, Van Blerk S, Barthel C, Serres C, Rais O, Roulet A, Servant F, Duron O, Lelouvier B. Cross-alteration of murine skin and tick microbiome concomitant with pathogen transmission after Ixodes ricinus bite. MICROBIOME 2023; 11:250. [PMID: 37952001 PMCID: PMC10638774 DOI: 10.1186/s40168-023-01696-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Accepted: 10/11/2023] [Indexed: 11/14/2023]
Abstract
BACKGROUND Ticks are major vectors of diseases affecting humans such as Lyme disease or domestic animals such as anaplasmosis. Cross-alteration of the vertebrate host skin microbiome and the tick microbiome may be essential during the process of tick feeding and for the mechanism of pathogen transmission. However, it has been poorly investigated. METHODS We used mice bitten by field-collected ticks (nymphs and adult ticks) in different experimental conditions to investigate, by 16S rRNA gene metabarcoding, the impact of blood feeding on both the mouse skin microbiome and the tick microbiome. We also investigated by PCR and 16S rRNA gene metabarcoding, the diversity of microorganisms transmitted to the host during the process of tick bite at the skin interface and the dissemination of the pathogen in host tissues (blood, heart, and spleen). RESULTS Most of the commensal bacteria present in the skin of control mice were replaced during the blood-feeding process by bacteria originating from the ticks. The microbiome of the ticks was also impacted by the blood feeding. Several pathogens including tick-borne pathogens (Borrelia/Borreliella, Anaplasma, Neoehrlichia, Rickettsia) and opportunistic bacteria (Williamsia) were transmitted to the skin microbiome and some of them disseminated to the blood or spleen of the mice. In the different experiments of this study, skin microbiome alteration and Borrelia/Borreliella transmission were different depending on the tick stages (nymphs or adult female ticks). CONCLUSIONS Host skin microbiome at the bite site was deeply impacted by the tick bite, to an extent which suggests a role in the tick feeding, in the pathogen transmission, and a potentially important impact on the skin physiopathology. The diversified taxonomic profiles of the tick microbiome were also modified by the blood feeding. Video Abstract.
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Affiliation(s)
- Nathalie Boulanger
- UR7290: Virulence bactérienne précoce: groupe Borrelia, FMTS, University of Strasbourg, Strasbourg, France.
| | | | | | - Cathy Barthel
- UR7290: Virulence bactérienne précoce: groupe Borrelia, FMTS, University of Strasbourg, Strasbourg, France
| | - Céline Serres
- Vaiomer, 516 rue Pierre et Marie Curie, 31670, Labège, France
| | - Olivier Rais
- Laboratoire d'écologie et d'épidémiologie parasitaires Institut de Biologie, University of Neuchatel, 2000, Neuchâtel, Switzerland
| | - Alain Roulet
- Vaiomer, 516 rue Pierre et Marie Curie, 31670, Labège, France
| | | | - Olivier Duron
- Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Centre National de la Recherche Scientifique (CNRS), Institut pour la Recherche et le Développement (IRD), Université de Montpellier (UM), 911 Avenue Agropolis, 34394, Montpellier, France
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Paulson AR, Lougheed SC, Huang D, Colautti RI. Multiomics Reveals Symbionts, Pathogens, and Tissue-Specific Microbiome of Blacklegged Ticks (Ixodes scapularis) from a Lyme Disease Hot Spot in Southeastern Ontario, Canada. Microbiol Spectr 2023; 11:e0140423. [PMID: 37184407 PMCID: PMC10269869 DOI: 10.1128/spectrum.01404-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 04/24/2023] [Indexed: 05/16/2023] Open
Abstract
Ticks in the family Ixodidae are important vectors of zoonoses, including Lyme disease (LD), which is caused by spirochete bacteria from the Borreliella (Borrelia) burgdorferi sensu lato complex. The blacklegged tick (Ixodes scapularis) continues to expand across Canada, creating hot spots of elevated LD risk at the leading edge of its expanding range. Current efforts to understand the risk of pathogen transmission associated with I. scapularis in Canada focus primarily on targeted screens, while natural variation in the tick microbiome remains poorly understood. Using multiomics consisting of 16S metabarcoding and ribosome-depleted, whole-shotgun RNA transcriptome sequencing, we examined the microbial communities associated with adult I. scapularis (n = 32), sampled from four tissue types (whole tick, salivary glands, midgut, and viscera) and three geographical locations within a LD hot spot near Kingston, Ontario, Canada. The communities consisted of both endosymbiotic and known or potentially pathogenic microbes, including RNA viruses, bacteria, and a Babesia sp. intracellular parasite. We show that β-diversity is significantly higher between the bacterial communities of individual tick salivary glands and midguts than that of whole ticks. Linear discriminant analysis effect size (LEfSe) determined that the three potentially pathogenic bacteria detected by V4 16S rRNA sequencing also differed among dissected tissues only, including a Borrelia strain from the B. burgdorferi sensu lato complex, Borrelia miyamotoi, and Anaplasma phagocytophilum. Importantly, we find coinfection of I. scapularis by multiple microbes, in contrast to diagnostic protocols for LD, which typically focus on infection from a single pathogen of interest (B. burgdorferi sensu stricto). IMPORTANCE As a vector of human health concern, blacklegged ticks (Ixodes scapularis) transmit pathogens that cause tick-borne diseases (TBDs), including Lyme disease (LD). Several hot spots of elevated LD risk have emerged across Canada as I. scapularis expands its range. Focusing on a hot spot in southeastern Ontario, we used high-throughput sequencing to characterize the microbiome of whole ticks and dissected salivary glands and midguts. Compared with whole ticks, salivary glands and midguts were more diverse and associated with distinct bacterial communities that are less dominated by Rickettsia endosymbiont bacteria and are enriched for pathogenic bacteria, including a B. burgdorferi sensu lato-associated Borrelia sp., Borrelia miyamotoi, and Anaplasma phagocytophilum. We also found evidence of coinfection of I. scapularis by multiple pathogens. Overall, our study highlights the challenges and opportunities associated with the surveillance of the microbiome of I. scapularis for pathogen detection using metabarcoding and metatranscriptome approaches.
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Affiliation(s)
- Amber R. Paulson
- Department of Biology, Queen’s University, Kingston, Ontario, Canada
| | | | - David Huang
- Department of Biology, Queen’s University, Kingston, Ontario, Canada
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Becker NS, Rollins RE, Stephens R, Sato K, Brachmann A, Nakao M, Kawabata H. Candidatus Lariskella arthopodarum endosymbiont is the main factor differentiating the microbiome communities of female and male Borrelia-positive Ixodes persulcatus ticks. Ticks Tick Borne Dis 2023; 14:102183. [PMID: 37172511 DOI: 10.1016/j.ttbdis.2023.102183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 04/10/2023] [Accepted: 04/13/2023] [Indexed: 05/15/2023]
Abstract
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.
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Affiliation(s)
- Noémie S Becker
- Division of Evolutionary Biology, Faculty of Biology, LMU Munich, Planegg-Martinsried, Germany.
| | - Robert E Rollins
- Institute of Avian Research "Vogelwarte Helgoland", Wilhelmshaven, Germany
| | - Rebecca Stephens
- Division of Evolutionary Biology, Faculty of Biology, LMU Munich, Planegg-Martinsried, Germany
| | - Kozue Sato
- Department of Bacteriology-I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Andreas Brachmann
- Genetics, Faculty of Biology, LMU Munich, Planegg-Martinsried, Germany
| | - Minoru Nakao
- Asahikawa Medical University, Department of Parasitology, Asahikawa, Japan
| | - Hiroki Kawabata
- Department of Bacteriology-I, National Institute of Infectious Diseases, Tokyo, Japan
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Militzer N, Pinecki Socias S, Nijhof AM. Changes in the Ixodes ricinus microbiome associated with artificial tick feeding. Front Microbiol 2023; 13:1050063. [PMID: 36704557 PMCID: PMC9871825 DOI: 10.3389/fmicb.2022.1050063] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 12/16/2022] [Indexed: 01/11/2023] Open
Abstract
Artificial tick feeding systems (ATFS) can be used to study tick biology and tick-pathogen interactions. Due to the long feeding duration of hard ticks, antibiotics are commonly added to the in vitro blood meal to prevent the blood from decaying. This may affect the ticks' microbiome, including mutualistic bacteria that play an important role in tick biology. This effect was examined by the consecutive feeding of Ixodes ricinus larvae, nymphs, and adults in vitro with and without the supplementation of gentamicin and in parallel on calves. DNA extracted from unfed females was analyzed by 16S rRNA sequencing. The abundance of Candidatus Midichloria mitochondrii, Rickettsia helvetica and Spiroplasma spp. was measured by qPCR in unfed larvae, nymphs, and adults. Larvae and nymphs fed on calves performed significantly better compared to both in vitro groups. Adults fed on blood supplemented with gentamicin and B vitamins had a higher detachment proportion and weight compared to the group fed with B vitamins but without gentamicin. The detachment proportion and weights of females did not differ significantly between ticks fed on calves and in vitro with gentamicin, but the fecundity was significantly higher in ticks fed on calves. 16S rRNA sequencing showed a higher microbiome species richness in ticks fed on calves compared to ticks fed in vitro. A shift in microbiome composition, with Ca. Midichloria mitochondrii as dominant species in females fed as juveniles on calves and R. helvetica as the most abundant species in females previously fed in vitro was observed. Females fed in vitro without gentamicin showed significant lower loads of Ca. M. mitochondrii compared to females fed in vitro with gentamicin and ticks fed on calves. Spiroplasma spp. were exclusively detected in female ticks fed on cattle by qPCR, but 16S rRNA sequencing results also showed a low abundance in in vitro females exposed to gentamicin. In conclusion, the employed feeding method and gentamicin supplementation affected the ticks' microbiome composition and fecundity. Since these changes may have an impact on tick biology and vector competence, they should be taken into account in studies employing ATFS.
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Affiliation(s)
- Nina Militzer
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Sophia Pinecki Socias
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Ard M. Nijhof
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany,Veterinary Centre for Resistance Research, Freie Universität Berlin, Berlin, Germany,*Correspondence: Ard M. Nijhof, ✉
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Krawczyk AI, Röttjers S, Coimbra-Dores MJ, Heylen D, Fonville M, Takken W, Faust K, Sprong H. Tick microbial associations at the crossroad of horizontal and vertical transmission pathways. Parasit Vectors 2022; 15:380. [PMID: 36271430 PMCID: PMC9585727 DOI: 10.1186/s13071-022-05519-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 09/29/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Microbial communities can affect disease risk by interfering with the transmission or maintenance of pathogens in blood-feeding arthropods. Here, we investigated whether bacterial communities vary between Ixodes ricinus nymphs which were or were not infected with horizontally transmitted human pathogens. METHODS Ticks from eight forest sites were tested for the presence of Borrelia burgdorferi sensu lato, Babesia spp., Anaplasma phagocytophilum, and Neoehrlichia mikurensis by quantitative polymerase chain reaction (qPCR), and their microbiomes were determined by 16S rRNA amplicon sequencing. Tick bacterial communities clustered poorly by pathogen infection status but better by geography. As a second approach, we analysed variation in tick microorganism community structure (in terms of species co-infection) across space using hierarchical modelling of species communities. For that, we analysed almost 14,000 nymphs, which were tested for the presence of horizontally transmitted pathogens B. burgdorferi s.l., A. phagocytophilum, and N. mikurensis, and the vertically transmitted tick symbionts Rickettsia helvetica, Rickettsiella spp., Spiroplasma ixodetis, and Candidatus Midichloria mitochondrii. RESULTS With the exception of Rickettsiella spp., all microorganisms had either significant negative (R. helvetica and A. phagocytophilum) or positive (S. ixodetis, N. mikurensis, and B. burgdorferi s.l.) associations with M. mitochondrii. Two tick symbionts, R. helvetica and S. ixodetis, were negatively associated with each other. As expected, both B. burgdorferi s.l. and N. mikurensis had a significant positive association with each other and a negative association with A. phagocytophilum. Although these few specific associations do not appear to have a large effect on the entire microbiome composition, they can still be relevant for tick-borne pathogen dynamics. CONCLUSIONS Based on our results, we propose that M. mitochondrii alters the propensity of ticks to acquire or maintain horizontally acquired pathogens. The underlying mechanisms for some of these remarkable interactions are discussed herein and merit further investigation. Positive and negative associations between and within horizontally and vertically transmitted symbionts.
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Affiliation(s)
- Aleksandra Iwona Krawczyk
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, 3720 MA, Bilthoven, The Netherlands. .,Laboratory of Entomology, Wageningen University & Research, 6708PB, Wageningen, The Netherlands.
| | - Sam Röttjers
- Department of Microbiology, Immunology and Transplantation, Laboratory of Molecular Bacteriology, KU Leuven, Rega Institute for Medical Research, 3000, Leuven, Belgium
| | - Maria João Coimbra-Dores
- Centre for Environmental and Marine Studies (CESAM), Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
| | - Dieter Heylen
- Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Diepenbeek, Belgium.,Department of Ecology and Evolutionary Biology, Princeton University, 106A Guyot Ln, Princeton, NJ, 08544, USA
| | - Manoj Fonville
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, 3720 MA, Bilthoven, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, 6708PB, Wageningen, The Netherlands
| | - Karoline Faust
- Department of Microbiology, Immunology and Transplantation, Laboratory of Molecular Bacteriology, KU Leuven, Rega Institute for Medical Research, 3000, Leuven, Belgium
| | - Hein Sprong
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, 3720 MA, Bilthoven, The Netherlands.
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Mofokeng LS, Smit NJ, Cook CA. Molecular Detection of Tick-Borne Bacteria from Amblyomma (Acari: Ixodidae) Ticks Collected from Reptiles in South Africa. Microorganisms 2022; 10:microorganisms10101923. [PMID: 36296199 PMCID: PMC9607068 DOI: 10.3390/microorganisms10101923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 09/19/2022] [Accepted: 09/23/2022] [Indexed: 11/16/2022] Open
Abstract
Reptiles are hosts for various tick species and tick-associated organisms, many of which are zoonotic. However, little is known about the presence and diversity of tick-borne bacteria infecting reptiles and their ticks in South Africa. Amblyomma ticks (n = 253) collected from reptiles were screened for the presence of Coxiella, Anaplasma, Rickettsia, and Borrelia species by amplification, sequencing and phylogenetic analysis of the 16S rRNA, 23S rRNA, gltA, OmpA, and Flagellin genes, respectively. This study recorded the presence of reptile associated Borrelia species and Coxiella-like endosymbiont in South Africa for the first time. Furthermore, a spotted fever group Rickettsia species was observed in 7 Amblyomma marmoreum and 14 Amblyomma sylvaticum from tortoises of genera Kinixys and Chersina. Francisella-like endosymbiont was observed from 2 Amblyomma latum collected from the Mozambique spitting cobra, Naja mossambica. Coxiella burnetii and Anaplasma spp., were not detected from the current samples. Although the direct evidence that reptiles can act as reservoir hosts remains to be determined, observations from this study provide indications that reptilian ticks may play a role in the transmission of pathogenic bacteria to homothermic animals. Furthermore, the absence of Anaplasma spp., and C. burnetii does not mean that these pathogens should be completely neglected.
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Evaluating Transmission Paths for Three Different Bartonella spp. in Ixodes ricinus Ticks Using Artificial Feeding. Microorganisms 2021; 9:microorganisms9050901. [PMID: 33922378 PMCID: PMC8146832 DOI: 10.3390/microorganisms9050901] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 04/20/2021] [Accepted: 04/20/2021] [Indexed: 12/16/2022] Open
Abstract
Bartonellae are facultative intracellular alpha-proteobacteria often transmitted by arthropods. Ixodes ricinus is the most important vector for arthropod-borne pathogens in Europe. However, its vector competence for Bartonella spp. is still unclear. This study aimed to experimentally compare its vector competence for three Bartonella species: B. henselae, B. grahamii, and B. schoenbuchensis. A total of 1333 ticks (1021 nymphs and 312 adults) were separated into four groups, one for each pathogen and a negative control group. Ticks were fed artificially with bovine blood spiked with the respective Bartonella species. DNA was extracted from selected ticks to verify Bartonella-infection by PCR. DNA of Bartonella spp. was detected in 34% of nymphs and females after feeding. The best engorgement results were obtained by ticks fed with B. henselae-spiked blood (65.3%) and B. schoenbuchensis (61.6%). Significantly more nymphs fed on infected blood (37.3%) molted into adults compared to the control group (11.4%). Bartonella DNA was found in 22% of eggs laid by previously infected females and in 8.6% of adults molted from infected nymphs. The transovarial and transstadial transmission of bartonellae suggest that I. ricinus could be a potential vector for three bacteria.
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