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Kabir A, Chouhan CS, Habib T, Hossain MZ, Raihan A, Yeasmin F, Siddique MP, Rahman AKMA, Nahar A, Rahman MS, Ehsan MA. Epidemiology of canine ehrlichiosis and molecular characterization of Erhlichia canis in Bangladeshi pet dogs. PLoS One 2024; 19:e0314729. [PMID: 39637034 PMCID: PMC11620671 DOI: 10.1371/journal.pone.0314729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 11/14/2024] [Indexed: 12/07/2024] Open
Abstract
BACKGROUND Ehrlichia canis, a rickettsial organism, is responsible for causing ehrlichiosis, a tick-borne disease affecting dogs. OBJECTIVES This study aimed to estimate ehrlichiosis prevalence and identify associated risk factors in pet dogs. METHODS A total of 246 peripheral blood samples were purposively collected from pet dogs in Dhaka, Mymensingh, and Rajshahi districts between December 2018 and December 2020. Risk factor data were obtained through face-to-face interviews with dog owners using a pre-structured questionnaire. Multivariable logistic regression analysis identified risk factors. Polymerase chain reaction targeting the 16S rRNA gene confirmed Ehrlichia spp. PCR results were further validated by sequencing. RESULTS The prevalence and case fatality of ehrlichiosis were 6.9% and 47.1%, respectively. Dogs in rural areas had 5.8 times higher odds of ehrlichiosis (odd ratio, OR: 5.84; 95% CI: 1.72-19.89) compared to urban areas. Dogs with access to other dogs had 5.14 times higher odds of ehrlichiosis (OR: 5.14; 95% CI: 1.63-16.27) than those without such access. Similarly, irregularly treated dogs with ectoparasitic drugs had 4.01 times higher odds of ehrlichiosis (OR: 4.01; 95% CI: 1.17-14.14) compared to regularly treated dogs. The presence of ticks on dogs increased ehrlichiosis odds nearly by 3 times (OR: 3.02; 95% CI: 1.02-8.97). Phylogenetic analysis, based on 17 commercially sequenced isolates, showed different clusters of aggregation, however, BAUMAH-13 (PP321265) perfectly settled with a China isolate (OK667945), similarly, BAUMAH-05 (PP321257) with Greece isolate (MN922610), BAUMAH-16 (PP321268) with Italian isolate (KX180945), and BAUMAH-07 (PP321259) with Thailand isolate (OP164610). CONCLUSIONS Pet owners and veterinarians in rural areas should be vigilant in monitoring dogs for ticks and ensuring proper preventive care. Limiting access to other dogs in high-risk areas can help mitigate disease spread. Tick prevention measures and regular treatment with ectoparasitic drugs will reduce the risk of ehrlichiosis in dogs. The observed genetic similarity of the Bangladeshi Ehrlichia canis strain highlights the need for ongoing surveillance and research to develop effective control and prevention strategies, both within Bangladesh and globally.
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Affiliation(s)
- Ajran Kabir
- Department of Microbiology & Hygiene, Bangladesh Agricultural University, Mymensingh, Bangladesh
| | | | - Tasmia Habib
- Department of Microbiology & Hygiene, Bangladesh Agricultural University, Mymensingh, Bangladesh
| | - Md. Zawad Hossain
- Doctor of Veterinary Medicine, Bangladesh Agricultural University, Mymensingh, Bangladesh
| | - Abu Raihan
- Doctor of Veterinary Medicine, Bangladesh Agricultural University, Mymensingh, Bangladesh
| | - Farzana Yeasmin
- Department of Medicine, Bangladesh Agricultural University, Mymensingh, Bangladesh
| | - Mahbubul Pratik Siddique
- Department of Microbiology & Hygiene, Bangladesh Agricultural University, Mymensingh, Bangladesh
| | | | - Azimun Nahar
- Department of Medicine, Bangladesh Agricultural University, Mymensingh, Bangladesh
| | - Md. Siddiqur Rahman
- Department of Medicine, Bangladesh Agricultural University, Mymensingh, Bangladesh
| | - Md. Amimul Ehsan
- Department of Medicine, Bangladesh Agricultural University, Mymensingh, Bangladesh
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Chien RC, Lin M, Duan N, Denton S, Kawahara J, Rikihisa Y. RipE expression correlates with high ATP levels in Ehrlichia, which confers resistance during the extracellular stage to facilitate a new cycle of infection. Front Cell Infect Microbiol 2024; 14:1416577. [PMID: 39411319 PMCID: PMC11473500 DOI: 10.3389/fcimb.2024.1416577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Accepted: 08/28/2024] [Indexed: 10/19/2024] Open
Abstract
Ehrlichiosis is a potentially life-threatening disease caused by infection with the obligatory intracellular bacteria Ehrlichia species. Ehrlichia japonica infection of mice provides an animal model of ehrlichiosis as it recapitulates full-spectrum and lethal ehrlichiosis in humans. The E. japonica transposon mutant of EHF0962, which encodes a previously uncharacterized hypothetical protein, is attenuated in both infection and virulence in mice. EHF0962 was hence named here as resistance-inducing protein of Ehrlichia (RipE). Using this ΔripE mutant, we studied how RipE protein contributes to Ehrlichia pathogenesis. Ehrlichia species have an intracellular developmental cycle and a brief extracellular stage to initiate a new cycle of infection. Majority of RipE proteins were expressed on the surface of the smaller infectious dense-core stage of bacteria. Extracellular ΔripE E. japonica contained significantly less adenosine triphosphate (ATP) and lost infectivity more rapidly in culture compared with wild-type (WT) E. japonica. Genetic complementation in the ΔripE mutant or overexpression of ripE in WT E. japonica significantly increased bacterial ATP levels, and RipE-overexpressing E. japonica was more virulent in mice than WT E. japonica. RipE is conserved among Ehrlichia species. Immunization of mice with recombinant RipE induced an in vitro infection-neutralizing antibody, significantly prolonged survival time after a lethal dose of E. japonica challenge, and cross-protected mice from infection by Ehrlichia chaffeensis, the agent of human monocytic ehrlichiosis. Our findings shed light on the extracellular stage of Ehrlichia, highlighting the importance of RipE and ATP levels in Ehrlichia for extracellular resistance and the next cycle of infection. Thus, RipE is a critical Ehrlichia protein for infection as such can be a potential vaccine target for ehrlichiosis.
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Affiliation(s)
| | | | | | | | | | - Yasuko Rikihisa
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, United States
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Sohn-Hausner N, Kmetiuk LB, Paula WVDF, de Paula LGF, Krawczak FDS, Biondo AW. One Health Approach on Ehrlichia canis: Serosurvey of Owners and Dogs, Molecular Detection in Ticks, and Associated Risk Factors in Tick-Infested Households of Southern Brazil. Vector Borne Zoonotic Dis 2024; 24:338-350. [PMID: 38502822 DOI: 10.1089/vbz.2023.0134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024] Open
Abstract
Background: Ehrlichia canis has been the main hemopathogen affecting domestic dogs in Brazil. Even though tick-infested dogs may lead to household infestation and predispose human exposure and public health concern, no comprehensive study has surveyed humans, dogs, and environmental ticks altogether. Materials and Methods: Accordingly, the present study aimed to assess tick-infested households, identify tick species, perform serological (immunofluorescence assay) and molecular (PCR and q-PCR) detection of Ehrlichia in ticks, in the eighth biggest metropolitan area of Brazil. Results: Between 2007 and 2020, 233/5973 (3.9%) out of all complaints were from tick-infested households of 200 different addresses. Overall, 370/552 (67.0%) ticks were collected and identified as adult and 182/552 (33.0%) as immature forms of Rhipicephalus sanguineus s.l. complex; a single tick from one owner, a female tick of Amblyomma sculptum; and 395 ticks from dogs, 319/395 (80.8%) adult and 72/395 (18.2%) immature forms of Rhipicephalus spp., and 4/395 (1.01%) female Amblyomma aureolatum. Overall, 2/135 (1.5%) owners and 13/136 (9.6%) dogs were seropositive for E. canis. The DNA of Anaplasmataceae family was molecularly detected in 16/50 (32.0%) R. sanguineus s.l. As expected, the number of monthly tick infestation complaints were directly associated, and mean (p = 0.01), maximum (p = 0.011), and minimum (p = 0.008) temperature were statistically significant and had a low positive correlation (0.24, 0.23, and 0.24, respectively). In addition, complaints were highly associated to all socioeconomic variables (p < 0.001), with the exception of the presence of vacant lots. Conclusions: Despite low samplings and human negative results, areas with low-income with adequate temperature and urban agglomerations have been shown to be associated risks for tick infestations, predisposing tick-borne diseases. In conclusion, monitoring should always be conducted in such areas, including One Health approach with serosurvey of owners and dogs, along with identification and molecular screening of ticks.
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Affiliation(s)
- Natacha Sohn-Hausner
- Graduate College of Cell and Molecular Biology, Federal University of Paraná, Curitiba, Brazil
| | - Louise Bach Kmetiuk
- Graduate College of Cell and Molecular Biology, Federal University of Paraná, Curitiba, Brazil
| | | | | | | | - Alexander Welker Biondo
- Graduate College of Cell and Molecular Biology, Federal University of Paraná, Curitiba, Brazil
- Department of Veterinary Medicine, Federal University of Paraná, Curitiba, Brazil
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Zhang T, Chien RC, Budachetri K, Lin M, Boyaka P, Huang W, Rikihisa Y. Ehrlichia effector TRP120 manipulates bacteremia to facilitate tick acquisition. mBio 2024; 15:e0047624. [PMID: 38501870 PMCID: PMC11005420 DOI: 10.1128/mbio.00476-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 03/03/2024] [Indexed: 03/20/2024] Open
Abstract
Ehrlichia species are obligatory intracellular bacteria that cause a potentially fatal disease, human ehrlichiosis. The biomolecular mechanisms of tick acquisition of Ehrlichia and transmission between ticks and mammals are poorly understood. Ehrlichia japonica infection of mice recapitulates the full spectrum of human ehrlichiosis. We compared the pathogenicity and host acquisition of wild-type E. japonica with an isogenic transposon mutant of E. japonica that lacks tandem repeat protein 120 (TRP120) (ΔTRP120). Both wild-type and ΔTRP120 E. japonica proliferated similarly in cultures of mammalian and tick cells. Upon inoculation into mice, both wild-type and ΔTRP120 E. japonica multiplied to high levels in various tissues, with similar clinical chemistry and hematologic changes, proinflammatory cytokine induction, and fatal disease. However, the blood levels of ΔTRP120 E. japonica were almost undetectable within 24 h, whereas the levels of the wild type increased exponentially. Greater than 90% of TRP120 was released from infected cells into the culture medium. Mouse blood monocytes exposed to native TRP120 from culture supernatants showed significantly reduced cell surface expression of the transmigration-related markers Ly6C and CD11b. Larval ticks attached to mice infected with either wild-type or ΔTRP120 E. japonica imbibed similar amounts of blood and subsequently molted to nymphs at similar rates. However, unlike wild-type E. japonica, the ΔTRP120 mutant was minimally acquired by larval ticks and subsequent molted nymphs and, thus, failed to transmit to naïve mice. Thus, TRP120 is required for bacteremia but not disease. These findings suggest a novel mechanism whereby an obligatory intracellular bacterium manipulates infected blood monocytes to sustain the tick-mammal transmission cycle. IMPORTANCE Effective prevention of tick-borne diseases such as human ehrlichiosis requires an understanding of how disease-causing organisms are acquired. Ehrlichia species are intracellular bacteria that require infection of both mammals and ticks, involving cycles of transmission between them. Mouse models of ehrlichiosis and tick-mouse transmission can advance our fundamental understanding of the pathogenesis and prevention of ehrlichiosis. Herein, a mutant of Ehrlichia japonica was used to investigate the role of a single Ehrlichia factor, named tandem repeat protein 120 (TRP120), in infection of mammalian and tick cells in culture, infection and disease progression in mice, and tick acquisition of E. japonica from infected mice. Our results suggest that TRP120 is necessary only for Ehrlichia proliferation in circulating mouse blood and ongoing bacteremia to permit Ehrlichia acquisition by ticks. This study provides new insights into the importance of bacterial factors in regulating bacteremia, which may facilitate tick acquisition of pathogens.
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Affiliation(s)
- Tsian Zhang
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Rory C. Chien
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Khemraj Budachetri
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Mingqun Lin
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Prosper Boyaka
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Weiyan Huang
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Yasuko Rikihisa
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
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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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Ehrlichiosis in Dogs: A Comprehensive Review about the Pathogen and Its Vectors with Emphasis on South and East Asian Countries. Vet Sci 2022; 10:vetsci10010021. [PMID: 36669021 PMCID: PMC9863373 DOI: 10.3390/vetsci10010021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 12/17/2022] [Accepted: 12/24/2022] [Indexed: 12/31/2022] Open
Abstract
Ehrlichiosis in dogs is an emerging vector borne rickettsial zoonotic disease of worldwide distribution. In general, three Ehrlichial species (Ehrlichia canis, E. ewingii, and E. chaffeensis) are involved in infecting dogs. Among them, E. canis is the well-known etiological pathogen affecting platelets, monocytes, and granulocytes. Dogs act as a reservoir, while the main vector responsible for disease transmission is Rhipicephalus sanguineus. However, in east Asian countries, Haemaphysalis longicornis is considered the principal vector for disease transmission. This disease affects multiple organs and systems and has three clinical manifestations, including acute, subclinical, and chronic. Definitive diagnosis involves visualization of morulae on cytology, detection of antibodies through an indirect immunofluorescence test (IFAT), and DNA amplification by polymerase chain reaction (PCR). In canine ehrlichiosis, no predilection of age or sex is observed; however, Siberian Huskies and German Shepherds are more likely to develop severe clinical manifestations. Doxycycline, rifampicin, and minocycline are proven to be effective drugs against canine ehrlichiosis. This review is intended to describe a brief overview of Ehrlichia infection in dogs, its reported prevalence in east and south Asian countries, and the latest knowledge regarding chemotherapy and associated vectors responsible for the disease transmission. This manuscript also identifies the prevailing knowledge gaps which merit further attention by the scientific community.
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Efficacy and Immune Correlates of OMP-1B and VirB2-4 Vaccines for Protection of Dogs from Tick Transmission of Ehrlichia chaffeensis. mBio 2022; 13:e0214022. [PMID: 36342170 PMCID: PMC9765013 DOI: 10.1128/mbio.02140-22] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Ehrlichia chaffeensis, an obligatory intracellular bacterium, causes human monocytic ehrlichiosis, an emerging disease transmitted by the Lone Star tick, Amblyomma americanum. Here, we investigated the vaccine potential of OMP-1B and VirB2-4. Among the highly expressed and immunodominant E. chaffeensis porin P28s/OMP-1s, OMP-1B is predominantly expressed by E. chaffeensis in A. americanum ticks, whereas VirB2-4 is a pilus protein of the type IV secretion system essential for E. chaffeensis infection of host cells. Immunization with recombinant OMP-1B (rOMP-1B) or recombinant VirB2-4 (rVirB2-4) protected mice from E. chaffeensis infection as effectively as Entry-triggering protein of Ehrlichia immunization. Dogs vaccinated with a nanoparticle vaccine composed of rOMP-1B or rVirB2-4 and an immunostimulating complex developed high antibody titers against the respective antigen. Upon challenge with E. chaffeensis-infected A. americanum ticks, E. chaffeensis was undetectable in the blood of rOMP-1B or rVirB2-4 immunized dogs on day 3 or 6 post-tick attachment and for the duration of the experiment, whereas dogs sham-vaccinated with the complex alone were persistently infected for the duration of the experiment. E. chaffeensis exponentially replicates in blood-feeding ticks to facilitate transmission. Previously infected ticks removed from OMP-1B-immunized dogs showed significantly lower bacterial load relative to ticks removed from sham-immunized dogs, suggesting in-tick neutralization. Peripheral blood leukocytes from rVirB2-4-vaccinated dogs secreted significantly elevated amounts of interferon-γ soon after tick attachment by ELISpot assay and reverse transcription-quantitative PCR, suggesting interferon-γ-mediated Ehrlichia inhibition. Thus, Ehrlichia surface-exposed proteins OMP-1B and VirB2-4 represent new potential vaccine candidates for blocking tick-borne ehrlichial transmission. IMPORTANCE Ehrlichia are tick-borne pathogens that cause a potentially fatal illness-ehrlichiosis-in animals and humans worldwide. Currently, no vaccine is available for ehrlichiosis, and treatment options are limited. Ticks are biological vectors of Ehrlichia, i.e., Ehrlichia exponentially replicates in blood-sucking ticks before infecting animals. Ticks also inoculate immunomodulatory substances into animals. Thus, it is important to study effects of candidate vaccines on Ehrlichia infection in both animals and ticks and the immune responses of animals shortly after infected tick challenge. Here, we investigated the efficacy of vaccination with functionality-defined two surface-exposed outer membrane proteins of Ehrlichia chaffeensis, OMP-1B and VirB2-4, in a mouse infection model and then in a dog-tick transmission model. Our results begin to fill gaps in our understanding of Ehrlichia-derived protective antigens against tick-transmission and immune correlates and mechanisms that could help future development of vaccines for immunization of humans and animals to counter tick-transmitted ehrlichiosis.
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Identification of Bacterial Communities and Tick-Borne Pathogens in Haemaphysalis spp. Collected from Shanghai, China. Trop Med Infect Dis 2022; 7:tropicalmed7120413. [PMID: 36548668 PMCID: PMC9787663 DOI: 10.3390/tropicalmed7120413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 11/30/2022] [Accepted: 11/30/2022] [Indexed: 12/04/2022] Open
Abstract
Ticks can carry and transmit a large number of pathogens, including bacteria, viruses and protozoa, posing a huge threat to human health and animal husbandry. Previous investigations have shown that the dominant species of ticks in Shanghai are Haemaphysalis flava and Haemaphysalis longicornis. However, no relevant investigations and research have been carried out in recent decades. Therefore, we investigated the bacterial communities and tick-borne pathogens (TBPs) in Haemaphysalis spp. from Shanghai, China. Ixodid ticks were collected from 18 sites in Shanghai, China, and identified using morphological and molecular methods. The V3-V4 hypervariable regions of the bacterial 16S rRNA gene were amplified from the pooled tick DNA samples and subject to metagenomic analysis. The microbial diversity in the tick samples was estimated using the alpha diversity that includes the observed species index and Shannon index. The Unifrac distance matrix as determined using the QIIME software was used for unweighted Unifrac Principal coordinates analysis (PCoA). Individual tick DNA samples were screened with genus-specific or group-specific nested polymerase chain reaction (PCR) for these TBPs and combined with a sequencing assay to confirm the results of the V3-V4 hypervariable regions of the bacterial 16S rRNA gene. We found H. flava and H. longicornis to be the dominant species of ticks in Shanghai in this study. Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria are the main bacterial communities of Haemaphysalis spp. The total species abundances of Proteobacteria, Firmicutes and Bacteroidetes, are 48.8%, 20.8% and 18.1%, respectively. At the level of genus analysis, H. longicornis and H. flava carried at least 946 genera of bacteria. The bacteria with high abundance include Lactobacillus, Coxiella, Rickettsia and Muribaculaceae. Additionally, Rickettsia rickettsii, Rickettsia japonica, Candidatus Rickettsia jingxinensis, Anaplasma bovis, Ehrlichia ewingii, Ehrlichia chaffeensis, Coxiella spp. and Coxiella-like endosymbiont were detected in Haemaphysalis spp. from Shanghai, China. This study is the first report of bacterial communities and the prevalence of some main pathogens in Haemaphysalis spp. from Shanghai, China, and may provide insights and evidence for bacterial communities and the prevalence of the main pathogen in ticks. This study also indicates that people and other animals in Shanghai, China, are exposed to several TBPs.
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Diversity unearthed by the estimated molecular phylogeny and ecologically quantitative characteristics of uncultured Ehrlichia bacteria in Haemaphysalis ticks, Japan. Sci Rep 2021; 11:687. [PMID: 33436999 PMCID: PMC7804854 DOI: 10.1038/s41598-020-80690-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 12/24/2020] [Indexed: 11/09/2022] Open
Abstract
Ehrlichia species are obligatory intracellular bacteria transmitted by arthropods, and some of these species cause febrile diseases in humans and livestock. Genome sequencing has only been performed with cultured Ehrlichia species, and the taxonomic status of such ehrlichiae has been estimated by core genome-based phylogenetic analysis. However, many uncultured ehrlichiae exist in nature throughout the world, including Japan. This study aimed to conduct a molecular-based taxonomic and ecological characterization of uncultured Ehrlichia species or genotypes from ticks in Japan. We first surveyed 616 Haemaphysalis ticks by p28-PCR screening and analyzed five additional housekeeping genes (16S rRNA, groEL, gltA, ftsZ, and rpoB) from 11 p28-PCR-positive ticks. Phylogenetic analyses of the respective genes showed similar trees but with some differences. Furthermore, we found that V1 in the V1-V9 regions of Ehrlichia 16S rRNA exhibited the greatest variability. From an ecological viewpoint, the amounts of ehrlichiae in a single tick were found to equal approx. 6.3E+3 to 2.0E+6. Subsequently, core-partial-RGGFR-based phylogenetic analysis based on the concatenated sequences of the five housekeeping loci revealed six Ehrlichia genotypes, which included potentially new Ehrlichia species. Thus, our approach contributes to the taxonomic profiling and ecological quantitative analysis of uncultured or unidentified Ehrlichia species or genotypes worldwide.
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Lin M, Xiong Q, Chung M, Daugherty SC, Nagaraj S, Sengamalay N, Ott S, Godinez A, Tallon LJ, Sadzewicz L, Fraser C, Dunning Hotopp JC, Rikihisa Y. Comparative Analysis of Genome of Ehrlichia sp. HF, a Model Bacterium to Study Fatal Human Ehrlichiosis. BMC Genomics 2021; 22:11. [PMID: 33407096 PMCID: PMC7789307 DOI: 10.1186/s12864-020-07309-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 12/07/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The genus Ehrlichia consists of tick-borne obligatory intracellular bacteria that can cause deadly diseases of medical and agricultural importance. Ehrlichia sp. HF, isolated from Ixodes ovatus ticks in Japan [also referred to as I. ovatus Ehrlichia (IOE) agent], causes acute fatal infection in laboratory mice that resembles acute fatal human monocytic ehrlichiosis caused by Ehrlichia chaffeensis. As there is no small laboratory animal model to study fatal human ehrlichiosis, Ehrlichia sp. HF provides a needed disease model. However, the inability to culture Ehrlichia sp. HF and the lack of genomic information have been a barrier to advance this animal model. In addition, Ehrlichia sp. HF has several designations in the literature as it lacks a taxonomically recognized name. RESULTS We stably cultured Ehrlichia sp. HF in canine histiocytic leukemia DH82 cells from the HF strain-infected mice, and determined its complete genome sequence. Ehrlichia sp. HF has a single double-stranded circular chromosome of 1,148,904 bp, which encodes 866 proteins with a similar metabolic potential as E. chaffeensis. Ehrlichia sp. HF encodes homologs of all virulence factors identified in E. chaffeensis, including 23 paralogs of P28/OMP-1 family outer membrane proteins, type IV secretion system apparatus and effector proteins, two-component systems, ankyrin-repeat proteins, and tandem repeat proteins. Ehrlichia sp. HF is a novel species in the genus Ehrlichia, as demonstrated through whole genome comparisons with six representative Ehrlichia species, subspecies, and strains, using average nucleotide identity, digital DNA-DNA hybridization, and core genome alignment sequence identity. CONCLUSIONS The genome of Ehrlichia sp. HF encodes all known virulence factors found in E. chaffeensis, substantiating it as a model Ehrlichia species to study fatal human ehrlichiosis. Comparisons between Ehrlichia sp. HF and E. chaffeensis will enable identification of in vivo virulence factors that are related to host specificity, disease severity, and host inflammatory responses. We propose to name Ehrlichia sp. HF as Ehrlichia japonica sp. nov. (type strain HF), to denote the geographic region where this bacterium was initially isolated.
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Affiliation(s)
- Mingqun Lin
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH, 43210, USA.
| | - Qingming Xiong
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH, 43210, USA
| | - Matthew Chung
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Sean C Daugherty
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Sushma Nagaraj
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Naomi Sengamalay
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Sandra Ott
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Al Godinez
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Luke J Tallon
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Lisa Sadzewicz
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Claire Fraser
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
- Department of Medicine, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Julie C Dunning Hotopp
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
- Department of Microbiology and Immunology, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
- Greenebaum Cancer Center, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Yasuko Rikihisa
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH, 43210, USA.
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Cicuttin GL, De Salvo MN, Pérez PD, Silva D, Félix ML, Venzal JM, Nava S. A novel Ehrlichia strain (Rickettsiales: Anaplasmataceae) detected in Amblyomma triste (Acari: Ixodidae), a tick species of public health importance in the Southern Cone of America. Pathog Glob Health 2020; 114:318-322. [PMID: 32684117 DOI: 10.1080/20477724.2020.1795579] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
The aim of this work was to report the detection of a putative novel Ehrlichia strain associated with the tick Amblyomma triste. Free-living adult ticks determined as A. triste were collected by drag-sampling in Argentina and Uruguay. Molecular detection of Ehrlichia agents was performed targeting three different loci: 16S rRNA gene, dsb gene and a fragment of groESL heat shock operon. In total, 164 adults of A. triste (38 from INTA E.E.A Delta del Paraná in Argentina and 126 from Toledo Chico in Uruguay) were analyzed. One tick (0.6%) collected in INTA E.E.A. Delta del Paraná (Argentina) was positive. The phylogenetic analyses show that the Ehrlichia strain found in this study (named Ehrlichia sp. strain Delta) represents an independent lineage within the genus Ehrlichia, close to E. chaffeensis and E. muris. This is also the first report of an Ehrlichia agent infecting the tick A. triste. The medical and veterinary significance of Ehrlichia sp. strain Delta remains to be demonstrated. However, it is important to mention that adults of A. triste are aggressive to humans and domestic mammals. Therefore, the potential role of A. triste in the transmission of Ehrlichia agents to humans or domestic animals across its distributional range should be highlighted, even more considering that Ehrlichia sp. strain Delta is phylogenetically related to the zoonotic E. chaffeensis, which is recognized as pathogenic to both humans and animals.
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Affiliation(s)
- Gabriel L Cicuttin
- Instituto de Zoonosis Luis Pasteur , Ciudad Autónoma de Buenos Aires, Argentina
| | - María N De Salvo
- Instituto de Zoonosis Luis Pasteur , Ciudad Autónoma de Buenos Aires, Argentina
| | - Paula Díaz Pérez
- Instituto de Zoonosis Luis Pasteur , Ciudad Autónoma de Buenos Aires, Argentina
| | - Darío Silva
- Instituto de Zoonosis Luis Pasteur , Ciudad Autónoma de Buenos Aires, Argentina
| | - María L Félix
- Laboratorio de Vectores y Enfermedades Transmitidas, Facultad de Veterinaria, CENUR Litoral Norte, Universidad de la República , Salto, Uruguay
| | - José M Venzal
- Laboratorio de Vectores y Enfermedades Transmitidas, Facultad de Veterinaria, CENUR Litoral Norte, Universidad de la República , Salto, Uruguay
| | - Santiago Nava
- Estación Experimental Agropecuaria Rafaela, and Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto Nacional de Tecnología Agropecuaria , Santa Fe, Argentina
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Bekebrede H, Lin M, Teymournejad O, Rikihisa Y. Discovery of in vivo Virulence Genes of Obligatory Intracellular Bacteria by Random Mutagenesis. Front Cell Infect Microbiol 2020; 10:2. [PMID: 32117791 PMCID: PMC7010607 DOI: 10.3389/fcimb.2020.00002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 01/06/2020] [Indexed: 11/13/2022] Open
Abstract
Ehrlichia spp. are emerging tick-borne obligatory intracellular bacteria that cause febrile and sometimes fatal diseases with abnormal blood cell counts and signs of hepatitis. Ehrlichia HF strain provides an excellent mouse disease model of fatal human ehrlichiosis. We recently obtained and established stable culture of Ehrlichia HF strain in DH82 canine macrophage cell line, and obtained its whole genome sequence and annotation. To identify genes required for in vivo virulence of Ehrlichia, we constructed random insertional HF strain mutants by using Himar1 transposon-based mutagenesis procedure. Of total 158 insertional mutants isolated via antibiotic selection in DH82 cells, 74 insertions were in the coding regions of 55 distinct protein-coding genes, including TRP120 and multi-copy genes, such as p28/omp-1, virB2, and virB6. Among 84 insertions mapped within the non-coding regions, seven are located in the putative promoter region since they were within 50 bp upstream of the seven distinct genes. Using limited dilution methods, nine stable clonal mutants that had no apparent defect for multiplication in DH82 cells, were obtained. Mouse virulence of seven mutant clones was similar to that of wild-type HF strain, whereas two mutant clones showed significantly retarded growth in blood, livers, and spleens, and the mice inoculated with them lived longer than mice inoculated with wild-type. The two clones contained mutations in genes encoding a conserved hypothetical protein and a staphylococcal superantigen-like domain protein, respectively, and both genes are conserved among Ehrlichia spp., but lack homology to other bacterial genes. Inflammatory cytokine mRNA levels in the liver of mice infected with the two mutants were significantly diminished than those infected with HF strain wild-type, except IL-1β and IL-12 p40 in one clone. Thus, we identified two Ehrlichia virulence genes responsible for in vivo infection, but not for infection and growth in macrophages.
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Affiliation(s)
| | | | | | - Yasuko Rikihisa
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, United States
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Eberhardt AT, Fernandez C, Fargnoli L, Beldomenico PM, Monje LD. A putative novel strain of Ehrlichia infecting Amblyomma tigrinum associated with Pampas fox (Lycalopex gymnocercus) in Esteros del Iberá ecoregion, Argentina. Ticks Tick Borne Dis 2019; 11:101318. [PMID: 31711730 DOI: 10.1016/j.ttbdis.2019.101318] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 10/07/2019] [Accepted: 10/21/2019] [Indexed: 11/17/2022]
Abstract
The current work evaluated road-killed Pampas foxes (Lycalopex gymnocercus) and their ticks for the presence of vector-borne agents in the ecoregion Esteros del Iberá in northeastern Argentina. Spleen, lung and blood samples and Amblyomma tigrinum adult ticks collected from the foxes were tested by polymerase chain reaction (PCR) assays targeting bacteria of the genera Ehrlichia, Anaplasma, and Rickettsia. All foxes tested were negative for the three genera, but evidence of Ehrlichia and Rickettsia infection was detected in the ticks. One A. tigrinum (out of 12 tested) was infected by an ehrlichial agent, here named Ehrlichia sp. strain Iberá, related to ehrlichial agents recently detected in platypuses in Tasmania (Ornithorhynchus anatinus) and in voles (Myodes rutilus and Myodes rufocanus) and shrews (Sorex araneus) in the Russian Far East. Regarding Rickettsia, all A. tigrinum ticks (100%) were infected by ´Candidatus Rickettsia andeanae´, a member of the spotted fever group rickettsia of unknown pathogenicity. Further research is necessary to unveil the ecology of Ehrlichia sp. strain Iberá as well as its zoonotic relevance. The species of the genus Ehrlichia are known to be pathogenic to mammals, including humans and domestic animals, thus the presence of this ehrlichial agent in A. tigrinum is a potential risk for veterinary and public health, as the adults of A. tigrinum are common parasites of dogs in rural and peri-urban environments, and humans are also frequently bitten by this tick species.
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Affiliation(s)
- Ayelen T Eberhardt
- Laboratorio de Ecología de Enfermedades, Instituto de Ciencias Veterinarias del Litoral (ICIVET-Litoral), Universidad Nacional del Litoral (UNL), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Esperanza, Santa Fe, Argentina
| | - Camilo Fernandez
- Facultad de Ciencias Veterinarias del Litoral, Universidad Nacional del Litoral (UNL), Esperanza, Santa Fe, Argentina
| | - Lucía Fargnoli
- Laboratorio de Ecología de Enfermedades, Instituto de Ciencias Veterinarias del Litoral (ICIVET-Litoral), Universidad Nacional del Litoral (UNL), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Esperanza, Santa Fe, Argentina
| | - Pablo M Beldomenico
- Laboratorio de Ecología de Enfermedades, Instituto de Ciencias Veterinarias del Litoral (ICIVET-Litoral), Universidad Nacional del Litoral (UNL), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Esperanza, Santa Fe, Argentina; Facultad de Ciencias Veterinarias del Litoral, Universidad Nacional del Litoral (UNL), Esperanza, Santa Fe, Argentina
| | - Lucas D Monje
- Laboratorio de Ecología de Enfermedades, Instituto de Ciencias Veterinarias del Litoral (ICIVET-Litoral), Universidad Nacional del Litoral (UNL), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Esperanza, Santa Fe, Argentina.
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Ehrlichia Isolate from a Minnesota Tick: Characterization and Genetic Transformation. Appl Environ Microbiol 2019; 85:AEM.00866-19. [PMID: 31076433 DOI: 10.1128/aem.00866-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 05/02/2019] [Indexed: 11/20/2022] Open
Abstract
Ehrlichia muris subsp. eauclairensis is recognized as the etiological agent of human ehrlichiosis in Minnesota and Wisconsin. We describe the culture isolation of this organism from a field-collected tick and detail its relationship to other species of Ehrlichia The isolate could be grown in a variety of cultured cell lines and was effectively transmitted between Ixodes scapularis ticks and rodents, with PCR and microscopy demonstrating a broad pattern of dissemination in arthropod and mammalian tissues. Conversely, Amblyomma americanum ticks were not susceptible to infection by the Ehrlichia Histologic sections further revealed that the wild-type isolate was highly virulent for mice and hamsters, causing severe systemic disease that was frequently lethal. A Himar1 transposase system was used to create mCherry- and mKate-expressing EmCRT mutants, which retained the ability to infect rodents and ticks.IMPORTANCE Ehrlichioses are zoonotic diseases caused by intracellular bacteria that are transmitted by ixodid ticks. Here we report the culture isolation of bacteria which are closely related to, or the same as the Ehrlichia muris subsp. eauclairensis, a recently recognized human pathogen. EmCRT, obtained from a tick removed from deer at Camp Ripley, MN, is the second isolate of this subspecies described and is distinctive in that it was cultured directly from a field-collected tick. The isolate's cellular tropism, pathogenic changes caused in rodent tissues, and tick transmission to and from rodents are detailed in this study. We also describe the genetic mutants created from the EmCRT isolate, which are valuable tools for the further study of this intracellular pathogen.
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Muñoz-Leal S, Clemes YS, Lopes MG, Acosta ICL, Serpa MCA, Mayorga LFSP, Gennari SM, González-Acuña D, Labruna MB. Novel Ehrlichia sp. detected in Magellanic penguins (Sphenicus magellanicus) and in the seabird tick Ixodes uriae from Magdalena Island, southern Chile. Ticks Tick Borne Dis 2019; 10:101256. [PMID: 31255535 DOI: 10.1016/j.ttbdis.2019.06.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 06/12/2019] [Accepted: 06/24/2019] [Indexed: 01/17/2023]
Abstract
Ehrlichia spp. are obligatory intracellular microorganisms that infect hematopoietic, endothelial or blood cells of mammals. Ticks are the only vectors of these agents in nature. To date, the role of birds and their associated ticks as reservoirs of ehrlichiae remains almost unexplored. In this study, we performed a molecular screening for bacteria of Anaplasmataceae family in samples of spleen (n = 72) and lung (n = 17), recovered from 72 carcasses of Magellanic penguins (Spheniscus magellanicus) in Brazil and Chile. One apparently unengorged tick (Ixodes uriae) was also collected while wandering upon one of the carcasses and submitted to molecular analyses as well. Through conventional and nested PCR protocols three genes (16S rRNA, dsb and groEL) of a new Ehrlichia sp. were partially characterized upon organs of three penguins and in the tick coming from Magdalena Island (Chile). First matches after BLASTn comparisons showed that our sequences share 99.4% (16S rRNA), 94.6% (groEL) and 79.3% (dsb) of identity with "Candidatus Ehrlichia ornithorhynchi", Ehrlichia sp. NS101 and Ehrlichia canis CCZ, respectively. Matrixes of genetic distance including other representatives of the Ehrlichia genus point a 99.4%, 94.0%, and 80.0% of identity with 16S rRNA, groEL and dsb genes from Ehrlichia sp. It25, Ehrlichia sp. NS101, and Ehrlichia chaffeensis San Louis, respectively. A Bayesian phylogenetic analysis of Anaplasmataceae 16S rRNA gene places the detected Ehrlichia sp. into a group with Ehrlichia sp. BAT and Ehrlichia sp. Natal. Although depicting different topologies, Bayesian unrooted phylogenetic trees constructed for groEL and dsb genes position this Ehrlichia sp. into well-supported branches, which reinforces the finding of a new taxon. For the moment, any pathogenic effect of this new Ehrlichia sp. on penguins is still unknown. However, this fact becomes important to assess from a conservation point of view since populations of Magellanic penguins are currently threatened and in an ongoing decrease.
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Affiliation(s)
- Sebastián Muñoz-Leal
- Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Prof. Orlando Marques de Paiva, 87, Cidade Universitária, São Paulo, SP, 05508-270, Brazil.
| | - Yara S Clemes
- Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Prof. Orlando Marques de Paiva, 87, Cidade Universitária, São Paulo, SP, 05508-270, Brazil
| | - Marcos G Lopes
- Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Prof. Orlando Marques de Paiva, 87, Cidade Universitária, São Paulo, SP, 05508-270, Brazil
| | - Igor C L Acosta
- Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Prof. Orlando Marques de Paiva, 87, Cidade Universitária, São Paulo, SP, 05508-270, Brazil; RRDM - FURG - Programa de Monitoramento da Biodiversidade Aquática na Área Ambiental I - Av. Itália km 8 S/N, Campus Carreiros, 96203-900, Rio Grande, RS, Brazil
| | - Maria Carolina A Serpa
- Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Prof. Orlando Marques de Paiva, 87, Cidade Universitária, São Paulo, SP, 05508-270, Brazil
| | - Luis Felipe S P Mayorga
- Instituto de Pesquisa e Reabilitação de Animais Marinhos (IPRAM), Rodovia BR 262 Km 0 sem numero, CEP 29140130, Cariacica, ES, Brazil
| | - Solange M Gennari
- Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Prof. Orlando Marques de Paiva, 87, Cidade Universitária, São Paulo, SP, 05508-270, Brazil
| | - Daniel González-Acuña
- Laboratorio de Parásitos y Enfermedades de Fauna Silvestre, Departamento de Ciencia Animal, Facultad de Ciencias Veterinarias, Universidad de Concepción, Av. Vicente Méndez 595, Chillán, Chile
| | - Marcelo B Labruna
- Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Prof. Orlando Marques de Paiva, 87, Cidade Universitária, São Paulo, SP, 05508-270, Brazil
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Taira M, Ando S, Kawabata H, Fujita H, Kadosaka T, Sato H, Monma N, Ohashi N, Saijo M. Isolation and molecular detection of Ehrlichia species from ticks in western, central, and eastern Japan. Ticks Tick Borne Dis 2018; 10:344-351. [PMID: 30501980 DOI: 10.1016/j.ttbdis.2018.11.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 11/08/2018] [Accepted: 11/11/2018] [Indexed: 11/28/2022]
Abstract
Ehrlichiosis is a tick-borne bacterial disease caused by pathogens of the Ehrlichia genus. Although human ehrlichiosis has not been reported in Japan, Ehrlichia spp., which are closely related to Ehrlichia chaffeensis, were detected in several species of ixodid ticks. In this study, the presence of Ehrlichia spp. in ticks in Japan was studied by using isolation and molecular detection methods. In total, 1237 ticks were collected from vegetation in western, central, and eastern parts of Japan. The ticks were tested for detection of ehrlichial DNA with a nested polymerase chain reaction and/or isolation by inoculation of mice with the homogenate. Ehrlichial DNA was detected in 29 of these ticks. The ehrlichial DNAs, groEL and 16S rRNA genes, detected in Ixodes turdus showed a high similarity to those of E. chaffeensis with 94.7% and 99.2% identity, respectively. Ehrlichia sp. HF and Candidatus Neoehrlichia mikurensis were also detected in I. ovatus. Furthermore, Ehrlichia sp. HF was isolated from laboratory mice that were intraperitoneal inoculated with I. ovatus tick homogenate. Some ehrlichial agents detected in Ixodes ticks might be a previously unknown Ehrlichia species. In this study, Candidatus N. mikurensis was detected in I. ovatus ticks. Because I. ovatus is distributed widely and cases of its tick bite in humans are ubiquitously reported in Japan, there is a potential for ehrlichiosis to be endemic to Japan, necessitating intensive surveillance of this infectious disease.
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Affiliation(s)
- Masakatsu Taira
- United Graduate School of Agricultural Science and Veterinary Science, Gifu University, Gifu, Japan; Division of Virology and Medical Zoology, Chiba Prefectural Institute of Public Health, Chiba, Japan; Department of Virology 1, National Institute of Infectious Diseases, Tokyo, Japan.
| | - Shuji Ando
- Department of Virology 1, National Institute of Infectious Diseases, Tokyo, Japan
| | - Hiroki Kawabata
- United Graduate School of Agricultural Science and Veterinary Science, Gifu University, Gifu, Japan; Department of Bacteriology 1, National Institute of Infectious Diseases, Tokyo, Japan
| | - Hiromi Fujita
- Mahara Institute of Medical Acarology, Tokushima, Japan
| | | | - Hiroko Sato
- Akita Prefectural Research Center for Public Health and Environment, Akita, Japan
| | - Naoto Monma
- Fukushima Prefectural Institute for Public Health, Fukushima, Japan
| | - Norio Ohashi
- Department of Food and Nutritional Sciences, Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, Shizuoka, Japan
| | - Masayuki Saijo
- United Graduate School of Agricultural Science and Veterinary Science, Gifu University, Gifu, Japan; Department of Virology 1, National Institute of Infectious Diseases, Tokyo, Japan
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Two novel Ehrlichia strains detected in Amblyomma tigrinum ticks associated to dogs in peri-urban areas of Argentina. Comp Immunol Microbiol Infect Dis 2017; 53:40-44. [DOI: 10.1016/j.cimid.2017.07.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 06/30/2017] [Accepted: 07/01/2017] [Indexed: 11/22/2022]
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18
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CD11c+ T-bet+ memory B cells: Immune maintenance during chronic infection and inflammation? Cell Immunol 2017; 321:8-17. [PMID: 28838763 DOI: 10.1016/j.cellimm.2017.07.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 07/18/2017] [Indexed: 01/30/2023]
Abstract
CD11c+ T-bet+ B cells have now been detected and characterized in different experimental and clinical settings, in both mice and humans. Whether such cells are monolithic, or define subsets of B cells with different functions is not yet known. Our studies have identified CD11c+ IgM+ CD19hi splenic IgM memory B cells that appear at approximately three weeks post-ehrlichial infection, and persist indefinitely, during low-level chronic infection. Although the CD11c+ T-bet+ B cells we have described are distinct, they appear to share many features with similar cells detected under diverse conditions, including viral infections, aging, and autoimmunity. We propose that CD11c+ T-bet+ B cells as a group share characteristics of memory B cells that are maintained under conditions of inflammation and/or low-level chronic antigen stimulation. In some cases, these cells may be advantageous, by providing immunity to re-infection, but in others may be deleterious, by contributing to aged-associated autoimmune responses.
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Associated Factors to Seroprevalence of Ehrlichia spp. in Dogs of Quintana Roo, Mexico. J Trop Med 2016; 2016:4109467. [PMID: 28096818 PMCID: PMC5209617 DOI: 10.1155/2016/4109467] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 10/31/2016] [Accepted: 11/13/2016] [Indexed: 11/18/2022] Open
Abstract
The objective of this study was to determine the seroprevalence to Ehrlichia spp. in dogs from Xcalak, Quintana Roo, Mexico, and the associated factors. Serum samples were obtained from 118 dogs and used in an indirect immunofluorescent assay test for the detection of antibodies against Ehrlichia spp. A questionnaire was used to obtain information about possible variables associated with seroprevalence. These variables were analyzed through Chi2 test and logistic regression. Dog seroprevalence of antibodies against Ehrlichia spp. was 64% (75/118). Fifty-two percent (61/118) of dogs had tick infestation which was identified as Rhipicephalus sanguineus sensu lato. Anemia was observed in 36% of dogs. Leucopenia (2.5%), thrombocytopenia (70%), and hemorrhage (14%) were also observed. Thirty-one percent (23/75) of dogs with anemia, 4% (3/75) of dogs with leucopenia, 80% (60/75) of dogs with thrombocytopenia, 17% (13/75) of dogs with hemorrhages, and 59% (44/75) of dogs with ticks were positive for Ehrlichia spp. antibodies. The factors associated with seroprevalence were age (1–3 and >3 years old, OR = 7.77 and OR = 15.39, resp.), tick infestation (OR = 3.13), and thrombocytopenia (OR = 3.36). In conclusion, seroprevalence of Ehrlichia spp. was high in the community of Xcalak and its associated factors were age, tick infestation, and thrombocytopenia.
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Abstract
Ehrlichia chaffeensis is an obligatory intracellular and cholesterol-dependent bacterium that has evolved special proteins and functions to proliferate inside leukocytes and cause disease. E. chaffeensis has a multigene family of major outer membrane proteins with porin activity and induces infectious entry using its entry-triggering protein to bind the human cell surface protein DNase X. During intracellular replication, three functional pairs of two-component systems are sequentially expressed to regulate metabolism, aggregation, and the development of stress-resistance traits for transmission. A type IV secretion effector of E. chaffeensis blocks mitochondrion-mediated host cell apoptosis. Several type I secretion proteins are secreted at the Ehrlichia-host interface. E. chaffeensis strains induce strikingly variable inflammation in mice. The central role of MyD88, but not Toll-like receptors, suggests that Ehrlichia species have unique inflammatory molecules. A recent report about transient targeted mutagenesis and random transposon mutagenesis suggests that stable targeted knockouts may become feasible in Ehrlichia.
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Affiliation(s)
- Yasuko Rikihisa
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210;
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21
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Yu PF, Niu QL, Liu ZJ, Yang JF, Chen Z, Guan GQ, Liu GY, Luo JX, Yin H. Molecular epidemiological surveillance to assess emergence and re-emergence of tick-borne infections in tick samples from China evaluated by nested PCRs. Acta Trop 2016; 158:181-188. [PMID: 26943995 DOI: 10.1016/j.actatropica.2016.02.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 02/24/2016] [Accepted: 02/29/2016] [Indexed: 10/22/2022]
Abstract
An investigation was performed to detect eight pathogens in ticks collected from grass tips or animals in the southern, central and northeast regions of China. DNA samples extracted from ticks were collected from ten different locations in eight provinces of China and subjected to screening for tick-borne pathogens, including Borrelia burgdorferi sensu lato, Ehrlichia spp., Rickettsia spp., Babesia/Theileria spp., Ehrlichia ruminantium, Coxiella burnetii, and Francisella tularensis, using nested PCR assays and sequencing analysis. The results indicated that Borrelia spp., Rickettsia spp., and Babesia/Theileria spp. were detected in all of the investigated provinces. Ehrlichia spp. was also found in all of the surveyed areas, except Guangxi, Luobei and Tonghe counties in Heilongjiang province. The average prevalence of these pathogens was 18.4% (95% CI=12.8-42.5), 60.3% (95% CI=18.2-65.3), 26.0% (95% CI=25.8-65.1), and 28.7% (95% CI=5.6-35.2), respectively. A sequencing analysis of the pCS20 gene of E. ruminantium revealed an E. ruminantium-like organism (1/849, 0.1%, 95% CI=0-0.3) in one tick DNA sample extracted from Rhipicephalus (Boophilus) microplus in Hunan. In addition, Borrelia americana in Ixodes persulcatus, Babesia occultans in Haemaphysalis qinghaiensis and both Rhipicephalus sanguineus and an Ehrlichia muris-like organism in R. (B.) microplus was detected, possibly for the first time in China. Four DNA sequences closely related to Borrelia carolinensis and/or Borrelia bissettii from Haemaphysalis longicornis, Candidatus Rickettsia principis from H. qinghaiensis, and I. persulcatus and Ehrlichia canis (named E. canis-like) from Haemaphysalis bispinosa were also detected in this work.
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Koh FX, Panchadcharam C, Tay ST. Vector-Borne Diseases in Stray Dogs in Peninsular Malaysia and Molecular Detection of Anaplasma and Ehrlichia spp. from Rhipicephalus sanguineus (Acari: Ixodidae) Ticks. JOURNAL OF MEDICAL ENTOMOLOGY 2016; 53:183-187. [PMID: 26494821 DOI: 10.1093/jme/tjv153] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 09/13/2015] [Indexed: 06/05/2023]
Abstract
Little data are available on the prevalence and transmission of vector-borne diseases in stray dogs in Peninsular Malaysia. This study was designed to determine the occurrence of vector-borne pathogens in Malaysian stray dogs using serological and molecular approaches. In total, 48 dog blood samples were subjected to serological analysis using SNAP 4Dx kit (IDEXX Laboratories, Westbrook, ME). The presence of Ehrlichia and Anaplasma DNA in the dog blood samples and Rhipicephalus sanguineus (Latreille) ticks was detected using nested polymerase chain reaction assays. Positive serological findings against Ehrlichia canis and Anaplasma phagocytophilum were obtained in 17 (39.5%) and four (9.3%) of 43 dog samples, respectively. None of the dog blood samples were positive for Borrelia burgdorferi and Dirofilaria immitis. DNA of E. canis and A. phagocytophilum was detected in 12 (25.5%) and two (4.3%) of 47 dog blood samples, and 17 (51.5%) and one (3.0%) of 33 R. sanguineus ticks, respectively. Additionally, DNA of Ehrlichia spp. closely related to Ehrlichia chaffeensis was detected in two (6.1%) R. sanguineus ticks. This study highlights the prevalence of anaplasmosis and ehrlichiosis in dogs in Malaysia. Due to the zoonotic potential of Ehrlichia and Anaplasma spp., appropriate measures should be instituted for prevention and control of vector-borne diseases in dogs.
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Affiliation(s)
- Fui Xian Koh
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia (; )
| | | | - Sun Tee Tay
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia (; ),
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Detection of Rickettsia and Ehrlichia spp. in Ticks Associated with Exotic Reptiles and Amphibians Imported into Japan. PLoS One 2015. [PMID: 26207382 PMCID: PMC4514593 DOI: 10.1371/journal.pone.0133700] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
One of the major routes of transmission of rickettsial and ehrlichial diseases is via ticks that infest numerous host species, including humans. Besides mammals, reptiles and amphibians also carry ticks that may harbor Rickettsia and Ehrlichia strains that are pathogenic to humans. Furthermore, reptiles and amphibians are exempt from quarantine in Japan, thus facilitating the entry of parasites and pathogens to the country through import. Accordingly, in the current study, we examined the presence of Rickettsia and Ehrlichia spp. genes in ticks associated with reptiles and amphibians originating from outside Japan. Ninety-three ticks representing nine tick species (genera Amblyomma and Hyalomma) were isolated from at least 28 animals spanning 10 species and originating from 12 countries (Ghana, Jordan, Madagascar, Panama, Russia, Sri Lanka, Sudan, Suriname, Tanzania, Togo, Uzbekistan, and Zambia). None of the nine tick species are indigenous in Japan. The genes encoding the common rickettsial 17-kDa antigen, citrate synthase (gltA), and outer membrane protein A (ompA) were positively detected in 45.2% (42/93), 40.9% (38/93), and 23.7% (22/93) of the ticks, respectively, by polymerase chain reaction (PCR). The genes encoding ehrlichial heat shock protein (groEL) and major outer membrane protein (omp-1) were PCR-positive in 7.5% (7/93) and 2.2% (2/93) of the ticks, respectively. The p44 gene, which encodes the Anaplasma outer membrane protein, was not detected. Phylogenetic analysis showed that several of the rickettsial and ehrlichial sequences isolated in this study were highly similar to human pathogen genes, including agents not previously detected in Japan. These data demonstrate the global transportation of pathogenic Rickettsia and Ehrlichia through reptile- and amphibian-associated ticks. These imported animals have potential to transfer pathogens into human life. These results highlight the need to control the international transportation of known and potential pathogens carried by ticks in reptiles, amphibians, and other animals, in order to improve national and international public health.
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Ogawa K, Komagata O, Hayashi T, Itokawa K, Morikawa S, Sawabe K, Tomita T. Field and Laboratory Evaluations of the Efficacy of DEET Repellent against Ixodes Ticks. Jpn J Infect Dis 2015; 69:131-4. [PMID: 26073735 DOI: 10.7883/yoken.jjid.2015.038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The objective of this study was to clarify the efficacy of a currently available N,N-diethyl-m-toluamide (DEET) repellent against tick species in Japan. We performed 2 different field trials: "human trap," and "flag-dragging." In total, 482 ticks were collected from white flannel cloths in the field studies. The collected tick species were Ixodes persulcatus and I. ovatus, which accounted for 5.3% and 94.7% of the ticks in the human trap test and 31.4% and 68.6% in the flag-dragging test, respectively. The repellency levels of DEET-treated flannel cloths in the human trap and flag-dragging tests were 84.0% and 99.7%, respectively. The escape times for I. persulcatus and I. ovatus female adults from DEET-treated flannel cloths were determined. The median escape times for I. persulcatus and I. ovatus on DEET-treated flannel cloths were 48 s (95% confidence interval [CI]: 30-96) and 10 s (95% CI: 5-24), respectively. In contrast, many ticks remained on the untreated flannel cloths for 10 min after mounting. These results indicate that DEET repellents appear to prevent tick bites and that the use of DEET repellents against ticks is an effective personal protection measure.
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Affiliation(s)
- Kohei Ogawa
- Department of Medical Entomology, National Institute of Infectious Diseases
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Rar VA, Pukhovskaya NM, Ryabchikova EI, Vysochina NP, Bakhmetyeva SV, Zdanovskaia NI, Ivanov LI, Tikunova NV. Molecular-genetic and ultrastructural characteristics of 'Candidatus Ehrlichia khabarensis', a new member of the Ehrlichia genus. Ticks Tick Borne Dis 2015; 6:658-67. [PMID: 26096852 DOI: 10.1016/j.ttbdis.2015.05.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 05/22/2015] [Accepted: 05/28/2015] [Indexed: 11/24/2022]
Abstract
Recently, a new Ehrlichia genetic variant, Ehrlichia sp. Khabarovsk, was identified in tissue samples of small mammals captured in the Russian Far East. To further characterize Ehrlichia sp. Khabarovsk, tissue homogenate from a naturally infected gray red-backed vole (Myodes rufocanus) was passaged three times in newborn laboratory mice. Using nested PCR Ehrlichia sp. Khabarovsk DNA was detected in tissue samples from infected mice at 1-4 weeks post inoculation. Electron microscopic examination revealed morulae containing gram-negative bacterial cells in monocytes of mouse spleen and liver. The size and ultrastructure of these cells corresponded to those described previously and allowed us to identify the bacteria as Ehrlichia sp. The comparison of ehrlichial 16S rRNA, groEL and gltA genes and putative GroEL and GltA amino acid sequences has demonstrated that Ehrlichia sp. Khabarovsk, like Ehrlichia ruminantium, is more distant from all other Ehrlichia species than these species are between themselves. Phylogenetic analysis has shown that Ehrlichia sp. Khabarovsk belongs to the clade formed by Ehrlichia spp. but clusters separately from other Ehrlichia species and genetic variants. These data indicate that Ehrlichia sp. Khabarovsk can be considered as a new candidate species. We propose to designate it as 'Candidatus Ehrlichia khabarensis' according to the territory where this species was found.
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Affiliation(s)
- V A Rar
- Institute of Chemical Biology and Fundamental Medicine, SB RAS, Novosibirsk, Russian Federation.
| | - N M Pukhovskaya
- Khabarovsk Antiplague Station, Khabarovsk, Russian Federation
| | - E I Ryabchikova
- Institute of Chemical Biology and Fundamental Medicine, SB RAS, Novosibirsk, Russian Federation
| | - N P Vysochina
- Khabarovsk Antiplague Station, Khabarovsk, Russian Federation
| | - S V Bakhmetyeva
- Khabarovsk Antiplague Station, Khabarovsk, Russian Federation
| | - N I Zdanovskaia
- Khabarovsk Antiplague Station, Khabarovsk, Russian Federation
| | - L I Ivanov
- Khabarovsk Antiplague Station, Khabarovsk, Russian Federation
| | - N V Tikunova
- Institute of Chemical Biology and Fundamental Medicine, SB RAS, Novosibirsk, Russian Federation
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Yu Z, Wang H, Wang T, Sun W, Yang X, Liu J. Tick-borne pathogens and the vector potential of ticks in China. Parasit Vectors 2015; 8:24. [PMID: 25586007 PMCID: PMC4300027 DOI: 10.1186/s13071-014-0628-x] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 12/29/2014] [Indexed: 11/13/2022] Open
Abstract
Ticks, as obligate blood-sucking ectoparasites, attack a broad range of vertebrates and transmit a great diversity of pathogenic microorganisms. They are considered second only to mosquitoes as vectors of human disease, and the most important vector of pathogens of domestic and wild animals. Of the 117 described species in the Chinese tick fauna, 60 are known to transmit one or more diseases: 36 species isolated within China and 24 species isolated outside China. Moreover, 38 of these species carry multiple pathogens, indicating the potentially vast role of these vectors in transmitting pathogens. Spotted fever is the most common tick-borne disease, and is carried by at least 27 tick species, with Lyme disease and human granulocytic anaplasmosis ranked as the second and third most widespread tick-borne diseases, carried by 13 and 10 species, respectively. Such knowledge provides us with clues for the identification of tick-associated pathogens and suggests ideas for the control of tick-borne diseases in China. However, the numbers of tick-associated pathogens and tick-borne diseases in China are probably underestimated because of the complex distribution and great diversity of tick species in this country.
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Affiliation(s)
- Zhijun Yu
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China.
| | - Hui Wang
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China.
| | - Tianhong Wang
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China.
| | - Wenying Sun
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China.
| | - Xiaolong Yang
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China.
| | - Jingze Liu
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China.
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Qiu Y, Nakao R, Ohnuma A, Kawamori F, Sugimoto C. Microbial population analysis of the salivary glands of ticks; a possible strategy for the surveillance of bacterial pathogens. PLoS One 2014; 9:e103961. [PMID: 25089898 PMCID: PMC4121176 DOI: 10.1371/journal.pone.0103961] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 07/07/2014] [Indexed: 12/31/2022] Open
Abstract
Ticks are one of the most important blood-sucking vectors for infectious microorganisms in humans and animals. When feeding they inject saliva, containing microbes, into the host to facilitate the uptake of blood. An understanding of the microbial populations within their salivary glands would provide a valuable insight when evaluating the vectorial capacity of ticks. Three tick species (Ixodes ovatus, I. persulcatus and Haemaphysalis flava) were collected in Shizuoka Prefecture of Japan between 2008 and 2011. Each tick was dissected and the salivary glands removed. Bacterial communities in each salivary gland were characterized by 16S amplicon pyrosequencing using a 454 GS-Junior Next Generation Sequencer. The Ribosomal Database Project (RDP) Classifier was used to classify sequence reads at the genus level. The composition of the microbial populations of each tick species were assessed by principal component analysis (PCA) using the Metagenomics RAST (MG-RAST) metagenomic analysis tool. Rickettsia-specific PCR was used for the characterization of rickettsial species. Almost full length of 16S rDNA was amplified in order to characterize unclassified bacterial sequences obtained in I. persulcatus female samples. The numbers of bacterial genera identified for the tick species were 71 (I. ovatus), 127 (I. persulcatus) and 59 (H. flava). Eighteen bacterial genera were commonly detected in all tick species. The predominant bacterial genus observed in all tick species was Coxiella. Spiroplasma was detected in Ixodes, and not in H. flava. PCA revealed that microbial populations in tick salivary glands were different between tick species, indicating that host specificities may play an important role in determining the microbial complement. Four female I. persulcatus samples contained a high abundance of several sequences belonging to Alphaproteobacteria symbionts. This study revealed the microbial populations within the salivary glands of three species of ticks, and the results will contribute to the knowledge and prediction of emerging tick-borne diseases.
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Affiliation(s)
- Yongjin Qiu
- Division of Collaboration and Education, Hokkaido University Research Center for Zoonosis Control, Sapporo, Japan
| | - Ryo Nakao
- Unit of Risk Analysis and Management, Hokkaido University Research Center for Zoonosis Control, Sapporo, Japan
| | - Aiko Ohnuma
- Administration Office, Hokkaido University Research Center for Zoonosis Control, Sapporo, Japan
| | - Fumihiko Kawamori
- Department of Microbiology, Shizuoka Prefectural Institute of Public Health and Environmental Science, Shizuoka, Japan
| | - Chihiro Sugimoto
- Division of Collaboration and Education, Hokkaido University Research Center for Zoonosis Control, Sapporo, Japan
- * E-mail:
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Saito TB, Thirumalapura NR, Shelite TR, Rockx-Brouwer D, Popov VL, Walker DH. An animal model of a newly emerging human ehrlichiosis. J Infect Dis 2014; 211:452-61. [PMID: 24990203 DOI: 10.1093/infdis/jiu372] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Human ehrlichioses are emerging life-threatening diseases transmitted by ticks. Animal models have been developed to study disease development; however, there is no valid small animal model that uses a human ehrlichial pathogen. The objective of this study was to develop a mouse model for ehrlichiosis with the newly discovered human pathogen, Ehrlichia muris-like agent (EMLA). METHODS Three strains of mice were inoculated with different doses of EMLA by the intravenous, intraperitoneal, or intradermal route and evaluated for clinical and pathologic changes during the course of infection. RESULTS EMLA infected C57Bl/6, BALB/c, and C3H/HeN mice and induced lethal or persistent infection in a route- and dose-dependent manner. The clinical chemistry and hematologic changes were similar to those of human infection by Ehrlichia chaffeensis or EMLA. Bacterial distribution in tissues differed after intradermal infection, compared with the distribution after intravenous or intraperitoneal injection. Lethal infection did not cause remarkable pathologic changes, but it caused fluid imbalance. EMLA infection of endothelium and mononuclear cells likely plays a role in the severe outcome. CONCLUSIONS The EMLA mouse model mimics human infection and can be used to study pathogenesis and immunity and for development of a vector transmission model of ehrlichiosis.
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Affiliation(s)
- Tais Berelli Saito
- Department of Pathology, University of Texas Medical Branch at Galveston
| | | | - Thomas R Shelite
- Department of Pathology, University of Texas Medical Branch at Galveston
| | | | - Vsevolod L Popov
- Department of Pathology, University of Texas Medical Branch at Galveston
| | - David H Walker
- Department of Pathology, University of Texas Medical Branch at Galveston
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Aguiar DM, Ziliani TF, Zhang X, Melo ALT, Braga IA, Witter R, Freitas LC, Rondelli ALH, Luis MA, Sorte ECB, Jaune FW, Santarém VA, Horta MC, Pescador CA, Colodel EM, Soares HS, Pacheco RC, Onuma SSM, Labruna MB, McBride JW. A novel Ehrlichia genotype strain distinguished by the TRP36 gene naturally infects cattle in Brazil and causes clinical manifestations associated with ehrlichiosis. Ticks Tick Borne Dis 2014; 5:537-44. [PMID: 24915874 DOI: 10.1016/j.ttbdis.2014.03.010] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 03/19/2014] [Accepted: 03/31/2014] [Indexed: 10/25/2022]
Abstract
A novel Ehrlichia genotype most closely related to E. canis was reported in North American cattle in 2010, and a similar agent was subsequently identified in the hemolymph of Brazilian Rhipicephalus (Boophilus) microplus ticks and isolated in 2012. The purpose of this study was to determine whether this or other novel ehrlichial agents naturally infect Brazilian cattle. Using PCR targeting the genus-conserved dsb gene, DNA from this novel ehrlichial agent in Brazilian cattle was detected. Attempts to isolate the organism in vitro were performed using DH82 cells, but morulae and ehrlichial DNA could only be detected for approximately one month. In order to further molecularly characterize the organism, PCR was performed using primers specific for multiple E. canis genes (dsb, rrs, and trp36). Sequence obtained from the conserved rrs and dsb genes demonstrated that the organism was 99-100% identical to the novel Ehrlichia genotypes previously reported in North American cattle (rrs gene) and Brazilian ticks (rrs and dsb genes). However, analysis of the trp36 gene revealed substantial strain diversity between these Ehrlichia genotypes strains, including divergent tandem repeat sequences. In order to obtain preliminary information on the potential pathogenicity of this ehrlichial agent and clinical course of infection, a calf was experimentally infected. The calf showed clinical signs of ehrlichiosis, including fever, depression, lethargy, thrombocytopenia, and morulae were observed in peripheral blood monocytes. This study reports a previously unrecognized disease-causing Ehrlichia sp. in Brazilian cattle that is consistent with the genotype previously described in North America cattle and ticks from Brazil. Hence, it is likely that this is the organism previously identified as Ehrlichia bovis in Brazil in 1982. Furthermore, we have concluded that strains of these Ehrlichia genotypes can be molecularly distinguished by the trp36 gene, which has been widely utilized to define E. canis strain diversity.
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Affiliation(s)
- Daniel M Aguiar
- Department of Pathology, Center of Biodefense and Emerging Infectious Diseases, Sealy Center for Vaccine Development and Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA; Laboratório de Virologia e Rickettsioses, Hospital Veterinário da Universidade Federal de Mato Grosso (HOVET-UFMT), Cuiabá, MT, Brazil.
| | - Thayza F Ziliani
- Laboratório de Virologia e Rickettsioses, Hospital Veterinário da Universidade Federal de Mato Grosso (HOVET-UFMT), Cuiabá, MT, Brazil
| | - Xiaofeng Zhang
- Department of Pathology, Center of Biodefense and Emerging Infectious Diseases, Sealy Center for Vaccine Development and Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Andreia L T Melo
- Laboratório de Virologia e Rickettsioses, Hospital Veterinário da Universidade Federal de Mato Grosso (HOVET-UFMT), Cuiabá, MT, Brazil
| | - Isis A Braga
- Laboratório de Virologia e Rickettsioses, Hospital Veterinário da Universidade Federal de Mato Grosso (HOVET-UFMT), Cuiabá, MT, Brazil
| | - Rute Witter
- Laboratório de Virologia e Rickettsioses, Hospital Veterinário da Universidade Federal de Mato Grosso (HOVET-UFMT), Cuiabá, MT, Brazil
| | - Leodil C Freitas
- Laboratório de Parasitologia Veterinária e Doenças Parasitárias, HOVET-UFMT, Cuiabá, MT, Brazil
| | | | - Michele A Luis
- Clinica Médica de Grandes Animais, HOVET-UFMT, Cuiabá, MT, Brazil
| | - Eveline C B Sorte
- Laboratório de Patologia Clínica Veterinária, HOVET-UFMT, Cuiabá, MT, Brazil
| | - Felipe W Jaune
- Laboratório de Virologia e Rickettsioses, Hospital Veterinário da Universidade Federal de Mato Grosso (HOVET-UFMT), Cuiabá, MT, Brazil
| | - Vamilton A Santarém
- Laboratório de Medicina Veterinária Preventiva II, Universidade do Oeste Paulista, Presidente Prudente, SP, Brazil
| | - Mauricio C Horta
- Colegiado do curso de Medicina Veterinária, Universidade Federal do Vale do São Francisco, Petrolina, PE, Brazil
| | | | - Edson M Colodel
- Laboratório de Patologia Veterinária, HOVET-UFMT, Cuiabá, MT, Brazil
| | - Herbert S Soares
- Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Richard C Pacheco
- Laboratório de Parasitologia Veterinária e Doenças Parasitárias, HOVET-UFMT, Cuiabá, MT, Brazil
| | - Selma S M Onuma
- Estação Ecológica de Taiamã, Instituto Chico Mendes de Conservação da biodiversidade (ICMBio), Cáceres, MT, Brazil
| | - Marcelo B Labruna
- Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Jere W McBride
- Department of Pathology, Center of Biodefense and Emerging Infectious Diseases, Sealy Center for Vaccine Development and Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
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Type I interferons promote severe disease in a mouse model of lethal ehrlichiosis. Infect Immun 2014; 82:1698-709. [PMID: 24491580 DOI: 10.1128/iai.01564-13] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Human monocytic ehrlichiosis (HME) is caused by a tick-borne obligate intracellular pathogen of the order Rickettsiales. HME disease can range from mild to a fatal, toxic shock-like syndrome, yet the mechanisms regulating pathogenesis are not well understood. We define a central role for type I interferons (alpha interferon [IFN-α] and IFN-β) in severe disease in a mouse model of fatal ehrlichiosis caused by Ixodes ovatus Ehrlichia (IOE). IFN-α and IFN-β were induced by IOE infection but not in response to a less virulent strain, Ehrlichia muris. The major sources of type I IFNs during IOE infection were plasmacytoid dendritic cells and monocytes. Mice lacking the receptor for type I IFNs (Ifnar deficient) or neutralization of IFN-α and IFN-β resulted in a reduced bacterial burden. Ifnar-deficient mice exhibited significantly increased survival after IOE infection, relative to that of wild-type (WT) mice, that correlated with increased type II IFN (IFN-γ) production. Pathogen-specific antibody responses were also elevated in Ifnar-deficient mice, and this required IFN-γ. Remarkably, increased IFN-γ and IgM were not essential for protection in the absence of type I IFN signaling. The direct effect of type I IFNs on hematopoietic and nonhematopoietic cells was evaluated in bone marrow chimeric mice. We observed that chimeric mice containing Ifnar-deficient hematopoietic cells succumbed to infection early, whereas Ifnar-deficient mice containing WT hematopoietic cells exhibited increased survival, despite having a higher bacterial burden. These data demonstrate that IFN-α receptor signaling in nonhematopoietic cells is important for pathogenesis. Thus, type I IFNs are induced during a rickettsial infection in vivo and promote severe disease.
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Rar VA, Epikhina TI, Pukhovskaya NM, Vysochina NP, Ivanov LI. Genetic variability of anaplasmataceae bacteria determined in Haemaphysalis spp. and Dermacentor sp. Ticks on the territory of the Russian Far East. MOLECULAR GENETICS MICROBIOLOGY AND VIROLOGY 2013. [DOI: 10.3103/s0891416813020055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Evaluation of peripheral blood lymphocyte subsets in family-owned dogs naturally infected by Ehrlichia canis. Comp Immunol Microbiol Infect Dis 2012; 35:391-6. [DOI: 10.1016/j.cimid.2012.03.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 03/05/2012] [Accepted: 03/16/2012] [Indexed: 11/22/2022]
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Rar V, Golovljova I. Anaplasma, Ehrlichia, and “Candidatus Neoehrlichia” bacteria: Pathogenicity, biodiversity, and molecular genetic characteristics, a review. INFECTION GENETICS AND EVOLUTION 2011; 11:1842-61. [DOI: 10.1016/j.meegid.2011.09.019] [Citation(s) in RCA: 182] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 09/23/2011] [Accepted: 09/23/2011] [Indexed: 12/18/2022]
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Ghose P, Ali AQ, Fang R, Forbes D, Ballard B, Ismail N. The interaction between IL-18 and IL-18 receptor limits the magnitude of protective immunity and enhances pathogenic responses following infection with intracellular bacteria. THE JOURNAL OF IMMUNOLOGY 2011; 187:1333-46. [PMID: 21715688 DOI: 10.4049/jimmunol.1100092] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The binding of IL-18 to IL-18Rα induces both proinflammatory and protective functions during infection, depending on the context in which it occurs. IL-18 is highly expressed in the liver of wild-type (WT) C57BL/6 mice following lethal infection with highly virulent Ixodes ovatus ehrlichia (IOE), an obligate intracellular bacterium that causes acute fatal toxic shock-like syndrome. In this study, we found that IOE infection of IL-18Rα(-/-) mice resulted in significantly less host cell apoptosis, decreased hepatic leukocyte recruitment, enhanced bacterial clearance, and prolonged survival compared with infected WT mice, suggesting a pathogenic role for IL-18/IL-18Rα in Ehrlichia-induced toxic shock. Although lack of IL-18R decreased the magnitude of IFN-γ producing type-1 immune response, enhanced resistance of IL-18Rα(-/-) mice against Ehrlichia correlated with increased proinflammatory cytokines at sites of infection, decreased systemic IL-10 production, increased frequency of protective NKT cells producing TNF-α and IFN-γ, and decreased frequency of pathogenic TNF-α-producing CD8(+) T cells. Adoptive transfer of immune WT CD8(+) T cells increased bacterial burden in IL-18Rα(-/-) mice following IOE infection. Furthermore, rIL-18 treatment of WT mice infected with mildly virulent Ehrlichia muris impaired bacterial clearance and enhanced liver injury. Finally, lack of IL-18R signal reduced dendritic cell maturation and their TNF-α production, suggesting that IL-18 might promote the adaptive pathogenic immune responses against Ehrlichia by influencing T cell priming functions of dendritic cells. Together, these results suggested that the presence or absence of IL-18R signals governs the pathogenic versus protective immunity in a model of Ehrlichia-induced immunopathology.
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Affiliation(s)
- Purnima Ghose
- Department of Pathology, Meharry Medical College, Nashville, TN 37028, USA
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Abstract
Human ehrlichiosis and anaplasmosis are acute febrile tick-borne diseases caused by various members of the genera Ehrlichia and Anaplasma (Anaplasmataceae). Human monocytotropic ehrlichiosis has become one of the most prevalent life-threatening tick-borne disease in the United States. Ehrlichiosis and anaplasmosis are becoming more frequently diagnosed as the cause of human infections, as animal reservoirs and tick vectors have increased in number and humans have inhabited areas where reservoir and tick populations are high. Ehrlichia chaffeensis, the etiologic agent of human monocytotropic ehrlichiosis (HME), is an emerging zoonosis that causes clinical manifestations ranging from a mild febrile illness to a fulminant disease characterized by multiorgan system failure. Anaplasma phagocytophilum causes human granulocytotropic anaplasmosis (HGA), previously known as human granulocytotropic ehrlichiosis. This article reviews recent advances in the understanding of ehrlichial diseases related to microbiology, epidemiology, diagnosis, pathogenesis, immunity, and treatment of the 2 prevalent tick-borne diseases found in the United States, HME and HGA.
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Koh YS, Koo JE, Biswas A, Kobayashi KS. MyD88-dependent signaling contributes to host defense against ehrlichial infection. PLoS One 2010; 5:e11758. [PMID: 20668698 PMCID: PMC2909256 DOI: 10.1371/journal.pone.0011758] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 07/01/2010] [Indexed: 01/01/2023] Open
Abstract
The ehrlichiae are small Gram-negative obligate intracellular bacteria in the family Anaplasmataceae. Ehrlichial infection in an accidental host may result in fatal diseases such as human monocytotropic ehrlichiosis, an emerging, tick-borne disease. Although the role of adaptive immune responses in the protection against ehrlichiosis has been well studied, the mechanism by which the innate immune system is activated is not fully understood. Using Ehrlichia muris as a model organism, we show here that MyD88-dependent signaling pathways play a pivotal role in the host defense against ehrlichial infection. Upon E. muris infection, MyD88-deficient mice had significantly impaired clearance of E. muris, as well as decreased inflammation, characterized by reduced splenomegaly and recruitment of macrophages and neutrophils. Furthermore, MyD88-deficient mice produced markedly lower levels of IL-12, which correlated well with an impaired Th1 immune response. In vitro, dendritic cells, but not macrophages, efficiently produced IL-12 upon E. muris infection through a MyD88-dependent mechanism. Therefore, MyD88-dependent signaling is required for controlling ehrlichial infection by playing an essential role in the immediate activation of the innate immune system and inflammatory cytokine production, as well as in the activation of the adaptive immune system at a later stage by providing for optimal Th1 immune responses.
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Affiliation(s)
- Young-Sang Koh
- Department of Cancer Immunology & AIDS, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Microbiology and Brain Korea 21 Program, Jeju National University School of Medicine, Jeju, Jeju-Do, South Korea
| | - Jung-Eun Koo
- Department of Microbiology and Brain Korea 21 Program, Jeju National University School of Medicine, Jeju, Jeju-Do, South Korea
| | - Amlan Biswas
- Department of Cancer Immunology & AIDS, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Koichi S. Kobayashi
- Department of Cancer Immunology & AIDS, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Stevenson HL, Estes MD, Thirumalapura NR, Walker DH, Ismail N. Natural killer cells promote tissue injury and systemic inflammatory responses during fatal Ehrlichia-induced toxic shock-like syndrome. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 177:766-76. [PMID: 20616341 DOI: 10.2353/ajpath.2010.091110] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Human monocytotropic ehrlichiosis is caused by Ehrlichia chaffeensis, a Gram-negative bacterium lacking lipopolysaccharide. We have shown that fatal murine ehrlichiosis is associated with CD8(+)T cell-mediated tissue damage, tumor necrosis factor-alpha, and interleukin (IL)-10 overproduction, and CD4(+)Th1 hyporesponsiveness. In this study, we examined the relative contributions of natural killer (NK) and NKT cells in Ehrlichia-induced toxic shock. Lethal ehrlichial infection in wild-type mice induced a decline in NKT cell numbers, and late expansion and migration of activated NK cells to the liver, a main infection site that coincided with development of hepatic injury. The spatial and temporal changes in NK and NKT cells in lethally infected mice correlated with higher NK cell cytotoxic activity, higher expression of cytotoxic molecules such as granzyme B, higher production of interferon-gamma and tumor necrosis factor-alpha, increased hepatic infiltration with CD8alphaCD11c(+) dendritic cells and CD8(+)T cells, decreased splenic CD4(+)T cells, increased serum concentrations of IL-12p40, IL-18, RANTES, and monocyte chemotactic protein-1, and elevated production of IL-18 by liver mononuclear cells compared with nonlethally infected mice. Depletion of NK cells prevented development of severe liver injury, decreased serum levels of interferon-gamma, tumor necrosis factor-alpha, and IL-10, and enhanced bacterial elimination. These data indicate that NK cells promote immunopathology and defective anti-ehrlichial immunity, possibly via decreasing the protective immune response mediated by interferon-gamma producing CD4(+)Th1 and NKT cells.
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Affiliation(s)
- Heather L Stevenson
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
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Antigen display, T-cell activation, and immune evasion during acute and chronic ehrlichiosis. Infect Immun 2009; 77:4643-53. [PMID: 19635826 DOI: 10.1128/iai.01433-08] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
How spatial and temporal changes in major histocompatibility complex/peptide antigen presentation to CD4 T cells regulate CD4 T-cell responses during intracellular bacterial infections is relatively unexplored. We have shown that immunization with an ehrlichial outer membrane protein, OMP-19, protects mice against fatal ehrlichial challenge infection, and we identified a CD4 T-cell epitope (IA(b)/OMP-19(107-122)) that elicited CD4 T cells following either immunization or infection. Here, we have used an IA(b)/OMP-19(107-122)-specific T-cell line to monitor antigen display ex vivo during acute and chronic infection with Ehrlichia muris, a bacterium that establishes persistent infection in C57BL/6 mice. The display of IA(b)/OMP-19(107-122) by host antigen-presenting cells was detected by measuring intracellular gamma interferon (IFN-gamma) production by the T-cell line. After intravenous infection, antigen presentation was detected in the spleen, peritoneal exudate cells, and lymph nodes, although the kinetics of antigen display differed among the tissues. Antigen presentation and bacterial colonization were closely linked in each anatomical location, and there was a direct relationship between antigen display and CD4 T-cell effector function. Spleen and lymph node dendritic cells (DCs) were efficient presenters of IA(b)/OMP-19(107-122), demonstrating that DCs play an important role in ehrlichial infection and immunity. Chronic infection and antigen presentation occurred within the peritoneal cavity, even in the presence of highly activated CD4 T cells. These data indicated that the ehrlichiae maintain chronic infection not by inhibiting antigen presentation or T-cell activation but, in part, by avoiding signals mediated by activated T cells.
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Thomas S, Thirumalapura N, Crossley EC, Ismail N, Walker DH. Antigenic protein modifications in Ehrlichia. Parasite Immunol 2009; 31:296-303. [PMID: 19493209 PMCID: PMC2731653 DOI: 10.1111/j.1365-3024.2009.01099.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
To develop effective vaccination strategies againstEhrlichia, we have previously reported developing an animal model of cross-protection in which C57BL/6 mice primed withE. muris were resistant to lethal infection withIxodes ovatus ehrlichia (IOE). Polyclonal antibody produced in mice after priming withE. muris and later injected with IOE-detected antigenic proteins inE. muris and IOE cell lysates. Cross-reaction of antigenic proteins was observed when we probed both theE. muris and IOE cell lysates with IOE andE. muris-specific polyclonal antibody. Analysis of the total proteins ofE. muris and IOE by two dimensional electrophoresis showed that bothE. muris and IOE have the same antigenic proteins. Finally, studies on post-translational protein modifications using a novel technique, Eastern blotting, showed thatE. muris proteins are more lipoylated and glycosylated than those of IOE.
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Affiliation(s)
- S Thomas
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, USA
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Munderloh UG, Silverman DJ, MacNamara KC, Ahlstrand GG, Chatterjee M, Winslow GM. Ixodes ovatus Ehrlichia exhibits unique ultrastructural characteristics in mammalian endothelial and tick-derived cells. Ann N Y Acad Sci 2009; 1166:112-9. [PMID: 19538270 DOI: 10.1111/j.1749-6632.2009.04520.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Tick-borne pathogens in the genus Ehrlichia cause emerging zoonoses. Although laboratory mice are susceptible to Ehrlichia infections, many isolates do not cause clinical illness. In contrast, the Ixodes ovatus Ehrlichia-like agent (IOE) causes disease and immune responses in mice comparable to the human illness caused by Ehrlichia chaffeensis. No culture system had been developed for IOE, however, which limited studies of this pathogen. We reasoned that endothelial and tick cell lines could potentially serve as host cells, since the IOE is found in ticks and in endothelial cells in mice. Infected spleen cells from RAG-deficient mice were overlaid onto ISE6 and RF/6A cultures, and colonies typical of Ehrlichia were noted in RF/6A cells within 2 weeks. Infection of ISE6 cells was established after transfer of IOE from RF/6A cells. Electron microscopy revealed densely packed inclusions in infected RF/6A and ISE6 cells; these inclusions contained copious amounts of filamentous structures, apparently originating from Ehrlichial cells. In particular, within RF/6A cells the structures assumed an ordered morphology of finely combed hair. IOE from RF/6A cells, when inoculated into C57BL/6 and RAG-deficient mice, induced fatal disease. These data reveal unique structural features of IOE that may contribute to the pathogen's high virulence.
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Affiliation(s)
- Ulrike G Munderloh
- Department of Entomology, University of Minnesota, St. Paul, Minnesota 55108, USA
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Takano A, Ando S, Kishimoto T, Fujita H, Kadosaka T, Nitta Y, Kawabata H, Watanabe H. Presence of a novel Ehrlichia sp. in Ixodes granulatus found in Okinawa, Japan. Microbiol Immunol 2009; 53:101-6. [PMID: 19291093 DOI: 10.1111/j.1348-0421.2008.00093.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ehrlichia-specific DNA fragments of Ehrlichia omp-1 and groEL genes were found in two I. granulatus ticks which had been collected from wild small mammals in a subtropical zone in Japan. The DNA sequences of groEL and 16SrDNA of the suspected Ehrlichia were clustered into a group of E. chaffeensis, E. muris, and Ehrlichia sp. HF565 found in I. ovatus, but were distinctly different. Therefore the Ehrlichia strain was designated as a novel Ehrlichia sp. 360. The Ehrlichia sp. 360 was detected in I. granulatus but not in any other ticks. This suggests that I. granulatus is a probable vector of Ehrlichia sp. 360 in Japan.
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Affiliation(s)
- Ai Takano
- Department of Bacteriology, National Institute of Infectious Diseases, Tokyo, Japan
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Chapes SK, Ganta RR. Defining the immune response to Ehrlichia species using murine models. Vet Parasitol 2008; 158:344-59. [PMID: 19028013 DOI: 10.1016/j.vetpar.2008.09.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Revised: 09/06/2008] [Accepted: 09/09/2008] [Indexed: 01/01/2023]
Abstract
Pathogenic bacteria belonging to the family Anaplasmataceae include species of the genera Ehrlichia and Anaplasma. Ehrlichia chaffeensis, first known as the causative agent of human monocytic ehrlichiosis, also infects several vertebrate hosts including white-tailed deer, dogs, coyotes and goats. E. chaffeensis is transmitted from the bite of an infected hard tick, such as Amblyomma americanum. E. chaffeensis and other tick-transmitted pathogens have adapted to both the tick and vertebrate host cell environments. Although E. chaffeensis persists in both vertebrate and tick hosts for long periods of time, little is known about that process. Immunological studies will be valuable in assessing how the pathogen persists in nature in both vertebrate and invertebrate hosts. Understanding the host immune response to the pathogen originating from dual host backgrounds is also important to develop effective methods of diagnosis, control and treatment. In this paper, we provide our perspective of the current understanding of the immune response against E. chaffeensis in relation to other related Anaplasmataceae pathogens.
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Affiliation(s)
- Stephen K Chapes
- Division of Biology, College of Arts and Sciences, Kansas State University, Manhattan, KS 66506, USA
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Stich RW, Schaefer JJ, Bremer WG, Needham GR, Jittapalapong S. Host surveys, ixodid tick biology and transmission scenarios as related to the tick-borne pathogen, Ehrlichia canis. Vet Parasitol 2008; 158:256-73. [PMID: 18963493 DOI: 10.1016/j.vetpar.2008.09.013] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Revised: 08/20/2008] [Accepted: 08/20/2008] [Indexed: 10/21/2022]
Abstract
The ehrlichioses have been subject to increasing interest from veterinary and public health perspectives, but experimental studies of these diseases and their etiologic agents can be challenging. Ehrlichia canis, the primary etiologic agent of canine monocytic ehrlichiosis, is relatively well characterized and offers unique advantages and opportunities to study interactions between a monocytotropic pathogen and both its vertebrate and invertebrate hosts. Historically, advances in tick-borne disease control strategies have typically followed explication of tick-pathogen-vertebrate interactions, thus it is reasonable to expect novel, more sustainable approaches to control of these diseases as the transmission of their associated infections are investigated at the molecular through ecological levels. Better understanding of the interactions between E. canis and its canine and tick hosts would also elucidate similar interactions for other Ehrlichia species as well as the potential roles of canine sentinels, reservoirs and models of tick-borne zoonoses. This article summarizes natural exposure studies and experimental investigations of E. canis in the context of what is understood about biological vectors of tick-borne Anaplasmataceae.
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Affiliation(s)
- R W Stich
- Department of Veterinary Pathobiology, The University of Missouri, Columbia, MO 65211, USA.
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44
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Protective heterologous immunity against fatal ehrlichiosis and lack of protection following homologous challenge. Infect Immun 2008; 76:1920-30. [PMID: 18285501 DOI: 10.1128/iai.01293-07] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The roles of antibodies and memory T cells in protection against virulent Ehrlichia have not been completely investigated. In this study, we addressed these issues by using murine models of mild and fatal ehrlichiosis caused by related monocytotropic Ehrlichia strains. Mice were primed with either Ehrlichia muris or closely related virulent ehrlichiae transmitted by Ixodes ovatus (IOE) ticks given intraperitoneally or intradermally. All groups were reinfected intraperitoneally, 30 days later, with a lethal high dose of IOE. Priming with E. muris, but not IOE, induced strong CD4+ and CD8+ memory type 1 T-cell responses, Ehrlichia-specific immunoglobulin G (IgG) antibodies, and persistent infection. Compared to IOE-primed mice, subsequent lethal IOE challenge of E. muris-primed mice, resulted in (i) 100% protection against lethal infection, (ii) strong Ehrlichia-specific secondary gamma interferon (IFN-gamma)-producing effector/effector memory CD4+ and CD8+ T-cell responses, (iii) enhanced secondary anti-ehrlichial antibody response, (iv) accelerated bacterial clearance, and (v) the formation of granulomas in the liver and lung. E. muris-primed mice challenged with IOE had lower levels of serum interleukin-1alpha (IL-1alpha), IL-6, and IL-10 compared to unprimed mice challenged with IOE. Interestingly, the fatal secondary response in IOE-primed mice correlated with (i) decline in the Ehrlichia-specific CD4+ and CD8+ type 1 responses, (ii) marked hepatic apoptosis and necrosis, and (iii) substantial bacterial clearance, suggesting that fatal secondary response is due to immune-mediated tissue damage. In conclusion, protection against fatal ehrlichial infection correlates with strong expansion of IFN-gamma-producing CD4+ and CD8+ effector memory type 1 T cells, which appear to be maintained in the presence of IgG antibodies and persistent infection.
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Regulatory roles of CD1d-restricted NKT cells in the induction of toxic shock-like syndrome in an animal model of fatal ehrlichiosis. Infect Immun 2008; 76:1434-44. [PMID: 18212072 DOI: 10.1128/iai.01242-07] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CD1d-restricted NKT cells are key players in host defense against various microbial infections. Using a murine model of fatal ehrlichiosis, we investigated the role of CD1d-restricted NKT cells in induction of toxic shock-like syndrome caused by gram-negative, lipopolysaccharide-lacking, monocytotropic Ehrlichia. Our previous studies showed that intraperitoneal infection of wild-type (WT) mice with virulent Ehrlichia (Ixodes ovatus Ehrlichia [IOE]) results in CD8+ T-cell-mediated fatal toxic shock-like syndrome marked by apoptosis of CD4+ T cells, a weak CD4+ Th1 response, overproduction of tumor necrosis factor alpha and interleukin-10, and severe liver injury. Although CD1d-/- mice succumbed to high-dose IOE infection similar to WT mice, they did not develop signs of toxic shock, as shown by elevated bacterial burdens, low serum levels of tumor necrosis factor, normal serum levels of liver enzymes, and the presence of few apoptotic hepatic cells. An absence of NKT cells restored the percentages and absolute numbers of CD4+ and CD8+ T cells and CD11b+ cells in the spleen compared to WT mice and was also associated with decreased expression of Fas on splenic CD4+ lymphocytes and granzyme B in hepatic CD8+ lymphocytes. Furthermore, our data show that NKT cells promote apoptosis of macrophages and up-regulation of the costimulatory molecule CD40 on antigen-presenting cells, including dendritic cells, B cells, and macrophages, which may contribute to the induction of pathogenic T-cell responses. In conclusion, our data suggest that NKT cells mediate Ehrlichia-induced T-cell-mediated toxic shock-like syndrome, most likely via cognate and noncognate interactions with antigen-presenting cells.
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Tabara K, Arai S, Kawabuchi T, Itagaki A, Ishihara C, Satoh H, Okabe N, Tsuji M. Molecular survey of Babesia microti, Ehrlichia species and Candidatus neoehrlichia mikurensis in wild rodents from Shimane Prefecture, Japan. Microbiol Immunol 2008; 51:359-67. [PMID: 17446675 DOI: 10.1111/j.1348-0421.2007.tb03923.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A significant number of patients are diagnosed with "fevers of unknown origin" (FUO) in Shimane Prefecture in Japan where tick-borne diseases are endemic. We conducted molecular surveys for Babesia microti, Ehrlichia species, and Candidatus Neoehrlichia mikurensis in 62 FUO cases and 62 wild rodents from Shimane Prefecture, Japan. PCR using primers specific for the Babesia 18S small-subunit rRNA (rDNA) gene and Anaplasmataceae groESL amplified products from 45% (28/62) and 25.8% (16/62) of captured mice, respectively. Of the 28 18S rDNA PCR positives, 23 and five samples were positive for Hobetsu- and Kobe-type B. microti, respectively. In contrast, of the 16 groESL PCR positives, eight, one and seven samples were positive for Ehrlichia muris, Ehrlichia sp. HF565 and Candidatus N. mikurensis, respectively. Inoculation of selected blood samples into Golden Syrian hamsters indicated the presence of Hobetsu- and Kobe-type B. microti in four and one sample, respectively. Isolation of the latter strain was considered important as previous studies suggested that the distribution of this type was so far confined to Awaji Island in Hyogo Prefecture, where the first case of transfusion-associated human babesiosis originated. DNA samples from 62 FUO human cases tested negative for B. microti 18S rDNA gene, Anaplasmataceae groESL gene, Rickettsia japonica 17K genus-common antigen gene and Orientia tsutsugamushi 56K antigen gene by PCRs. We also conducted seroepidemiological surveys on 62 human sera collected in Shimane Prefecture from the FUO patients who were suspected of carrying tick-borne diseases. However, indirect immunofluorescent antibody tests using B. microti- and E. muris-infected cells detected IgG against E. muris in only a single positive sample. This study demonstrates the presence of several potentially important tick-borne pathogens in Shimane Prefecture and suggests the need for further study on the causative agents of FUOs.
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Affiliation(s)
- Kenji Tabara
- The Shimane Prefectural Institute of Public Health and Environmental Science, Matsue, Shimane, Japan
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47
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Popov VL, Korenberg EI, Nefedova VV, Han VC, Wen JW, Kovalevskii YV, Gorelova NB, Walker DH. Ultrastructural Evidence of the Ehrlichial Developmental Cycle in Naturally InfectedIxodes persulcatusTicks in the Course of Coinfection with Rickettsia, Borrelia, and a Flavivirus. Vector Borne Zoonotic Dis 2007; 7:699-716. [DOI: 10.1089/vbz.2007.0148] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Vsevolod L. Popov
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas
- Center for Biodefense and Emerging Infectious Diseases, Galveston, Texas
| | - Edward I. Korenberg
- N.F. Gamaleya Research Institute for Epidemiology and Microbiology, Russian Academy of Medical Sciences, Moscow, Russia
| | - Valentina V. Nefedova
- N.F. Gamaleya Research Institute for Epidemiology and Microbiology, Russian Academy of Medical Sciences, Moscow, Russia
| | - Violet C. Han
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas
| | - Julie W. Wen
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas
| | - Yurii V. Kovalevskii
- N.F. Gamaleya Research Institute for Epidemiology and Microbiology, Russian Academy of Medical Sciences, Moscow, Russia
| | - Natalia B. Gorelova
- N.F. Gamaleya Research Institute for Epidemiology and Microbiology, Russian Academy of Medical Sciences, Moscow, Russia
| | - David H. Walker
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas
- Center for Biodefense and Emerging Infectious Diseases, Galveston, Texas
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Detection of Ehrlichia muris DNA from sika deer (Cervus nippon yesoensis) in Hokkaido, Japan. Vet Parasitol 2007; 150:370-3. [PMID: 17964725 DOI: 10.1016/j.vetpar.2007.09.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Revised: 09/18/2007] [Accepted: 09/18/2007] [Indexed: 11/21/2022]
Abstract
Ehrlichia muris DNA was detected in the blood of sika deer (Cervus nippon yesoensis) by species-specific PCR based on the citrate synthase gene, which was shown to be more sensitive than species-specific PCR based on the 16S rRNA gene. Among 102 deer examined, one deer was positive. Deer may be a possible mammalian reservoir of E. muris.
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49
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Nandi B, Hogle K, Vitko N, Winslow GM. CD4 T-cell epitopes associated with protective immunity induced following vaccination of mice with an ehrlichial variable outer membrane protein. Infect Immun 2007; 75:5453-9. [PMID: 17698576 PMCID: PMC2168300 DOI: 10.1128/iai.00713-07] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The ehrlichiae express variable outer membrane proteins (OMPs) that play important roles in both pathogenesis and host defense. Previous studies revealed that OMPs are immunodominant B-cell antigens and that passive transfer of anti-OMP antibodies can protect SCID mice from fatal ehrlichial infection. In this study, we used a model of fatal monocytotropic ehrlichiosis caused by Ehrlichia bacteria from Ixodes ovatus (IOE) to determine whether OMP immunization could generate protective immunity in immunocompetent mice. Immunization of C57BL/6 mice with a purified recombinant OMP expressed by IOE omp19 generated protection from fatal IOE infection and elicited robust humoral and CD4 T-cell responses. To identify CD4 T-cell epitopes within OMPs, we performed enzyme-linked immunospot analyses for gamma interferon (IFN-gamma) production using a panel of overlapping 16-mer peptides from IOE OMP-19. Five immunoreactive peptides comprising residues 30 to 45, 77 to 92, 107 to 122, 197 to 212, and 247 to 264 were identified; the strongest response was generated against OMP-19(107-122). Most of the peptides are conserved between E. muris and E. chaffeensis OMP-19, and they elicited IFN-gamma production in CD4 T cells from E. muris-infected mice, indicating that T-cell epitope cross-reactivity likely contributes to heterologous immunity. Accordingly, CD4 T-cell responses to both OMP-19 and OMP-19(107-122) were of greater magnitude following high-dose IOE challenge of mice that had been immunized by prior infection with E. muris. Our studies cumulatively identify B- and T-cell epitopes that are associated with protective homologous and heterologous immunity during ehrlichial infection.
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Affiliation(s)
- Bisweswar Nandi
- Wadsworth Center, 120 New Scotland Avenue, Albany, NY 12208, USA
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50
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Ismail N, Crossley EC, Stevenson HL, Walker DH. Relative importance of T-cell subsets in monocytotropic ehrlichiosis: a novel effector mechanism involved in Ehrlichia-induced immunopathology in murine ehrlichiosis. Infect Immun 2007; 75:4608-20. [PMID: 17562770 PMCID: PMC1951155 DOI: 10.1128/iai.00198-07] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Infection with gram-negative monocytotropic Ehrlichia strains results in a fatal toxic shock-like syndrome characterized by a decreased number of Ehrlichia-specific CD4(+) Th1 cells, the expansion of tumor necrosis factor alpha (TNF-alpha)-producing CD8(+) T cells, and the systemic overproduction of interleukin-10 (IL-10) and TNF-alpha. Here, we investigated the role of CD4(+) and CD8(+) T cells in immunity to Ehrlichia and the pathogenesis of fatal ehrlichiosis caused by infection with low- and high-dose (10(3) and 10(5) bacterial genomes/mouse, respectively) ehrlichial inocula. The CD4(+) T-cell-deficient mice showed exacerbated susceptibility to a lethal high- or low-dose infection and harbored higher bacterial numbers than did wild-type (WT) mice. Interestingly, the CD8(+) T-cell-deficient mice were resistant to a low dose but succumbed to a high dose of Ehrlichia. The absence of CD8(+) T cells abrogated TNF-alpha and IL-10 production, reduced tissue injury and bacterial burden, restored splenic CD4(+) T-cell numbers, and increased the frequency of Ehrlichia-specific CD4(+) Th1 cells in comparison to infected WT mice. Although fatal disease is perforin independent, our data suggested that perforin played a critical role in controlling bacterial burden and mediating liver injury. Similar to WT mice, mortality of infected perforin-deficient mice was associated with CD4(+) T-cell apoptosis and a high serum concentration of IL-10. Depletion of IL-10 restored the number of CD4(+) and CD8(+) T cells in infected WT mice. Our data demonstrate a novel mechanism of immunopathology in which CD8(+) T cells mediate Ehrlichia-induced toxic shock, which is associated with IL-10 overproduction and CD4(+) T-cell apoptosis.
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Affiliation(s)
- Nahed Ismail
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, 301 University Blvd., Galveston, TX 77555-0609, USA.
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