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van Schaik EJ, Fratzke AP, Gregory AE, Dumaine JE, Samuel JE. Vaccine development: obligate intracellular bacteria new tools, old pathogens: the current state of vaccines against obligate intracellular bacteria. Front Cell Infect Microbiol 2024; 14:1282183. [PMID: 38567021 PMCID: PMC10985213 DOI: 10.3389/fcimb.2024.1282183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 03/01/2024] [Indexed: 04/04/2024] Open
Abstract
Obligate intracellular bacteria have remained those for which effective vaccines are unavailable, mostly because protection does not solely rely on an antibody response. Effective antibody-based vaccines, however, have been developed against extracellular bacteria pathogens or toxins. Additionally, obligate intracellular bacteria have evolved many mechanisms to subvert the immune response, making vaccine development complex. Much of what we know about protective immunity for these pathogens has been determined using infection-resolved cases and animal models that mimic disease. These studies have laid the groundwork for antigen discovery, which, combined with recent advances in vaccinology, should allow for the development of safe and efficacious vaccines. Successful vaccines against obligate intracellular bacteria should elicit potent T cell memory responses, in addition to humoral responses. Furthermore, they ought to be designed to specifically induce strong cytotoxic CD8+ T cell responses for protective immunity. This review will describe what we know about the potentially protective immune responses to this group of bacteria. Additionally, we will argue that the novel delivery platforms used during the Sars-CoV-2 pandemic should be excellent candidates to produce protective immunity once antigens are discovered. We will then look more specifically into the vaccine development for Rickettsiaceae, Coxiella burnetti, and Anaplasmataceae from infancy until today. We have not included Chlamydia trachomatis in this review because of the many vaccine related reviews that have been written in recent years.
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Affiliation(s)
- E J van Schaik
- Department of Microbial Pathogenesis and Immunology, School of Medicine, Texas A&M University, Medical Research and Education Building, Bryan, TX, United States
| | - A P Fratzke
- Department of Microbial Pathogenesis and Immunology, School of Medicine, Texas A&M University, Medical Research and Education Building, Bryan, TX, United States
- Charles River Laboratories, Reno, NV, United States
| | - A E Gregory
- Department of Microbial Pathogenesis and Immunology, School of Medicine, Texas A&M University, Medical Research and Education Building, Bryan, TX, United States
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, United States
| | - Jennifer E Dumaine
- Department of Microbial Pathogenesis and Immunology, School of Medicine, Texas A&M University, Medical Research and Education Building, Bryan, TX, United States
| | - J E Samuel
- Department of Microbial Pathogenesis and Immunology, School of Medicine, Texas A&M University, Medical Research and Education Building, Bryan, TX, United States
- Department of Veterinary Pathobiology, School of Veterinary Medicine, Texas A&M University (TAMU), College Station, TX, United States
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Luo T, Patel JG, Zhang X, McBride JW. Antibody reactive immunomes of Ehrlichia chaffeensis and E. canis are diverse and defined by conformational antigenic determinants. Front Cell Infect Microbiol 2024; 13:1321291. [PMID: 38264730 PMCID: PMC10803646 DOI: 10.3389/fcimb.2023.1321291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 12/19/2023] [Indexed: 01/25/2024] Open
Abstract
For decades, the defined antibody reactive proteins of Ehrlichia chaffeensis and E. canis were limited to a small group with linear antibody epitopes. Recently, our laboratory has utilized an immunomics-based approach to rapidly screen and identify undefined Ehrlichia chaffeensis and E. canis antigenic proteins and antibody epitopes. In this study, we analyzed the remaining portion (~50%) of the E. chaffeensis and E. canis proteomes (n = 444 and n = 405 proteins, respectively), that were not examined in previous studies, to define the complete immunomes of these important pathogens. Almost half of the E. chaffeensis proteins screened (196/444) reacted with antibodies in convalescent HME patient sera, while only 43 E. canis proteins reacted with CME dog sera. New major immunoreactive proteins were identified in E. chaffeensis (n = 7) and E. canis (n = 1), increasing the total number of E. chaffeensis (n = 14) and E. canis proteins (n = 18) that exhibited antibody reactivity comparable to well-defined major antigenic proteins (TRP120 and TRP19). All of the E. chaffeensis but only some E. canis major immunoreactive proteins contained major conformation-dependent antibody epitopes. The E. chaffeensis immunoreactive proteins were generally small (< 250 amino acids; ~27kDa) and the E. canis proteins were slightly larger (> 320 amino acids; ~35 kDa). The majority of these new Ehrlichia major immunoreactive proteins were predicted to be type I secreted effectors, some of which contained transmembrane domains. Characterization of the immunomes of E. chaffeensis and E. canis and understanding the host specific Ehrlichia immune responses will facilitate identification of protective antigens and define the biophysical epitope characteristics vital to effective vaccine development for the ehrlichioses.
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Affiliation(s)
- Tian Luo
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Jignesh G. Patel
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Xiaofeng Zhang
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, United States
- Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX, United States
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
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3
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Sabzi S, Shahbazi S, Noori Goodarzi N, Haririzadeh Jouriani F, Habibi M, Bolourchi N, Mirzaie A, Badmasti F. Genome-Wide Subtraction Analysis and Reverse Vaccinology to Detect Novel Drug Targets and Potential Vaccine Candidates Against Ehrlichia chaffeensis. Appl Biochem Biotechnol 2023; 195:107-124. [PMID: 36053401 PMCID: PMC9437403 DOI: 10.1007/s12010-022-04116-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2022] [Indexed: 01/17/2023]
Abstract
Human monocytotropic ehrlichiosis is an emerging tick-borne infection caused by the obligate intracellular pathogen, Ehrlichia chaffeensis. The non-specific symptoms can range from a self-limiting fever to a fatal septic-like syndrome and may be misdiagnosed. The limited treatment choices including doxycycline are effective only in the initiation phase of the infection. It seems that novel therapeutic targets and new vaccine strategies could be effective to control this pathogen. This study is comprised of two major phases. First, the common proteins retrieved through subtractive analysis and potential drug targets were evaluated by subcellular localization, homology prediction, metabolic pathways, druggability, essentiality, protein-protein interaction networks, and protein data bank availability. In the second phase, surface-exposed proteins were assessed based on antigenicity, allergenicity, physiochemical properties, B cell and T cell epitopes, conserved domains, and protein-protein interaction networks. A multi-epitope vaccine was designed and characterized using molecular dockings and immune simulation analysis. Six proteins including WP_011452818.1, WP_011452723.1, WP_006010413.1, WP_006010278.1, WP_011452938.1, and WP_006010644.1 were detected. They belong to unique metabolic pathways of E. chaffeensis that are considered as new essential drug targets. Based on the reverse vaccinology, WP_011452702.1, WP_044193405.1, WP_044170604.1, and WP_006010191.1 proteins were potential vaccine candidates. Finally, four B cell epitopes, including SINNQDRNC, FESVSSYNI, SGKKEISVQSN, and QSSAKRKST, were used to generate the multi-epitope vaccine based on LCL platform. The vaccine showed strong interactions with toll-like receptors and acceptable immune-reactivity by immune simulation analysis. The findings of this study may represent a turning point in developing an effective drug and vaccine against E. chaffeensis. However, further experimental analyses have remained.
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Affiliation(s)
- Samira Sabzi
- Department of Bacteriology, Pasteur Institute of Iran, Tehran, Iran ,Department of Molecular Biology, Pasteur Institute of Iran, Tehran, Iran
| | - Shahla Shahbazi
- Department of Molecular Biology, Pasteur Institute of Iran, Tehran, Iran
| | - Narjes Noori Goodarzi
- Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Mehri Habibi
- Department of Molecular Biology, Pasteur Institute of Iran, Tehran, Iran
| | - Negin Bolourchi
- Department of Bacteriology, Pasteur Institute of Iran, Tehran, Iran
| | - Amir Mirzaie
- Department of Biology, Parand Branch, Islamic Azad University, Parand, Iran
| | - Farzad Badmasti
- Department of Bacteriology, Pasteur Institute of Iran, Tehran, Iran ,Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran
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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: 2] [Impact Index Per Article: 1.0] [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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Recombinant Ehrlichia canis GP19 Protein as a Promising Vaccine Prototype Providing a Protective Immune Response in a Mouse Model. Vet Sci 2022; 9:vetsci9080386. [PMID: 36006302 PMCID: PMC9414908 DOI: 10.3390/vetsci9080386] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/24/2022] [Accepted: 07/25/2022] [Indexed: 12/03/2022] Open
Abstract
Simple summary One of the limitations of vaccine development against E. canis infection is the indefinite knowledge of the protective immunity in the host. In this study, recombinant protein GP19 was produced as a vaccine prototype, rGP19, for inducing protective immune responses in a mouse model against E. canis. Antibody responses against E. canis were evaluated and revealed that the immunized mice with rGP19 showed higher antibody levels than in adjuvant-immunized and naive mice, both pre- and post-challenging with E. canis. DNA from blood, liver, and spleen were extracted to determine ehrlichial loads. The rGP19-immunized mice showed significantly lower ehrlichial loads in blood, liver, and spleen DNA compared with adjuvant-immunized mice. This study also detected IFN-γ-producing CD4+ T cells in the rGP19-immunized mice and then were later infected with E. canis on day 14 of the post-infection period using flow cytometry. Additionally, Cytokine mRNA expression was investigated and revealed up-regulation of IFNG and IL1 mRNA expression in rGP19-immunized mice. The present study provides evidence of rGP19 that can eliminate E. canis by manipulating both humoral and cell-mediated immune responses in the laboratory animal model. Abstract The intracellular bacterium Ehrlichia canis is the causative pathogen of canine monocytic ehrlichiosis (CME) in dogs. Despite its veterinary and medical importance, there is currently no available vaccine against this pathogen. In this study, the recombinant GP19 (rGP19) was produced and used as a recombinant vaccine prototype in a mouse model against experimental E. canis infection. The efficacy of the rGP19 vaccine prototype in the part of stimulating B and T cell responses and conferring protection in mice later challenged with E. canis pathogen were evaluated. The rGP19-specific antibody response was evaluated by ELISA after E. canis challenge exposure (on days 0, 7, and 14 post-challenge), and demonstrated significantly higher mean antibody levels in rGP19-immunized mice compared with adjuvant-immunized and naive mice. Significantly lower ehrlichial loads in blood, liver, and spleen DNA samples were detected in the immunized mice with rGP19 by qPCR. The up-regulation of IFNG and IL1 mRNA expression were observed in mice immunized with rGP19. In addition, this study detected IFN-γ-producing memory CD4+ T cells in the rGP19-immunized mice and later infected with E. canis on day 14 post-infection period using flow cytometry. The present study provided a piece of evidence that rGP19 may eliminate E. canis by manipulating Th1 and B cell roles and demonstrated a promising strategy in vaccine development against E. canis infection in the definitive host for further study.
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Ismail N, Sharma A, Soong L, Walker DH. Review: Protective Immunity and Immunopathology of Ehrlichiosis. ZOONOSES (BURLINGTON, MASS.) 2022; 2:10.15212/zoonoses-2022-0009. [PMID: 35876763 PMCID: PMC9300479 DOI: 10.15212/zoonoses-2022-0009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Human monocytic ehrlichiosis, a tick transmitted infection, ranges in severity from apparently subclinical to a fatal toxic shock-like fatal disease. Models in immunocompetent mice range from an abortive infection to uniformly lethal depending on the infecting Ehrlichia species, dose of inoculum, and route of inoculation. Effective immunity is mediated by CD4+ T lymphocytes and gamma interferon. Lethal infection occurs with early overproduction of proinflammatory cytokines and overproduction of TNF alpha and IL-10 by CD8+ T lymphocytes. Furthermore, fatal ehrlichiosis is associated with signaling via TLR 9/MyD88 with upregulation of several inflammasome complexes and secretion of IL-1 beta, IL-1 alpha, and IL-18 by hepatic mononuclear cells, suggesting activation of canonical and noncanonical inflammasome pathways, a deleterious role for IL-18, and the protective role for caspase 1. Autophagy promotes ehrlichial infection, and MyD88 signaling hinders ehrlichial infection by inhibiting autophagy induction and flux. Activation of caspase 11 during infection of hepatocytes by the lethal ehrlichial species after interferon alpha receptor signaling results in the production of inflammasome-dependent IL-1 beta, extracellular secretion of HMGB1, and pyroptosis. The high level of HMGB1 in lethal ehrlichiosis suggests a role in toxic shock. Studies of primary bone marrow-derived macrophages infected by highly avirulent or mildly avirulent ehrlichiae reveal divergent M1 and M2 macrophage polarization that links with generation of pathogenic CD8 T cells, neutrophils, and excessive inflammation or with strong expansion of protective Th1 and NKT cells, resolution of inflammation and clearance of infection, respectively.
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Affiliation(s)
- Nahed Ismail
- Clinical Microbiology, Laboratory Medicine, University of Illinois at Chicago-College of Medicine, University of Illinois Hospitals & Health Science System, Chicago, IL
| | - Aditya Sharma
- Clinical Microbiology, Laboratory Medicine, University of Illinois at Chicago-College of Medicine, University of Illinois Hospitals & Health Science System, Chicago, IL
| | - Lynn Soong
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX
- Department of Pathology, Center for Biodefense & Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX
| | - David H. Walker
- Department of Pathology, Center for Biodefense & Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX
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Thomas S. Development of a SONIX Vaccine to Protect Against Ehrlichiosis. Methods Mol Biol 2022; 2410:423-429. [PMID: 34914061 DOI: 10.1007/978-1-0716-1884-4_22] [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: 06/14/2023]
Abstract
The obligately Gram-negative intracellular bacterium Ehrlichia that resides in mononuclear phagocytes is the etiologic agent of human monocytotropic ehrlichiosis (HME). HME is an emerging and often life-threatening, tick-transmitted infectious disease in the USA. Currently, three different Ehrlichia species can cause ehrlichiosis in humans in the USA-Ehrlichia chaffeensis, Ehrlichia ewingii, and Ehrlichia muris subspecies eauclairensis. Ehrlichia also causes diseases in companion animals and domesticated ruminants. Ehrlichia are vector-borne diseases and transmitted by tick bites. As yet there are no commercially available vaccines to protect against these pathogens. Previously we developed structure-based vaccines and subunit vaccines to protect against ehrlichiosis in animal models. Though the vaccines are efficient in inducing protection, there is a delay in clearing the pathogens in challenge studies. In this chapter we demonstrate the development of a SONIX vaccine that is more potent than conventional vaccines. The vaccination strategy may be useful in Emergency Use Authorization (EUA) scenarios during public health emergencies.
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Affiliation(s)
- Sunil Thomas
- Lankenau Institute for Medical Research, Wynnewood, PA, USA.
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Torina A, Blanda V, Villari S, Piazza A, La Russa F, Grippi F, La Manna MP, Di Liberto D, de la Fuente J, Sireci G. Immune Response to Tick-Borne Hemoparasites: Host Adaptive Immune Response Mechanisms as Potential Targets for Therapies and Vaccines. Int J Mol Sci 2020; 21:ijms21228813. [PMID: 33233869 PMCID: PMC7699928 DOI: 10.3390/ijms21228813] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/12/2020] [Accepted: 11/12/2020] [Indexed: 02/06/2023] Open
Abstract
Tick-transmitted pathogens cause infectious diseases in both humans and animals. Different types of adaptive immune mechanisms could be induced in hosts by these microorganisms, triggered either directly by pathogen antigens or indirectly through soluble factors, such as cytokines and/or chemokines, secreted by host cells as response. Adaptive immunity effectors, such as antibody secretion and cytotoxic and/or T helper cell responses, are mainly involved in the late and long-lasting protective immune response. Proteins and/or epitopes derived from pathogens and tick vectors have been isolated and characterized for the immune response induced in different hosts. This review was focused on the interactions between tick-borne pathogenic hemoparasites and different host effector mechanisms of T- and/or B cell-mediated adaptive immunity, describing the efforts to define immunodominant proteins or epitopes for vaccine development and/or immunotherapeutic purposes. A better understanding of these mechanisms of host immunity could lead to the assessment of possible new immunotherapies for these pathogens as well as to the prediction of possible new candidate vaccine antigens.
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Affiliation(s)
- Alessandra Torina
- Area Diagnostica Sierologica, Istituto Zooprofilattico Sperimentale della Sicilia, via Gino Marinuzzi 3, 90129 Palermo, Italy; (A.T.); (F.G.)
- Laboratorio di Riferimento OIE Theileriosi, Istituto Zooprofilattico Sperimentale della Sicilia, via Gino Marinuzzi 3, 90129 Palermo, Italy
| | - Valeria Blanda
- Laboratorio di Riferimento OIE Theileriosi, Istituto Zooprofilattico Sperimentale della Sicilia, via Gino Marinuzzi 3, 90129 Palermo, Italy
- Laboratorio di Entomologia e Controllo Vettori Ambientali, Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90129 Palermo, Italy; (S.V.); (A.P.); (F.L.R.)
- Correspondence:
| | - Sara Villari
- Laboratorio di Entomologia e Controllo Vettori Ambientali, Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90129 Palermo, Italy; (S.V.); (A.P.); (F.L.R.)
| | - Antonio Piazza
- Laboratorio di Entomologia e Controllo Vettori Ambientali, Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90129 Palermo, Italy; (S.V.); (A.P.); (F.L.R.)
| | - Francesco La Russa
- Laboratorio di Entomologia e Controllo Vettori Ambientali, Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90129 Palermo, Italy; (S.V.); (A.P.); (F.L.R.)
| | - Francesca Grippi
- Area Diagnostica Sierologica, Istituto Zooprofilattico Sperimentale della Sicilia, via Gino Marinuzzi 3, 90129 Palermo, Italy; (A.T.); (F.G.)
| | - Marco Pio La Manna
- Central Laboratory of Advanced Diagnostic and Biological Research (CLADIBIOR), BIND, University Hospital “Paolo Giaccone”, Università degli studi di Palermo, Via del Vespro 129, 90100 Palermo, Italy; (M.P.L.M.); (D.D.L.); (G.S.)
| | - Diana Di Liberto
- Central Laboratory of Advanced Diagnostic and Biological Research (CLADIBIOR), BIND, University Hospital “Paolo Giaccone”, Università degli studi di Palermo, Via del Vespro 129, 90100 Palermo, Italy; (M.P.L.M.); (D.D.L.); (G.S.)
| | - José de la Fuente
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13005 Ciudad Real, Spain;
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - Guido Sireci
- Central Laboratory of Advanced Diagnostic and Biological Research (CLADIBIOR), BIND, University Hospital “Paolo Giaccone”, Università degli studi di Palermo, Via del Vespro 129, 90100 Palermo, Italy; (M.P.L.M.); (D.D.L.); (G.S.)
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Wang Y, Nair ADS, Alhassan A, Jaworski DC, Liu H, Trinkl K, Hove P, Ganta CK, Burkhardt N, Munderloh UG, Ganta RR. Multiple Ehrlichia chaffeensis Genes Critical for Its Persistent Infection in a Vertebrate Host Are Identified by Random Mutagenesis Coupled with In Vivo Infection Assessment. Infect Immun 2020; 88:e00316-20. [PMID: 32747600 PMCID: PMC7504954 DOI: 10.1128/iai.00316-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 07/23/2020] [Indexed: 12/14/2022] Open
Abstract
Ehrlichia chaffeensis, a tick-transmitted obligate intracellular rickettsial agent, causes human monocytic ehrlichiosis. In recent reports, we described substantial advances in developing random and targeted gene disruption methods to investigate the functions of E. chaffeensis genes. We reported earlier that the Himar1 transposon-based random mutagenesis is a valuable tool in defining E. chaffeensis genes critical for its persistent growth in vivo in reservoir and incidental hosts. The method also aided in extending studies focused on vaccine development and immunity. Here, we describe the generation and mapping of 55 new mutations. To define the critical nature of the bacterial genes, infection experiments were carried out in the canine host with pools of mutant organisms. Infection evaluation in the physiologically relevant host by molecular assays and by xenodiagnoses allowed the identification of many proteins critical for the pathogen's persistent in vivo growth. Genes encoding proteins involved in biotin biosynthesis, protein synthesis and fatty acid biosynthesis, DNA repair, electron transfer, and a component of a multidrug resistance (MDR) efflux pump were concluded to be essential for the pathogen's in vivo growth. Three known immunodominant membrane proteins, i.e., two 28-kDa outer membrane proteins (P28/OMP) and a 120-kDa surface protein, were also recognized as necessary for the pathogen's obligate intracellular life cycle. The discovery of many E. chaffeensis proteins crucial for its continuous in vivo growth will serve as a major resource for investigations aimed at defining pathogenesis and developing novel therapeutics for this and related pathogens of the rickettsial family Anaplasmataceae.
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Affiliation(s)
- Ying Wang
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
| | - Arathy D S Nair
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
| | - Andy Alhassan
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
- Department of Pathobiology, School of Veterinary Medicine, St. George's University, West Indies, Grenada
| | - Deborah C Jaworski
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
| | - Huitao Liu
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
| | - Kathleen Trinkl
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
| | - Paidashe Hove
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
- Department of Pathobiology, School of Veterinary Medicine, St. George's University, West Indies, Grenada
| | - Charan K Ganta
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
| | - Nicole Burkhardt
- Department of Entomology, University of Minnesota, St. Paul, Minnesota, USA
| | - Ulrike G Munderloh
- Department of Entomology, University of Minnesota, St. Paul, Minnesota, USA
| | - Roman R Ganta
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
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Trivedi N, Weisel F, Smita S, Joachim S, Kader M, Radhakrishnan A, Clouser C, Rosenfeld AM, Chikina M, Vigneault F, Hershberg U, Ismail N, Shlomchik MJ. Liver Is a Generative Site for the B Cell Response to Ehrlichia muris. Immunity 2019; 51:1088-1101.e5. [PMID: 31732168 DOI: 10.1016/j.immuni.2019.10.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 07/24/2019] [Accepted: 10/15/2019] [Indexed: 02/01/2023]
Abstract
The B cell response to Ehrlichia muris is dominated by plasmablasts (PBs), with few-if any-germinal centers (GCs), yet it generates protective immunoglobulin M (IgM) memory B cells (MBCs) that express the transcription factor T-bet and harbor V-region mutations. Because Ehrlichia prominently infects the liver, we investigated the nature of liver B cell response and that of the spleen. B cells within infected livers proliferated and underwent somatic hypermutation (SHM). Vh-region sequencing revealed trafficking of clones between the spleen and liver and often subsequent local clonal expansion and intraparenchymal localization of T-bet+ MBCs. T-bet+ MBCs expressed MBC subset markers CD80 and PD-L2. Many T-bet+ MBCs lacked CD11b or CD11c expression but had marginal zone (MZ) B cell phenotypes and colonized the splenic MZ, revealing T-bet+ MBC plasticity. Hence, liver and spleen are generative sites of B cell responses, and they include V-region mutation and result in liver MBC localization.
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Affiliation(s)
- Nikita Trivedi
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA 15261, USA; Graduate Program in Microbiology and Immunology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Florian Weisel
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Shuchi Smita
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA 15261, USA; Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Stephen Joachim
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Muhamuda Kader
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | | | | | | | - Maria Chikina
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | | | | | - Nahed Ismail
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Mark Jay Shlomchik
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA 15261, USA.
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11
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Tominello TR, Oliveira ERA, Hussain SS, Elfert A, Wells J, Golden B, Ismail N. Emerging Roles of Autophagy and Inflammasome in Ehrlichiosis. Front Immunol 2019; 10:1011. [PMID: 31134081 PMCID: PMC6517498 DOI: 10.3389/fimmu.2019.01011] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 04/23/2019] [Indexed: 12/16/2022] Open
Abstract
Human monocytic ehrlichiosis (HME) is a potentially life-threatening tick-borne rickettsial disease (TBRD) caused by the obligate intracellular Gram-negative bacteria, Ehrlichia. Fatal HME presents with acute ailments of sepsis and toxic shock-like symptoms that can evolve to multi-organ failure and death. Early clinical and laboratory diagnosis of HME are problematic due to non-specific flu-like symptoms and limitations in the current diagnostic testing. Several studies in murine models showed that cell-mediated immunity acts as a “double-edged sword” in fatal ehrlichiosis. Protective components are mainly formed by CD4 Th1 and NKT cells, in contrast to deleterious effects originated from neutrophils and TNF-α-producing CD8 T cells. Recent research has highlighted the central role of the inflammasome and autophagy as part of innate immune responses also leading to protective or pathogenic scenarios. Recognition of pathogen-associated molecular patterns (PAMPS) or damage-associated molecular patterns (DAMPS) triggers the assembly of the inflammasome complex that leads to multiple outcomes. Recognition of PAMPs or DAMPs by such complexes can result in activation of caspase-1 and -11, secretion of the pro-inflammatory cytokines IL-1β and IL-18 culminating into dysregulated inflammation, and inflammatory cell death known as pyroptosis. The precise functions of inflammasomes and autophagy remain unexplored in infections with obligate intracellular rickettsial pathogens, such as Ehrlichia. In this review, we discuss the intracellular innate immune surveillance in ehrlichiosis involving the regulation of inflammasome and autophagy, and how this response influences the innate and adaptive immune responses against Ehrlichia. Understanding such mechanisms would pave the way in research for novel diagnostic, preventative and therapeutic approaches against Ehrlichia and other rickettsial diseases.
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Affiliation(s)
- Tyler R Tominello
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Edson R A Oliveira
- Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Shah S Hussain
- Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Amr Elfert
- Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Jakob Wells
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Brandon Golden
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Nahed Ismail
- Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
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12
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Crosby FL, Lundgren AM, Hoffman C, Pascual DW, Barbet AF. VirB10 vaccination for protection against Anaplasma phagocytophilum. BMC Microbiol 2018; 18:217. [PMID: 30563470 PMCID: PMC6299599 DOI: 10.1186/s12866-018-1346-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 11/16/2018] [Indexed: 12/18/2022] Open
Abstract
Background Human granulocytic anaplasmosis (HGA) is a tick-borne disease caused by the etiologic agent Anaplasma phagocytophilum. HGA was designated a nationally notifiable disease in the United States in 1998. Currently there are no vaccines available against HGA. Conserved membrane proteins that are subdominant in Anaplasma species, such as VirB9 and VirB10, may represent better vaccine targets than the variable immunodominant surface proteins. VirB9 and VirB10 are constituents of the Type 4 secretion system (T4SS) that is conserved amongst many intracellular bacteria and performs essential functions for invasion and survival in host cells. Results Immunogenicity and contribution to protection, provided after intramuscular vaccination of plasmid DNA encoding VirB9-1, VirB9-2, and VirB10 followed by inoculation of homologous recombinant proteins, in a prime-boost immunization strategy was evaluated in a murine model of HGA. Recombinant VirB9-1-, VirB9-2-, and VirB10-vaccinated mice developed antibody responses that specifically reacted with A. phagocytophilum organisms. However, only the mice vaccinated with VirB10 developed a significant increase in IFN-γ CD4+ T cells and partial protection against challenge with A. phagocytophilum. Conclusions This work provides evidence that A. phagocytophilum T4SS VirB10 is partially protective in a murine model against infection in an IFN-γ-dependent fashion and suggests that this protein may be a potential vaccine candidate against this and possibly other pathogenic bacteria with a T4SS.
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Affiliation(s)
- Francy L Crosby
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, 2015 SW 16th Avenue, Gainesville, FL, 32608, USA.
| | - Anna M Lundgren
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, 2015 SW 16th Avenue, Gainesville, FL, 32608, USA
| | - Carol Hoffman
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, 2015 SW 16th Avenue, Gainesville, FL, 32608, USA
| | - David W Pascual
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, 2015 SW 16th Avenue, Gainesville, FL, 32608, USA
| | - Anthony F Barbet
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, 2015 SW 16th Avenue, Gainesville, FL, 32608, USA
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13
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Salim B, Amin M, Igarashi M, Ito K, Jongejan F, Katakura K, Sugimoto C, Nakao R. Recombination and purifying and balancing selection determine the evolution of major antigenic protein 1 (map 1) family genes in Ehrlichia ruminantium. Gene 2018; 683:216-224. [PMID: 30316923 DOI: 10.1016/j.gene.2018.10.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 10/01/2018] [Accepted: 10/11/2018] [Indexed: 01/26/2023]
Abstract
Heartwater is an economically important disease of ruminants caused by the tick-borne bacterium Ehrlichia ruminantium. The disease is present throughout sub-Saharan Africa as well as on several islands in the Caribbean, where it poses a risk of spreading onto the American mainland. The dominant immune response of infected animals is directed against the variable outer membrane proteins of E. ruminantium encoded by a polymorphic multigene family. Here, we examined the full-length sequence of the major antigenic protein 1 (map1) family genes in multiple E. ruminantium isolates from different African countries and the Caribbean, collected at different time points to infer the possible role of recombination breakpoint and natural selection. A high level of recombination was found particularly in map1 and map1-2. Evidence of strong negative purifying selection in map1 and balancing selection to maintain genetic variation across these samples from geographically distinct countries suggests host-pathogen co-evolution. This co-evolution between the host and pathogen results in balancing selection by maintaining genetic diversity that could be explained by the demographic history of long-term pathogen pressure. This signifies the adaptive role and the molecular evolutionary forces underpinning E. ruminantium map1 multigene family antigenicity.
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Affiliation(s)
- Bashir Salim
- Department of Parasitology, Faculty of Veterinary Medicine, University of Khartoum, P.O Box 32, Khartoum-North, Sudan; Laboratory of Parasitology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Mutaz Amin
- Faculty of Medicine, University of Khartoum, Qasr Street, 11111 Khartoum, Sudan
| | - Manabu Igarashi
- Division of Global Epidemiology, Hokkaido University Research Center for Zoonosis Control, Sapporo, Japan.
| | - Kimihito Ito
- Division of Bioinformatics, Hokkaido University Research Center for Zoonosis Control, Sapporo, Japan.
| | - Frans Jongejan
- Utrecht Centre for Tick-borne Diseases (UCTD), FAO Reference Centre for Ticks and Tick-borne Diseases, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands; Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa.
| | - Ken Katakura
- Laboratory of Parasitology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
| | - Chihiro Sugimoto
- Division of Collaboration and Education, Hokkaido University Research Center for Zoonosis Control, Sapporo, Japan.
| | - Ryo Nakao
- Laboratory of Parasitology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
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14
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Abstract
Human ehrlichiosis and anaplasmosis are acute febrile tick-borne infectious diseases caused by various members from the genera Ehrlichia and Anaplasma. Ehrlichia chaffeensis is the major etiologic agent of human monocytotropic ehrlichiosis (HME), while Anaplasma phagocytophilum is the major cause of human granulocytic anaplasmosis (HGA). The clinical manifestations of HME and HGA ranges from subclinical to potentially life-threatening diseases associated with multi-organ failure. Macrophages and neutrophils are the major target cells for Ehrlichia and Anaplasma, respectively. The threat to public health is increasing with newly emerging ehrlichial and anaplasma agents, yet vaccines for human ehrlichioses and anaplasmosis are not available, and therapeutic options are limited. This article reviews recent advances in the understanding of HME and HGA.
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15
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Rickettsia rickettsii outer membrane protein YbgF induces protective immunity in C3H/HeN mice. Hum Vaccin Immunother 2015; 11:642-9. [PMID: 25714655 DOI: 10.1080/21645515.2015.1011572] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Rickettsia rickettsii is the etiological agent of Rocky Mountain spotted fever (RMSF). YbgF and TolC are outer membrane-associated proteins of R. rickettsii that play important roles in its interaction with host cells. We investigated the immunogenicity of YbgF and TolC for protection against RMSF. We immunized C3H/HeN mice with recombinant R. rickettsii YbgF (rYbgF) or TolC (rTolC). Rickettsial burden and impairment in the lungs, spleens, and livers of rYbgF-immunized mice were significantly lower than in rTolC-immunized mice. The ratio of IgG2a to IgG1 in rYbgF-immunized mice continued to increase over the course of our experiments, while that in rTolC-immunized mice was reduced. The proliferation and cytokine secretion of CD4(+) and CD8(+) T cells isolated from R. rickettsii-infected mice were analyzed following antigen stimulation. The results indicated that proliferation and interferon (IFN)-γ secretion of CD4(+) or CD8(+) T cells in R. rickettsii-infected mice were significantly greater than in uninfected mice after stimulation with rYbgF. YbgF is a novel protective antigen of R. rickettsii. Protection conferred by YbgF is dependent upon IFN-γ-producing CD4(+) and CD8(+) T cells and IgG2a, which act in synergy to control R. rickettsii infection.
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16
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Guillemi EC, Tomassone L, Farber MD. Tick-borne Rickettsiales: Molecular tools for the study of an emergent group of pathogens. J Microbiol Methods 2015; 119:87-97. [PMID: 26471201 DOI: 10.1016/j.mimet.2015.10.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 10/09/2015] [Accepted: 10/09/2015] [Indexed: 12/16/2022]
Abstract
The use of molecular techniques in recent years has enhanced the sensitivity and specificity of the diagnosis of Rickettsiales, a bacterial order which includes significant emerging and re-emerging pathogens of humans and animals. Molecular detection enables the accurate identification at the species level, providing additional information on the epidemiology and course of the clinical cases. Moreover, PCR and enzyme restriction analysis of the vector blood meal can be employed to study the tick feeding source and possibly identify pathogen's reservoir. Here, we review the molecular tools available for the identification and characterization of tick-borne bacteria from the genera Rickettsia, Ehrlichia and Anaplasma and for the study of ticks feeding behavior. We summarize the significant criteria for taxonomic identification of Rickettsiales species and propose a procedure algorithm for the classification of bacterial isolates as members of this order.
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Affiliation(s)
- Eliana C Guillemi
- Inst. de Biotecnología, INTA Castelar. Los Reseros y N. Repetto, 1686 Hurlingham, Buenos Aires, Argentina.
| | - Laura Tomassone
- Dipartimento di Scienze Veterinarie, Università degli Studi di Torino, Largo Braccini 2, 10095 Grugliasco, Torino, Italy
| | - Marisa D Farber
- Inst. de Biotecnología, INTA Castelar. Los Reseros y N. Repetto, 1686 Hurlingham, Buenos Aires, Argentina
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17
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Attenuated Mutants of Ehrlichia chaffeensis Induce Protection against Wild-Type Infection Challenge in the Reservoir Host and in an Incidental Host. Infect Immun 2015; 83:2827-35. [PMID: 25916990 DOI: 10.1128/iai.00487-15] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 04/24/2015] [Indexed: 02/05/2023] Open
Abstract
Ehrlichia chaffeensis, a tick-borne rickettsial organism, causes the disease human monocytic ehrlichiosis. The pathogen also causes disease in several other vertebrates, including dogs and deer. In this study, we assessed two clonally purified E. chaffeensis mutants with insertions within the genes Ech_0379 and Ech_0660 as vaccine candidates in deer and dogs. Infection with the Ech_0379 mutant and challenge with wild-type E. chaffeensis 1 month following inoculation with the mutant resulted in the reduced presence of the organism in blood compared to the presence of wild-type infection in both deer and dogs. The Ech_0660 mutant infection resulted in its rapid clearance from the bloodstream. The wild-type infection challenge following Ech_0660 mutant inoculation also caused the pathogen's clearance from blood and tissue samples as assessed at the end of the study. The Ech_0379 mutant-infected and -challenged animals also remained positive for the organism in tissue samples in deer but not in dogs. This is the first study that documents that insertion mutations in E. chaffeensis that cause attenuated growth confer protection against wild-type infection challenge. This study is important in developing vaccines to protect animals and people against Ehrlichia species infections.
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18
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Surface protein Adr2 of Rickettsia rickettsii induced protective immunity against Rocky Mountain spotted fever in C3H/HeN mice. Vaccine 2014; 32:2027-33. [PMID: 24582636 DOI: 10.1016/j.vaccine.2014.02.057] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 02/10/2014] [Accepted: 02/14/2014] [Indexed: 11/22/2022]
Abstract
BACKGROUND Rickettsia rickettsii is the pathogen of Rocky Mountain spotted fever (RMSF), a life-threatening tick-transmitted infection. Adr2 was a surface-exposed adhesion protein of R. rickettsii and its immunoprotection against RMSF was investigated in mice. METHODS Recombinant Adr2 (rAdr2) was used to immunize C3H/HeN mice, and the rickettsial loads in organs of the mice were detected after challenge with R. rickettsii. The levels of specific antibodies of sera from the immunized mice were determined and the sera from immunized mice were applied to neutralize R. rickettsii. Proliferation and cytokine secretion of CD4(+) and CD8(+) T cells isolated from R. rickettsii-infected mice were also assayed after rAdr2 stimulation. RESULTS After R. rickettsii challenge, the rickettsial loads in spleens, livers, and lungs were significantly lower and the impairment degrees of these organs in rAdr2-immunized mice were markedly slighter, compared with those in negative control mice. The ratio of specific IgG2a/IgG1 of rAdr2-immunized mice kept increasing during the immunization. After treatment with rAdr2-immunized sera, the total number of R. rickettsii organisms adhering and invading host cells was significantly lower than that treated with PBS-immunized sera. Interferon-γ secretion by CD4(+) or CD8(+) T cells and tumor necrosis factor-α secretion by CD4(+) T cells from R. rickettsii-infected mice were respectively significantly greater than those from uninfected mice after rAdr2 stimulation. CONCLUSION Adr2 is a protective antigen of R. rickettsii. Protection offered by Adr2 is mainly dependent on antigen-specific cell-mediated immune responses, including efficient activity of CD4(+) and CD8(+) T cells to produce great amount of TNF-α and/or IFN-γ as well as rapid increase of specific IgG2a, which synergistically activate and opsonize host cells to killing intracellular rickettsiae.
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19
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Thirumalapura NR, Crocquet-Valdes PA, Saito TB, Thomas S, McBride JW, Walker DH. Recombinant Ehrlichia P29 protein induces a protective immune response in a mouse model of ehrlichiosis. Vaccine 2013; 31:5960-7. [PMID: 24144475 DOI: 10.1016/j.vaccine.2013.10.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 09/19/2013] [Accepted: 10/08/2013] [Indexed: 01/26/2023]
Abstract
Ehrlichioses are emerging tick-borne bacterial diseases of humans and animals for which no vaccines are available. The diseases are caused by obligately intracellular bacteria belonging to the genus Ehrlichia. Several immunoreactive proteins of ehrlichiae have been identified based on their reactivity with immune sera from human patients and animals. These include the major outer membrane proteins, ankyrin repeat proteins and tandem repeat proteins (TRP). Polyclonal antibodies directed against the tandem repeats (TRs) of Ehrlichia chaffeensis TRP32, TRP47 and TRP120 have been shown to provide protection in mice. In the present study, we evaluated E. muris P29, which is the ortholog of E. chaffeensis TRP47 and E. canis TRP36, as a subunit vaccine in a mouse model of ehrlichiosis. Our study indicated that unlike E. chaffeensis TRP47 and E. canis TRP36, orthologs of E. muris (P29) and E. muris-like agent (EMLA) do not contain tandem repeats. Immunization of mice with recombinant E. muris P29 induced significant protection against a challenge infection. The protection induced by E. muris P29 was associated with induction of strong antibody responses. In contrast to development of P29-specific IgG antibodies following immunization, development of P29-specific IgG antibodies, but not IgM antibodies, was impaired during persistent E. muris infection. Furthermore, our study indicated that CD4+ T cells target P29 during E. muris infection and differentiate into IFN-γ-producing Th1 effector/memory cells. In conclusion, our study indicated that orthologs of E. muris P29 showed considerable variation in the central tandem repeat region among different species, induction of P29-specific IgG antibody response was impaired during persistent E. muris infection, and rP29 induced protective immune responses.
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MESH Headings
- Animals
- Antibodies, Bacterial/blood
- Bacterial Proteins/genetics
- Bacterial Proteins/immunology
- Bacterial Vaccines/administration & dosage
- Bacterial Vaccines/genetics
- Bacterial Vaccines/immunology
- CD4-Positive T-Lymphocytes/immunology
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- Disease Models, Animal
- Ehrlichia/genetics
- Ehrlichia/immunology
- Ehrlichiosis/immunology
- Ehrlichiosis/prevention & control
- Female
- Immunologic Memory
- Interferon-gamma/metabolism
- Mice
- Mice, Inbred C57BL
- Molecular Sequence Data
- Recombinant Proteins/genetics
- Recombinant Proteins/immunology
- Sequence Analysis, DNA
- Vaccines, Subunit/administration & dosage
- Vaccines, Subunit/genetics
- Vaccines, Subunit/immunology
- Vaccines, Synthetic/administration & dosage
- Vaccines, Synthetic/genetics
- Vaccines, Synthetic/immunology
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Affiliation(s)
- Nagaraja R Thirumalapura
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555-0609, United States; Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0609, United States; Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, TX 77555-0609, United States; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555-0609, United States.
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20
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Alves RN, Rieck SE, Ueira-Vieira C, Labruna MB, Beletti ME. Isolation, in vitro propagation, genetic analysis, and immunogenic characterization of an Ehrlichia canis strain from southeastern Brazil. J Vet Sci 2013; 15:241-8. [PMID: 24136211 PMCID: PMC4087226 DOI: 10.4142/jvs.2014.15.2.241] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 08/14/2013] [Indexed: 11/23/2022] Open
Abstract
Amplification of the 16S rRNA gene from a blood sample obtained from a dog in southeastern Brazil was used to confirm a naturally acquired Ehrlichia (E.) canis infection. Following isolation and culturing of the new bacterial strain called Uberlândia, partial sequences of the dsb and p28 genes were obtained. The dsb partial sequence of the novel strain was 100% similar to dsb gene sequences of E. canis obtained from different geographic areas around the world. Conversely, the p28 partial sequence for the E. canis Uberlândia strain differed at several nucleotides from other sequences available in GenBank. To confirm the antigenic profile of the Uberlândia strain, an indirect immunofluorescence assay against E. canis antigens was performed using dog sera collected from two different areas in Brazil (Uberlândia and São Paulo). The results suggest that both antigens were able to identify animals seropositive for E. canis in Brazil since these Brazilian strains appear to be highly conserved.
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21
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Mohan Kumar D, Yamaguchi M, Miura K, Lin M, Los M, Coy JF, Rikihisa Y. Ehrlichia chaffeensis uses its surface protein EtpE to bind GPI-anchored protein DNase X and trigger entry into mammalian cells. PLoS Pathog 2013; 9:e1003666. [PMID: 24098122 PMCID: PMC3789761 DOI: 10.1371/journal.ppat.1003666] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 08/12/2013] [Indexed: 11/19/2022] Open
Abstract
Ehrlichia chaffeensis, an obligatory intracellular rickettsial pathogen, enters and replicates in monocytes/macrophages and several non-phagocytic cells. E. chaffeensis entry into mammalian cells is essential not only for causing the emerging zoonosis, human monocytic ehrlichiosis, but also for its survival. It remains unclear if E. chaffeensis has evolved a specific surface protein that functions as an 'invasin' to mediate its entry. We report a novel entry triggering protein of Ehrlichia, EtpE that functions as an invasin. EtpE is an outer membrane protein and an antibody against EtpE (the C-terminal fragment, EtpE-C) greatly inhibited E. chaffeensis binding, entry and infection of both phagocytes and non-phagocytes. EtpE-C-immunization of mice significantly inhibited E. chaffeensis infection. EtpE-C-coated latex beads, used to investigate whether EtpE-C can mediate cell invasion, entered both phagocytes and non-phagocytes and the entry was blocked by compounds that block E. chaffeensis entry. None of these compounds blocked uptake of non-coated beads by phagocytes. Yeast two-hybrid screening revealed that DNase X, a glycosylphosphatidyl inositol-anchored mammalian cell-surface protein binds EtpE-C. This was confirmed by far-Western blotting, affinity pull-down, co-immunoprecipitation, immunofluorescence labeling, and live-cell image analysis. EtpE-C-coated beads entered bone marrow-derived macrophages (BMDMs) from wild-type mice, whereas they neither bound nor entered BMDMs from DNase X(-/-) mice. Antibody against DNase X or DNase X knock-down by small interfering RNA impaired E. chaffeensis binding, entry, and infection. E. chaffeensis entry and infection rates of BMDMs from DNase X(-/-) mice and bacterial load in the peripheral blood in experimentally infected DNase X(-/-) mice, were significantly lower than those from wild-type mice. Thus this obligatory intracellular pathogen evolved a unique protein EtpE that binds DNase X to enter and infect eukaryotic cells. This study is the first to demonstrate the invasin and its mammalian receptor, and their in vivo relevance in any ehrlichial species.
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Affiliation(s)
- Dipu Mohan Kumar
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Mamoru Yamaguchi
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Koshiro Miura
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Mingqun Lin
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Marek Los
- Department of Clinical & Experimental Medicine, Integrative Regenerative Medical Center Linköping University, Linkoping, Sweden
| | | | - Yasuko Rikihisa
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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