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Teixeira SC, Teixeira TL, Tavares PCB, Alves RN, da Silva AA, Borges BC, Martins FA, Dos Santos MA, de Castilhos P, E Silva Brígido RT, Notário AFO, Silveira ACA, da Silva CV. Subversion strategies of lysosomal killing by intracellular pathogens. Microbiol Res 2023; 277:127503. [PMID: 37748260 DOI: 10.1016/j.micres.2023.127503] [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: 07/16/2023] [Revised: 09/08/2023] [Accepted: 09/17/2023] [Indexed: 09/27/2023]
Abstract
Many pathogenic organisms need to reach either an intracellular compartment or the cytoplasm of a target cell for their survival, replication or immune system evasion. Intracellular pathogens frequently penetrate into the cell through the endocytic and phagocytic pathways (clathrin-mediated endocytosis, phagocytosis and macropinocytosis) that culminates in fusion with lysosomes. However, several mechanisms are triggered by pathogenic microorganisms - protozoan, bacteria, virus and fungus - to avoid destruction by lysosome fusion, such as rupture of the phagosome and thereby release into the cytoplasm, avoidance of autophagy, delaying in both phagolysosome biogenesis and phagosomal maturation and survival/replication inside the phagolysosome. Here we reviewed the main data dealing with phagosome maturation and evasion from lysosomal killing by different bacteria, protozoa, fungi and virus.
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Affiliation(s)
- Samuel Cota Teixeira
- Instituto de Ciências Biomédicas, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil
| | - Thaise Lara Teixeira
- Instituto de Ciências Biomédicas, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil
| | | | | | - Aline Alves da Silva
- Instituto de Ciências Biomédicas, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil
| | - Bruna Cristina Borges
- Instituto de Ciências Biomédicas, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil
| | - Flávia Alves Martins
- Instituto de Ciências Biomédicas, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil
| | - Marlus Alves Dos Santos
- Instituto de Ciências Biomédicas, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil
| | - Patrícia de Castilhos
- Instituto de Ciências Biomédicas, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil
| | | | | | | | - Claudio Vieira da Silva
- Instituto de Ciências Biomédicas, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
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Sharma AK, El Andaloussi A, Ismail N. Evasion of host antioxidative response via disruption of NRF2 signaling in fatal Ehrlichia-induced liver injury. PLoS Pathog 2023; 19:e1011791. [PMID: 37956169 PMCID: PMC10681308 DOI: 10.1371/journal.ppat.1011791] [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: 03/09/2023] [Revised: 11/27/2023] [Accepted: 10/30/2023] [Indexed: 11/15/2023] Open
Abstract
Ehrlichia is Gram negative obligate intracellular bacterium that cause human monocytotropic ehrlichiosis (HME). HME is characterized by acute liver damage and inflammation that may progress to fatal toxic shock. We previously showed that fatal ehrlichiosis is due to deleterious activation of inflammasome pathways, which causes excessive inflammation and liver injury. Mammalian cells have developed mechanisms to control oxidative stress via regulation of nuclear factor erythroid 2 related 2 (NRF2) signaling. However, the contribution of NRF2 signaling to Ehrlichia-induced inflammasome activation and liver damage remains elusive. In this study, we investigated the contribution of NRF2 signaling in hepatocytes (HCs) to the pathogenesis of Ehrlichia-induced liver injury following infection with virulent Ixodes ovatus Ehrlichia (IOE, AKA E. japonica). Employing murine model of fatal ehrlichiosis, we found that virulent IOE inhibited NRF2 signaling in liver tissue of infected mice and in HCs as evidenced by downregulation of NRF2 expression, and downstream target GPX4, as well as decreased NRF2 nuclear translocation, a key step in NRF2 activation. This was associated with activation of non-canonical inflammasomes pathway marked by activation of caspase 11, accumulation of reactive oxygen species (ROS), mitochondrial dysfunction, and endoplasmic reticulum (ER) stress. Mechanistically, treatment of IOE-infected HCs with the antioxidant 3H-1,2-Dithiole-3-Thione (D3T), that induces NRF2 activation, attenuated oxidative stress and caspase 11 activation, as well as restored cell viability. Importantly, treatment of IOE-infected mice with D3T resulted in attenuated liver pathology, decreased inflammation, enhanced bacterial clearance, prolonged survival, and resistance to fatal ehrlichiosis. Our study reveals, for the first time, that targeting anti-oxidative signaling pathway is a key approach in the treatment of severe and potential Ehrlichia-induced acute liver injury and sepsis.
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Affiliation(s)
- Aditya Kumar Sharma
- Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Abdeljabar El Andaloussi
- Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
- BioImmune Solutions Inc., 605–1355, Le Corbusier, Laval, Quebec, Canada
| | - Nahed Ismail
- Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
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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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Harrus S. Perspectives on the pathogenesis and treatment of canine monocytic ehrlichiosis (Ehrlichia canis). Vet J 2015; 204:239-40. [PMID: 25957922 DOI: 10.1016/j.tvjl.2015.04.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 04/15/2015] [Accepted: 04/17/2015] [Indexed: 12/30/2022]
Affiliation(s)
- Shimon Harrus
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot 7610000, Israel.
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6
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The spreading process of Ehrlichia canis in macrophages is dependent on actin cytoskeleton, calcium and iron influx and lysosomal evasion. Vet Microbiol 2013; 168:442-6. [PMID: 24378068 DOI: 10.1016/j.vetmic.2013.11.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 11/25/2013] [Accepted: 11/30/2013] [Indexed: 12/28/2022]
Abstract
Ehrlichia canis is an obligate intracellular microorganism and the etiologic agent of canine monocytic ehrlichiosis. The invasion process has already been described for some bacteria in this genus, such as E. muris and E. chaffeensis, and consists of four stages: adhesion, internalisation, intracellular proliferation and intercellular spreading. However, little is known about the spreading process of E. canis. The aim of this study was to analyse the role of the actin cytoskeleton, calcium, iron and lysosomes from the host cell in the spreading of E. canis in dog macrophages in vitro. Different inhibitory drugs were used: cytochalasin D (actin polymerisation inhibitor), verapamil (calcium channel blocker) and deferoxamine (iron chelator). Our results showed a decrease in the number of bacteria in infected cells treated with all drugs when compared to controls. Lysosomes in infected cells were cytochemically labelled with acid phosphatase to allow the visualisation of phagosome-lysosome fusion and were further analysed by transmission electron microscopy. Phagosome-lysosome fusion was rarely observed in vacuoles containing viable E. canis. These data suggest that the spreading process of E. canis in vitro is dependent on cellular components analysed and lysosomal evasion.
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Bertin F, Reising A, Slovis N, Constable P, Taylor S. Clinical and Clinicopathological Factors Associated with Survival in 44 Horses with Equine Neorickettsiosis (Potomac Horse Fever). J Vet Intern Med 2013; 27:1528-34. [PMID: 24118378 DOI: 10.1111/jvim.12209] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 06/01/2013] [Accepted: 08/21/2013] [Indexed: 12/01/2022] Open
Affiliation(s)
- F.R. Bertin
- Department of Veterinary Clinical Sciences; College of Veterinary Medicine; Purdue University; West Lafayette IN
| | - A. Reising
- Hagyard Equine Medical Institute; Lexington KY
| | - N.M. Slovis
- Hagyard Equine Medical Institute; Lexington KY
| | - P.D. Constable
- Department of Veterinary Clinical Sciences; College of Veterinary Medicine; Purdue University; West Lafayette IN
| | - S.D. Taylor
- Department of Veterinary Clinical Sciences; College of Veterinary Medicine; Purdue University; West Lafayette IN
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Gibson KE, Pastenkos G, Moesta S, Rikihisa Y. Neorickettsia risticii surface-exposed proteins: proteomics identification, recognition by naturally-infected horses, and strain variations. Vet Res 2011; 42:71. [PMID: 21635728 PMCID: PMC3127766 DOI: 10.1186/1297-9716-42-71] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Accepted: 06/02/2011] [Indexed: 11/16/2022] Open
Abstract
Neorickettsia risticii is the Gram-negative, obligate, and intracellular bacterial pathogen responsible for Potomac horse fever (PHF): an important acute systemic disease of horses. N. risticii surface proteins, critical for immune recognition, have not been thoroughly characterized. In this paper, we identified the 51-kDa antigen (P51) as a major surface-exposed outer membrane protein of older and contemporary strains of N. risticii through mass spectrometry of streptavidin-purified biotinylated surface-labeled proteins. Western blot analysis of sera from naturally-infected horses demonstrated universal and strong recognition of recombinant P51 over other Neorickettsia recombinant proteins. Comparisons of amino acid sequences for predicted secondary structures of P51, as well as Neorickettsia surface proteins 2 (Nsp2) and 3 (Nsp3) among N. risticii strains from horses with PHF during a 26-year period throughout the United States revealed that the majority of variations among strains were concentrated in regions predicted to be external loops of their β-barrel structures. Large insertions or deletions occurred within a tandem-repeat region in Ssa3. These data demonstrate patterns of geographical association for P51 and temporal associations for Nsp2, Nsp3, and Ssa3, indicating evolutionary trends for these Neorickettsia surface antigen genes. This study showed N. risticii surface protein population dynamics, providing groundwork for designing immunodiagnostic targets for PHF.
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Affiliation(s)
- Kathryn E Gibson
- Department of Veterinary Biosciences, The Ohio State University College of Veterinary Medicine, 1925 Coffey Rd, Columbus, OH 43210, USA.
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Oliver OE, Stämpfli H. Acute diarrhea in the adult horse: case example and review. Vet Clin North Am Equine Pract 2007; 22:73-84. [PMID: 16627106 DOI: 10.1016/j.cveq.2005.12.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Affiliation(s)
- Olimpo E Oliver
- Clinica de Grandes Animales, Departamento de Salud Animal, Facultad de Medicina Veterinaria y de Zootecnia, Universidad Nacional de Bogota de Santa Fe, Bogota, Colombia.
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Abstract
Phagosomes are fascinating subcellular structures. After all, there are only a few compartments that are born before our very eyes and whose development we can follow in a light microscope until their contents disintegrate and are completely absorbed. Yet, some phagosomes are taken advantage of by pathogenic microorganisms, which change their fate. Research into phagosome biogenesis has flourished in recent years - the purpose of this review is to give a glimpse of where this research stands, with emphasis on the cell biology of macrophage phagosomes, on new model organisms for the study of phagosome biogenesis and on intracellular pathogens and their interference with normal phagosome function.
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Affiliation(s)
- Albert Haas
- Cell Biology Institute, University of Bonn, Ulrich-Haberland-Str. 61a, 53121 Bonn, Germany.
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Wormser GP, Filozov A, Telford SR, Utpat S, Kamer RS, Liveris D, Wang G, Zentmaier L, Schwartz I, Aguero-Rosenfeld ME. Dissociation between Inhibition and Killing by Levofloxacin in Human Granulocytic Anaplasmosis. Vector Borne Zoonotic Dis 2006; 6:388-94. [PMID: 17187574 DOI: 10.1089/vbz.2006.6.388] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Human granulocytic anaplasmosis (HGA) is a potentially fatal tick-borne infection caused by Anaplasma phagocytophilum. Treatment options are limited for this entity, with doxycycline being the drug of choice. Certain fluoroquinolones such as levofloxacin are active against A. phagocytophilum in vitro. We report a hospitalized patient with HGA who improved coincident with a 13-day course of levofloxacin therapy, but clinically and microbiologically relapsed 15 days after completion of treatment. Relapse of infection after levofloxacin therapy was reproduced in a severe combined immune-deficient (SCID) mouse infection model. Quinolone therapy should not be considered curative of HGA.
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Affiliation(s)
- Gary P Wormser
- Division of Infectious Diseases, Depatment of Medicine, New York Medical College, Westcheser Medical Center, Valhalla, New York, USA.
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Reed SM, Bayly WM, Sellon DC. Mechanisms of Infectious Disease. EQUINE INTERNAL MEDICINE 2004. [PMCID: PMC7278211 DOI: 10.1016/b0-72-169777-1/50004-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Abstract
Members of the family Anaplasmataceae are obligatory intracellular bacteria with unique host cell specificities. Depending on each bacterial species, granulocytes, platelets, endothelial cells, monocytes, macrophages, red blood cells, and cells of invertebrates are specifically infected. This unique host cell specificity has been the major hurdle to overcome in order to cultivate this group of bacteria. Because these bacteria cannot survive outside host cells, once released from a host cell, they need to rapidly induce signals for their own internalization into another host cell unique to each species. How these bacteria enter and continue to survive and replicate within the host milieu, then exit the host cell is largely unknown. Recently, however, unique strategies employed by some of these bacteria for successful parasitism of mammalian leukocytes have begun to be uncovered. When these bacteria interact with host cells, signals are transduced both inside the host cells and inside the bacteria. These signals disable the alarm system, as well as microbicidal mechanisms, of the leukocytes and condition the host cells to accept these intruders to share space and nutrient resources. Signals transduced inside the bacteria allow them to finely tune their metabolism and physiology in the new host cell environment and to disguise themselves as "insiders" so that their sojourn does not upset the host cell physiology until they have sufficiently multiplied. This paper discusses our recent findings on these topics.
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Affiliation(s)
- Yasuko Rikihisa
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210-1093, USA.
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Teng CH, Palaniappan RUM, Chang YF. Cloning and characterization of an Ehrlichia canis gene encoding a protein localized to the morula membrane. Infect Immun 2003; 71:2218-25. [PMID: 12654844 PMCID: PMC152100 DOI: 10.1128/iai.71.4.2218-2225.2003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A gene encoding a 23.5-kDa ehrlichial morula membrane protein designated MmpA was cloned by screening an Ehrlichia canis expression library with convalescent dog sera, which resulted in three positive clones. Sequence analysis of the insert DNAs from all three clones indicated an open reading frame with a size of 666 bp that encodes MmpA. The structural analysis of MmpA indicated that it is a transmembrane protein with extreme hydrophobicity. Southern blot analysis of the HindIII-digested chromosomal DNA demonstrated the presence of a single copy of the mmpA gene in E. canis and Ehrlichia chaffeensis but not in the human granulocytic ehrlichiosis agent. The mmpA gene was amplified, cloned, and expressed as a fusion protein. Polyclonal antibodies to the recombinant protein (rMmpA) were raised in rabbits. Western blot analysis of E. canis and E. chaffeensis lysates with the anti-rMmpA serum resulted in the presence of an MmpA band only in E. canis, not in E. chaffeenesis. Sera from dogs which were either naturally or experimentally infected with E. canis recognized the recombinant protein. Double immunofluorescence confocal microscopy studies demonstrated that MmpA was localized mainly on the morula membrane of E. canis. Since the morula membrane is the interface between the ehrlichial growing environment and the host cytoplasm, MmpA may play a role in bacterium-host cell interactions.
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Affiliation(s)
- Ching-Hao Teng
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
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Blouin EF, Kocan KM, de la Fuente J, Saliki JT. Effect of tetracycline on development of Anaplasma marginale in cultured Ixodes scapularis cells. Vet Parasitol 2002; 107:115-26. [PMID: 12072219 DOI: 10.1016/s0304-4017(02)00117-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Infections of the tick-borne ehrlichial pathogen, Anaplasma marginale, in cattle have been controlled, in part, by administration of low doses of tetracycline. Recently, a cell culture system was developed for A. marginale using a tick cell line derived from embryonic Ixodes scapularis. This study was designed to determine the effect of tetracycline on A. marginale propagated in a tick cell culture assay. Various concentrations of tetracycline (0, 0.01, 0.10, 1.0, 5, 10, 20 or 100 microg/ml) were added in medium to cultures 48h after cell monolayers were inoculated with A. marginale. A. marginale growth in the drug treated and control cultures was subsequently evaluated by indirect ELISA at 7 days post-infection (PI) and daily by light and electron microscopy (LM and EM). Infectivity of the culture-derived A. marginale was determined by inoculation of susceptible cattle with treated and untreated control cultures. Tetracycline doses of 5, 10, 20 and 100 microg/ml resulted in significant inhibition of A. marginale growth as determined by ELISA. Morphologic deterioration of Anaplasma, as determined by LM and EM, occurred in cultures treated with the same drug concentrations. A. marginale replication, inhibited in cultures treated on days 2-6 PI with 20 microg/ml tetracycline, was not apparent 96 days after antibiotic removal. Infected cell cultures treated with medium containing 20 microg/ml tetracycline proved to be non-infective when inoculated into susceptible splenectomized calves. All parameters studied herein demonstrated that tetracycline killed A. marginale in cultured tick cells. The Anaplasma-tick cell culture drug assay therefore, would be useful for screening and evaluating novel antibiotics for control of anaplasmosis.
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Affiliation(s)
- Edmour F Blouin
- Department of Veterinary Pathobiology, 250 McElroy Hall, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA.
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Unver A, Ohashi N, Tajima T, Stich RW, Grover D, Rikihisa Y. Transcriptional analysis of p30 major outer membrane multigene family of Ehrlichia canis in dogs, ticks, and cell culture at different temperatures. Infect Immun 2001; 69:6172-8. [PMID: 11553557 PMCID: PMC98748 DOI: 10.1128/iai.69.10.6172-6178.2001] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ehrlichia canis, an obligatory intracellular bacterium of monocytes and macrophages, causes canine monocytic ehrlichiosis. E. canis immunodominant 30-kDa major outer membrane proteins are encoded by a polymorphic multigene family consisting of more than 20 paralogs. In the present study, we analyzed the mRNA expression of 14 paralogs in experimentally infected dogs and Rhipicephalus sanguineus ticks by reverse transcription-PCR using gene-specific primers followed by Southern blotting. Eleven out of 14 paralogs in E. canis were transcribed in increasing numbers and transcription levels, while the mRNA expression of the 3 remaining paralogs was not detected in blood monocytes of infected dogs during the 56-day postinoculation period. Three different groups of R. sanguineus ticks (adult males and females and nymphs) were separately infected with E. canis by feeding on the infected dogs. In these pools of acquisition-fed ticks as well as in the transmission-fed adult ticks, the transcript from only one paralog was detected, suggesting the predominant transcription of that paralog or the suppression of the remaining paralogs in ticks. Expression of the same paralog was higher whereas expression of the remaining paralogs was lower in E. canis cultivated in dog monocyte cell line DH82 at 25 degrees C than in E. canis cultivated at 37 degrees C. Analysis of differential expression of p30 multigenes in dogs, ticks, or monocyte cell cultures would help in understanding the role of these gene products in pathogenesis and E. canis transmission as well as in designing a rational vaccine candidate immunogenic against canine ehrlichiosis.
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Affiliation(s)
- A Unver
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210-1093, USA
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McDonough KA, Florczyk MA, Kress Y. Intracellular passage within macrophages affects the trafficking of virulent tubercle bacilli upon reinfection of other macrophages in a serum-dependent manner. TUBERCLE AND LUNG DISEASE : THE OFFICIAL JOURNAL OF THE INTERNATIONAL UNION AGAINST TUBERCULOSIS AND LUNG DISEASE 2001; 80:259-71. [PMID: 11162767 DOI: 10.1054/tuld.2000.0268] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
SETTING The interaction of tubercle bacilli with macrophages is central to understanding of tuberculosis disease. OBJECTIVE The objective was to determine whether prior passage within macrophages affects the behavior of Mycobacterium tuberculosis (Mtb) upon re-entry into other macrophages. DESIGN Transmission electron microscopy was used to monitor fusion of bacterial phagosomes with late endosomal/lysosomal compartments using thoria as a fluid phase marker. Two-dimensional polyacrylamide gel electrophoresis was used to study bacterial protein expression within macrophages. RESULTS H37Rv and BCG expressed novel proteins within macrophages. H37Rv also underwent less fusion after intracellular (IC) (24.2+/-7.7%) than extracellular (XC) (67.4+/-5.5%) passage when the bacteria entered new macrophages in small clusters. These effects were inhibited by serum, and were not observed with H37Ra or BCG bacteria (78.9+/-1.6% fused for all conditions). In addition, vacuoles which contained single bacilli were less likely to acquire markers (26.9+/-2.6%) than those that contained multiple bacilli (77.3+/-2.8%). CONCLUSION These results indicate that phagolysosomal fusion patterns can be modulated by a variety of factors and that virulent Mtb bacteria may express proteins within macrophages that alter their interaction with these host cells.
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Affiliation(s)
- K A McDonough
- Wadsworth Center, University at Albany, PO Box 22002, 120 New Scotland Avenue, Albany, NY 12201-2002, USA.
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Waner T, Harrus S, Jongejan F, Bark H, Keysary A, Cornelissen AW. Significance of serological testing for ehrlichial diseases in dogs with special emphasis on the diagnosis of canine monocytic ehrlichiosis caused by Ehrlichia canis. Vet Parasitol 2001; 95:1-15. [PMID: 11163693 DOI: 10.1016/s0304-4017(00)00407-6] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dogs are susceptible to a number of ehrlichial diseases. Among them, canine monocytic ehrlichiosis is an important and potentially fatal disease of dogs caused by the rickettsia Ehrlichia canis. Diagnosis of the disease relies heavily on the detection of antibodies and is usually carried out using the indirect immunofluoresence antibody (IFA) test. The IFA test may be confounded by cross-reactivities between a number of the canine ehrlichial pathogens. This article presents a review of the ehrlichial diseases affecting dogs with reference to their immune responses, host specificities, cross-reactivites and diagnosis. Diagnostic means such as Western immunblot, dot-blot and PCR are discussed. The use of the IFA test as a diagnostic means for E. canis is presented along with its potential pitfalls. The review emphasizes that the disease process, cross-reactivites with other ehrlichial species, multiple tick-borne infections and persistent IFA antibody titers post-treatment, should all be considered when interpreting E. canis serological results.
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Affiliation(s)
- T Waner
- Israel Institute for Biological Research, P.O. Box 19, Ness Ziona 70400, Israel.
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Affiliation(s)
- Y Rikihisa
- Department of Veterinary Biosciences, College of Veterinary Medicine, Ohio State University, Columbus 43210, USA.
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21
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Affiliation(s)
- T A Oelschlaeger
- Institut für Molekulare Infektionsbiologie, Universität Wuerzburg, Germany
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22
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Dowling PM, Russell AM. Pharmacokinetics of a long-acting oxytetracycline-polyethylene glycol formulation in horses. J Vet Pharmacol Ther 2000; 23:107-10. [PMID: 10849256 DOI: 10.1046/j.1365-2885.2000.00249.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- P M Dowling
- Department of Veterinary Physiological Sciences, Western College of Veterinary Medicine, 52 Campus Drive, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada
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Abstract
Bacterial and protozoon intracellular parasites have evolved diverse mechanisms for evasion of host cellular defenses associated with adaptations for survival in distinct intracellular compartments. As the reagents identifying discrete steps in vesicle maturation and trafficking have become increasingly available, it has become clear that the vacuoles occupied by intracellular parasites are much more diverse than had been previously appreciated. Many parasites induce selective fusion competence with the vacuoles they occupy, without affecting vesicular trafficking elsewhere in the cell. A likely means of controlling vesicular interactions is modification of the parasitophorous vacuole membrane by the insertion of parasite-specific proteins. A rapidly expanding class of bacterial proteins that modify the vacuolar membrane are the chlamydial inclusion membrane proteins. Although the functions of most of these proteins remain to be defined, the majority are expressed early in the infectious process, suggesting that modification of the vacuole is critical to the outcome of the host-parasite interaction.
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Affiliation(s)
- T Hackstadt
- Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, NIAID, Rocky Mountain Laboratories, Hamilton, MT 59840, USA.
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Barnewall RE, Ohashi N, Rikihisa Y. Ehrlichia chaffeensis and E. sennetsu, but not the human granulocytic ehrlichiosis agent, colocalize with transferrin receptor and up-regulate transferrin receptor mRNA by activating iron-responsive protein 1. Infect Immun 1999; 67:2258-65. [PMID: 10225882 PMCID: PMC115965 DOI: 10.1128/iai.67.5.2258-2265.1999] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ehrlichia chaffeensis and E. sennetsu are genetically divergent obligatory intracellular bacteria of human monocytes and macrophages, and the human granulocytic ehrlichiosis (HGE) agent is an obligatory intracellular bacterium of granulocytes. Infection with both E. chaffeensis and E. sennetsu, but not HGE agent, in the acute monocytic leukemia cell line THP-1 almost completely inhibited by treatment with deferoxamine, a cell-permeable iron chelator. Transferrin receptors (TfRs) accumulated on both E. chaffeensis and E. sennetsu, but not HGE agent, inclusions in THP-1 cells or the cells of the promyelocytic leukemia cell line HL-60. Reverse transcription-PCR showed an increase in the level of TfR mRNA 6 h postinfection which peaked at 24 h postinfection with both E. chaffeensis and E. sennetsu infection in THP-1 or HL-60 cells. In contrast, HGE agent in THP-1 or HL-60 cells induced no increase in TfR mRNA levels. Heat treatment of E. chaffeensis or the addition of monodansylcadaverine, a transglutaminase inhibitor, 3 h prior to infection inhibited the up-regulation of TfR mRNA. The addition of oxytetracycline 6 h after E. chaffeensis infection caused a decrease in TfR mRNA which returned to the basal level by 24 h postinfection. These results indicate that both internalization and continuous proliferation of ehrlichial organisms or the production of ehrlichial proteins are required for the up-regulation of TfR mRNA. Results of electrophoretic mobility shift assays showed that both E. chaffeensis and E. sennetsu infection increased the binding activity of iron-responsive protein 1 (IRP-1) to the iron-responsive element at 6 h postinfection and remained elevated at 24 h postinfection. However, HGE agent infection had no effect on IRP-1 binding activity. This result suggests that activation of IRP-1 and subsequent stabilization of TfR mRNA comprise the mechanism of TfR mRNA up-regulation by E. chaffeensis and E. sennetsu infection.
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Affiliation(s)
- R E Barnewall
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210-1092, USA
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Mott J, Barnewall RE, Rikihisa Y. Human granulocytic ehrlichiosis agent and Ehrlichia chaffeensis reside in different cytoplasmic compartments in HL-60 cells. Infect Immun 1999; 67:1368-78. [PMID: 10024584 PMCID: PMC96470 DOI: 10.1128/iai.67.3.1368-1378.1999] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/1998] [Accepted: 11/18/1998] [Indexed: 12/23/2022] Open
Abstract
The human granulocytic ehrlichiosis (HGE) agent resides and multiplies exclusively in cytoplasmic vacuoles of granulocytes. Double immunofluorescence labeling was used to characterize the nature of the HGE agent replicative inclusions and to compare them with inclusions containing the human monocytic ehrlichia, Ehrlichia chaffeensis, in HL-60 cells. Although both Ehrlichia spp. can coinfect HL-60 cells, they resided in separate inclusions. Inclusions of both Ehrlichia spp. were not labeled with either anti-lysosome-associated membrane protein 1 or anti-CD63. Accumulation of myeloperoxidase-positive granules were seen around HGE agent inclusions but not around E. chaffeensis inclusions. 3-(2, 4-Dinitroanilino)-3'-amino-N-methyldipropylamine and acridine orange were not localized to either inclusion type. Vacuolar-type H+-ATPase was not colocalized with HGE agent inclusions but was weakly colocalized with E. chaffeensis inclusions. E. chaffeensis inclusions were labeled with the transferrin receptor, early endosomal antigen 1, and rab5, but HGE agent inclusions were not. Some HGE agent and E. chaffeensis inclusions colocalized with major histocompatibility complex class I and II antigens. These two inclusions were not labeled for annexins I, II, IV, and VI; alpha-adaptin; clathrin heavy chain; or beta-coatomer protein. Vesicle-associated membrane protein 2 colocalized to both inclusions. The cation-independent mannose 6-phosphate receptor was not colocalized with either inclusion type. Endogenously synthesized sphingomyelin, from C6-NBD-ceramide, was not incorporated into either inclusion type. Brefeldin A did not affect the growth of either Ehrlichia sp. in HL-60 cells. These results suggest that the HGE agent resides in inclusions which are neither early nor late endosomes and does not fuse with lysosomes or Golgi-derived vesicles, while E. chaffeensis resides in an early endosomal compartment which accumulates the transferrin receptor.
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Affiliation(s)
- J Mott
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210-1092, USA
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Lilliehöök I, Johannisson A, Magnusson U, Egenvall A, Trowald-Wigh G, Håkansson L. Granulocyte function in dogs experimentally infected with a Swedish granulocytic Ehrlichia species. Vet Immunol Immunopathol 1999; 67:141-52. [PMID: 10077420 DOI: 10.1016/s0165-2427(98)00219-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Granulocyte function was studied in six dogs inoculated with a Swedish granulocytic Ehrlichia species and in four control dogs. Whole blood chemiluminescence (CL) was enhanced in the dogs with granulocytic ehrlichiosis. Both CL after stimulation with zymosan and spontaneous CL was significantly increased at peak of infection compared with pre-infection levels. Ingestion of FITC-labelled serum-opsonized yeast cells was high and stable in both groups. The ingestion was lower when the yeast cells were opsonized with anti-yeast IgG. However, there was no difference between groups. The labelling intensity of anti-human CD11b, CD18 and CD32 mAb on the granulocytes in dogs with ehrlichiosis was similar to that in control dogs. The opsonic activity in serum collected at the peak of infection was not different from serum drawn prior to inoculation. Opsonic activity was investigated both by yeast cell ingestion and by chemiluminescence after stimulation with zymosan. The serum from infected dogs enhanced the respiratory burst without stimulation with zymosan of leukocytes from healthy dogs. This suggests that serum at the peak of infection contains granulocyte activators. In this study we found normal phagocytosis together with evidence of enhanced oxidative metabolism in the granulocytes from dogs with granulocytic ehrlichiosis.
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Affiliation(s)
- I Lilliehöök
- Department of Clinical Chemistry, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences, Uppsala.
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27
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Haas A. Reprogramming the phagocytic pathway--intracellular pathogens and their vacuoles (review). Mol Membr Biol 1998; 15:103-21. [PMID: 9859108 DOI: 10.3109/09687689809074522] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Phagocytic immune cells (particularly macrophages and neutrophils) take up and digest particles that have invaded our bodies. In doing so, they represent a very early line of defence against a microbial attack. During uptake, the particles are wrapped by a portion of the phagocyte's plasma membrane, and a new endocytic compartment, the phagosome, is formed. The typical fate of a phagosome is its fusion with lysosomes to yield a phagolysosome in which the particle is digested. Recent data show that some 'intracellular microorganisms' that can cause severe illnesses (tuberculosis, leprosy, legionnaire's disease and others) manage to reprogramme the host phagocytes not to deliver them to the lysosomal compartment. This probably results in increased survival of the pathogens. The analysis of the composition of such 'novel' compartments and research on the molecular mechanisms underlying the microbial interference with host cell functions are likely to yield important insights into: (1) which endocytic/phagocytic compartments phagocytes employ to handle ingested material in general; (2) how some pathogenic microorganisms can reprogramme the phagocytic pathway; and possibly (3) how infections caused by these microorganisms can be treated more effectively. Here, some studies are presented analysing which compartments intracellular pathogens inhabit and how microbes might be able to reprogramme their host cells.
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Affiliation(s)
- A Haas
- Department of Microbiology, Biocentre of the University, Würzburg, Germany
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28
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Webster P, IJdo JW, Chicoine LM, Fikrig E. The agent of Human Granulocytic Ehrlichiosis resides in an endosomal compartment. J Clin Invest 1998; 101:1932-41. [PMID: 9576758 PMCID: PMC508780 DOI: 10.1172/jci1544] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The composition of cytoplasmic vacuoles containing the agent of Human Granulocytic Ehrlichiosis (HGE) was studied to investigate how this pathogen exists within infected host cells. Electron microscopy demonstrated that the HGE organism resides in a membrane-bound compartment within HL-60 cells: early forms of the HGE agent have a round reticular appearance while later structures are small and dense. Vacuoles containing HGE bacteria incorporated endocytosed colloidal gold particles, suggesting that they are part of the endocytic pathway. Antibodies directed to the mannose-6-phosphate receptor labeled vacuole membranes. Antibodies to the transferrin receptor and to the lysosomal membrane glycoprotein LAMP 1 did not. Moreover, 3-(2,4-dinitroanilino)-3'-amino-N-methyldipropylamine, which normally accumulates in compartments with low pH, was not present inside these vacuoles. These results suggest that vacuoles containing the agent of HGE fail to mature into phagolysosomes. We conclude that the agent of HGE appears to enter and modify part of the endocytic pathway.
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Affiliation(s)
- P Webster
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520-8031, USA
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29
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Abstract
Bacterial obligate intracellular parasites have evolved diverse mechanisms for evasion of host cellular defenses. These mechanisms involve adaptations for survival in distinct intracellular compartments. Intracellular niches inhabited by obligate intracellular parasites include the cytoplasm, arrested early endosomes, lysosomes, and vesicles that do not fuse with the endosomal compartment but intersect with an exocytic pathway.
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Affiliation(s)
- T Hackstadt
- Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840, USA.
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30
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Zhang Y, Rikihisa Y. Tyrosine phosphorylation is required for ehrlichial internalization and replication in P388D1 cells. Infect Immun 1997; 65:2959-64. [PMID: 9199472 PMCID: PMC175414 DOI: 10.1128/iai.65.7.2959-2964.1997] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Replication of Ehrlichia risticii was inhibited in P388D1 cells when a protein tyrosine kinase inhibitor (genistein or herbimycin A) was added after internalization of the organism at 3 h postinfection. Upon addition of genistein at day 1, 2, 3, or 4 postinfection, further proliferation of E. risticii was prevented. The inhibition was reversible, since regrowth of E. risticii occurred upon the removal of genistein. Genistein prevented spreading of E. risticii from P388D1 cells to THP-1 cells. Genistein did not prevent binding of [35S]methionine-labeled E. risticii to P388D1 cells but did prevent internalization of [35S]methionine-labeled E. risticii. 14CO2 production from L-[14C]glutamine in Percoll density gradient-purified E. risticii was not inhibited by genistein or herbimycin A, which suggests that these reagents did not directly inhibit ehrlichial energy metabolism. Double indirect immunofluorescence labeling with antiphosphotyrosine antibody and anti-E. risticii antibody revealed colocalization of tyrosine phosphoproteins with ehrlichial inclusions. There was, however, no colocalization of phosphotyrosine with phagosomes containing 0.5-microm-diameter fluorescent beads. Western immunoblot analysis revealed that 52- and 54-kDa proteins were tyrosine phosphorylated only in infected cells and that phosphorylation of these two proteins was reduced when infected cells were treated with genistein for 6 h. These results suggest that protein tyrosine phosphorylation is specific and essential for ehrlichial internalization, replication, and spreading in macrophages but not for binding.
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Affiliation(s)
- Y Zhang
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus 43210, USA
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31
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Barnewall RE, Rikihisa Y, Lee EH. Ehrlichia chaffeensis inclusions are early endosomes which selectively accumulate transferrin receptor. Infect Immun 1997; 65:1455-61. [PMID: 9119487 PMCID: PMC175153 DOI: 10.1128/iai.65.4.1455-1461.1997] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Ehrlichia chaffeensis is an obligatory intracellular bacterium which infects macrophages and monocytes. Double immunofluorescence labeling was used to characterize the nature of E. chaffeensis inclusion in the human promyelocytic leukemia cell line THP-1. E. chaffeensis was labeled with dog anti-E. chaffeensis serum and fluorescein isothiocyanate-conjugated anti-dog immunoglobulin G (IgG). Lissamine rhodamine-conjugated anti-mouse IgG was used to label various mouse monoclonal antibodies. Ehrlichial inclusions did not fuse with lysosomes, since they were not labeled with anti-CD63 or anti-LAMP-1. The ehrlichial inclusions were slightly acidic, since they weakly accumulated 3-(2,4-dinitroanilino)-3'-amino-N-methyldipropylamine and stained weakly positive for vacuolar type H+ ATPase. Some ehrlichial inclusions were labeled positive with antibodies against HLA-DR, HLA-ABC, and beta2 microglobulin, while other inclusions in the same cell were labeled negative. The inclusions were labeled strongly positive for transferrin receptors (TfRs) and negative for the clathrin heavy chain. Time course labeling for TfRs showed that up to 3 h postinfection, most of the ehrlichial inclusions were negative for TfRs. After 6 h postinfection, 100% of the ehrlichial inclusions became TfR positive and the intensity of labeling was increased during the subsequent 3 days. Reverse transcription-PCR showed a gradual increase in the level of TfR mRNA postinfection, which reached a peak at 24 h postinfection. These results suggest that ehrlichial inclusions are early endosomes which selectively accumulate TfRs and that the ehrlichiae up-regulate TfR mRNA expression.
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Affiliation(s)
- R E Barnewall
- Department of Veterinary Biosciences, College of Veterinary Medicine, Ohio State University, Columbus 43210-1092, USA
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32
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33
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Williams NM, Cross RJ, Timoney PJ. Respiratory burst activity associated with phagocytosis of Ehrlichia risticii by mouse peritoneal macrophages. Res Vet Sci 1994; 57:194-9. [PMID: 7817006 DOI: 10.1016/0034-5288(94)90057-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Peritoneal macrophages from two strains of mice, BALB/c and C3H/HeN, were analysed by flow cytometry for a respiratory burst associated with the phagocytosis of Ehrlichia risticii. Resident murine peritoneal macrophages failed to respond with a respiratory burst after phagocytosing E risticii. In contrast, mice previously infected with E risticii yielded peritoneal macrophages that did generate a respiratory burst on phagocytosing ehrlichiae.
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Affiliation(s)
- N M Williams
- Department of Veterinary Science, University of Kentucky, Lexington 40546
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34
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Messick JB, Rikihisa Y. Inhibition of binding, entry, or intracellular proliferation of Ehrlichia risticii in P388D1 cells by anti-E. risticii serum, immunoglobulin G, or Fab fragment. Infect Immun 1994; 62:3156-61. [PMID: 8039884 PMCID: PMC302940 DOI: 10.1128/iai.62.8.3156-3161.1994] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The effects of equine antiserum, immunoglobulin G (IgG) specific for Ehrlichia risticii, and its Fab fragment on E. risticii binding to, internalization into, and proliferation in P388D1 cells were studied by immunofluorescence flow cytometry. Anti-E. risticii equine serum or IgG inhibited E. risticii at a stage beyond binding and internalization. In contrast, monovalent anti-E. risticii equine Fab fragments inhibited E. risticii binding and internalization into P388D1 cells. In the presence of control equine serum, IgG, or its Fab fragment, E. risticii cells were bound, were internalized and subsequently grew within P388D1 cells, and eventually destroyed the host cells as effectively as was the case without equine serum, IgG, or Fab fragments. Anti-E. risticii IgG but not normal horse IgG inhibited L-[14C]glutamine metabolism in Percoll gradient-purified E. risticii. These findings suggest that the Fab fragment of intact anti-E. risticii IgG blocks the ligands on E. risticii responsible for non-IgG-mediated internalization and diverts them to bind via the Fc receptor. Following Fc-mediated entry of E. risticii, the antibody interfered with the metabolic activity of E. risticii cells, rendering them incapable of proliferation in P388D1 cells and resulting in the eventual destruction of the organisms.
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Affiliation(s)
- J B Messick
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Ohio State University, Columbus 43210-1092
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35
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Messick JB, Rikihisa Y. Characterization of Ehrlichia risticii binding, internalization, and proliferation in host cells by flow cytometry. Infect Immun 1993; 61:3803-10. [PMID: 8359901 PMCID: PMC281080 DOI: 10.1128/iai.61.9.3803-3810.1993] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The binding, internalization, and proliferation of Ehrlichia risticii in P388D1 cells and equine polymorphonuclear (PMN) leukocytes were studied by immunofluorescent staining and flow cytometric analysis. The binding of ehrlichiae to P388D1 cells at 4 degrees C was dose dependent, and the antigens of bound organisms were susceptible to pronase treatment. Additionally, the binding of ehrlichiae to P388D1 cells was diminished when either P388D1 cells or ehrlichiae were treated with 1% paraformaldehyde for 30 min or 0.25% trypsin for 15 min. These results indicate that the ehrlichial ligand and host cell receptor are likely surface proteins. Following incubation at 37 degrees C, bound E. risticii and/or its antigens were removed with pronase and indirect immunofluorescent staining in the presence of saponin was used to examine intracellular ehrlichiae. Our results indicate that E. risticii was internalized into P388D1 cells within 3 h and proliferated by 48 h of incubation. The microfilament-disrupting agent cytochalasin D and the transglutaminase inhibitor monodansylcadaverine were used to differentiate between phagocytosis (sensitive to cytochalasin) and receptor-mediated endocytosis (sensitive to monodansylcadaverine) of E. risticii by P388D1 cells. In concentrations that produced distinctive morphological changes and inhibited phagocytosis of polystyrene latex beads, cytochalasin D did not suppress the infectivity of E. risticii. Binding, internalization, or proliferation of E. risticii was not affected by cytochalasin D. However, monodansylcadaverine inhibited infection of E. risticii in a dose-dependent manner. The agent did not affect the attachment of ehrlichiae to host cells, but it did suppress internalization and proliferation. These results suggest that E. risticii is internalized by receptor-mediated endocytosis and that productive infection by E. risticii does not depend on phagocytosis by the P388D1 cells. Although E. risticii did not bind to the surface of equine PMN leukocytes at 4 degrees C, organisms were taken up by this cell at 37 degrees C. E. risticii, however, failed to survive in equine PMN leukocytes.
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Affiliation(s)
- J B Messick
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Columbus, Ohio 43210-1092
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36
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Abstract
E. risticii, the cause of classic Potomac horse fever, is now known to produce two disease syndromes: EEC and EEA. The pathogen appears to commonly infect horses based on seroepidemiologic studies; however, the method of transmission remains unknown. The most common clinical disease is EEC, commonly called Potomac horse fever, which presents a wide spectrum of clinical signs. Diagnosis is currently dependent on serology, which frequently does not lead to a definitive diagnosis and at best results in a retrospective diagnosis. A new diagnostic approach, polymerase chain reaction, may offer a rapid and accurate diagnostic test but is yet to be proven. Antimicrobials found to be highly effective in treating EEC include intravenous oxytetracycline and the oral combination of erythromycin and rifampin. Without an understanding of the mode of transmission, prevention of EEC will remain impossible. Although two commercial bacterins are available, vaccination does not result in complete protection. EEA is a recently recognized clinical syndrome caused by E. risticii. After recovery from EEC, pregnant mares may abort. Based on histologic examination, the aborted fetus appears to be a victim of an ehrlichial colitis as well as placentitis. The effect of antimicrobials and vaccination on the occurrence of EEA has yet to be investigated.
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Affiliation(s)
- J E Palmer
- Department of Clinical Studies, New Bolton Center, University of Pennsylvania School of Veterinary Medicine, Kennett Square
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37
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Williams NM, Timoney PJ. In vitro killing of Ehrlichia risticii by activated and immune mouse peritoneal macrophages. Infect Immun 1993; 61:861-7. [PMID: 8432606 PMCID: PMC302812 DOI: 10.1128/iai.61.3.861-867.1993] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Normal resident murine peritoneal macrophages inoculated in vitro with Ehrlichia risticii readily phagocytized the organism but were unable to suppress ehrlichial replication as determined by indirect fluorescent-antibody staining of the inoculated cells. In contrast, macrophages from Corynebacterium parvum-inoculated and E. risticii-recovered mice rapidly eliminated the ehrlichiae. Macrophages from E. risticii-recovered mice were as effective as the C. parvum-activated cells in phagocytizing and eliminating the organism. Opsonization of E. risticii with homologous antiserum prior to inoculation of macrophage cultures resulted in enhancement of phagocytosis and greater suppression of E. risticii replication in all macrophage groups. These findings indicate that the pathogenesis of E. risticii infection centers on the ability of the organism to enter and replicate within the macrophage with avoidance of macrophage antimicrobial effects. An immune response results in macrophage activation with enhancement of the macrophage's ability to eliminate E. risticii. Opsonization of E. risticii with anti-E. risticii serum renders E. risticii more susceptible to macrophage destruction.
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Affiliation(s)
- N M Williams
- Department of Veterinary Science, University of Kentucky, Lexington 40546-0099
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38
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Brouqui P, Raoult D. In vitro antibiotic susceptibility of the newly recognized agent of ehrlichiosis in humans, Ehrlichia chaffeensis. Antimicrob Agents Chemother 1992; 36:2799-803. [PMID: 1482148 PMCID: PMC245548 DOI: 10.1128/aac.36.12.2799] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Ehrlichiosis in humans, a rickettsial disease recently discovered in the United States, is generally treated successfully with tetracyclines; however treatment with these agents is usually avoided with children and pregnant women. The in vitro susceptibility of Ehrlichia chaffeensis, the agent of human ehrlichiosis in the United States, was assessed by a quantitative evaluation of infected DH82 cells cultivated in 96-well microtiter plates in the presence of different concentrations of selected antibiotics. Extracellular MICs and MBCs were evaluated after 72 h of exposure to the antibiotics. Doxycycline and rifampin were found to exert rapidly bactericidal effects, with MBCs in the extracellular culture medium of less than 0.5 and 0.125 microgram/ml, respectively. E. chaffeensis was resistant to chloramphenicol, ciprofloxacin, erythromycin, co-trimoxazole, penicillin, and gentamicin, which had MICs greater than 16, 4, 8, 4, 40, and 32 micrograms/ml, respectively. These observations are consistent with the finding that human ehrlichiosis appears to respond to tetracycline therapy, which has been the therapy of first choice. Further clinical investigations are necessary to evaluate the role of rifampin in the treatment of human ehrlichiosis, especially in children.
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Affiliation(s)
- P Brouqui
- Unité des Rickettsies, Faculté de Médecine, Marseille, France
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39
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Choi EY, Kim KJ, Jeon KW. Lysosomal membrane proteins of Amoeba proteus, as studied with monoclonal antibodies. THE JOURNAL OF PROTOZOOLOGY 1992; 39:671-7. [PMID: 1453355 DOI: 10.1111/j.1550-7408.1992.tb04447.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Monoclonal antibodies were prepared against lysosomal membrane proteins of amoebae and used to follow lysosome-phagosome fusion after induced phagocytosis. The specificity of antibodies was checked by indirect immunofluorescence microscopy, immunoelectron microscopy, and localization of the antigen in subcellular fractions. The antibody-recognized proteins started to appear on the membranes of phagolysosomes about 5 min after phagocytosis as detected by indirect immunofluorescence, and the intensity of fluorescence increased for up to 1 h. Results of injection experiments in which purified antibodies had been injected into living cells and probed by indirect fluorescence indicated that the antigens were located on the cytoplasmic side of the lysosomal membranes. Lysosomes fuse with phagosomes on the one hand but not with non-fusible vesicles such as symbiosomes on the other. The results support the view that a membrane component(s) of non-fusible vesicles somehow prevents lysosomes from fusing with them.
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Affiliation(s)
- E Y Choi
- Department of Zoology, University of Tennessee, Knoxville 37996
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40
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Shankarappa B, Dutta SK, Mattingly-Napier B. Identification of the protective 44-kilodalton recombinant antigen of Ehrlichia risticii. Infect Immun 1992; 60:612-7. [PMID: 1730496 PMCID: PMC257673 DOI: 10.1128/iai.60.2.612-617.1992] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Protective studies were conducted with mice by using recombinantly produced antigens, polyacrylamide gel electrophoresis-fractionated antigens, and a monoclonal antibody specific to the 28-kDa antigen of Ehrlichia risticii. Analysis of E. risticii-infected cell culture used as the challenge inoculum indicated an inverse relationship between the progression of cell culture infection and the infective capability of E. risticii for mice. A recombinant 44-kDa antigen was found to protect mice considerably against challenge infection, while the monoclonal antibody and fractionated antigens were not protective. A potentiation of protection was observed when the recombinant 44-kDa antigen was combined with the recombinant 70-kDa antigen and used for mouse immunization.
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Affiliation(s)
- B Shankarappa
- Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park 20742-3711
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41
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Abstract
In the late 1970s, a new infectious disease in horses, involving acute enteritis, was recognised in the Potomac River area of Maryland, U.S.A. The causative agent was identified subsequently as a new species of rickettsial organism, later named Ehrlichia risticii. Since then, the disease has been reported in many other states, and in enzootic areas vaccination is common. Signs associated with the clinical disease included depression, fever, anorexia, decreased or absent intestinal sounds, profuse watery diarrhoea and laminitis. However, considerable variation in clinical manifestations has been reported in both the natural and experimental disease. Accurate diagnosis depends on serological testing; currently, the immunofluorescent antibody test (IFA) is used widely, although an enzyme-linked immunosorbent assay (ELISA) has been developed recently. Mortality in untreated cases is 15 to 35 per cent. Antibiotics of the tetracycline series have shown activity against the organism in vitro, in an in vivo murine model and appear to be useful in clinical cases.
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Affiliation(s)
- P Mulville
- Department of Medicine, Tufts University School of Veterinary Medicine, North Grafton, Massachusetts 01536
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Park J, Rikihisa Y. Inhibition of Ehrlichia risticii infection in murine peritoneal macrophages by gamma interferon, a calcium ionophore, and concanavalin A. Infect Immun 1991; 59:3418-23. [PMID: 1910000 PMCID: PMC258901 DOI: 10.1128/iai.59.10.3418-3423.1991] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Ehrlichia risticii incubated with mouse peritoneal macrophages elicited with thioglycolate broth survived and replicated, thereby allowing examination of the effects of several immunopotentiating agents. Treatment of the macrophages with recombinant murine gamma interferon (rMuIFN-gamma) in vitro at 1 day before or 3 h after infection made the macrophages resistant to infection with E. risticii, and macrophages treated with rMuIFN-gamma at 1 to 3 days after infection developed the capacity to eradicate intracellular E. risticii. Similar effects were seen with macrophages treated with the Ca2+ ionophore A23187 before or after E. risticii infection in vitro. Concanavalin A treatment before or 3 h after infection caused the macrophages to become resistant to infection with E. risticii but could confer neither ehrlichiacidal nor ehrlichiastic activity to them once infection had been established for more than 1 day. Bacterial products such as lipopolysaccharide and muramyl dipeptide were less or not at all effective, respectively, in conferring antiehrlichial activity to macrophages. Finally, protein kinase C activator, phorbol myristate acetate, and recombinant tumor necrosis factor did not induce any antiehrlichial activity in macrophages when the macrophages were treated either before or after infection.
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Affiliation(s)
- J Park
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Ohio State University, Columbus 43210-1092
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43
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Kurita N, Terao K, Brummer E, Ito E, Nishimura K, Miyaji M. Resistance of Histoplasma capsulatum to killing by human neutrophils. Evasion of oxidative burst and lysosomal-fusion products. Mycopathologia 1991; 115:207-13. [PMID: 1660960 DOI: 10.1007/bf00462229] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The basis for resistance of yeast form of Histoplasma capsulatum to antifungal activity of human neutrophils was studied. In limiting dilution assays and short term coculture assays human neutrophils were ineffective in killing H. capsulatum whereas Candida albicans was readily killed. By contrast, in a cell free hydrogen peroxide-peroxidase-halide system H. capsulatum was as sensitive to killing as C. albicans. Moreover, lysate of human neutrophils effectively substituted for horse-radish peroxidase in a cell free system for killing H. capsulatum. H. capsulatum elicited significant products of the oxidative burst in human neutrophils as detected by luminol-enhanced chemiluminescence. However, the response was two-fold less (p less than 0.05) than that induced by C. albicans. Transmission electron microscopy studies showed that phagosome-lysosome fusion took place when neutrophils phagocytosed C. albicans or H. capsulatum. Taken together, these findings indicate that, even though H. capsulatum elicits an oxidative burst and phagosome-lysosome fusion within the phagosome, it is capable of evading damage in short term assays.
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Affiliation(s)
- N Kurita
- Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Japan
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Abstract
The tribe Ehrlichieae consists of gram-negative minute cocci that are obligate intracellular parasites classified in the family Rickettsiaceae. Although ehrlichial organisms have been observed in leukocytes for many years, only a few species have been cultured in quantities sufficient for biochemical and molecular analyses. Recents studies on 16S-rRNA sequence analysis and energy metabolism showed that the genus Ehrlichia is closely related to the genus Rickettsia. There is, however, no antigenic cross-reactivity between these genera. Ehrlichial organisms cause a disease called "ehrlichiosis," a noncontagious infectious disease known to be transmitted by a tick in several cases and by a fluke in one case. Ehrlichia spp. infect dogs, ruminants, horses, and humans. Recently, two new ehrlichial diseases, Potomac horse fever and human ehrlichiosis, were discovered in the United States. The etiologic agent of Potomac horse fever, Ehrlichia risticii, is closely related to the known human pathogen Ehrlichia sennetsu. The etiologic agent of human ehrlichiosis is related to Ehrlichia canis, a canine pathogen. In contrast to the genus Rickettsia, members of the tribe Ehrlichieae reside primarily in the cytoplasmic vacuoles of monocytes or granulocytes and cause hematologic abnormalities, lymphadenopathy, and other pathologic changes in the host. However, the actual mechanisms whereby Ehrlichia spp. infect leukocytes, multiply in them, and produce various forms of systemic disease have not been defined. Depending on the ehrlichial species involved, serologic or direct microscopic observation of stained blood smears is currently used to diagnose ehrlichial disease.
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Affiliation(s)
- Y Rikihisa
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Ohio State University, Columbus 43210
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Kaylor PS, Crawford TB, McElwain TF, Palmer GH. Passive transfer of antibody to Ehrlichia risticii protects mice from ehrlichiosis. Infect Immun 1991; 59:2058-62. [PMID: 2037365 PMCID: PMC257965 DOI: 10.1128/iai.59.6.2058-2062.1991] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Mice that recovered from Ehrlichia risticii infection were immune to a challenge dose of 100 50% lethal doses. Immune or normal mouse serum was passively transferred to mice challenged with E. risticii. Clinical signs of ehrlichiosis were completely prevented in 22 of 24 recipients of immune serum, and the onset of signs of illness was delayed in the remaining two mice compared with the onset of illness in 24 of 24 recipients of nonimmune serum. Purified immunoglobulin G (IgG) was used to passively protect mice from infection with E. risticii. All 15 mice that received IgG from normal serum but none of the 15 mice that received IgG from immune serum developed clinical signs of illness. Antibodies in immune mouse serum immunoprecipitated [35S]methionine metabolically labeled E. risticii proteins with apparent molecular masses ranging from 14 to 90 kDa. The major antigens recognized by dilute immune serum in immunoblot analysis had molecular masses of 62, 53, 40, 33, 27, and 25 kDa, and the 62- and 27-kDa antigens were prominent in immunoprecipitations with dilute antibody. Antigens with molecular masses of 62, 53, 40, 33, and 27 kDa are likely surface exposed, as determined by immunoprecipitation of 125I-labeled organisms with immune mouse serum.
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Affiliation(s)
- P S Kaylor
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman 99164
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46
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Tamura A, Urakami H, Ohashi N. A comparative view of Rickettsia tsutsugamushi and the other groups of rickettsiae. Eur J Epidemiol 1991; 7:259-69. [PMID: 1909244 DOI: 10.1007/bf00145675] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Recent researches on the rickettsial group microorganisms are summarized in their comparative aspects of morphology, cultivation and multiplication, susceptibility to chemotherapeutics, chemical structure of envelopes, nucleic acid, protein constitution, and gene structures. From this overview, Rickettsia tsutsugamushi seems to have different properties from the others and should be reclassified into a new genus, and a new species name as Orientia tsutsugamushi is proposed.
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Affiliation(s)
- A Tamura
- Department of Microbiology, Niigata College of Pharmacy, Japan
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47
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Abstract
The isolation and cultivation of the agent of Potomac horse fever, Ehrlichia risticii, by Holland, Ristic, et al., afforded Weisburg et al. an opportunity to examine its phylogeny. E. risticii is clearly related to the genus Rickettsia and not to chlamydiae. A reevaluation of the significance of phenotypic characteristics is thus required, since ehrlichiae, in some respects, resemble chlamydiae. For example, unlike rickettsiae, ehrlichiae and chlamydiae multiply in the phagosome of their host cells, but may not have the same mechanism of inhibition of phagosome-lyososome fusion. Rickettsiae, which multiply in the cytoplasm, may have a mechanism of survival in the phagosome similar to that of the ehrlichiae, but, in addition, utilize a phospholipase, which permits prompt escape from the phagosome. Rickettsiae, as most Gram negatives, multiply by binary fisson. Chlamydiae, on the other hand, undergo a cycle of development. Elementary bodies (EB) infect, but do not divide, while the reverse is true of reticulate bodies (RB). Ehrlichiae superficially resemble chlamydiae rather than rickettsiae, but ehrlichiae have not yet been submitted to the rigorous criteria of separation of EB and RB. Investigations in our laboratory of the metabolic activities of E. risticii and E. sennetsu link them to the rickettsiae and not to the chlamydiae. Ehrlichiae and rickettsiae, but not chlamydiae, derive some ATP from their catabolic activities. In conclusion, in further investigations of the monocytic ehrlichiae, it is safer to be guided by what we know of rickettsiae, than chlamydiae.
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Affiliation(s)
- E Weiss
- Naval Medical Research Institute, Bethesda, MD 20889
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Brouqui P, Raoult D. In vitro susceptibility of Ehrlichia sennetsu to antibiotics. Antimicrob Agents Chemother 1990; 34:1593-6. [PMID: 2221869 PMCID: PMC171879 DOI: 10.1128/aac.34.8.1593] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Antibiotic efficacies were evaluated by Diff-Quik (Dade, Düdingen, Federal Republic of Germany) staining of Ehrlichia sennetsu in P388D1 murine macrophages grown in 96-well microtiter plates. Sennetsu disease is generally cured with tetracyclines. In vivo, E. sennetsu is susceptible to doxycycline and is resistant to erythromycin, penicillin, and chloramphenicol. Our study confirmed, in vitro, the efficacy of doxycycline, which had an MIC of 0.125 micrograms/ml. E. sennetsu was found to be resistant to erythromycin, chloramphenicol, penicillin, gentamicin, and co-trimoxazole, while it was very susceptible to ciprofloxacin (MIC, 0.125 micrograms/ml) and rifampin (MIC, 0.5 micrograms/ml).
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Affiliation(s)
- P Brouqui
- Centre National de Reference des Rickettsioses, Centre Hospitalier Universitaire Timone, Marseille, France
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Weiss E, Dasch GA, Kang YH, Williams JC. Comparison of properties of isolated ehrlichiae and scrub typhus rickettsiae. Ann N Y Acad Sci 1990; 590:76-84. [PMID: 1974128 DOI: 10.1111/j.1749-6632.1990.tb42210.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- E Weiss
- Naval Medical Research Institute, Bethesda, Maryland 20814
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50
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Weiss E, Williams JC, Dasch GA, Kang YH. Energy metabolism of monocytic Ehrlichia. Proc Natl Acad Sci U S A 1989; 86:1674-8. [PMID: 2922404 PMCID: PMC286763 DOI: 10.1073/pnas.86.5.1674] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
We investigated if the monocytic Ehrlichia are totally dependent on their host cells for energy, or, as Rickettsia, are capable of some ATP synthesis in vitro. The Miyayama strain of Ehrlichia sennetsu and the Maryland and Illinois strains of Ehrlichia risticii were cultivated in a mouse macrophage cell line, separated from host cell constituents by procedures that included Renografin or Percoll gradient centrifugation, and tested after cryopreservation. Cells incubated without a metabolizing substrate contained little, if any, ATP. When the Ehrlichia cells were incubated for 1 hr at 34 degrees C with glutamine, significant amounts of ATP were detected. The amounts of ATP attained with glutamine were decreased in some instances by the addition of atractyloside, an inhibitor of adenine nucleotide translocase in mitochondria, and were decreased consistently and to a greater extent by 2,4-dinitrophenol. When ATP, instead of glutamine, was added to the ehrlichiae, upon incubation the amount of ATP was markedly decreased. Comparable responses under all these conditions were obtained with Rickettsia typhi, although the final ATP levels were higher. Control preparations derived from uninfected mouse macrophages or from the discards of the Ehrlichia purification procedures contained negligible amounts of ATP, which were not increased by incubation with glutamine. We conclude that with respect to ATP metabolism, the monocytic Ehrlichia resemble Rickettsia more closely than Chlamydia, even though Ehrlichia resemble Chlamydia in their intracellular location in the phagosomes and in possibly having a developmental cycle.
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Affiliation(s)
- E Weiss
- Naval Medical Research Institute, Bethesda, MD 20814
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