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Mukhtar MU, Mahmood MA, Fayyaz Z, Klinpakdee K, Abdullah M. Opening the Black Box of Host Range, Vectorial Diversity, and Genetic Variants of Genus Anaplasma: The Contributing Factors Toward Its Zoonosis. Vector Borne Zoonotic Dis 2024; 24:265-273. [PMID: 38227393 DOI: 10.1089/vbz.2023.0043] [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: 01/17/2024] Open
Abstract
Background: Genus Anaplasma of the family Anaplasmataceae possesses bacteria of hematopoietic origin, which are obligate intracellular Gram-negative bacteria transmitted mainly by tick vectors. The members of this group of infectious agents are not new as etiological agents of animal diseases worldwide. However, now, reports of their zoonotic potential have gained currency to study these pathogens. The emergence of new species of Anaplasma and the spread of existing species to new areas and hosts highlight the importance of monitoring and improving diagnostic and treatment options for zoonotic diseases caused by Anaplasma. Conclusion: This review focuses on the general and distinctive characteristics of Anaplasma spp., with particular emphasis on the novel species and their diverse spectrum of hosts as potential risk factors impacting its emerging zoonosis.
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Affiliation(s)
- Muhammad Uzair Mukhtar
- Department of Medical Entomology and Parasitology, Institute of Public Health, Lahore, Pakistan
| | - Muhammad Asif Mahmood
- Department of Medical Entomology and Parasitology, Institute of Public Health, Lahore, Pakistan
| | - Zahra Fayyaz
- Department of Infectious Diseases, Institute of Public Health, Lahore, Pakistan
| | - Kanoknaphat Klinpakdee
- Faculty of Veterinary Medicine, Rajamangala University of Technology Tawan-Ok, Chonburi, Thailand
| | - Muhammad Abdullah
- Department of Paramedical Education, Institute of Public Health, Lahore, Pakistan
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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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Patterson LL, Byerly CD, Solomon R, Pittner N, Bui DC, Patel J, McBride JW. Ehrlichia Notch signaling induction promotes XIAP stability and inhibits apoptosis. Infect Immun 2023; 91:e0000223. [PMID: 37594275 PMCID: PMC10501217 DOI: 10.1128/iai.00002-23] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 06/07/2023] [Indexed: 08/19/2023] Open
Abstract
Ehrlichia chaffeensis has evolved multiple strategies to evade innate defenses of the mononuclear phagocyte. Recently, we reported the E. chaffeensis tandem repeat protein (TRP)120 effector functions as a Notch ligand mimetic and a ubiquitin ligase that degrades the nuclear tumor suppressor, F-box and WD repeat domain-containing 7, a negative regulator of Notch. The Notch intracellular domain (NICD) is known to inhibit apoptosis primarily by interacting with X-linked inhibitor of apoptosis protein (XIAP) to prevent degradation. In this study, we determined that E. chaffeensis activation of Notch signaling increases XIAP levels, thereby inhibiting apoptosis through both the intrinsic and executioner pathways. Increased NICD and XIAP levels were detected during E. chaffeensis infection and after TRP120 Notch ligand mimetic peptide treatment. Conversely, XIAP levels were reduced in the presence of Notch inhibitor DAPT. Cytoplasmic and nuclear colocalization of NICD and XIAP was observed during infection and a direct interaction was confirmed by co-immunoprecipitation. Procaspase levels increased temporally during infection, consistent with increased XIAP levels; however, knockdown (KD) of XIAP during infection significantly increased apoptosis and Caspase-3, -7, and -9 levels. Furthermore, treatment with SM-164, a second mitochondrial activator of caspases (Smac/DIABLO) antagonist, resulted in decreased procaspase levels and increased caspase activation, induced apoptosis, and significantly decreased infection. In addition, RNAi KD of XIAP also decreased infection and significantly increased apoptosis. Moreover, ectopic expression of TRP120 HECT Ub ligase catalytically defective mutant in HeLa cells decreased NICD and XIAP levels and increased caspase activation compared to HeLa cells with functional HECT Ub ligase catalytic activity (TRP120-WT). This investigation reveals a mechanism whereby E. chaffeensis modulates Notch signaling to stabilize XIAP and inhibit apoptosis.
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Affiliation(s)
- LaNisha L. Patterson
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Caitlan D. Byerly
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Regina Solomon
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Nicholas Pittner
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Duc Cuong Bui
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jignesh Patel
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, USA
- Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, Texas, USA
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, USA
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4
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Patterson LL, Byerly CD, Solomon R, Pittner N, Bui DC, Patel J, McBride JW. Ehrlichia Notch signaling induction promotes XIAP stability and inhibits apoptosis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.06.523066. [PMID: 36711597 PMCID: PMC9881962 DOI: 10.1101/2023.01.06.523066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Ehrlichia chaffeensis has evolved multiple strategies to evade innate defenses of the mononuclear phagocyte. Recently, we reported the E. chaffeensis TRP120 effector functions as a Notch ligand mimetic and a ubiquitin ligase that degrades the nuclear tumor suppressor, F-box and WD repeat domain-containing 7 (FBW7), a negative regulator of Notch. The Notch receptor intracellular domain (NICD) is known to inhibit apoptosis primarily by interacting with X-linked inhibitor of apoptosis protein (XIAP) to prevent degradation. In this study, we determined E. chaffeensis activation of Notch signaling increases XIAP levels, thereby inhibiting intrinsic apoptosis. Increased NICD and XIAP levels were detected during E. chaffeensis infection and after TRP120 Notch ligand mimetic peptide treatment. Conversely, XIAP levels were reduced in the presence of Notch inhibitor DAPT. Cytoplasmic colocalization of NICD and XIAP was observed during infection and a direct interaction was confirmed by co-immunoprecipitation. Procaspase levels increased temporally during infection, consistent with increased XIAP levels; however, knockdown of XIAP during infection significantly increased apoptosis and Caspase-3, -7 and -9 levels. Further, treatment with SM-164, a second mitochondrial activator of caspases (Smac/DIABLO) antagonist, resulted in decreased procaspase levels and increased caspase activation, induced apoptosis, and significantly decreased infection. In addition, iRNA knockdown of XIAP also decreased infection and significantly increased apoptosis. Moreover, ectopic expression of TRP120 HECT Ub ligase catalytically defective mutant in HeLa cells decreased NICD and XIAP levels and increased caspase activation compared to WT. This investigation reveals a mechanism whereby E. chaffeensis repurposes Notch signaling to stabilize XIAP and inhibit apoptosis. Author Summary Ehrlichia chaffeensis is a tick-borne, obligately intracellular bacterium that exhibits tropism for mononuclear phagocytes. E. chaffeensis survives by mobilizing various molecular strategies to promote cell survival, including modulation of apoptosis. This investigation reveals an E. chaffeensis initiated, Notch signaling regulated, antiapoptotic mechanism involving inhibitor of apoptosis proteins (IAPs). Herein, we demonstrate that E. chaffeensis induced Notch activation results in Notch intracellular domain stabilization of X-linked inhibitor of apoptosis protein (XIAP) to inhibit intrinsic apoptosis. This study highlights a novel mechanistic strategy whereby intracellular pathogens repurpose evolutionarily conserved eukaryotic signaling pathways to engage an antiapoptotic program for intracellular survival.
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Diniz PPV, Moura de Aguiar D. Ehrlichiosis and Anaplasmosis. Vet Clin North Am Small Anim Pract 2022; 52:1225-1266. [DOI: 10.1016/j.cvsm.2022.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Liu H, Knox CA, Jakkula LUMR, Wang Y, Peddireddi L, Ganta RR. Evaluating EcxR for Its Possible Role in Ehrlichia chaffeensis Gene Regulation. Int J Mol Sci 2022; 23:12719. [PMID: 36361509 PMCID: PMC9657007 DOI: 10.3390/ijms232112719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/17/2022] [Accepted: 10/19/2022] [Indexed: 04/14/2024] Open
Abstract
Ehrlichia chaffeensis, a tick-transmitted intraphagosomal bacterium, is the causative agent of human monocytic ehrlichiosis. The pathogen also infects several other vertebrate hosts. E. chaffeensis has a biphasic developmental cycle during its growth in vertebrate monocytes/macrophages and invertebrate tick cells. Host- and vector-specific differences in the gene expression from many genes of E. chaffeensis are well documented. It is unclear how the organism regulates gene expression during its developmental cycle and for its adaptation to vertebrate and tick host cell environments. We previously mapped promoters of several E. chaffeensis genes which are recognized by its only two sigma factors: σ32 and σ70. In the current study, we investigated in assessing five predicted E. chaffeensis transcription regulators; EcxR, CtrA, MerR, HU and Tr1 for their possible roles in regulating the pathogen gene expression. Promoter segments of three genes each transcribed with the RNA polymerase containing σ70 (HU, P28-Omp14 and P28-Omp19) and σ32 (ClpB, DnaK and GroES/L) were evaluated by employing multiple independent molecular methods. We report that EcxR binds to all six promoters tested. Promoter-specific binding of EcxR to several gene promoters results in varying levels of gene expression enhancement. This is the first detailed molecular characterization of transcription regulators where we identified EcxR as a gene regulator having multiple promoter-specific interactions.
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Affiliation(s)
| | | | | | | | | | - Roman R. Ganta
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA
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Martins PDC, de Souza HADS, Blanco CM, Santos-de-Oliveira L, Pratt-Riccio LR, Daniel-Ribeiro CT, Totino PRR. Modulation of Signal Regulatory Protein α (SIRPα) by Plasmodium Antigenic Extract: A Preliminary In Vitro Study on Peripheral Blood Mononuclear Cells. Microorganisms 2022; 10:microorganisms10050903. [PMID: 35630348 PMCID: PMC9144821 DOI: 10.3390/microorganisms10050903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 01/29/2022] [Accepted: 02/04/2022] [Indexed: 11/17/2022] Open
Abstract
Signal regulatory protein α (SIRPα) is an immunoreceptor expressed in myeloid innate immune cells that signals for inhibition of both phagocytosis and inflammatory response. Malaria parasites have evolutionarily selected multiple mechanisms that allow them to evade host immune defenses, including the modulation of cells belonging to innate immunity. Notwithstanding, little attention has been given to SIRPα in the context of immunosuppressive states induced by malaria. The present study attempted to investigate if malaria parasites are endowed with the capacity of modulating the expression of SIRPα on cells of innate immune system. Human peripheral blood mononuclear cells (PBMC) from healthy individuals were incubated in the presence of lipopolysaccharide (LPS) or crude extracts of P. falciparum or P. vivax and then, the expression of SIRPα was evaluated by flow cytometry. As expected, LPS showed an inhibitory effect on the expression of SIRPα in the population of monocytes, characterized by cell morphology in flow cytometry analysis, while Plasmodium extracts induced a significant positive modulation. Additional phenotyping of cells revealed that the modulatory potential of Plasmodium antigens on SIRPα expression was restricted to the population of monocytes (CD14+CD11c+), as no effect on myeloid dendritic cells (CD14−CD11c+) was observed. We hypothesize that malaria parasites explore inhibitory signaling of SIRPα to suppress antiparasitic immune responses contributing to the establishment of infection. Nevertheless, further studies are still required to better understand the role of SIRPα modulation in malaria immunity and pathogenesis.
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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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Beasley EA, Pessôa-Pereira D, Scorza BM, Petersen CA. Epidemiologic, Clinical and Immunological Consequences of Co-Infections during Canine Leishmaniosis. Animals (Basel) 2021; 11:ani11113206. [PMID: 34827938 PMCID: PMC8614518 DOI: 10.3390/ani11113206] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/03/2021] [Accepted: 11/04/2021] [Indexed: 11/24/2022] Open
Abstract
Simple Summary Canine leishmaniosis (CanL), the most severe, visceralizing form of disease caused by Leishmania infantum transmitted by phlebotomine sand flies. CanL is frequently diagnosed in the Mediterranean basin and South America, although it is also found in other regions, including the United States (U.S.). Dogs in these regions are at risk for co-infections, prominently tick-borne diseases. Our review examines epidemiologic, clinical, and immunologic mechanisms found during the most common eight CanL co-infections reported in published literature. Co-infections alter immunologic processes and disease progression impacting CanL diagnosis, therapeutic responses, and prognosis. Abstract Canine leishmaniosis (CanL) is a vector-borne, parasitic disease. CanL is endemic in the Mediterranean basin and South America but also found in Northern Africa, Asia, and the U.S. Regions with both competent sand fly vectors and L. infantum parasites are also endemic for additional infectious diseases that could cause co-infections in dogs. Growing evidence indicates that co-infections can impact immunologic responses and thus the clinical course of both CanL and the comorbid disease(s). The aim for this review is to summarize epidemiologic, clinical, and immunologic factors contributing to eight primary co-infections reported with CanL: Ehrlichia spp., Anaplasma spp., Borrelia spp., Babesia spp., Trypanosoma cruzi, Toxoplasma gondii, Dirofilaria immitis, Paracoccidioides braziliensis. Co-infection causes mechanistic differences in immunity which can alter diagnostics, therapeutic management, and prognosis of dogs with CanL. More research is needed to further explore immunomodulation during CanL co-infection(s) and their clinical impact.
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Affiliation(s)
- Erin A. Beasley
- Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, IA 52242, USA; (E.A.B.); (D.P.-P.); (B.M.S.)
- Center for Emerging Infectious Diseases, University of Iowa, Iowa City, IA 52242, USA
| | - Danielle Pessôa-Pereira
- Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, IA 52242, USA; (E.A.B.); (D.P.-P.); (B.M.S.)
- Center for Emerging Infectious Diseases, University of Iowa, Iowa City, IA 52242, USA
| | - Breanna M. Scorza
- Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, IA 52242, USA; (E.A.B.); (D.P.-P.); (B.M.S.)
- Center for Emerging Infectious Diseases, University of Iowa, Iowa City, IA 52242, USA
| | - Christine A. Petersen
- Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, IA 52242, USA; (E.A.B.); (D.P.-P.); (B.M.S.)
- Center for Emerging Infectious Diseases, University of Iowa, Iowa City, IA 52242, USA
- Correspondence:
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El Hamiani Khatat S, Daminet S, Duchateau L, Elhachimi L, Kachani M, Sahibi H. Epidemiological and Clinicopathological Features of Anaplasma phagocytophilum Infection in Dogs: A Systematic Review. Front Vet Sci 2021; 8:686644. [PMID: 34250067 PMCID: PMC8260688 DOI: 10.3389/fvets.2021.686644] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 05/17/2021] [Indexed: 11/13/2022] Open
Abstract
Anaplasma phagocytophilum is a worldwide emerging zoonotic tick-borne pathogen transmitted by Ixodid ticks and naturally maintained in complex and incompletely assessed enzootic cycles. Several studies have demonstrated an extensive genetic variability with variable host tropisms and pathogenicity. However, the relationship between genetic diversity and modified pathogenicity is not yet understood. Because of their proximity to humans, dogs are potential sentinels for the transmission of vector-borne pathogens. Furthermore, the strong molecular similarity between human and canine isolates of A. phagocytophilum in Europe and the USA and the positive association in the distribution of human and canine cases in the USA emphasizes the epidemiological role of dogs. Anaplasma phagocytophilum infects and survives within neutrophils by disregulating neutrophil functions and evading specific immune responses. Moreover, the complex interaction between the bacterium and the infected host immune system contribute to induce inflammatory injuries. Canine granulocytic anaplasmosis is an acute febrile illness characterized by lethargy, inappetence, weight loss and musculoskeletal pain. Hematological and biochemistry profile modifications associated with this disease are unspecific and include thrombocytopenia, anemia, morulae within neutrophils and increased liver enzymes activity. Coinfections with other tick-borne pathogens (TBPs) may occur, especially with Borrelia burgdorferi, complicating the clinical presentation, diagnosis and response to treatment. Although clinical studies have been published in dogs, it remains unclear if several clinical signs and clinicopathological abnormalities can be related to this infection.
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Affiliation(s)
- Sarah El Hamiani Khatat
- Department of Medicine, Surgery and Reproduction, Hassan II Institute of Agronomy and Veterinary Medicine, Rabat, Morocco
| | - Sylvie Daminet
- Department of Companion Animals, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Luc Duchateau
- Department of Comparative Physiology and Biometrics, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Latifa Elhachimi
- Department of Pathology and Veterinary Public Health, Unit of Parasitology, Hassan II Institute of Agronomy and Veterinary Medicine, Rabat, Morocco
| | - Malika Kachani
- College of Veterinary Medicine, Western University of Health Sciences, Pomona, CA, United States
| | - Hamid Sahibi
- Department of Pathology and Veterinary Public Health, Unit of Parasitology, Hassan II Institute of Agronomy and Veterinary Medicine, Rabat, Morocco
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Sanches GS, Villar M, Couto J, Ferrolho J, Fernández de Mera IG, André MR, Barros-Battesti DM, Machado RZ, Bechara GH, Mateos-Hernández L, de la Fuente J, Antunes S, Domingos A. Comparative Proteomic Analysis of Rhipicephalus sanguineus sensu lato (Acari: Ixodidae) Tropical and Temperate Lineages: Uncovering Differences During Ehrlichia canis Infection. Front Cell Infect Microbiol 2021; 10:611113. [PMID: 33585280 PMCID: PMC7879575 DOI: 10.3389/fcimb.2020.611113] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 12/03/2020] [Indexed: 01/03/2023] Open
Abstract
The tick vector Rhipicephalus sanguineus is established as a complex of closely related species with high veterinary-medical significance, in which the presence of different genetic, morphological, and biological traits has resulted in the recognition of different lineages within taxa. One of the most striking differences in the "temperate" and "tropical" lineages of R. sanguineus (s.l.) is the vector competence to Ehrlichia canis, suggesting that these ticks tolerate and react differently to pathogen infection. The present study addresses the SG and MG proteome of the R. sanguineus tropical and temperate lineages and compares their proteomic profile during E. canis infection. Batches of nymphs from the two lineages were allowed to feed on naïve and experimentally E. canis infected dogs and after molting, adults were dissected, and salivary glands and midgut tissues separated. Samples were screened for the presence of E. canis before proteomic analyses. The representation of the proteins identified in infected and non-infected tissues of each lineage was compared and gene ontology used for protein classification. Results highlight important differences in those proteomic profiles that added to previous reported genetic, biological, behavioral, and morphological differences, strengthening the hypothesis of the existence of two different species. Comparing infected and non-infected tissues, the results show that, while in midgut tissues the response to E. canis infection is similar in the salivary glands, the two lineages show a different pattern of protein representation. Focusing on the proteins found only in the infected condition, the data suggests that the cement cone produced during tick feeding may be implicated in pathogen infection. This study adds useful information to the debate on the controversial R. sanguineus systematic status, to the discussion related with the different vectorial competence occurring between the two lineages and identifies potential targets for efficient tick and tick-borne disease control.
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Affiliation(s)
- Gustavo Seron Sanches
- Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa (GHTM-IHMT-UNL), Lisboa, Portugal.,Escola de Ciências da Vida, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil
| | - Margarita Villar
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ciudad Real, Spain.,Biochemistry Section, Faculty of Science and Chemical Technologies, and Regional Centre for Biomedical Research [CRIB], University of Castilla-La Mancha, Ciudad Real, Spain
| | - Joana Couto
- Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa (GHTM-IHMT-UNL), Lisboa, Portugal
| | - Joana Ferrolho
- Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa (GHTM-IHMT-UNL), Lisboa, Portugal
| | | | - Marcos Rogério André
- Departamento de Patologia Veterinária, Universidade Estadual Paulista (FCAV-UNESP), Jaboticabal, Brazil
| | | | | | | | - Lourdes Mateos-Hernández
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ciudad Real, Spain.,UMR BIPAR, INRAE, ANSES, École Nationale Vétérinaire d'Alfort, Université Paris-Est, Paris, France
| | - José de la Fuente
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ciudad Real, Spain.,Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States
| | - Sandra Antunes
- Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa (GHTM-IHMT-UNL), Lisboa, Portugal
| | - Ana Domingos
- Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa (GHTM-IHMT-UNL), Lisboa, Portugal
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12
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Thiriot JD, Martinez-Martinez YB, Endsley JJ, Torres AG. Hacking the host: exploitation of macrophage polarization by intracellular bacterial pathogens. Pathog Dis 2020; 78:5739920. [PMID: 32068828 DOI: 10.1093/femspd/ftaa009] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 02/17/2020] [Indexed: 12/17/2022] Open
Abstract
Macrophages play an integral role in host defenses against intracellular bacterial pathogens. A remarkable plasticity allows for adaptation to the needs of the host to orchestrate versatile innate immune responses to a variety of microbial threats. Several bacterial pathogens have adapted to macrophage plasticity and modulate the classical (M1) or alternative (M2) activation bias towards a polarization state that increases fitness for intracellular survival. Here, we summarize the current understanding of the host macrophage and intracellular bacterial interface; highlighting the roles of M1/M2 polarization in host defense and the mechanisms employed by several important intracellular pathogens to modulate macrophage polarization to favor persistence or proliferation. Understanding macrophage polarization in the context of disease caused by different bacterial pathogens is important for the identification of targets for therapeutic intervention.
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Affiliation(s)
- Joseph D Thiriot
- Department of Microbiology and Immunology , University of Texas Medical Branch, 301 University Blvd, Galveston, Texas 77555 USA
| | - Yazmin B Martinez-Martinez
- Department of Microbiology and Immunology , University of Texas Medical Branch, 301 University Blvd, Galveston, Texas 77555 USA
| | - Janice J Endsley
- Department of Microbiology and Immunology , University of Texas Medical Branch, 301 University Blvd, Galveston, Texas 77555 USA
| | - Alfredo G Torres
- Department of Microbiology and Immunology , University of Texas Medical Branch, 301 University Blvd, Galveston, Texas 77555 USA.,Department of Pathology, University of Texas Medical Branch , University of Texas Medical Branch, 301 University Blvd, Galveston, Texas 77555 USA
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Schäfer I, Kohn B. Anaplasma phagocytophilum infection in cats: A literature review to raise clinical awareness. J Feline Med Surg 2020; 22:428-441. [PMID: 32326861 PMCID: PMC7787687 DOI: 10.1177/1098612x20917600] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PRACTICAL RELEVANCE Granulocytic anaplasmosis is a disease in humans and animals caused by the Gram-negative bacterium Anaplasma phagocytophilum within the family Anaplasmataceae. The pathogen is transmitted by ticks of the Ixodes species. Infections with A phagocytophilum have often been described in dogs but reports on natural infections in cats are rare. An infection with A phagocytophilum should be considered as a differential diagnosis in cats if the history reveals tick infestation and/or outdoor access in combination with the relevant clinical signs. GLOBAL IMPORTANCE A phagocytophilum is also important in human medicine because of its zoonotic potential. Due to the risk of vector-borne infections for both feline and public health, cats should be protected with ectoparasiticides, especially in endemic areas. AIM The aim of this review is to give an overview of the published data and summarise the epidemiology, pathogenesis, diagnosis, clinical signs and therapy of feline granulocytic anaplasmosis. As clinical signs are vague and non-specific, this review aims to raise awareness of A phagocytophilum infection, both among clinicians, so that they consider testing potentially exposed cats, and scientists, in order to prompt further research. EVIDENCE BASE Sixteen publications describing 55 cats have been reviewed. Thirty-four cats were well diagnosed based on guidelines of the European Advisory Board on Cat Diseases and blood analyses were performed to varying extents for these cats. Because of the limited number of studies and a lack of knowledge in cats, clinical signs and blood analyses are compared with available data in dogs.
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Affiliation(s)
- Ingo Schäfer
- Faculty of Veterinary Medicine, Clinic for Small Animals, Freie Universität Berlin, Oertzenweg 19b, Building 1, 14163 Berlin, Germany
| | - Barbara Kohn
- Faculty of Veterinary Medicine, Clinic for Small Animals, Freie Universität Berlin, Oertzenweg 19b, Building 1, 14163 Berlin, Germany
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Qurollo BA, Buch J, Chandrashekar R, Beall MJ, Breitschwerdt EB, Yancey CB, Caudill AH, Comyn A. Clinicopathological findings in 41 dogs (2008-2018) naturally infected with Ehrlichia ewingii. J Vet Intern Med 2019; 33:618-629. [PMID: 30604457 PMCID: PMC6430920 DOI: 10.1111/jvim.15354] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 10/12/2018] [Indexed: 12/29/2022] Open
Abstract
Background Ehrlichia ewingii is the most seroprevalent Ehrlichia‐infecting dogs in the southern and mid‐western United States. Fever, lameness, and polyarthritis are commonly reported findings in dogs naturally infected with E. ewingii. Objectives To evaluate clinicopathologic findings in a population of dogs naturally infected with E. ewingii. Animals Forty‐one dogs PCR positive for E. ewingii and PCR negative for other targeted vector‐borne organisms. Methods Retrospective study. Clinical and clinicopathologic data including physical examination findings, CBC, serum biochemistry, urinalysis (UA), symmetric dimethylarginine (SDMA), and vector‐borne disease diagnostic results were reviewed. Results Frequent clinical diagnoses other than ehrlichiosis (28/41; 68.3%) were renal disease (7/41; 17.1%) and immune‐mediated hemolytic anemia (IMHA) (6/41; 14.6%). The most frequent physical examination finding was joint pain (14/41; 34.1%). Prominent hematologic and biochemical abnormalities included abnormal lymphocyte counts (22/36; 61.1%); neutrophilia (21/37; 56.8%); increased alkaline phosphatase (20/35; 57.1%) and alanine transaminase (14/35; 40%) activities; and increased SDMA concentration (11/34; 32.4%). Urinalysis abnormalities included proteinuria (20/27; 74%), most with inactive sediments (16/20; 80%). Dogs were seroreactive by Ehrlichia canis immunofluorescence assay (IFA; 17/39; 43.6%) and Ehrlichia ELISA (34/41; 82.9%). Seroreactivity by IFA for other vector‐borne pathogens included Bartonella (1/39; 2.6%), Rickettsia rickettsii (spotted‐fever group rickettsiae) (12/39; 30.8%), and Borrelia burgdorferi by ELISA (1/41; 2.4%). Conclusions and Clinical Importance Renal disease, IMHA, proteinuria, neutrophilia, abnormal lymphocytes, and increased liver enzyme activities were common in this group of E. ewingii‐infected dogs. Studies are needed to determine if E. ewingii contributes to comorbidities or is a precipitating factor in clinical syndromes in persistently infected dogs.
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Affiliation(s)
- Barbara A Qurollo
- Vector Borne Disease Diagnostic Laboratory, Comparative Medicine Institute, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
| | - Jesse Buch
- IDEXX Laboratories, Inc, Westbrook, Maine
| | | | | | - Edward B Breitschwerdt
- Vector Borne Disease Diagnostic Laboratory, Comparative Medicine Institute, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
| | - Caroline B Yancey
- Department of Population Medicine and Diagnostic Services, Cornell University College of Veterinary Medicine, Ithaca, New York
| | - Alexander H Caudill
- Vector Borne Disease Diagnostic Laboratory, Comparative Medicine Institute, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
| | - Alaire Comyn
- Vector Borne Disease Diagnostic Laboratory, Comparative Medicine Institute, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
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Barros-Battesti DM, Machado RZ, André MR, de Sousa KCM, Franze DA, Lima-Duarte L, Cirelli-Moraes A, Nunes PH, Labruna MB, Moraes-Filho J, Martins MM, Szabó MPJ. Successful Infection of Tick Cell Cultures of Rhipicephalus sanguineus (Tropical Lineage) with Ehrlichia canis. Vector Borne Zoonotic Dis 2018; 18:653-662. [PMID: 30222504 DOI: 10.1089/vbz.2017.2197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
There are two distinct lineages of ticks, Rhipicephalus sanguineus, in South America: tropical and temperate lineages. Only the tropical lineage is recognized as competent vector for Ehrlichia canis. The epidemiological data of canine monocytic ehrlichiosis is congruent with the distribution of the two lineages of R. sanguineus. Herein, we report the infection of R. sanguineus (tropical lineage) cell cultures with E. canis, after cryopreservation. R. sanguineus (tropical lineage) cell identity was confirmed by sequencing using a 16S rDNA gene fragment. Tick cell cultures were prepared in L-15B medium supplemented with 10%, 15%, and 20% Fetal Bovine Serum (FBS), and 10% of Tryptose Phosphate Broth (TPB). Cell cultures developed better at the concentration of 20% of FBS. Cultures in the fifth harvest (approximately 7 months later) were selected for the first infections. Optimal R. sanguineus cell growth and adhesion was observed (5.0 × 106 cells/mL, and the population doubling time every 57 h). Once infected with E. canis, the cultures were maintained in L-15B medium supplemented with 2% and 5% of FBS fortified with iron and 10% TPB. Infected cells were also cryopreserved. DNA was extracted from infected and noninfected cells and analyzed using quantitative real-time PCR targeting the E. canis-dsb gene. Primary culture of the fifth passage was infected by E. canis and it maintained the pathogen for at least 40 days before partial cell destruction. Subcultures of infected cells (fresh and cryopreserved cultures) onto new tick cell cultures were successful. The E. canis infection was confirmed by real-time PCR and light and transmission electron microscopy. The R. sanguineus (tropical lineage) cells infected with E. canis successfully infected new tick cell cultures, showing that these cells could be an alternative substrate for maintenance of this pathogen.
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Affiliation(s)
- Darci Moraes Barros-Battesti
- 1 Department of Veterinary Pathology, Faculty of Agricultural and Veterinary Sciences, State University Julio de Mesquita Filho (UNESP) , Jaboticabal, Brazil
- 2 Laboratory of Parasitology, Butantan Institute , São Paulo, Brazil
| | - Rosangela Zacarias Machado
- 1 Department of Veterinary Pathology, Faculty of Agricultural and Veterinary Sciences, State University Julio de Mesquita Filho (UNESP) , Jaboticabal, Brazil
| | - Marcos Rogério André
- 1 Department of Veterinary Pathology, Faculty of Agricultural and Veterinary Sciences, State University Julio de Mesquita Filho (UNESP) , Jaboticabal, Brazil
| | - Keyla Carstens Marques de Sousa
- 1 Department of Veterinary Pathology, Faculty of Agricultural and Veterinary Sciences, State University Julio de Mesquita Filho (UNESP) , Jaboticabal, Brazil
| | | | | | | | - Pablo Henrique Nunes
- 3 Federal University of Latin American Integration-UNILA , Foz do Iguaçu, Brazil
| | - Marcelo Bahia Labruna
- 4 Department of Preventive Veterinary Medicine and Animal Science, School of Veterinary Medicine, University of São Paulo , São Paulo, Brazil
| | - Jonas Moraes-Filho
- 4 Department of Preventive Veterinary Medicine and Animal Science, School of Veterinary Medicine, University of São Paulo , São Paulo, Brazil
- 5 Veterinary Medicine, University of Santo Amaro , São Paulo, Brazil
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Chirek A, Silaghi C, Pfister K, Kohn B. Granulocytic anaplasmosis in 63 dogs: clinical signs, laboratory results, therapy and course of disease. J Small Anim Pract 2017; 59:112-120. [PMID: 29171663 DOI: 10.1111/jsap.12787] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Revised: 09/24/2017] [Accepted: 09/28/2017] [Indexed: 11/27/2022]
Abstract
OBJECTIVES To describe the clinical signs, laboratory results, therapy and course of disease in dogs with canine granulocytic anaplasmosis in which co-infections had been excluded. METHODS Medical records of dogs naturally infected with Anaplasma phagocytophilum were retrospectively evaluated with regard to clinical signs and laboratory abnormalities at the time of presentation, therapy and course of disease. RESULTS Nine hundred and seventy-four dogs with clinical signs suspicious for canine granulocytic anaplasmosis were tested for A. phagocytophilum DNA by modified real-time PCR; 72 dogs had a positive result. Nine of the positive dogs were excluded from further evaluation due to other diseases or lack of data. The most common clinical signs in the 63 A. phagocytophilum-positive dogs included in the study were lethargy and reduced activity (83%), fever (67%) and inappetence (63%). Thrombocytopenia was the most common laboratory abnormality (86%), followed by increased liver enzyme activities and hyperbilirubinaemia (77%), anaemia (70%), hypoalbuminaemia (62%) and leucocytosis (27%). Of 36 thrombocytopenic dogs tested for platelet-bound antibodies, 44% were positive. Of the 63 infected dogs, 59 (97%) recovered, two dogs died (epileptic seizures and immune-mediated haemolytic anaemia) and two were lost to follow-up. CLINICAL SIGNIFICANCE In areas where it is endemic, canine granulocytic anaplasmosis should be considered as a potential cause of acute nonspecific clinical signs or immune-mediated disease if tick exposure cannot be excluded.
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Affiliation(s)
- A Chirek
- Clinic for Small Animals, Faculty of Veterinary Medicine, Freie Universität Berlin, 14163, Berlin, Germany
| | - C Silaghi
- Comparative Tropical Medicine and Parasitoloy, Ludwig-Maximilians-Universität München, 80802, Munich, Germany.,National Center of Vector Entomology, Institute of Parasitology, University of Zurich, 8057, Zurich, Switzerland
| | - K Pfister
- Comparative Tropical Medicine and Parasitoloy, Ludwig-Maximilians-Universität München, 80802, Munich, Germany.,Parasite Consulting GmbH, CH-3006, Bern, Switzerland
| | - B Kohn
- Clinic for Small Animals, Faculty of Veterinary Medicine, Freie Universität Berlin, 14163, Berlin, Germany
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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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18
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Dillon LAL, Suresh R, Okrah K, Corrada Bravo H, Mosser DM, El-Sayed NM. Simultaneous transcriptional profiling of Leishmania major and its murine macrophage host cell reveals insights into host-pathogen interactions. BMC Genomics 2015; 16:1108. [PMID: 26715493 PMCID: PMC4696162 DOI: 10.1186/s12864-015-2237-2] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 11/24/2015] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Parasites of the genus Leishmania are the causative agents of leishmaniasis, a group of diseases that range in manifestations from skin lesions to fatal visceral disease. The life cycle of Leishmania parasites is split between its insect vector and its mammalian host, where it resides primarily inside of macrophages. Once intracellular, Leishmania parasites must evade or deactivate the host's innate and adaptive immune responses in order to survive and replicate. RESULTS We performed transcriptome profiling using RNA-seq to simultaneously identify global changes in murine macrophage and L. major gene expression as the parasite entered and persisted within murine macrophages during the first 72 h of an infection. Differential gene expression, pathway, and gene ontology analyses enabled us to identify modulations in host and parasite responses during an infection. The most substantial and dynamic gene expression responses by both macrophage and parasite were observed during early infection. Murine genes related to both pro- and anti-inflammatory immune responses and glycolysis were substantially upregulated and genes related to lipid metabolism, biogenesis, and Fc gamma receptor-mediated phagocytosis were downregulated. Upregulated parasite genes included those aimed at mitigating the effects of an oxidative response by the host immune system while downregulated genes were related to translation, cell signaling, fatty acid biosynthesis, and flagellum structure. CONCLUSIONS The gene expression patterns identified in this work yield signatures that characterize multiple developmental stages of L. major parasites and the coordinated response of Leishmania-infected macrophages in the real-time setting of a dual biological system. This comprehensive dataset offers a clearer and more sensitive picture of the interplay between host and parasite during intracellular infection, providing additional insights into how pathogens are able to evade host defenses and modulate the biological functions of the cell in order to survive in the mammalian environment.
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Affiliation(s)
- Laura A L Dillon
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA. .,Center for Bioinformatics and Computational Biology, University of Maryland, College Park, MD, 20742, USA.
| | - Rahul Suresh
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA.
| | - Kwame Okrah
- Department of Mathematics, University of Maryland, College Park, MD, 20742, USA.
| | - Hector Corrada Bravo
- Center for Bioinformatics and Computational Biology, University of Maryland, College Park, MD, 20742, USA. .,Department of Computer Science, University of Maryland, College Park, MD, 20742, USA.
| | - David M Mosser
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA.
| | - Najib M El-Sayed
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA. .,Center for Bioinformatics and Computational Biology, University of Maryland, College Park, MD, 20742, USA. .,Present Address: 3128 Bioscience Research Bldg., University of Maryland, College Park, MD, 20742, USA.
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Yang Q, Stevenson HL, Scott MJ, Ismail N. Type I interferon contributes to noncanonical inflammasome activation, mediates immunopathology, and impairs protective immunity during fatal infection with lipopolysaccharide-negative ehrlichiae. THE AMERICAN JOURNAL OF PATHOLOGY 2014; 185:446-61. [PMID: 25481711 DOI: 10.1016/j.ajpath.2014.10.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 09/18/2014] [Accepted: 10/09/2014] [Indexed: 12/29/2022]
Abstract
Ehrlichia species are intracellular bacteria that cause fatal ehrlichiosis, mimicking toxic shock syndrome in humans and mice. Virulent ehrlichiae induce inflammasome activation leading to caspase-1 cleavage and IL-18 secretion, which contribute to development of fatal ehrlichiosis. We show that fatal infection triggers expression of inflammasome components, activates caspase-1 and caspase-11, and induces host-cell death and secretion of IL-1β, IL-1α, and type I interferon (IFN-I). Wild-type and Casp1(-/-) mice were highly susceptible to fatal ehrlichiosis, had overwhelming infection, and developed extensive tissue injury. Nlrp3(-/-) mice effectively cleared ehrlichiae, but displayed acute mortality and developed liver injury similar to wild-type mice. By contrast, Ifnar1(-/-) mice were highly resistant to fatal disease and had lower bacterial burden, attenuated pathology, and prolonged survival. Ifnar1(-/-) mice also had improved protective immune responses mediated by IFN-γ and CD4(+) Th1 and natural killer T cells, with lower IL-10 secretion by T cells. Importantly, heightened resistance of Ifnar1(-/-) mice correlated with improved autophagosome processing, and attenuated noncanonical inflammasome activation indicated by decreased activation of caspase-11 and decreased IL-1β, compared with other groups. Our findings demonstrate that IFN-I signaling promotes host susceptibility to fatal ehrlichiosis, because it mediates ehrlichia-induced immunopathology and supports bacterial replication, perhaps via activation of noncanonical inflammasomes, reduced autophagy, and suppression of protective CD4(+) T cells and natural killer T-cell responses against ehrlichiae.
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Affiliation(s)
- Qin Yang
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Heather L Stevenson
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Melanie J Scott
- Department of Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Nahed Ismail
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.
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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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Abstract
Tick-borne diseases are prevalent throughout the world and present a diagnostic challenge owing to their nonspecific clinical symptoms. Many tick-borne diseases involve the central and peripheral nervous systems. Early diagnosis or at least suspicion of a tick-borne cause is necessary to institute early empiric treatment. After a brief review of tick biology, we present the most common tick-borne diseases. A brief discussion of epidemiology, the transmission route, and pathogenesis is followed by a discussion of the clinical manifestations, diagnosis and treatment options when available. The review emphasizes the infectious causes with a significant neurological manifestation.
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Mathema VB, Manzoor Z, Koo JE, Koh YS. Inhibition of cell death of bone marrow-derived macrophages infected with Ehrlichia muris. Ticks Tick Borne Dis 2013; 4:185-90. [PMID: 23352172 DOI: 10.1016/j.ttbdis.2012.11.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 11/14/2012] [Accepted: 11/14/2012] [Indexed: 01/12/2023]
Abstract
Ehrlichia muris is a Gram-negative obligate intracellular bacterium belonging to the family Anaplasmataceae. It preferentially replicates inside macrophages by utilizing nutrients and processes of the host cell. In the present article, we studied the effects of E. muris infection on cell death of bone marrow-derived macrophages (BMDMs). Primary BMDMs were used for accessing E. muris-induced cell death, pro-inflammatory cytokine production and Western blot analysis. Human embryonic kidney cell line 293T (HEK293T) was used to access nuclear factor-kappaB (NF-κB) activity. BMDMs infected with E. muris showed significant inhibition of cell death when compared to uninfected cells. E. muris infection resulted in IκBα degradation, thus activation of NF-κB. In NF-κB reporter gene assay, the HEK293T cells infected with E. muris exhibited robust NF-κB-dependent luciferase activity in a bacterial dose-dependent manner. Furthermore, E. muris-induced inhibition of BMDMs cell death was abolished in the presence of MG132, a proteasome inhibitor that blocks NF-κB activation. Taken together, the results suggest that E. muris infection of BMDMs may have an inhibitory effect on cell death via a mechanism dependent on NF-κB activation.
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Voth DE, Broederdorf LJ, Graham JG. Bacterial Type IV secretion systems: versatile virulence machines. Future Microbiol 2012; 7:241-57. [PMID: 22324993 DOI: 10.2217/fmb.11.150] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Many bacterial pathogens employ multicomponent protein complexes to deliver macromolecules directly into their eukaryotic host cell to promote infection. Some Gram-negative pathogens use a versatile Type IV secretion system (T4SS) that can translocate DNA or proteins into host cells. T4SSs represent major bacterial virulence determinants and have recently been the focus of intense research efforts designed to better understand and combat infectious diseases. Interestingly, although the two major classes of T4SSs function in a similar manner to secrete proteins, the translocated 'effectors' vary substantially from one organism to another. In fact, differing effector repertoires likely contribute to organism-specific host cell interactions and disease outcomes. In this review, we discuss the current state of T4SS research, with an emphasis on intracellular bacterial pathogens of humans and the diverse array of translocated effectors used to manipulate host cells.
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Affiliation(s)
- Daniel E Voth
- Department of Microbiology & Immunology, University of Arkansas for Medical Sciences, 4301 W. Markham, Little Rock, AR 72205, USA.
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The role of cytoskeleton, components of inositol phospholipid signaling pathway and iron in Ehrlichia canis in vitro proliferation. Vet Res Commun 2012; 36:195-9. [DOI: 10.1007/s11259-012-9525-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/02/2012] [Indexed: 01/10/2023]
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Kuriakose JA, Miyashiro S, Luo T, Zhu B, McBride JW. Ehrlichia chaffeensis transcriptome in mammalian and arthropod hosts reveals differential gene expression and post transcriptional regulation. PLoS One 2011; 6:e24136. [PMID: 21915290 PMCID: PMC3167834 DOI: 10.1371/journal.pone.0024136] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 08/05/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Human monocytotropic ehrlichiosis is an emerging life-threatening zoonosis caused by obligately intracellular bacterium, Ehrlichia chaffeensis. E. chaffeensis is transmitted by the lone star tick, Amblyomma americanum, and replicates in mononuclear phagocytes in mammalian hosts. Differences in the E. chaffeensis transcriptome in mammalian and arthropod hosts are unknown. Thus, we determined host-specific E. chaffeensis gene expression in human monocyte (THP-1) and in Amblyomma and Ixodes tick cell lines (AAE2 and ISE6) using a whole genome microarray. METHODOLOGY/PRINCIPAL FINDINGS The majority (∼80%) of E. chaffeensis genes were expressed during infection in human and tick cells. There were few differences observed in E. chaffeensis gene expression between the vector Amblyomma and non-vector Ixodes tick cells, but extensive host-specific and differential gene expression profiles were detected between human and tick cells, including higher transcriptional activity in tick cells and identification of gene subsets that were differentially expressed in the two hosts. Differentially and host-specifically expressed ehrlichial genes encoded major immunoreactive tandem repeat proteins (TRP), the outer membrane protein (OMP-1) family, and hypothetical proteins that were 30-80 amino acids in length. Consistent with previous observations, high expression of p28 and OMP-1B genes was detected in human and tick cells, respectively. Notably, E. chaffeensis genes encoding TRP32 and TRP47 were highly upregulated in the human monocytes and expressed as proteins; however, although TRP transcripts were expressed in tick cells, the proteins were not detected in whole cell lysates demonstrating that TRP expression was post transcriptionally regulated. CONCLUSIONS/SIGNIFICANCE Ehrlichia gene expression is highly active in tick cells, and differential gene expression among a wide variety of host-pathogen associated genes occurs. Furthermore, we demonstrate that genes associated with host-pathogen interactions are differentially expressed and regulated by post transcriptional mechanisms.
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Affiliation(s)
- Jeeba A. Kuriakose
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Simone Miyashiro
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Tian Luo
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Bing Zhu
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Jere W. McBride
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
- Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- * E-mail:
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Ehrlichia chaffeensis TRP120 binds a G+C-rich motif in host cell DNA and exhibits eukaryotic transcriptional activator function. Infect Immun 2011; 79:4370-81. [PMID: 21859854 DOI: 10.1128/iai.05422-11] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Ehrlichia chaffeensis is an obligately intracellular bacterium that modulates host cell gene transcription in the mononuclear phagocyte, but the host gene targets and mechanisms involved in transcriptional modulation are not well-defined. In this study, we identified a novel tandem repeat DNA-binding domain in the E. chaffeensis 120-kDa tandem repeat protein (TRP120) that directly binds host cell DNA. TRP120 was observed by immunofluorescent microscopy in the nucleus of E. chaffeensis-infected host cells and was detected in nuclear extracts by Western immunoblotting with TRP120-specific antibody. The TRP120 binding sites and associated host cell target genes were identified using high-throughput deep sequencing (Illumina) of immunoprecipitated DNA (chromatin immunoprecipitation and high-throughput DNA sequencing). Multiple em motif elicitation (MEME) analysis of the most highly enriched TRP120-bound sequences revealed a G+C-rich DNA motif, and recombinant TRP120 specifically bound synthetic oligonucleotides containing the motif. TRP120 target gene binding sites were mapped most frequently to intersecting regions (intron/exon; 49%) but were also identified in upstream regulatory regions (25%) and downstream locations (26%). Genes targeted by TRP120 were most frequently associated with transcriptional regulation, signal transduction, and apoptosis. TRP120 targeted inflammatory chemokine genes, CCL2, CCL20, and CXCL11, which were strongly upregulated during E. chaffeensis infection and were also upregulated by direct transfection with recombinant TRP120. This study reveals that TRP120 is a novel DNA-binding protein that is involved in a host gene transcriptional regulation strategy.
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Mechanisms of obligatory intracellular infection with Anaplasma phagocytophilum. Clin Microbiol Rev 2011; 24:469-89. [PMID: 21734244 PMCID: PMC3131063 DOI: 10.1128/cmr.00064-10] [Citation(s) in RCA: 161] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Anaplasma phagocytophilum persists in nature by cycling between mammals and ticks. Human infection by the bite of an infected tick leads to a potentially fatal emerging disease called human granulocytic anaplasmosis. A. phagocytophilum is an obligatory intracellular bacterium that replicates inside mammalian granulocytes and the salivary gland and midgut cells of ticks. A. phagocytophilum evolved the remarkable ability to hijack the regulatory system of host cells. A. phagocytophilum alters vesicular traffic to create an intracellular membrane-bound compartment that allows replication in seclusion from lysosomes. The bacterium downregulates or actively inhibits a number of innate immune responses of mammalian host cells, and it upregulates cellular cholesterol uptake to acquire cholesterol for survival. It also upregulates several genes critical for the infection of ticks, and it prolongs tick survival at freezing temperatures. Several host factors that exacerbate infection have been identified, including interleukin-8 (IL-8) and cholesterol. Host factors that overcome infection include IL-12 and gamma interferon (IFN-γ). Two bacterial type IV secretion effectors and several bacterial proteins that associate with inclusion membranes have been identified. An understanding of the molecular mechanisms underlying A. phagocytophilum infection will foster the development of creative ideas to prevent or treat this emerging tick-borne disease.
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Xiong Q, Rikihisa Y. The prenylation inhibitor manumycin A reduces the viability of Anaplasma phagocytophilum. J Med Microbiol 2011; 60:744-749. [PMID: 21349982 PMCID: PMC3167922 DOI: 10.1099/jmm.0.029231-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Anaplasma phagocytophilum is an obligately intracellular bacterium and is the causative agent of human granulocytic anaplasmosis (HGA), an emerging and major tick-borne disease in the USA and other parts of the world. This study showed that the prenylation inhibitor manumycin A effectively blocked A. phagocytophilum infection in host cells (HL-60 or RF/6A cells). A. phagocytophilum infection activated extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase in host cells, and manumycin A treatment reduced ERK activation in A. phagocytophilum-infected host cells. As ERK activation is required for A. phagocytophilum infection, we examined whether manumycin A inhibited the bacteria directly or through host ERK signalling. Treatment of A. phagocytophilum alone with manumycin A significantly reduced the bacterial infectivity of host cells and bacterial viability in the absence of host cells, whereas pre-treatment of host cells did not inhibit bacterial infection in host cells. The inhibitory effect of manumycin A on A. phagocytophilum infection in host cells was achieved even at a concentration 100 times lower than that required for effective inhibition of mammalian cell signalling. These results suggested that manumycin A directly inactivates the bacterium, resulting in reduced infection and ERK1/2 activation. Thus, the manumycin group of drugs may have a therapeutic potential for HGA.
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Affiliation(s)
- Qingming Xiong
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, 1925 Coffey Road, Columbus, OH 43210, USA
| | - Yasuko Rikihisa
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, 1925 Coffey Road, Columbus, OH 43210, USA
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Palacios-Chaves L, Conde-Álvarez R, Gil-Ramírez Y, Zúñiga-Ripa A, Barquero-Calvo E, Chacón-Díaz C, Chaves-Olarte E, Arce-Gorvel V, Gorvel JP, Moreno E, de Miguel MJ, Grilló MJ, Moriyón I, Iriarte M. Brucella abortus ornithine lipids are dispensable outer membrane components devoid of a marked pathogen-associated molecular pattern. PLoS One 2011; 6:e16030. [PMID: 21249206 PMCID: PMC3017556 DOI: 10.1371/journal.pone.0016030] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Accepted: 12/03/2010] [Indexed: 11/19/2022] Open
Abstract
The brucellae are α-Proteobacteria facultative intracellular parasites that cause an important zoonosis. These bacteria escape early detection by innate immunity, an ability associated to the absence of marked pathogen-associated molecular patterns in the cell envelope lipopolysaccharide, lipoproteins and flagellin. We show here that, in contrast to the outer membrane ornithine lipids (OL) of other Gram negative bacteria, Brucella abortus OL lack a marked pathogen-associated molecular pattern activity. We identified two OL genes (olsB and olsA) and by generating the corresponding mutants found that olsB deficient B. abortus did not synthesize OL or their lyso-OL precursors. Liposomes constructed with B. abortus OL did not trigger IL-6 or TNF-α release by macrophages whereas those constructed with Bordetella pertussis OL and the olsB mutant lipids as carriers were highly active. The OL deficiency in the olsB mutant did not promote proinflammatory responses or generated attenuation in mice. In addition, OL deficiency did not increase sensitivity to polymyxins, normal serum or complement consumption, or alter the permeability to antibiotics and dyes. Taken together, these observations indicate that OL have become dispensable in the extant brucellae and are consistent within the trend observed in α-Proteobacteria animal pathogens to reduce and eventually eliminate the envelope components susceptible of recognition by innate immunity.
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Affiliation(s)
- Leyre Palacios-Chaves
- Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
| | - Raquel Conde-Álvarez
- Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
- Focal Area Infection Biology, Biozentrum of the University of Basel, Basel, Switzerland
| | - Yolanda Gil-Ramírez
- Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
| | - Amaia Zúñiga-Ripa
- Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
| | - Elías Barquero-Calvo
- Programa de Investigación en Enfermedades Tropicales, Escuela de Medicina Veterinaria, Universidad Nacional, Heredia, Costa Rica
| | - Carlos Chacón-Díaz
- Centro de Investigación en Enfermedades Tropicales, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica
- Programa de Investigación en Enfermedades Tropicales, Escuela de Medicina Veterinaria, Universidad Nacional, Heredia, Costa Rica
| | - Esteban Chaves-Olarte
- Centro de Investigación en Enfermedades Tropicales, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica
- Programa de Investigación en Enfermedades Tropicales, Escuela de Medicina Veterinaria, Universidad Nacional, Heredia, Costa Rica
| | - Vilma Arce-Gorvel
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, Faculté de Sciences de Luminy, Marseille, INSERM U631, CNRS UMR6102, Marseille, France
| | - Jean-Pierre Gorvel
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, Faculté de Sciences de Luminy, Marseille, INSERM U631, CNRS UMR6102, Marseille, France
| | - Edgardo Moreno
- Centro de Investigación en Enfermedades Tropicales, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San Pedro, Costa Rica
| | - María-Jesús de Miguel
- Centro de Investigación y Tecnología Agroalimentaria (CITA), Unidad de Sanidad Animal, Gobierno de Aragón, Zaragoza, Spain
| | - María-Jesús Grilló
- Instituto de Agrobiotecnología, CSIC-UPNA-Gobierno de Navarra, Pamplona, Spain
| | - Ignacio Moriyón
- Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
| | - Maite Iriarte
- Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
- * E-mail:
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Abstract
Human ehrlichiosis and anaplasmosis are acute febrile tick-borne diseases caused by various members of the genera Ehrlichia and Anaplasma (Anaplasmataceae). Human monocytotropic ehrlichiosis has become one of the most prevalent life-threatening tick-borne disease in the United States. Ehrlichiosis and anaplasmosis are becoming more frequently diagnosed as the cause of human infections, as animal reservoirs and tick vectors have increased in number and humans have inhabited areas where reservoir and tick populations are high. Ehrlichia chaffeensis, the etiologic agent of human monocytotropic ehrlichiosis (HME), is an emerging zoonosis that causes clinical manifestations ranging from a mild febrile illness to a fulminant disease characterized by multiorgan system failure. Anaplasma phagocytophilum causes human granulocytotropic anaplasmosis (HGA), previously known as human granulocytotropic ehrlichiosis. This article reviews recent advances in the understanding of ehrlichial diseases related to microbiology, epidemiology, diagnosis, pathogenesis, immunity, and treatment of the 2 prevalent tick-borne diseases found in the United States, HME and HGA.
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Affiliation(s)
- Jane E Sykes
- Department of Medicine & Epidemiology, University of California-Davis, CA 95616, USA.
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Harris HL, Brennan LJ, Keddie BA, Braig HR. Bacterial symbionts in insects: balancing life and death. Symbiosis 2010. [DOI: 10.1007/s13199-010-0065-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Anaplasma phagocytophilum and Ehrlichia chaffeensis: subversive manipulators of host cells. Nat Rev Microbiol 2010; 8:328-39. [PMID: 20372158 DOI: 10.1038/nrmicro2318] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Anaplasma spp. and Ehrlichia spp. cause several emerging human infectious diseases. Anaplasma phagocytophilum and Ehrlichia chaffeensis are transmitted between mammals by blood-sucking ticks and replicate inside mammalian white blood cells and tick salivary-gland and midgut cells. Adaptation to a life in eukaryotic cells and transmission between hosts has been assisted by the deletion of many genes that are present in the genomes of free-living bacteria (including genes required for the biosynthesis of lipopolysaccharide and peptidoglycan), by the acquisition of a cholesterol uptake pathway and by the expansion of the repertoire of genes encoding the outer-membrane porins and type IV secretion system. Here, I review the specialized properties and other adaptations of these intracellular bacteria.
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Niu H, Kozjak-Pavlovic V, Rudel T, Rikihisa Y. Anaplasma phagocytophilum Ats-1 is imported into host cell mitochondria and interferes with apoptosis induction. PLoS Pathog 2010; 6:e1000774. [PMID: 20174550 PMCID: PMC2824752 DOI: 10.1371/journal.ppat.1000774] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2008] [Accepted: 01/15/2010] [Indexed: 12/14/2022] Open
Abstract
Anaplasma phagocytophilum, the causative agent of human granulocytic anaplasmosis, infects human neutrophils and inhibits mitochondria-mediated apoptosis. Bacterial factors involved in this process are unknown. In the present study, we screened a genomic DNA library of A. phagocytophilum for effectors of the type IV secretion system by a bacterial two-hybrid system, using A. phagocytophilum VirD4 as bait. A hypothetical protein was identified as a putative effector, hereby named Anaplasmatranslocated substrate 1 (Ats-1). Using triple immunofluorescence labeling and Western blot analysis of infected cells, including human neutrophils, we determined that Ats-1 is abundantly expressed by A. phagocytophilum, translocated across the inclusion membrane, localized in the host cell mitochondria, and cleaved. Ectopically expressed Ats-1 targeted mitochondria in an N-terminal 17 residue-dependent manner, localized in matrix or at the inner membrane, and was cleaved as native protein, which required residues 55–57. In vitro-translated Ats-1 was imported in a receptor-dependent manner into isolated mitochondria. Ats-1 inhibited etoposide-induced cytochrome c release from mitochondria, PARP cleavage, and apoptosis in mammalian cells, as well as Bax-induced yeast apoptosis. Ats-1(55–57) had significantly reduced anti-apoptotic activity. Bax redistribution was inhibited in both etoposide-induced and Bax-induced apoptosis by Ats-1. Taken together, Ats-1 is the first example of a bacterial protein that traverses five membranes and prevents apoptosis at the mitochondria. Anaplasma phagocytophilum is the pathogen that causes human granulocytic anaplasmosis, an emerging infectious disease. As an obligate intracellular organism, this bacterium cannot reproduce outside of eukaryotic cells due to the loss of many genes that are present in free-living bacteria. Paradoxically, it specifically infects short-lived white blood cells that play critical roles in anti-microbial defense, by subverting a number of host innate immune responses including programmed cell death (apoptosis). A. phagocytophilum factors that are involved in this process are largely unknown. In this study, we first searched A. phagocytophilum proteins that are secreted by its specialized secretion system into eukaryotic cells. We found a protein of unknown function, here named Ats-1, which is abundantly produced by A. phagocytophilum and traverses five membranes to enter the mitochondria of human cells. Our further study showed that Ats-1 reduces the sensitivity of mitochondria to respond to apoptosis-inducing factors, leading to the inhibition of host cell apoptosis. Thus, present findings identified a bacterial protein that allows infected white blood cells to live longer to support bacterial growth. The absence of similarity of the sequence or the mode of action to any other known cell death suppressor suggests that Ats-1 defines a previously undescribed class of anti-apoptotic protein. This protein and the mechanism thereof may provide insight regarding a new therapeutic target for treatment of human granulocytic anaplasmosis.
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Affiliation(s)
- Hua Niu
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, United States of America
| | - Vera Kozjak-Pavlovic
- Biocenter, Department of Microbiology, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Thomas Rudel
- Biocenter, Department of Microbiology, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Yasuko Rikihisa
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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New insights into molecular Ehrlichia chaffeensis-host interactions. Microbes Infect 2010; 12:337-45. [PMID: 20116446 DOI: 10.1016/j.micinf.2010.01.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Accepted: 01/20/2010] [Indexed: 12/24/2022]
Abstract
Ehrlichia chaffeensis is an obligately intracellular bacterium that exhibits tropism for mononuclear phagocytes and survives by reprogramming the host cell. Here we review new information regarding the newly characterized effector molecules and the complex network of molecular host-pathogen interactions that the organism exploits enabling it to thrive and persist intracellularly.
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Glaser C, Christie L, Bloch KC. Rickettsial and ehrlichial infections. HANDBOOK OF CLINICAL NEUROLOGY 2010; 96:143-158. [PMID: 20109680 DOI: 10.1016/s0072-9752(09)96010-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Rickettsial diseases represent a clinically homogeneous group of infections characterized by fever, headache myalgias, variable presence of a rash, and a broad spectrum of neurological manifestations. Epidemiological information including time of year, geography, history of arthropod exposure, and animal contact gives important clues to the diagnosis, and should be actively elicited. Abnormalities in hematological indices of liver function tests should also increase suspicion for illness. Delay in initiation of doxycycline therapy while awaiting laboratory confirmation of infection has been associated with progressive neurological impairment and death. Clinicians should maintain a low threshold to initiate empiric therapy for rickettsial diseases in any patient with neurological findings and compatible exposures, signs, or laboratories, as these syndromes represent readily treatable causes of neurological dysfunction.
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Affiliation(s)
- Carol Glaser
- Viral and Rickettsial Disease Laboratory, Richmond, VA, USA.
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Rikihisa Y, Lin M. Anaplasma phagocytophilum and Ehrlichia chaffeensis type IV secretion and Ank proteins. Curr Opin Microbiol 2010; 13:59-66. [PMID: 20053580 DOI: 10.1016/j.mib.2009.12.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Revised: 12/02/2009] [Accepted: 12/09/2009] [Indexed: 02/04/2023]
Abstract
The obligatory intracellular bacterial pathogens Anaplasma and Ehrlichia infect leukocytes by hijacking host-cell components and processes. The type IV secretion system is up-regulated during infection. Among type IV secretion candidate substrates, an ankyrin repeat protein of Anaplasma phagocytophilum, AnkA, is delivered into the host cytoplasm via a complex that includes VirD4. AnkA is highly tyrosine phosphorylated and binds to the Abl interactor 1, SHP-1, and nuclear DNA fragments. Ehrlichia chaffeensis AnkA was recently reported to be translocated into host-cell nucleus. The recent discovery of several ankyrin repeat proteins secreted via the type IV secretion system of different intracellular bacteria suggests that a common strategy evolved to subvert host-cell functions.
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Affiliation(s)
- Yasuko Rikihisa
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA.
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38
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Carrade D, Foley J, Borjesson D, Sykes J. Canine Granulocytic Anaplasmosis: A Review. J Vet Intern Med 2009; 23:1129-41. [DOI: 10.1111/j.1939-1676.2009.0384.x] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Nuclear translocated Ehrlichia chaffeensis ankyrin protein interacts with a specific adenine-rich motif of host promoter and intronic Alu elements. Infect Immun 2009; 77:4243-55. [PMID: 19651857 DOI: 10.1128/iai.00376-09] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ehrlichiae are obligately intracellular bacteria that reside and replicate in phagocytes by circumventing host cell defenses and modulating cellular processes, including host cell gene transcription. However, the mechanisms by which ehrlichiae influence host gene transcription have largely remained undetermined. Numerous ankyrin and tandem repeat-containing proteins associated with host-pathogen interactions have been identified in Ehrlichia species, but their roles in pathobiology are unknown. In this study, we determined by confocal immunofluorescence microscopy and by immunodetection in purified nuclear extracts that the ankyrin repeat-containing protein p200 is translocated to the nuclei of Ehrlichia-infected monocytes. Chromatin immunoprecipitation (ChIP) with DNA sequencing revealed an Ehrlichia chaffeensis p200 interaction located within host promoter and intronic Alu-Sx elements, the most abundant repetitive elements in the human genome. A specific adenine-rich (mid-A-stretch) motif within Alu-Sx elements was identified using electrophoretic mobility shift and NoShift assays. Whole-genome analysis with ChIP and DNA microarray analysis (ChIP-chip) determined that genes (n = 456) with promoter Alu elements primarily related to transcription, apoptosis, ATPase activity, and structural proteins associated with the nucleus and membrane-bound organelles were the primary targets of p200. Several p200 target genes (encoding tumor necrosis factor alpha, Stat1, and CD48) associated with ehrlichial pathobiology were strongly upregulated during infection, as determined by quantitative PCR. This is the first study to identify a nuclear translocation of bacterially encoded protein by E. chaffeensis and to identify a specific binding motif and genes that are primary targets of a novel molecular strategy to reprogram host cell gene expression to promote survival of the pathogen.
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Antigen display, T-cell activation, and immune evasion during acute and chronic ehrlichiosis. Infect Immun 2009; 77:4643-53. [PMID: 19635826 DOI: 10.1128/iai.01433-08] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
How spatial and temporal changes in major histocompatibility complex/peptide antigen presentation to CD4 T cells regulate CD4 T-cell responses during intracellular bacterial infections is relatively unexplored. We have shown that immunization with an ehrlichial outer membrane protein, OMP-19, protects mice against fatal ehrlichial challenge infection, and we identified a CD4 T-cell epitope (IA(b)/OMP-19(107-122)) that elicited CD4 T cells following either immunization or infection. Here, we have used an IA(b)/OMP-19(107-122)-specific T-cell line to monitor antigen display ex vivo during acute and chronic infection with Ehrlichia muris, a bacterium that establishes persistent infection in C57BL/6 mice. The display of IA(b)/OMP-19(107-122) by host antigen-presenting cells was detected by measuring intracellular gamma interferon (IFN-gamma) production by the T-cell line. After intravenous infection, antigen presentation was detected in the spleen, peritoneal exudate cells, and lymph nodes, although the kinetics of antigen display differed among the tissues. Antigen presentation and bacterial colonization were closely linked in each anatomical location, and there was a direct relationship between antigen display and CD4 T-cell effector function. Spleen and lymph node dendritic cells (DCs) were efficient presenters of IA(b)/OMP-19(107-122), demonstrating that DCs play an important role in ehrlichial infection and immunity. Chronic infection and antigen presentation occurred within the peritoneal cavity, even in the presence of highly activated CD4 T cells. These data indicated that the ehrlichiae maintain chronic infection not by inhibiting antigen presentation or T-cell activation but, in part, by avoiding signals mediated by activated T cells.
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Kocan KM, Zivkovic Z, Blouin EF, Naranjo V, Almazán C, Mitra R, de la Fuente J. Silencing of genes involved in Anaplasma marginale-tick interactions affects the pathogen developmental cycle in Dermacentor variabilis. BMC DEVELOPMENTAL BIOLOGY 2009; 9:42. [PMID: 19607704 PMCID: PMC2714835 DOI: 10.1186/1471-213x-9-42] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2009] [Accepted: 07/16/2009] [Indexed: 11/10/2022]
Abstract
BACKGROUND The cattle pathogen, Anaplasma marginale, undergoes a developmental cycle in ticks that begins in gut cells. Transmission to cattle occurs from salivary glands during a second tick feeding. At each site of development two forms of A. marginale (reticulated and dense) occur within a parasitophorous vacuole in the host cell cytoplasm. However, the role of tick genes in pathogen development is unknown. Four genes, found in previous studies to be differentially expressed in Dermacentor variabilis ticks in response to infection with A. marginale, were silenced by RNA interference (RNAi) to determine the effect of silencing on the A. marginale developmental cycle. These four genes encoded for putative glutathione S-transferase (GST), salivary selenoprotein M (SelM), H+ transporting lysosomal vacuolar proton pump (vATPase) and subolesin. RESULTS The impact of gene knockdown on A. marginale tick infections, both after acquiring infection and after a second transmission feeding, was determined and studied by light microscopy. Silencing of these genes had a different impact on A. marginale development in different tick tissues by affecting infection levels, the densities of colonies containing reticulated or dense forms and tissue morphology. Salivary gland infections were not seen in any of the gene-silenced ticks, raising the question of whether these ticks were able to transmit the pathogen. CONCLUSION The results of this RNAi and light microscopic analyses of tick tissues infected with A. marginale after the silencing of genes functionally important for pathogen development suggest a role for these molecules during pathogen life cycle in ticks.
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Affiliation(s)
- Katherine M Kocan
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
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Rikihisa Y, Lin M, Niu H, Cheng Z. Type IV secretion system of Anaplasma phagocytophilum and Ehrlichia chaffeensis. Ann N Y Acad Sci 2009; 1166:106-11. [PMID: 19538269 DOI: 10.1111/j.1749-6632.2009.04527.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The intracellular bacterial pathogens Ehrlichia chaffeensis and Anaplasma phagocytophilum have evolved to infect leukocytes and hijack biological compounds and processes of these host defensive cells. Bacterial type IV secretion (T4S) system transports macromolecules across the membrane in an ATP-dependent manner and is increasingly recognized as a virulence factor delivery mechanism that allows pathogens to modulate eukaryotic cell functions for their own benefit. Genes encoding T4S system homologous to those of a plant pathogen Agrobacterium tumefaciens have been identified in E. chaffeensis and A. phagocytophilum. Upon interaction with new host cells, E. chaffeensis and A. phagocytophilum genes encoding the T4S apparatus are upregulated. The delivered macromolecules are referred to as T4S substrates, or effectors, because they affect and alter basic host cellular processes, resulting in disease development. Recently, A. phagocytophilum 160-kDa AnkA protein was to be delivered by T4S system into the host cytoplasm. Thus, dynamic signal transduction events are likely induced by T4S substrates in the host cells for successful establishment of intracellular infection. Further studies on Ehrlichia and Anaplasma T4S effectors cognate host cell molecules will undoubtedly advance our understanding of the complex interplay between obligatory intracellular pathogens and their hosts. Such data can be applied toward treatment, diagnosis, and control of ehrlichiosis and anaplasmosis.
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Affiliation(s)
- Yasuko Rikihisa
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210, USA.
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The differential interaction of Brucella and ochrobactrum with innate immunity reveals traits related to the evolution of stealthy pathogens. PLoS One 2009; 4:e5893. [PMID: 19529776 PMCID: PMC2691993 DOI: 10.1371/journal.pone.0005893] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Accepted: 05/19/2009] [Indexed: 12/13/2022] Open
Abstract
Background During evolution, innate immunity has been tuned to recognize pathogen-associated molecular patterns. However, some α-Proteobacteria are stealthy intracellular pathogens not readily detected by this system. Brucella members follow this strategy and are highly virulent, but other Brucellaceae like Ochrobactrum are rhizosphere inhabitants and only opportunistic pathogens. To gain insight into the emergence of the stealthy strategy, we compared these two phylogenetically close but biologically divergent bacteria. Methodology/Principal Findings In contrast to Brucella abortus, Ochrobactrum anthropi did not replicate within professional and non-professional phagocytes and, whereas neutrophils had a limited action on B. abortus, they were essential to control O. anthropi infections. O. anthropi triggered proinflammatory responses markedly lower than Salmonella enterica but higher than B. abortus. In macrophages and dendritic cells, the corresponding lipopolysaccharides reproduced these grades of activation, and binding of O. anthropi lipopolysaccharide to the TLR4 co-receptor MD-2 and NF-κB induction laid between those of B. abortus and enteric bacteria lipopolysaccharides. These differences correlate with reported variations in lipopolysaccharide core sugars, sensitivity to bactericidal peptides and outer membrane permeability. Conclusions/Significance The results suggest that Brucellaceae ancestors carried molecules not readily recognized by innate immunity, so that non-drastic variations led to the emergence of stealthy intracellular parasites. They also suggest that some critical envelope properties, like selective permeability, are profoundly altered upon modification of pathogen-associated molecular patterns, and that this represents a further adaptation to the host. It is proposed that this adaptive trend is relevant in other intracellular α-Proteobacteria like Bartonella, Rickettsia, Anaplasma, Ehrlichia and Wolbachia.
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Managing canine vector-borne diseases of zoonotic concern: part two. Trends Parasitol 2009; 25:228-35. [PMID: 19346164 DOI: 10.1016/j.pt.2009.02.005] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Revised: 01/15/2009] [Accepted: 02/04/2009] [Indexed: 11/23/2022]
Abstract
Despite recent achievements in scientific knowledge related to canine vector-borne diseases (CVBDs) of zoonotic concern, their management is still impaired by several neglected issues related to accurate diagnosis and effective treatment of both single and co-infections. A better understanding of the pathogenesis and the progression of clinical, hematological and biochemical abnormalities of CVBDs will be important in choosing appropriate diagnostic tests and in establishing the best strategies for treatment and control. Nonetheless, the diagnosis and control of zoonotic infections in clinically healthy dogs remain challenging. This review discusses the crucial aspects involved in the diagnosis, treatment, prevention and control of CVBDs of zoonotic concern.
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Anaplasma phagocytophilum increases cathepsin L activity, thereby globally influencing neutrophil function. Infect Immun 2008; 76:4905-12. [PMID: 18765732 DOI: 10.1128/iai.00851-08] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Anaplasma phagocytophilum, the agent of human granulocytic anaplasmosis, is an unusual obligate intracellular pathogen that persists in neutrophils. A. phagocytophilum increases the binding of a repressor, CCAAT displacement protein (CDP), to the gp91(phox) promoter, thereby diminishing the host oxidative burst. We now show that A. phagocytophilum infection also enhances the binding of CDP to the promoters of human neutrophil peptide 1 and C/EBPepsilon--molecules important for neutrophil defense and maturation--suggesting that this is a general strategy used by this pathogen to alter polymorphonuclear leukocyte function. To explore the mechanism by which A. phagocytophilum increases CDP activity, we assessed the effects of this microbe on cathepsin L, a protease that cleaves CDP into a form with increased DNA binding ability. A. phagocytophilum infection resulted in elevated cathepsin L activity and the proteolysis of CDP. Blocking the action of cathepsin L with a chemical inhibitor or small interfering RNA targeting of this molecule caused a marked reduction in the degree of A. phagocytophilum infection. These data demonstrate that increasing cathepsin L activity is a strategy used by A. phagocytophilum to alter CDP activity and thereby globally influence neutrophil function. As therapeutic options for A. phagocytophilum and related organisms are limited, these results also identify a cellular pathway that may be targeted for the treatment of A. phagocytophilum infection.
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Reneer DV, Troese MJ, Huang B, Kearns SA, Carlyon JA. Anaplasma phagocytophilum PSGL-1-independent infection does not require Syk and leads to less efficient AnkA delivery. Cell Microbiol 2008; 10:1827-38. [PMID: 18485118 DOI: 10.1111/j.1462-5822.2008.01168.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Anaplasma phagocytophilum is an obligate intracellular bacterium that infects neutrophils to cause granulocytic anaplasmosis in humans and mammals. P-selectin glycoprotein ligand-1 (PSGL-1) and the tetrasaccharide sialyl Lewis x (sLe(x)), which caps the PSGL-1 N-terminus, are confirmed A. phagocytophilum receptors. A. phagocytophilum is capable of sLe(x)-modified PSGL-1-dependent and -independent infection. PSGL-1 N-terminus-mediated entry is dependent on spleen tyrosine kinase (Syk). Here, we determined that PSGL-1-independent entry does not alter bacterial replication and investigated whether it involves Syk using NCH-1A2, an enriched subpopulation of A. phagocytophilum NCH-1 obtained through cultivation in a sLe(x)-deficient HL-60 cell line, HL-60 A2. Pharmacological inhibition of Syk nearly abolishes NCH-1 infection, but does not alter NCH-1A2 invasion and only marginally reduces NCH-1A2 propagation. This phenomenon was confirmed by a competitive infection assay using PSGL-1-dependent and -independent A. phagocytophilum organisms transformed to express mCherry or green fluorescent protein respectively. We also assayed for delivery and tyrosine phosphorylation of the A. phagocytophilum effector, AnkA, following NCH-1or NCH-1A2 incubation with HL-60 or HL-60 A2 cells in the presence of PSGL-1 blocking antibody. PSGL-1 N-terminus recognition promotes optimal AnkA delivery while binding to sLe(x) or the unknown receptor is comparably less important for this process.
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Affiliation(s)
- Dexter V Reneer
- Department of Microbiology, Immunology, and Molecular Genetics, College of Medicine, University of Kentucky, Lexington, KY, USA
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Regulation of type IV secretion apparatus genes during Ehrlichia chaffeensis intracellular development by a previously unidentified protein. J Bacteriol 2008; 190:2096-105. [PMID: 18192398 DOI: 10.1128/jb.01813-07] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The type IV secretion (T4S) system is critical for the virulence of several pathogens. In the rickettsial pathogen Ehrlichia chaffeensis, the virBD genes are split into two operons, the virB3-virB6 (preceded by sodB) and virB8-virD4 operons. Between these two operons, there are duplications of virB4, virB8, and virB9. In this study we found that transcription of all five loci was downregulated prior to the release of E. chaffeensis from host THP-1 cells and was upregulated at the initiation of exponential growth. Electrophoretic mobility shift assays revealed an E. chaffeensis-encoded protein that specifically bound to the promoter regions upstream of the virBD loci. The protein was purified from the bacterial lysate by affinity chromatography using a biotinylated promoter region upstream of sodB. Mass spectrometry identified the protein as an E. chaffeensis 12.3-kDa hypothetical protein, which was designated EcxR. Recombinant EcxR bound to the promoter regions upstream of five individual virBD loci. EcxR also activated transcription of all five virBD loci in lacZ reporter constructs. The expression of ecxR was positively autoregulated by EcxR. These results suggest that the five virBD loci are coordinately regulated by EcxR to allow developmental stage-specific expression of the T4S system in E. chaffeensis.
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Molecular Pathology of Rickettsial Lung Infections. MOLECULAR PATHOLOGY LIBRARY 2008. [PMCID: PMC7147442 DOI: 10.1007/978-0-387-72430-0_38] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rickettsial infections of humans comprise a diverse group of infections caused by pathogens that are obligate intracellular bacteria with a genetic relationship, including the genera Rickettsia, Orientia, Ehrlichia, and Anaplasma. The host cells of these pathogens largely belie the systemic clinical manifestations, because Rickettsia and Orientia infect endothelial cells, and Ehrlichia and Anaplasma infect circulating leukocytes (monocytes and neutrophils, respectively). Thus, the predominant manifestations (fever, headache, myalgia, with or without rash) do not usually focus attention on the respiratory system; however, the underlying pathogenesis of these infections involves degrees of vascular compromise either by direct injury and inflammation or by the action of vasoactive proinflammatory molecules such as cytokines, chemokines, and prostaglandins. Given that the lung possesses the largest vascular bed in the human body, it is not surprising that pulmonary involvement is periodically identified and, when severely affected, is considered a potentially life-threatening complication.1,2
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Sarkar M, Reneer DV, Carlyon JA. Sialyl-Lewis x-independent infection of human myeloid cells by Anaplasma phagocytophilum strains HZ and HGE1. Infect Immun 2007; 75:5720-5. [PMID: 17893131 PMCID: PMC2168341 DOI: 10.1128/iai.00905-07] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 08/07/2007] [Accepted: 09/12/2007] [Indexed: 11/20/2022] Open
Abstract
Anaplasma phagocytophilum, the causative agent of human granulocytic anaplasmosis, is an obligate intracellular bacterium that infects neutrophils and neutrophil precursors. Bacterial recognition of P-selectin glycoprotein ligand-1 (PSGL-1) and the alpha2,3-sialylated- and alpha1,3-fucosylated-moiety sialyl-Lewis x (sLe(x)), which modifies the PSGL-1 N terminus, is important for adhesion to and invasion of myeloid cells. We have previously demonstrated that A. phagocytophilum organisms of the NCH-1 strain that utilize an sLe(x)-modified PSGL-1-independent means of entry can be enriched for by cultivation in undersialylated HL-60 cells that are unable to construct sLe(x). Because it was unknown whether other A. phagocytophilum isolates share this ability, we extended our studies to the geographically diverse strains HZ and HGE1. HL-60 A2 is a clonal cell line that is defective for sialylation and alpha1,3-fucosyltransferase. HL-60 A2 cell surfaces, therefore, not only lack sLe(x) but also are virtually devoid of any other sialic acid- and/or alpha1,3-fucose-modified glycan. By cultivating HZ and HGE1 in HL-60 A2 cells, we enriched for bacterial subpopulations (termed HZA2 and HGE1A2) that bind and/or infect myeloid cells in the absence of sialic acid and alpha1,3-fucose and in the presence of antibody that blocks the N terminus of PSGL-1. Thus, multiple A. phagocytophilum isolates share the ability to use sLe(x)-modified PSGL-1-dependent and -independent routes of entry into myeloid cells. HZA2 and HGE1A2 represent enriched bacterial populations that will aid dissection of the complexities of the interactions between A. phagocytophilum and host myeloid cells.
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Affiliation(s)
- Madhubanti Sarkar
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
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Darby AC, Cho NH, Fuxelius HH, Westberg J, Andersson SGE. Intracellular pathogens go extreme: genome evolution in the Rickettsiales. Trends Genet 2007; 23:511-20. [PMID: 17822801 DOI: 10.1016/j.tig.2007.08.002] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Revised: 07/17/2007] [Accepted: 08/24/2007] [Indexed: 10/22/2022]
Abstract
The Rickettsiales, a genetically diverse group of the alpha-Proteobacteria, include major mammalian pathogens, such as the agents of epidemic typhus, scrub typhus, ehrlichioses and heartwater disease. Sequenced genomes of this bacterial order have provided exciting insights into reductive genome evolution, antigenic variation and host cell manipulation. Recent results suggest that human pathogens emerged relatively late in the evolution of the Rickettsiales. Surprisingly, there is no association between pathogenicity and the acquisition of novel virulence genes. Here, we explore the genomic differences between members of the Rickettsiales and ask what are the changes that enable infectious agents to emerge from seemingly harmless bacteria.
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Affiliation(s)
- Alistair C Darby
- Department of Molecular Evolution, Evolutionary Biology Center, Uppsala University, Norbyvägen 18C, S-752 36 Uppsala, Sweden
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