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Carvalho CL, Lopes de Carvalho I, Zé-Zé L, Núncio MS, Duarte EL. Tularaemia: a challenging zoonosis. Comp Immunol Microbiol Infect Dis 2014; 37:85-96. [PMID: 24480622 PMCID: PMC7124367 DOI: 10.1016/j.cimid.2014.01.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 12/28/2013] [Accepted: 01/04/2014] [Indexed: 01/21/2023]
Abstract
In recent years, several emerging zoonotic vector-borne infections with potential impact on human health have been identified in Europe, including tularaemia, caused by Francisella tularensis. This remarkable pathogen, one of the most virulent microorganisms currently known, has been detected in increasingly new settings and in a wide range of wild species, including lagomorphs, rodents, carnivores, fish and invertebrate arthropods. Also, a renewed concern has arisen with regard to F. tularensis: its potential use by bioterrorists. Based on the information published concerning the latest outbreaks, the aim of this paper is to review the main features of the agent, its biology, immunology and epidemiology. Moreover, special focus will be given to zoonotic aspects of the disease, as tularaemia outbreaks in human populations have been frequently associated with disease in animals.
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Caspar Y, Sutera V, Boisset S, Denis JN, Maurin M. Bis-indolic compounds as potential new therapeutic alternatives for tularaemia. Front Cell Infect Microbiol 2014; 4:24. [PMID: 24579066 PMCID: PMC3936198 DOI: 10.3389/fcimb.2014.00024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 02/12/2014] [Indexed: 11/13/2022] Open
Abstract
Francisella tularensis is the etiological agent of tularaemia and a CDC class A biological threat agent. Few antibiotic classes are currently useful in treating tularaemia, including the aminoglycosides gentamicin and streptomycin, fluoroquinolones, and tetracyclines. However, treatment failures and relapses remain frequent and F. tularensis strains resistant to antibiotics have been easily selected in vitro. In this study, we evaluated the activity of new synthetic bis-indole derivatives against this pathogen. Minimum inhibitory concentrations (MICs) of four compounds (dcm01 to dcm04) were determined for the reference strains F. tularensis subsp. holarctica LVS NCTC10857, F. tularensis subsp. novicida CIP56.12 and F. philomiragia ATCC25015, and for 41 clinical strains of F. tularensis subsp. holarctica isolated in France. Minimal bactericidal concentrations (MBCs) were determined for the dcm02 and dcm04 compounds for the LVS and two clinical strains. Killing curves were also determined for the same three strains exposed to dcm04. All tested bis-indole compounds were bacteriostatic against F. tularensis subsp. holarctica strains, with a MIC90 of 8 μg/mL for dcm01, dcm02, and dcm03, and 2 μg/mL for dcm04. Only one strain was resistant to both dcm01 and dcm03, with MICs > 32 μg/mL. In contrast, F. tularensis subsp. novicida was resistant to all derivatives and F. philomiragia was only susceptible to dcm02 and dcm04, with MICs of 16 and 4 μg/mL, respectively. MBC and killing curve experiments revealed significant bactericidal activity (i.e., 3-log reduction of the bacterial inoculum) of the dcm02 and dcm04 compounds only for the LVS strain. In conclusion, we have identified novel synthetic bis-indole compounds that are active against F. tularensis subsp. holarctica. They may be drug candidates for the development of new therapeutic alternatives for tularaemia treatment. Their further characterization is needed, especially identification of their bacterial targets.
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Tobudic S, Nedomansky K, Poeppl W, Müller M, Faas A, Mooseder G, Allerberger F, Stanek G, Burgmann H. Seroprevalence for Coxiella burnetii, Francisella tularensis, Brucella abortus and Brucella melitensis in Austrian adults: a cross-sectional survey among military personnel and civilians. Ticks Tick Borne Dis 2014; 5:315-7. [PMID: 24572607 DOI: 10.1016/j.ttbdis.2013.12.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Revised: 12/15/2013] [Accepted: 12/17/2013] [Indexed: 11/30/2022]
Abstract
The prevalence of Coxiella burnetii, Francisella tularensis, Brucella abortus, and Brucella melitensis infections in Austria and the exposure risk of military personnel were assessed in an exploratory nationwide cross-sectional seroprevalence survey in 526 healthy adult individuals, 222 of which were soldiers and 304 were civilians. Screening for IgA/IgG antibodies to C. burnetii (Phase I) and IgG/IgM antibodies to C. burnetii (Phase II), and to F. tularensis was done with commercial enzyme-linked immunosorbent assays. To detect antibodies against B. abortus and B. melitensis, an in-house complement fixation test was used. Overall, 11 individuals (2.0%) showed antibodies to C. burnetii, 3 individuals (0.5%) were seropositive for F. tularensis, and one (0.3%) individual was borderline positive. All individuals positive or borderline for F. tularensis tested negative for antibodies against C. burnetii. All individuals tested negative for antibodies against B. melitensis/B. abortus. There were no significant differences between the seroprevalence of C. burnetii and F. tularensis among military personnel and civilians. Our data demonstrate serological evidence of a low rate of exposure to C. burnetii and F. tularensis among the Austrian adult population and military personnel.
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354
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Panayidou S, Ioannidou E, Apidianakis Y. Human pathogenic bacteria, fungi, and viruses in Drosophila: disease modeling, lessons, and shortcomings. Virulence 2014; 5:253-69. [PMID: 24398387 DOI: 10.4161/viru.27524] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Drosophila has been the invertebrate model organism of choice for the study of innate immune responses during the past few decades. Many Drosophila-microbe interaction studies have helped to define innate immunity pathways, and significant effort has been made lately to decipher mechanisms of microbial pathogenesis. Here we catalog 68 bacterial, fungal, and viral species studied in flies, 43 of which are relevant to human health. We discuss studies of human pathogens in flies revealing not only the elicitation and avoidance of immune response but also mechanisms of tolerance, host tissue homeostasis, regeneration, and predisposition to cancer. Prominent among those is the emerging pattern of intestinal regeneration as a defense response induced by pathogenic and innocuous bacteria. Immunopathology mechanisms and many microbial virulence factors have been elucidated, but their relevance to human health conventionally necessitates validation in mammalian models of infection.
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355
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Allen LAH. Neutrophils: potential therapeutic targets in tularemia? Front Cell Infect Microbiol 2013; 3:109. [PMID: 24409419 PMCID: PMC3873502 DOI: 10.3389/fcimb.2013.00109] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 12/14/2013] [Indexed: 01/18/2023] Open
Abstract
The central role of neutrophils in innate immunity and host defense has long been recognized, and the ability of these cells to efficiently engulf and kill invading bacteria has been extensively studied, as has the role of neutrophil apoptosis in resolution of the inflammatory response. In the past few years additional immunoregulatory properties of neutrophils were discovered, and it is now clear that these cells play a much greater role in control of the immune response than was previously appreciated. In this regard, it is noteworthy that Francisella tularensis is one of relatively few pathogens that can successfully parasitize neutrophils as well as macrophages, DC and epithelial cells. Herein we will review the mechanisms used by F. tularensis to evade elimination by neutrophils. We will also reprise effects of this pathogen on neutrophil migration and lifespan as compared with other infectious and inflammatory disease states. In addition, we will discuss the evidence which suggests that neutrophils contribute to disease progression rather than effective defense during tularemia, and consider whether manipulation of neutrophil migration or turnover may be suitable adjunctive therapeutic strategies.
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Brown MJ, Russo BC, O'Dee DM, Schmitt DM, Nau GJ. The contribution of the glycine cleavage system to the pathogenesis of Francisella tularensis. Microbes Infect 2013; 16:300-9. [PMID: 24374051 DOI: 10.1016/j.micinf.2013.12.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 12/04/2013] [Accepted: 12/17/2013] [Indexed: 02/07/2023]
Abstract
Biosynthesis and acquisition of nutrients during infection are integral to pathogenesis. Members of a metabolic pathway, the glycine cleavage system, have been identified in virulence screens of the intracellular bacterium Francisella tularensis but their role in pathogenesis remains unknown. This system generates 5,10-methylenetetrahydrofolate, a precursor of amino acid and DNA synthesis, from glycine degradation. To characterize this pathway, deletion of the gcvT homolog, an essential member of this system, was performed in attenuated and virulent F. tularensis strains. Deletion mutants were auxotrophic for serine but behaved similar to wild-type strains with respect to host cell invasion, intracellular replication, and stimulation of TNF-α. Unexpectedly, the glycine cleavage system was required for the pathogenesis of virulent F. tularensis in a murine model. Deletion of the gcvT homolog delayed mortality and lowered bacterial burden, particularly in the liver and bloodstream. To reconcile differences between the cell culture model and animal model, minimal tissue culture media was employed to mimic the nutritionally limiting environment of the host. This reevaluation demonstrated that the glycine cleavage system contributes to the intracellular replication of virulent F. tularensis in serine limiting environments. Thus, the glycine cleavage system is the serine biosynthetic pathway of F. tularensis and contributes to pathogenesis in vivo.
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357
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Francisella tularensis intracellular survival: to eat or to die. Microbes Infect 2013; 15:989-997. [PMID: 24513705 DOI: 10.1016/j.micinf.2013.09.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 09/23/2013] [Accepted: 09/23/2013] [Indexed: 12/15/2022]
Abstract
Francisella tularensis is a highly infectious facultative intracellular bacterium causing the zoonotic disease tularemia. Numerous attributes required for F. tularensis intracellular multiplication have been identified recently. However, the mechanisms by which the majority of them interfere with the infected host are still poorly understood. The following review summarizes our current knowledge on the different steps of Francisella intramacrophagic life cycle and expands on the importance of nutrient acquisition.
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358
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Yıldırım S, Turhan V, Karadenizli A, Önem Y, Karagöz E, Eroğlu C, Çiftçi F. Tuberculosis or tularemia? A molecular study in cervical lymphadenitis. Int J Infect Dis 2013; 18:47-51. [PMID: 24239221 DOI: 10.1016/j.ijid.2013.09.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 07/15/2013] [Accepted: 09/06/2013] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND Over the last two to three decades there has been a marked decrease in certain bacterial infections in Turkey. One of them is tuberculosis. Of note, statistics published by the Turkish Ministry of Health (MoH) show decreasing pulmonary tuberculosis (PTB), but on the other hand, increasing extrapulmonary tuberculosis (EPTB). The most common form of EPTB is tuberculous cervical lymphadenitis (TCL). The increase in the number of TCL cases despite the decline in cases of PTB is seen as a paradoxical issue. In contrast there has been an increase in the number of oropharyngeal tularemia cases in the last decade in Turkey. The aim of this study was to draw attention to the importance of differentiating between TCL and tularemia lymphadenitis, because these diseases may have a similar histopathological appearance. METHODS Thirty-two cases diagnosed as TCL were identified from the archives of a pathology laboratory (Patomer Pathology Laboratory, Bursa, Turkey). PCR tests for Francisella tularensis and Mycobacterium tuberculosis were carried out on the paraffin tissue blocks of these cases. At the same time, statistical data on PTB and EPTB for the period 1996-2010 were retrieved from the MoH and reviewed. Statistics related to tularemia, which has been diagnosed since 1988 and has been increasing in the last 10 years, were obtained from the Department of Zoonoses of the MoH. RESULTS Six out of 32 (19%) cases who had previously been diagnosed with 'casseifying granulomatous lymphadenitis consistent with tuberculosis' were found to be positive for tularemia by PCR test of the cervical lymph nodes. CONCLUSIONS Oropharyngeal tularemia should be kept in mind in the differential diagnosis of cervical lymphadenitis in widespread geographic regions of the Northern Hemisphere, including the Asian continent. In particular, if granulomatous inflammation with necrosis is seen histopathologically, tularemia should be excluded before making the diagnosis of TCL.
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359
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Schweighardt AJ, Battaglia A, Wallace MM. Detection of anthrax and other pathogens using a unique liquid array technology. J Forensic Sci 2013; 59:15-33. [PMID: 24147813 DOI: 10.1111/1556-4029.12283] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2012] [Revised: 09/29/2012] [Accepted: 10/07/2012] [Indexed: 11/30/2022]
Abstract
A bead-based liquid hybridization assay, Luminex(®) 100™, was used to identify four pathogenic bacteria, Bacillus anthracis, Clostridium botulinum, Francisella tularensis subsp. tularensis, and Yersinia pestis, and several close relatives. Hybridization between PCR-amplified target sequences and probe sequences (located within the 23S ribosomal RNA gene rrl and the genes related to the toxicity of each bacterium) was detected in single-probe or multiple-probe assays, depending on the organism. The lower limits of detection (LLDs) for the probes ranged from 0.1 to 10 ng. Sensitivity was improved using lambda exonuclease to digest the noncomplementary target strand. All contributors in 33 binary, ternary, and quaternary mixtures in which all components were present in a 1:1 ratio were identified with an 80% success rate. Twenty-eight binary mixtures in which the two components were combined in various ratios were further studied. All target sequences were detected, even when the minor component was overshadowed by a tenfold excess of the major component.
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360
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Franchini AM, Hunt D, Melendez JA, Drake JR. FcγR-driven release of IL-6 by macrophages requires NOX2-dependent production of reactive oxygen species. J Biol Chem 2013; 288:25098-25108. [PMID: 23857584 DOI: 10.1074/jbc.m113.474106] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Activation of the FcγR via antigen containing immune complexes can lead to the generation of reactive oxygen species, which are potent signal transducing molecules. However, whether ROS contribute to FcγR signaling has not been studied extensively. We set out to elucidate the role of NADPH oxidase-generated ROS in macrophage activation following FcγR engagement using antigen-containing immune complexes. We hypothesized that NOX2 generated ROS is necessary for propagation of downstream FcγR signaling and initiation of the innate immune response. Following exposure of murine bone marrow-derived macrophages (BMDMs) to inactivated Francisella tularensis (iFt)-containing immune complexes, we observed a significant increase in the innate inflammatory cytokine IL-6 at 24 h compared with macrophages treated with Ft LVS-containing immune complexes. Ligation of the FcγR by opsonized Ft also results in significant ROS production. Macrophages lacking the gp91(phox) subunit of NOX2 fail to produce ROS upon FcγR ligation, resulting in decreased Akt phosphorylation and a reduction in the levels of IL-6 compared with wild type macrophages. Similar results were seen following infection of BMDMs with catalase deficient Ft that fail to scavenge hydrogen peroxide. In conclusion, our findings demonstrate that ROS participate in elicitation of an effective innate immune in response to antigen-containing immune complexes through FcγR.
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Abstract
Francisella tularensis is a highly virulent bacterial pathogen that is easily aerosolized and has a low infectious dose. As an intracellular pathogen, entry of Francisella into host cells is critical for its survival and virulence. However, the initial steps of attachment and internalization of Francisella into host cells are not well characterized, and little is known about bacterial factors that promote these processes. This review highlights our current understanding of Francisella attachment and internalization into host cells. In particular, we emphasize the host cell types Francisella has been shown to interact with, as well as specific receptors and signaling processes involved in the internalization process. This review will shed light on gaps in our current understanding and future areas of investigation.
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362
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Okan NA, Kasper DL. The atypical lipopolysaccharide of Francisella. Carbohydr Res 2013; 378:79-83. [PMID: 23916469 DOI: 10.1016/j.carres.2013.06.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 06/15/2013] [Accepted: 06/20/2013] [Indexed: 01/17/2023]
Abstract
Bacterial lipopolysaccharides (LPSs) are ubiquitous molecules that are prominent components of the outer membranes of most gram-negative bacteria. Genetic and structural characterizations of Francisella LPS have revealed substantial differences when compared to more commonly studied LPSs of the Enterobacteriaceae. This review discusses both the general characteristics and the unusual features of Francisella LPS.
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363
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Live attenuated tularemia vaccines: recent developments and future goals. Vaccine 2013; 31:3485-91. [PMID: 23764535 DOI: 10.1016/j.vaccine.2013.05.096] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 05/20/2013] [Accepted: 05/24/2013] [Indexed: 12/24/2022]
Abstract
In the aftermath of the 2001 anthrax attacks in the U.S., numerous efforts were made to increase the level of preparedness against a biological attack both in the US and worldwide. As a result, there has been an increase in research interest in the development of vaccines and other countermeasures against a number of agents with the potential to be used as biological weapons. One such agent, Francisella tularensis, has been the subject of a surge in the level of research being performed, leading to a substantial increase in knowledge of the pathogenic mechanisms of the organism and the induced immune responses. This information has facilitated the development of multiple new Francisella vaccine candidates. Herein we review the latest live attenuated F. tularensis vaccine efforts. Historically, live attenuated vaccines have demonstrated the greatest degree of success in protection against tularemia and the greatest promise in recent efforts to develop of a fully protective vaccine. This review summarizes recent live attenuated Francisella vaccine candidates and the lessons learned from those studies, with the goal of collating known characteristics associated with successful attenuation, immunogenicity, and protection.
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364
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Dentan C, Pavese P, Pelloux I, Boisset S, Brion JP, Stahl JP, Maurin M. Treatment of tularemia in pregnant woman, France. Emerg Infect Dis 2013; 19:996-8. [PMID: 23735285 PMCID: PMC3713841 DOI: 10.3201/eid1906.130138] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
A pregnant woman who had oropharyngeal tularemia underwent treatment with azithromycin and lymph node resection and recovered without obstetrical complication or infection in the child. Azithromycin represents a first-line treatment option for tularemia during pregnancy in regions where the infecting strains of Francisella tularensis have no natural resistance to macrolides.
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365
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Cuccui J, Thomas RM, Moule MG, D'Elia RV, Laws TR, Mills DC, Williamson D, Atkins TP, Prior JL, Wren BW. Exploitation of bacterial N-linked glycosylation to develop a novel recombinant glycoconjugate vaccine against Francisella tularensis. Open Biol 2013; 3:130002. [PMID: 23697804 PMCID: PMC3866875 DOI: 10.1098/rsob.130002] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 05/01/2013] [Indexed: 11/12/2022] Open
Abstract
Glycoconjugate-based vaccines have proved to be effective at producing long-lasting protection against numerous pathogens. Here, we describe the application of bacterial protein glycan coupling technology (PGCT) to generate a novel recombinant glycoconjugate vaccine. We demonstrate the conjugation of the Francisella tularensis O-antigen to the Pseudomonas aeruginosa carrier protein exotoxin A using the Campylobacter jejuni PglB oligosaccharyltransferase. The resultant recombinant F. tularensis glycoconjugate vaccine is expressed in Escherichia coli where yields of 3 mg l(-1) of culture were routinely produced in a single-step purification process. Vaccination of BALB/c mice with the purified glycoconjugate boosted IgG levels and significantly increased the time to death upon subsequent challenge with F. tularensis subsp. holarctica. PGCT allows different polysaccharide and protein combinations to be produced recombinantly and could be easily applicable for the production of diverse glycoconjugate vaccines.
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366
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Origgi FC, Wu N, Pilo P. Francisella tularensis infection in a stone marten (Martes foina) without classic pathological lesions consistent with tularemia. J Vet Diagn Invest 2013; 25:519-21. [PMID: 23674461 DOI: 10.1177/1040638713489124] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The current report describes the isolation and typing of a strain of Francisella tularensis, the causative agent of tularemia, from the spleen of a stone marten (Martes foina) showing no classic lesions consistent with the disease. The identification of this bacterium, belonging to the World Health Organization risk 3 category and considered to have a low infectious dose, could be performed only because of an ongoing project screening F. tularensis in the environment sensu lato. The findings described herein should alert diagnostic laboratories of the possible presence of F. tularensis in clinical samples in countries where tularemia is endemic even in cases with no consistent anamnesis and from unsuspected animal species.
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Juruj C, Lelogeais V, Pierini R, Perret M, Py BF, Jamilloux Y, Broz P, Ader F, Faure M, Henry T. Caspase-1 activity affects AIM2 speck formation/stability through a negative feedback loop. Front Cell Infect Microbiol 2013; 3:14. [PMID: 23630667 PMCID: PMC3633939 DOI: 10.3389/fcimb.2013.00014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 04/05/2013] [Indexed: 11/13/2022] Open
Abstract
The inflammasome is an innate immune signaling platform leading to caspase-1 activation, maturation of pro-inflammatory cytokines and cell death. Recognition of DNA within the host cytosol induces the formation of a large complex composed of the AIM2 receptor, the ASC adaptor and the caspase-1 effector. Francisella tularensis, the agent of tularemia, replicates within the host cytosol. The macrophage cytosolic surveillance system detects Francisella through the AIM2 inflammasome. Upon Francisella novicida infection, we observed a faster kinetics of AIM2 speck formation in ASCKO and Casp1KO as compared to WT macrophages. This observation was validated by a biochemical approach thus demonstrating for the first time the existence of a negative feedback loop controlled by ASC/caspase-1 that regulates AIM2 complex formation/stability. This regulatory mechanism acted before pyroptosis and required caspase-1 catalytic activity. Our data suggest that sublytic caspase-1 activity could delay the formation of stable AIM2 speck, an inflammasome complex associated with cell death.
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Sampasa-Kanyinga H, Lévesque B, Anassour-Laouan-Sidi E, Côté S, Serhir B, Ward BJ, Libman MD, Drebot MA, Makowski K, Dimitrova K, Ndao M, Dewailly É. Zoonotic infections in communities of the James Bay Cree territory: An overview of seroprevalence. THE CANADIAN JOURNAL OF INFECTIOUS DISEASES & MEDICAL MICROBIOLOGY = JOURNAL CANADIEN DES MALADIES INFECTIEUSES ET DE LA MICROBIOLOGIE MEDICALE 2013; 24:79-84. [PMID: 24421806 PMCID: PMC3720002 DOI: 10.1155/2013/370321] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Cree communities of James Bay are at risk for contracting infectious diseases transmitted by wildlife. Data from serological testing for a range of zoonotic infections performed in the general population (six communities), or trappers and their spouses (one community), were abstracted from four population-based studies conducted in Cree territory (Quebec) between 2005 and 2009. Evidence of exposure to Trichinella species, Toxoplasma gondii, Toxocara canis, Echinococcus granulosus, Leptospira species, Coxiella burnetii and Francisella tularensis was verified in all communities, whereas antibodies against Sin Nombre virus and California serogroup viruses (Jamestown Canyon and snowshoe hare viruses) were evaluated in three and six communities, respectively. Seroprevalence varied widely among communities: snowshoe hare virus (1% to 42%), F tularensis (14% to 37%), Leptospira species (10% to 27%), Jamestown Canyon virus (9% to 24%), C burnetii (0% to 18%), T gondii (4% to 12%), T canis (0% to 10%), E granulosus (0% to 4%) and Trichinella species (0% to 1%). No subject had serological evidence of Sin Nombre virus exposure. These data suggest that large proportions of the Cree population have been exposed to at least one of the targeted zoonotic agents. The Cree population, particularly those most heavily exposed to fauna, as well as the medical staff living in these regions, should be aware of these diseases. Greater awareness would not only help to decrease exposures but would also increase the chance of appropriate diagnostic testing.
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Faith SA, Smith LP, Swatland AS, Reed DS. Growth conditions and environmental factors impact aerosolization but not virulence of Francisella tularensis infection in mice. Front Cell Infect Microbiol 2012; 2:126. [PMID: 23087911 PMCID: PMC3468843 DOI: 10.3389/fcimb.2012.00126] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 09/25/2012] [Indexed: 01/06/2023] Open
Abstract
In refining methodology to develop a mouse model for inhalation of Francisella tularensis, it was noted that both relative humidity and growth media impacted the aerosol concentration of the live vaccine strain (LVS) of F. tularensis. A relative humidity of less than 55% had a negative impact on the spray factor, the ratio between the concentration of LVS in the aerosol and the nebulizer. The spray factor was significantly higher for LVS grown in brain heart infusion (BHI) broth than LVS grown in Mueller–Hinton broth (MHb) or Chamberlain's chemically defined medium (CCDM). The variability between aerosol exposures was also considerably less with BHI. LVS grown in BHI survived desiccation far longer than MHb-grown or CCDM-grown LVS (~70% at 20 min for BHI compared to <50% for MHb and CCDM). Removal of the capsule by hypertonic treatment impacted the spray factor for CCDM-grown LVS or MHb-grown LVS but not BHI-grown LVS, suggesting the choice of culture media altered the adherence of the capsule to the cell membrane. The choice of growth media did not impact the LD50 of LVS but the LD99 of BHI-grown LVS was 1 log lower than that for MHb-grown LVS or CCDM-grown LVS. Splenomegaly was prominent in mice that succumbed to MHb- and BHI-grown LVS but not CCDM-grown LVS. Environmental factors and growth conditions should be evaluated when developing new animal models for aerosol infection, particularly for vegetative bacterial pathogens.
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Twine SM, Vinogradov E, Lindgren H, Sjostedt A, Conlan JW. Roles for wbtC, wbtI, and kdtA Genes in Lipopolysaccharide Biosynthesis, Protein Glycosylation, Virulence, and Immunogenicity in Francisella tularensis2 Strain SCHU S4. Pathogens 2012; 1:12-29. [PMID: 25152813 PMCID: PMC4141488 DOI: 10.3390/pathogens1010012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Using a strategy of gene deletion mutagenesis, we have examined the roles of genes putatively involved in lipopolysaccharide biosynthesis in the virulent facultative intracellular bacterial pathogen, Francisella tularensis subspecies tularensis, strain SCHU S4 in LPS biosynthesis, protein glycosylation, virulence and immunogenicity. One mutant, ΔwbtI, did not elaborate a long chain O-polysaccharide (OPS), was completely avirulent for mice, and failed to induce a protective immune response against challenge with wild type bacteria. Another mutant, ΔwbtC, produced a long chain OPS with altered chemical and electrophoretic characteristics. This mutant showed markedly reduced glycosylation of several known glycoproteins. Additionally this mutant was highly attenuated, and elicited a protective immune response against systemic, but not respiratory challenge with wild type SCHU S4. A third mutant, ΔkdtA, produced an unconjugated long chain OPS, lacking a detectable core structure, and which was not obviously expressed at the surface. It was avirulent and elicited partial protection against systemic challenge only.
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371
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Acetylcholine and an acetylcholinesterase inhibitor neostigmine can aggravate tularemia progress in BALB/c mice. Interdiscip Toxicol 2012; 5:21-4. [PMID: 22783145 PMCID: PMC3389505 DOI: 10.2478/v10102-012-0004-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Revised: 02/02/2012] [Accepted: 02/10/2012] [Indexed: 02/07/2023] Open
Abstract
The present experiment was aimed at assessing the application of neostigmine, an acetylcholinesterase (AChE) pseudo-irreversible inhibitor with poor penetration through the hematoencephalitic barrier, and the neurotransmitter acetylcholine (ACh). The experiment was done to evaluate their ability to modulate an infectious disease: tularemia. Mice infected with Franciselle tularensis and exposed to either ACh or neostigmine had a higher mortality and spleen bacterial burden when compared to infected mice exposed to saline solution only. The activated cholinergic anti-inflammatory pathway suppressed pathways necessary for tularemia resolution. Administration of AChE inhibitors to the individuals suffering from tularemia is contra-indicatory. Drugs based on AChE inhibition should be restricted when tularemia or disease with a similar pathogenesis is suspected.
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372
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Su J, Asare R, Yang J, Nair MKM, Mazurkiewicz JE, Abu-Kwaik Y, Zhang JR. The capBCA Locus is Required for Intracellular Growth of Francisella tularensis LVS. Front Microbiol 2011; 2:83. [PMID: 21747799 PMCID: PMC3128946 DOI: 10.3389/fmicb.2011.00083] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 04/07/2011] [Indexed: 12/18/2022] Open
Abstract
Francisella tularensis is the causative agent of tularemia and a category A bioterrorism agent. The molecular basis for the extreme virulence of F. tularensis remains unclear. Our recent study found that capBCA, three neighboring genes, are necessary for the infection of F. tularensis live vaccine strain (LVS) in a respiratory infection mouse model. We here show that the capBCA genes are necessary for in vivo growth of F. tularensis LVS in the lungs, spleens, and livers of BALB/c mice. Unmarked deletion of capBCA in type A strain Schu S4 resulted in significant attenuation in virulence although the level of the attenuation in Schu S4 was much less profound than in LVS. We further demonstrated that CapB protein is produced at a low level under the in vitro culture conditions, and capB alone is necessary for in vivo growth of F. tularensis LVS in the lungs of BALB/c mice. Finally, deletional mutations in capB alone or capBCA significantly impaired intracellular growth of F. tularensis LVS in cultured macrophages, thus suggesting that the capBCA genes are necessary for intracellular adaptation of F. tularensis. The requirement of this gene locus in intracellular adaption at least in part explains the significant attenuation of F. tularensis capBCA mutants in virulence.
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373
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Photonic biosensor assays to detect and distinguish subspecies of Francisella tularensis. SENSORS 2011; 11:3004-19. [PMID: 22163782 PMCID: PMC3231581 DOI: 10.3390/s110303004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2011] [Revised: 02/15/2011] [Accepted: 03/02/2011] [Indexed: 11/17/2022]
Abstract
The application of photonic biosensor assays to diagnose the category-A select agent Francisella tularensis was investigated. Both interferometric and long period fiber grating sensing structures were successfully demonstrated; both these sensors are capable of detecting the optical changes induced by either immunological binding or DNA hybridization. Detection was made possible by the attachment of DNA probes or immunoglobulins (IgG) directly to the fiber surface via layer-by-layer electrostatic self-assembly. An optical fiber biosensor was tested using a standard transmission mode long period fiber grating of length 15 mm and period 260 μm, and coated with the IgG fraction of antiserum to F. tularensis. The IgG was deposited onto the optical fiber surface in a nanostructured film, and the resulting refractive index change was measured using spectroscopic ellipsometry. The presence of F. tularensis was detected from the decrease of peak wavelength caused by binding of specific antigen. Detection and differentiation of F. tularensis subspecies tularensis (type A strain TI0902) and subspecies holarctica (type B strain LVS) was further accomplished using a single-mode multi-cavity fiber Fabry-Perot interferometric sensor. These sensors were prepared by depositing seven polymer bilayers onto the fiber tip followed by attaching one of two DNA probes: (a) a 101-bp probe from the yhhW gene unique to type-A strains, or (b) a 117-bp probe of the lpnA gene, common to both type-A and type-B strains. The yhhW probe was reactive with the type-A, but not the type-B strain. Probe lpnA was reactive with both type-A and type-B strains. Nanogram quantities of the target DNA could be detected, highlighting the sensitivity of this method for DNA detection without the use of PCR. The DNA probe reacted with 100% homologous target DNA, but did not react with sequences containing 2-bp mismatches, indicating the high specificity of the assay. These assays will fill an important void that exists for rapid, culture-free, and field-compatible diagnosis of F. tularensis.
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374
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Salomonsson EN, Forslund AL, Forsberg A. Type IV Pili in Francisella - A Virulence Trait in an Intracellular Pathogen. Front Microbiol 2011; 2:29. [PMID: 21687421 PMCID: PMC3109291 DOI: 10.3389/fmicb.2011.00029] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 02/04/2011] [Indexed: 11/13/2022] Open
Abstract
Francisella tularensis is a highly virulent intracellular human pathogen that is capable of rapid proliferation in the infected host. Mutants affected in intracellular survival and growth are highly attenuated which highlights the importance of the intracellular phase of the infection. Genomic analysis has revealed that Francisella encodes all genes required for expression of functional type IV pili (Tfp), and in this focused review we summarize recent findings regarding this system in the pathogenesis of tularemia. Tfp are dynamic adhesive structures that have been identified as major virulence determinants in several human pathogens, but it is not obvious what role these structures could have in an intracellular pathogen like Francisella. In the human pathogenic strains, genes required for secretion and assembly of Tfp and one pilin, PilA, have shown to be required for full virulence. Importantly, specific genetic differences have been identified between the different Francisella subspecies where in the most pathogenic type A variants all genes are intact while several Tfp genes are pseudogenes in the less pathogenic type B strains. This suggests that there has been a selection for expression of Tfp with different properties in the different subspecies. There is also a possibility that the genetic differences reflect adaptation to different environmental niches of the subspecies and plays a role in transmission of tularemia. This is also in line with recent findings where Tfp pilins are found to be glycosylated which could reflect a role for Tfp in the environment to promote survival and transmission. We are still far from understanding the role of Tfp in virulence and transmission of tularemia, but with the genomic information and genetic tools available we are in a good position to address these issues in the future.
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375
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Bosio CM. The subversion of the immune system by francisella tularensis. Front Microbiol 2011; 2:9. [PMID: 21687406 PMCID: PMC3109352 DOI: 10.3389/fmicb.2011.00009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 01/17/2011] [Indexed: 12/11/2022] Open
Abstract
Francisella tularensis is a highly virulent bacterial pathogen and the causative agent of tularemia. Perhaps the most impressive feature of this bacterium is its ability to cause lethal disease following inoculation of as few as 15 organisms. This remarkable virulence is, in part, attributed to the ability of this microorganism to evade, disrupt, and modulate host immune responses. The objective of this review is to discuss the mechanisms utilized by F. tularensis to evade and inhibit innate and adaptive immune responses. The capability of F. tularensis to interfere with developing immunity in the host was appreciated decades ago. Early studies in humans were the first to demonstrate the ability of F. tularensis to suppress innate immunity. This work noted that humans suffering from tularemia failed to respond to a secondary challenge of endotoxin isolated from unrelated bacteria. Further, anecdotal observations of individuals becoming repeatedly infected with virulent strains of F. tularensis suggests that this bacterium also interferes with the generation of adequate adaptive immunity. Recent advances utilizing the mouse model for in vivo studies and human cells for in vitro work have identified specific bacterial and host compounds that play a role in mediating ubiquitous suppression of the host immune response. Compilation of this work will undoubtedly aid in enhancing our understanding of the myriad of mechanisms utilized by virulent F. tularensis for successful infection, colonization, and pathogenesis in the mammalian host.
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