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Sample records for francisella tularensis strain

  1. Comparative genomic characterization of Francisella tularensis strains belonging to low and high virulence subspecies.

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    Mia D Champion

    2009-05-01

    Full Text Available Tularemia is a geographically widespread, severely debilitating, and occasionally lethal disease in humans. It is caused by infection by a gram-negative bacterium, Francisella tularensis. In order to better understand its potency as an etiological agent as well as its potential as a biological weapon, we have completed draft assemblies and report the first complete genomic characterization of five strains belonging to the following different Francisella subspecies (subsp.: the F. tularensis subsp. tularensis FSC033, F. tularensis subsp. holarctica FSC257 and FSC022, and F. tularensis subsp. novicida GA99-3548 and GA99-3549 strains. Here, we report the sequencing of these strains and comparative genomic analysis with recently available public Francisella sequences, including the rare F. tularensis subsp. mediasiatica FSC147 strain isolate from the Central Asian Region. We report evidence for the occurrence of large-scale rearrangement events in strains of the holarctica subspecies, supporting previous proposals that further phylogenetic subdivisions of the Type B clade are likely. We also find a significant enrichment of disrupted or absent ORFs proximal to predicted breakpoints in the FSC022 strain, including a genetic component of the Type I restriction-modification defense system. Many of the pseudogenes identified are also disrupted in the closely related rarely human pathogenic F. tularensis subsp. mediasiatica FSC147 strain, including modulator of drug activity B (mdaB (FTT0961, which encodes a known NADPH quinone reductase involved in oxidative stress resistance. We have also identified genes exhibiting sequence similarity to effectors of the Type III (T3SS and components of the Type IV secretion systems (T4SS. One of the genes, msrA2 (FTT1797c, is disrupted in F. tularensis subsp. mediasiatica and has recently been shown to mediate bacterial pathogen survival in host organisms. Our findings suggest that in addition to the duplication of

  2. Description of two new plasmids isolated from Francisella philomiragia strains and construction of shuttle vectors for the study of Francisella tularensis.

    Science.gov (United States)

    Le Pihive, E; Blaha, D; Chenavas, S; Thibault, F; Vidal, D; Valade, E

    2009-11-01

    Francisella tularensis is the causative agent of tularemia, a zoonotic disease often transmitted to humans by infected animals. The lack of useful specific genetic tools has long hampered the study of F. tularensis subspecies. We identified and characterized two new plasmids, pF242 and pF243, isolated from Francisella philomiragia strains ATCC 25016 and ATCC 25017, respectively. Sequence analysis revealed that pF242 and pF243 are closely related to pC194 and pFNL10 plasmids, respectively. Two generations of pF242- and pF243-based shuttle vectors, harboring several antibiotic resistance markers, were developed. We used the first generation to compare transformation efficiencies in two virulent F. tularensis subspecies. We found that electroporation was more efficient than cryotransformation: almost all vectors tested were successfully introduced by electroporation into Francisella strains with a high level of efficiency. The second generation of shuttle vectors, containing a multiple cloning site and/or gfp gene downstream of Francisella groES promotor, was used for GFP production in F. tularensis. The development of new shuttle vectors offers new perspectives in the genetic manipulation of F. tularensis, helping to elucidate the mechanisms underlying its virulence.

  3. Comparative Transcriptional Analyses of Francisella tularensis and Francisella novicida.

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    Siva T Sarva

    Full Text Available Francisella tularensis is composed of a number of subspecies with varied geographic distribution, host ranges, and virulence. In view of these marked differences, comparative functional genomics may elucidate some of the molecular mechanism(s behind these differences. In this study a shared probe microarray was designed that could be used to compare the transcriptomes of Francisella tularensis subsp. tularensis Schu S4 (Ftt, Francisella tularensis subsp. holarctica OR960246 (Fth, Francisella tularensis subsp. holarctica LVS (LVS, and Francisella novicida U112 (Fn. To gain insight into expression differences that may be related to the differences in virulence of these subspecies, transcriptomes were measured from each strain grown in vitro under identical conditions, utilizing a shared probe microarray. The human avirulent Fn strain exhibited high levels of transcription of genes involved in general metabolism, which are pseudogenes in the human virulent Ftt and Fth strains, consistent with the process of genome decay in the virulent strains. Genes encoding an efflux system (emrA2 cluster of genes, siderophore (fsl operon, acid phosphatase, LPS synthesis, polyamine synthesis, and citrulline ureidase were all highly expressed in Ftt when compared to Fn, suggesting that some of these may contribute to the relative high virulence of Ftt. Genes expressed at a higher level in Ftt when compared to the relatively less virulent Fth included genes encoding isochorismatases, cholylglycine hydrolase, polyamine synthesis, citrulline ureidase, Type IV pilus subunit, and the Francisella Pathogenicity Island protein PdpD. Fth and LVS had very few expression differences, consistent with the derivation of LVS from Fth. This study demonstrated that a shared probe microarray designed to detect transcripts in multiple species/subspecies of Francisella enabled comparative transcriptional analyses that may highlight critical differences that underlie the relative

  4. Genetic manipulation of Francisella tularensis

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    Xhavit eZogaj

    2011-01-01

    Full Text Available Francisella tularensis is a facultative intracellular pathogen that causes the disease tularemia. F. tularensis subsp. tularensis causes the most severe disease in humans and has been classified as a select A agent and potential bioweapon. There is currently no vaccine approved for human use, making genetic manipulation of this organism critical to unraveling the genetic basis of pathogenesis and developing countermeasures against tularemia. The development of genetic techniques applicable to F. tularensis have lagged behind those routinely used for other bacteria, primarily due to lack of research and the restricted nature of the biocontainment required for studying this pathogen. However, in recent years, genetic techniques, such as transposon mutagenesis and targeted gene disruption, have been developed, that have had a dramatic impact on our understanding of the genetic basis of F. tularensis virulence. In this review, we describe some of the methods developed for genetic manipulation of F. tularensis.

  5. Prior Inoculation with Type B Strains of Francisella tularensis Provides Partial Protection against Virulent Type A Strains in Cottontail Rabbits.

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    Vienna R Brown

    Full Text Available Francisella tularensis is a highly virulent bacterium that is capable of causing severe disease (tularemia in a wide range of species. This organism is characterized into two distinct subspecies: tularensis (type A and holarctica (type B which vary in several crucial ways, with some type A strains having been found to be considerably more virulent in humans and laboratory animals. Cottontail rabbits have been widely implicated as a reservoir species for this subspecies; however, experimental inoculation in our laboratory revealed type A organisms to be highly virulent, resulting in 100% mortality following challenge with 50-100 organisms. Inoculation of cottontail rabbits with the same number of organisms from type B strains of bacteria was found to be rarely lethal and to result in a robust humoral immune response. The objective of this study was to characterize the protection afforded by a prior challenge with type B strains against a later inoculation with a type A strain in North American cottontail rabbits (Sylvilagus spp. Previous infection with a type B strain of organism was found to lengthen survival time and in some cases prevent death following inoculation with a type A2 strain of F. tularensis. In contrast, inoculation of a type A1b strain was uniformly lethal in cottontail rabbits irrespective of a prior type B inoculation. These findings provide important insight about the role cottontail rabbits may play in environmental maintenance and transmission of this organism.

  6. Genome-wide DNA microarray analysis of Francisella tularensis strains demonstrates extensive genetic conservation within the species but identifies regions that are unique to the highly virulent F. tularensis subsp. tularensis

    NARCIS (Netherlands)

    Broekhuijsen, M.P.; Larsson, P.; Johansson, A.; Byström, M.; Eriksson, U.; Larsson, E.; Prior, R.G.; Sjöstedt, A.; Titball, R.W.; Forsman, M.

    2003-01-01

    Francisella tularensis is a potent pathogen and a possible bioterrorism agent. Little is known, however, to explain the molecular basis for its virulence and the distinct differences in virulence found between the four recognized subspecies, F. tularensis subsp. tularensis, F. tularensis subsp.

  7. Francisella tularensis - potential biological agent

    International Nuclear Information System (INIS)

    Taleski, V.

    2009-01-01

    Francisella tularensis is a small, nonmotile, aerobic, gram-negative coccobacillus capable of surviving for weeks at low temperatures in water, moist soil, hay, straw, or decaying animal carcasses. F. tularensis is the causative of the zoonotic disease tularemia. This bacterium was first identified in ground squirrels in Tulare County, California (1912). The human disease was recognized and described by Edward Francis (1922) as tularemia, and the agent was renamed Francisella tularensis in his honor. F. tularensis is one of the most infectious bacterial pathogens known, as few as 10-50 organisms can cause disease. Humans can become incidentally infected through diverse environmental exposures: bites by infected arthropods; handling infectious animal tissues or fluids; direct contact with or ingestion of contaminated food, water, or soil and inhalation of infective aerosols. Humans can develop severe and sometimes fatal illness, but do not transmit the disease to others. F. tularensis have few subspecies: 1) F. tularensis subsp. tularensis (type A), highly virulent, found only in North America. The bacterium is transmitted among animals and from animals to humans by ticks, occasionally deerfly, or by aerosols; 2) F. tularensis subsp. holarctica (type B), moderately virulent, occurs in Euroasia and North America, mainly associated with streams, lakes, ponds, rivers and semi-aquatic animals such as muskrats and beavers (water-borne disease). Type B tularemia has been observed during war times (during Second World War 100 000 cases occurred each year, in Kosovo in 2000 and 2003 over 300 cases each year); 3) F. tularensis subsp. mediasiatica, rarely reported, isolated only in Kazahstan and Turkmenistan; 4) F. tularensis subsp. novicida is of low virulence, isolated in USA, Canada, Spain and Australia; 5) F. tularensis subsp. philomiragia, is of low virulence, associated with salt water (Atlantic, Mediterranean). Tularemia is very rear in Macedonia, but in 1996 an

  8. Immunoproteomics analysis of the murine antibody response to vaccination with an improved Francisella tularensis live vaccine strain (LVS.

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    Susan M Twine

    2010-04-01

    Full Text Available Francisella tularensis subspecies tularensis is the causative agent of a spectrum of diseases collectively known as tularemia. An attenuated live vaccine strain (LVS has been shown to be efficacious in humans, but safety concerns have prevented its licensure by the FDA. Recently, F. tularensis LVS has been produced under Current Good Manufacturing Practice (CGMP guidelines. Little is known about the immunogenicity of this new vaccine preparation in comparison with extensive studies conducted with laboratory passaged strains of LVS. Thus, the aim of the current work was to evaluate the repertoire of antibodies produced in mouse strains vaccinated with the new LVS vaccine preparation.In the current study, we used an immunoproteomics approach to examine the repertoire of antibodies induced following successful immunization of BALB/c versus unsuccessful vaccination of C57BL/6 mice with the new preparation of F. tularensis LVS. Successful vaccination of BALB/c mice elicited antibodies to nine identified proteins that were not recognized by antisera from vaccinated but unprotected C57BL/6 mice. In addition, the CGMP formulation of LVS stimulated a greater repertoire of antibodies following vaccination compared to vaccination with laboratory passaged ATCC LVS strain. A total of 15 immunoreactive proteins were identified in both studies, however, 16 immunoreactive proteins were uniquely reactive with sera from the new formulation of LVS.This is the first report characterising the antibody based immune response of the new formulation of LVS in the widely used murine model of tularemia. Using two mouse strains, we show that successfully vaccinated mice can be distinguished from unsuccessfully vaccinated mice based upon the repertoire of antibodies generated. This opens the door towards downselection of antigens for incorporation into tularemia subunit vaccines. In addition, this work also highlights differences in the humoral immune response to

  9. Francisella tularensis type A Strains Cause the Rapid Encystment of Acanthamoeba castellanii and Survive in Amoebal Cysts for Three Weeks post Infection

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    El-Etr, S H; Margolis, J; Monack, D; Robison, R; Cohen, M; Moore, E; Rasley, A

    2009-07-28

    Francisella tularensis, the causative agent of the zoonotic disease tularemia, has recently gained increased attention due to the emergence of tularemia in geographical areas where the disease has been previously unknown, and the organism's potential as a bioterrorism agent. Although F. tularensis has an extremely broad host range, the bacterial reservoir in nature has not been conclusively identified. In this study, the ability of virulent F. tularensis strains to survive and replicate in the amoeba Acanthamoeba castellanii was explored. We observe that A. castellanii trophozoites rapidly encyst in response to F. tularensis infection and that this rapid encystment phenotype (REP) is caused by factor(s) secreted by amoebae and/or F. tularensis into the co-culture media. Further, our results indicate that in contrast to LVS, virulent strains of F. tularensis can survive in A. castellanii cysts for at least 3 weeks post infection and that induction of rapid amoeba encystment is essential for survival. In addition, our data indicate that pathogenic F. tularensis strains block lysosomal fusion in A. castellanii. Taken together, these data suggest that the interactions between F. tularensis strains and amoeba may play a role in the environmental persistence of F. tularensis.

  10. Francisella tularensis Confronts the Complement System

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    Susan R. Brock

    2017-12-01

    Full Text Available Francisella tularensis has developed a number of effective evasion strategies to counteract host immune defenses, not the least of which is its ability to interact with the complement system to its own advantage. Following exposure of the bacterium to fresh human serum, complement is activated and C3b and iC3b can be found covalently attached to the bacterial surface. However, the lipopolysaccharide and capsule of the F. tularensis cell wall prevent complement-mediated lysis and endow the bacterium with serum resistance. Opsonization of F. tularensis with C3 greatly increases its uptake by human neutrophils, dendritic cells and macrophages. Uptake occurs by an unusual looping morphology in human macrophages. Complement receptor 3 is thought to play an important role in opsonophagocytosis by human macrophages, and signaling through this receptor can antagonize Toll-like receptor 2-initiated macrophage activation. Complement C3 also determines the survival of infected human macrophages and perhaps other cell types. C3-opsonization of F. tularensis subsp. tularensis strain SCHU S4 results in greatly increased death of infected human macrophages, which requires more than complement receptor engagement and is independent of the intracellular replication by the pathogen. Given its entry into the cytosol of host cells, F. tularensis has the potential for a number of other complement-mediated interactions. Studies on the uptake C3-opsonized adenovirus have suggested the existence of a C3 sensing system that initiates cellular responses to cytosolic C3b present on invading microbes. Here we propose that C3 peptides enter the cytosol of human macrophages following phagosome escape of F. tularensis and are recognized as intruding molecular patterns that signal host cell death. With the discovery of new roles for intracellular C3, a better understanding of tularemia pathogenesis is likely to emerge.

  11. Rapid focused sequencing: a multiplexed assay for simultaneous detection and strain typing of Bacillus anthracis, Francisella tularensis, and Yersinia pestis.

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    Rosemary S Turingan

    Full Text Available BACKGROUND: The intentional release of Bacillus anthracis in the United States in 2001 has heightened concern about the use of pathogenic microorganisms in bioterrorism attacks. Many of the deadliest bacteria, including the Class A Select Agents Bacillus anthracis, Francisella tularensis, and Yersinia pestis, are highly infectious via the pulmonary route when released in aerosolized form. Hence, rapid, sensitive, and reliable methods for detection of these biothreats and characterization of their potential impact on the exposed population are of critical importance to initiate and support rapid military, public health, and clinical responses. METHODOLOGY/PRINCIPAL FINDINGS: We have developed microfluidic multiplexed PCR and sequencing assays based on the simultaneous interrogation of three pathogens per assay and ten loci per pathogen. Microfluidic separation of amplified fluorescently labeled fragments generated characteristic electrophoretic signatures for identification of each agent. The three sets of primers allowed significant strain typing and discrimination from non-pathogenic closely-related species and environmental background strains based on amplicon sizes alone. Furthermore, sequencing of the 10 amplicons per pathogen, termed "Rapid Focused Sequencing," allowed an even greater degree of strain discrimination and, in some cases, can be used to determine virulence. Both amplification and sequencing assays were performed in microfluidic biochips developed for fast thermal cycling and requiring 7 µL per reaction. The 30-plex sequencing assay resulted in genotypic resolution of 84 representative strains belonging to each of the three biothreat species. CONCLUSIONS/SIGNIFICANCE: The microfluidic multiplexed assays allowed identification and strain differentiation of the biothreat agents Bacillus anthracis, Francisella tularensis, and Yersinia pestis and clear discrimination from closely-related species and several environmental

  12. Mechanisms of heme utilization by Francisella tularensis.

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    Helena Lindgren

    Full Text Available Francisella tularensis is a highly virulent facultative intracellular pathogen causing the severe disease tularemia in mammals. As for other bacteria, iron is essential for its growth but very few mechanisms for iron acquisition have been identified. Here, we analyzed if and how F. tularensis can utilize heme, a major source of iron in vivo. This is by no means obvious since the bacterium lacks components of traditional heme-uptake systems. We show that SCHU S4, the prototypic strain of subspecies tularensis, grew in vitro with heme as the sole iron source. By screening a SCHU S4 transposon insertion library, 16 genes were identified as important to efficiently utilize heme, two of which were required to avoid heme toxicity. None of the identified genes appeared to encode components of a potential heme-uptake apparatus. Analysis of SCHU S4 deletion mutants revealed that each of the components FeoB, the siderophore system, and FupA, contributed to the heme-dependent growth. In the case of the former two systems, iron acquisition was impaired, whereas the absence of FupA did not affect iron uptake but led to abnormally high binding of iron to macromolecules. Overall, the present study demonstrates that heme supports growth of F. tularensis and that the requirements for the utilization are highly complex and to some extent novel.

  13. Virulence differences among Francisella tularensis subsp. tularensis clades in mice.

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    Claudia R Molins

    Full Text Available Francisella tularensis subspecies tularensis (type A and holarctica (type B are of clinical importance in causing tularemia. Molecular typing methods have further separated type A strains into three genetically distinct clades, A1a, A1b and A2. Epidemiological analyses of human infections in the United States suggest that A1b infections are associated with a significantly higher mortality rate as compared to infections caused by A1a, A2 and type B. To determine if genetic differences as defined by molecular typing directly correlate with differences in virulence, A1a, A1b, A2 and type B strains were compared in C57BL/6 mice. Here we demonstrate significant differences between survival curves for infections caused by A1b versus A1a, A2 and type B, with A1b infected mice dying earlier than mice infected with A1a, A2 or type B; these results were conserved among multiple strains. Differences were also detected among type A clades as well as between type A clades and type B with respect to bacterial burdens, and gross anatomy in infected mice. Our results indicate that clades defined within F. tularensis subsp. tularensis by molecular typing methods correlate with virulence differences, with A1b strains more virulent than A1a, A2 and type B strains. These findings indicate type A strains are not equivalent with respect to virulence and have important implications for public health as well as basic research programs.

  14. A Francisella tularensis live vaccine strain that improves stimulation of antigen-presenting cells does not enhance vaccine efficacy.

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    Deanna M Schmitt

    Full Text Available Vaccination is a proven strategy to mitigate morbidity and mortality of infectious diseases. The methodology of identifying and testing new vaccine candidates could be improved with rational design and in vitro testing prior to animal experimentation. The tularemia vaccine, Francisella tularensis live vaccine strain (LVS, does not elicit complete protection against lethal challenge with a virulent type A Francisella strain. One factor that may contribute to this poor performance is limited stimulation of antigen-presenting cells. In this study, we examined whether the interaction of genetically modified LVS strains with human antigen-presenting cells correlated with effectiveness as tularemia vaccine candidates. Human dendritic cells infected with wild-type LVS secrete low levels of proinflammatory cytokines, fail to upregulate costimulatory molecules, and activate human T cells poorly in vitro. One LVS mutant, strain 13B47, stimulated higher levels of proinflammatory cytokines from dendritic cells and macrophages and increased costimulatory molecule expression on dendritic cells compared to wild type. Additionally, 13B47-infected dendritic cells activated T cells more efficiently than LVS-infected cells. A deletion allele of the same gene in LVS displayed similar in vitro characteristics, but vaccination with this strain did not improve survival after challenge with a virulent Francisella strain. In vivo, this mutant was attenuated for growth and did not stimulate T cell responses in the lung comparable to wild type. Therefore, stimulation of antigen-presenting cells in vitro was improved by genetic modification of LVS, but did not correlate with efficacy against challenge in vivo within this model system.

  15. The Natural History of Pneumonic Tularemia in Female Fischer 344 Rats after Inhalational Exposure to Aerosolized Francisella tularensis Subspecies tularensis Strain SCHU S4.

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    Hutt, Julie A; Lovchik, Julie A; Dekonenko, Alexander; Hahn, Andrew C; Wu, Terry H

    2017-02-01

    The inbred Fischer 344 rat is being evaluated for testing novel vaccines and therapeutics against pneumonic tularemia. Although primary pneumonic tularemia in humans typically occurs by inhalation of aerosolized bacteria, the rat model has relied on intratracheal inoculation of organisms because of safety and equipment issues. We now report the natural history of pneumonic tularemia in female Fischer 344 rats after nose-only inhalational exposure to lethal doses of aerosolized Francisella tularensis subspecies tularensis, strain SCHU S4. Our results are consistent with initial uptake of aerosolized SCHU S4 from the nasal cavity, lungs, and possibly the gastrointestinal tract. Bacteremia with hematogenous dissemination was first detected 2 days after exposure. Shortly thereafter, the infected rats exhibited fever, tachypnea, and hypertension that persisted for 24 to 36 hours and then rapidly decreased as animals succumbed to infection between days 5 and 8 after exposure. Tachycardia was observed briefly, but only after the core body temperature and blood pressure began to decrease as the animals were near death. Initial neutrophilic and histiocytic inflammation in affected tissues became progressively more fibrinous and necrotizing over time. At death, as many as 10 10 colony-forming units were found in the lungs, spleen, and liver. Death was attributed to sepsis and disseminated intravascular coagulation. Overall, the pathogenesis of pneumonic tularemia in the female F344 rat model appears to replicate the disease in humans. Copyright © 2017 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  16. Geographic Differentiation of Francisella Tularensis using Molecular Methods

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    2006-05-01

    Department of Animal Health, Facultad de Veterinaria , Leon, Spain, 4 for contribution of his entire F. tularensis strain DNA collection. I thank Dr...Medicina Veterinaria , 1998. 15: p. 418-423. 32. de la Puente-Redondo, V.A., et al., Comparison of different PCR approaches for typing of Francisella

  17. Virulent Type A Francisella tularensis actively suppresses cytokine responses in human monocytes

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    Gillette, Devyn D.; Curry, Heather M.; Cremer, Thomas; Ravneberg, David; Fatehchand, Kavin; Shah, Prexy A.; Wewers, Mark D.; Schlesinger, Larry S.; Butchar, Jonathan P.; Tridandapani, Susheela; Gavrilin, Mikhail A.

    2014-01-01

    Background: Human monocyte inflammatory responses differ between virulent and attenuated Francisella infection. Results: A mixed infection model showed that the virulent F. tularensis Schu S4 can attenuate inflammatory cytokine responses to the less virulent F. novicida in human monocytes. Conclusion: F. tularensis dampens inflammatory response by an active process. Significance: This suppression may contribute to enhanced pathogenicity of F. tularensis. Francisella tularensis is a Gram-negative facultative bacterium that can cause the disease tularemia, even upon exposure to low numbers of bacteria. One critical characteristic of Francisella is its ability to dampen or subvert the host immune response. Previous work has shown that monocytes infected with highly virulent F. tularensis subsp. tularensis strain Schu S4 responded with a general pattern of quantitatively reduced pro-inflammatory signaling pathway genes and cytokine production in comparison to those infected with the less virulent related F. novicida. However, it has been unclear whether the virulent Schu S4 was merely evading or actively suppressing monocyte responses. By using mixed infection assays with F. tularensis and F. novicida, we show that F. tularensis actively suppresses monocyte pro-inflammatory responses. Additional experiments show that this suppression occurs in a dose-dependent manner and is dependent upon the viability of F. tularensis. Importantly, F. tularensis was able to suppress pro-inflammatory responses to earlier infections with F. novicida. These results lend support that F. tularensis actively dampens human monocyte responses and this likely contributes to its enhanced pathogenicity. PMID:24783062

  18. Draft genome sequence of Francisella tularensis subsp. holarctica BD11-00177

    NARCIS (Netherlands)

    Coolen, J.P.M.; Sjödin, A.; Maraha, B.; Hajer, G.F.; Forsman, M.; Verspui, E.; Frenay, H.M.E.; Notermans, D.W.; Vries, M.C. de; Reubsaet, F.A.G.; Paauw, A.; Roeselers, G.

    2013-01-01

    Francisella tularensis is a facultative intracellular bacterium in the class Gammaproteobacteria. This strain is of interest because it is the etiologic agent of tularemia and a highly virulent category A biothreat agent. Here we describe the draft genome sequence and annotation of Francisella

  19. Biohazard Analysis of Select Biodefense Vaccine Candidates - Venezuelan Equine Encephalitis Virus Strain 3526 and Francisella Tularensis LVS

    International Nuclear Information System (INIS)

    Rao, V.

    2007-01-01

    Biohazard assessment of biodefense vaccine candidates forms the basis for a facility- and activity-specific risk assessment performed to determine the biosafety levels and general safety standards required for biological product development. As a part of our support to the US biodefense vaccine development program, we perform a systematic biohazard assessment of potential vaccine candidates with the primary objective to, (a) Identify and characterize hazard elements associated with the wild type and vaccine strains, (b) Provide biohazard information on the etiologic agent (vaccine candidate) to assess Phase 1 clinical trial facility sites, (c) Provide a baseline to conduct an agent and facility-specific risk assessment at clinical trial facilities interested in performing phase 1 clinical trial, (d) Provide comparative hazard profiles of the vaccine candidates wit MSDS for wild-type to identify and establish appropriate protective biosafety levels, and (e) Support determination of a hazard level to select personal protective equipment as required under the OSHA guidelines. This paper will describe the biohazard analysis of two vaccine candidates, Venezuelan Equine Encephalitis Virus Strain 3526 and Francisella tularensis LVS, a viral and bacterial agent, respectively. As part of the biohazard assessment we preformed a thorough review of published literature on medical pathology, epidemiology, pre-clinical investigational studies, and environmental data on the etiologic agent subtypes and the vaccine candidates. Using standard analytical procedures, the data were then analyzed relative to two intrinsic hazard parameters-health hazard and environmental hazard. Using a weight-of-evidence (WOE) approach, the potential hazards of etiologic agent wild subtypes and vaccine candidates were ranked under three main categories: Public Health Hazard, Environmental Hazard, and Overall Hazard. A WOE scoring system allows for both a determination of the intrinsic hazard of each

  20. Biohazard Analysis of Select Biodefense Vaccine Candidates - Venezuelan Equine Encephalitis Virus Strain 3526 and Francisella Tularensis LVS

    Energy Technology Data Exchange (ETDEWEB)

    Rao, V [National Security Programs, Computer Science Corporation, Alexandria (United States)

    2007-07-01

    Biohazard assessment of biodefense vaccine candidates forms the basis for a facility- and activity-specific risk assessment performed to determine the biosafety levels and general safety standards required for biological product development. As a part of our support to the US biodefense vaccine development program, we perform a systematic biohazard assessment of potential vaccine candidates with the primary objective to, (a) Identify and characterize hazard elements associated with the wild type and vaccine strains, (b) Provide biohazard information on the etiologic agent (vaccine candidate) to assess Phase 1 clinical trial facility sites, (c) Provide a baseline to conduct an agent and facility-specific risk assessment at clinical trial facilities interested in performing phase 1 clinical trial, (d) Provide comparative hazard profiles of the vaccine candidates wit MSDS for wild-type to identify and establish appropriate protective biosafety levels, and (e) Support determination of a hazard level to select personal protective equipment as required under the OSHA guidelines. This paper will describe the biohazard analysis of two vaccine candidates, Venezuelan Equine Encephalitis Virus Strain 3526 and Francisella tularensis LVS, a viral and bacterial agent, respectively. As part of the biohazard assessment we preformed a thorough review of published literature on medical pathology, epidemiology, pre-clinical investigational studies, and environmental data on the etiologic agent subtypes and the vaccine candidates. Using standard analytical procedures, the data were then analyzed relative to two intrinsic hazard parameters-health hazard and environmental hazard. Using a weight-of-evidence (WOE) approach, the potential hazards of etiologic agent wild subtypes and vaccine candidates were ranked under three main categories: Public Health Hazard, Environmental Hazard, and Overall Hazard. A WOE scoring system allows for both a determination of the intrinsic hazard of each

  1. A 52 Kilodalton Protein Vaccine Candidate for Francisella tularensis

    Science.gov (United States)

    2004-12-01

    du vaccin vivant F. tularensis (LVS). Soixante pourcent (60%) des souris vaccindes ont survdcu la dose ltale multiple alors que toutes les souris non...le lysat des cellules de cultures vivantes du vaccin vivant F. tularensis. Plusieurs composants de Francisella tularensis ont dt6 identifids par cet...antiserum. Le s6rum de souris provenant de souris vaccin6es avec F. tularensis non- vivant n’a pas identifid ces composants. A partir de ces prot6ines

  2. Low Dose Vaccination with Attenuated Francisella tularensis Strain SchuS4 Mutants Protects against Tularemia Independent of the Route of Vaccination

    Science.gov (United States)

    Rockx-Brouwer, Dedeke; Chong, Audrey; Wehrly, Tara D.; Child, Robert; Crane, Deborah D.

    2012-01-01

    Tularemia, caused by the Gram-negative bacterium Francisella tularensis, is a severe, sometimes fatal disease. Interest in tularemia has increased over the last decade due to its history as a biological weapon. In particular, development of novel vaccines directed at protecting against pneumonic tularemia has been an important goal. Previous work has demonstrated that, when delivered at very high inoculums, administration of live, highly attenuated strains of virulent F. tularensis can protect against tularemia. However, lower vaccinating inoculums did not offer similar immunity. One concern of using live vaccines is that the host may develop mild tularemia in response to infection and use of high inoculums may contribute to this issue. Thus, generation of a live vaccine that can efficiently protect against tularemia when delivered in low numbers, e.g. tularemia when delivered at concentrations of approximately 50 or fewer bacteria. Attenuated strains for use as vaccines were selected by their inability to efficiently replicate in macrophages in vitro and impaired replication and dissemination in vivo. Although all strains were defective for replication in vitro within macrophages, protective efficacy of each attenuated mutant was correlated with their ability to modestly replicate and disseminate in the host. Finally, we demonstrate the parenteral vaccination with these strains offered superior protection against pneumonic tularemia than intranasal vaccination. Together our data provides proof of principle that low dose attenuated vaccines may be a viable goal in development of novel vaccines directed against tularemia. PMID:22662210

  3. Low dose vaccination with attenuated Francisella tularensis strain SchuS4 mutants protects against tularemia independent of the route of vaccination.

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    Dedeke Rockx-Brouwer

    Full Text Available Tularemia, caused by the gram-negative bacterium Francisella tularensis, is a severe, sometimes fatal disease. Interest in tularemia has increased over the last decade due to its history as a biological weapon. In particular, development of novel vaccines directed at protecting against pneumonic tularemia has been an important goal. Previous work has demonstrated that, when delivered at very high inoculums, administration of live, highly attenuated strains of virulent F. tularensis can protect against tularemia. However, lower vaccinating inoculums did not offer similar immunity. One concern of using live vaccines is that the host may develop mild tularemia in response to infection and use of high inoculums may contribute to this issue. Thus, generation of a live vaccine that can efficiently protect against tularemia when delivered in low numbers, e.g. <100 organisms, may address this concern. Herein we describe the ability of three defined, attenuated mutants of F. tularensis SchuS4, deleted for FTT0369c, FTT1676, or FTT0369c and FTT1676, respectively, to engender protective immunity against tularemia when delivered at concentrations of approximately 50 or fewer bacteria. Attenuated strains for use as vaccines were selected by their inability to efficiently replicate in macrophages in vitro and impaired replication and dissemination in vivo. Although all strains were defective for replication in vitro within macrophages, protective efficacy of each attenuated mutant was correlated with their ability to modestly replicate and disseminate in the host. Finally, we demonstrate the parenteral vaccination with these strains offered superior protection against pneumonic tularemia than intranasal vaccination. Together our data provides proof of principle that low dose attenuated vaccines may be a viable goal in development of novel vaccines directed against tularemia.

  4. The Francisella tularensis proteome and its recognition by antibodies

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    Sara L.N. Kilmury

    2011-01-01

    Full Text Available Francisella tularensis is the causative agent of a spectrum of diseases collectively known as tularemia. The extreme virulence of the pathogen in humans, combined with the low infectious dose and the ease of dissemination by aerosol have led to concerns about its abuse as a bioweapon. Until recently, nothing was known about the virulence mechanisms and even now, there is still a relatively poor understanding of pathogen virulence. Completion of increasing numbers of Francisella genome sequences, combined with comparative genomics and proteomics studies, are contributing to the knowledge in this area. Tularemia may be treated with antibiotics, but there is currently no licensed vaccine. An attenuated strain, the Live Vaccine Strain (LVS has been used to vaccinate military and at risk laboratory personnel, but safety concerns mean that it is unlikely to be licensed by the FDA for general use. Little is known about the protective immunity induced by vaccination with LVS, in humans or animals models. Immunoproteomics studies with sera from infected humans or vaccinated mouse strains, are being used in gel based or proteome microarray approaches to give insight into the humoral immune response. In addition, these data have the potential to be exploited in the identification of new diagnostic or protective antigens, the design of next generation live vaccine strains, and the development of subunit vaccines. Herein, we briefly review the current knowledge from Francisella comparative proteomics studies and then focus upon the findings from immunoproteomics approaches.

  5. Francisella tularensis subsp. novicida isolated from a human in Arizona

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    Birdsell Dawn N

    2009-11-01

    Full Text Available Abstract Background Francisella tularensis is the etiologic agent of tularemia and is classified as a select agent by the Centers for Disease Control and Prevention. Currently four known subspecies of F. tularensis that differ in virulence and geographical distribution are recognized:tularensis (type A, holarctica (type B, mediasiatica, and novicida. Because of the Select Agent status and differences in virulence and geographical location, the molecular analysis of any clinical case of tularemia is of particular interest. We analyzed an unusual Francisella clinical isolate from a human infection in Arizona using multiple DNA-based approaches. Findings We report that the isolate is F. tularensis subsp. novicida, a subspecies that is rarely isolated. Conclusion The rarity of this novicida subspecies in clinical settings makes each case study important for our understanding of its role in disease and its genetic relationship with other F. tularensis subspecies.

  6. Cell-mediated and humoral immune responses induced by scarification vaccination of human volunteers with a new lot of the live vaccine strain of Francisella tularensis.

    Science.gov (United States)

    Waag, D M; Galloway, A; Sandstrom, G; Bolt, C R; England, M J; Nelson, G O; Williams, J C

    1992-01-01

    Tularemia is a disease caused by the facultative intracellular bacterium Francisella tularensis. We evaluated a new lot of live F. tularensis vaccine for its immunogenicity in human volunteers. Scarification vaccination induced humoral and cell-mediated immune responses. Indications of a positive immune response after vaccination included an increase in specific antibody levels, which were measured by enzyme-linked immunosorbent and immunoblot assays, and the ability of peripheral blood lymphocytes to respond to whole F. tularensis bacteria as recall antigens. Vaccination caused a significant rise (P less than 0.05) in immunoglobulin A (IgA), IgG, and IgM titers. Lymphocyte stimulation indices were significantly increased (P less than 0.01) in vaccinees 14 days after vaccination. These data verify that this new lot of live F. tularensis vaccine is immunogenic. Images PMID:1400988

  7. Virulent Type A Francisella tularensis actively suppresses cytokine responses in human monocytes

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    Devyn D Gilette

    2014-04-01

    Full Text Available Francisella tularensis is a Gram-negative facultative bacterium that can cause the disease tularemia, even upon exposure to low numbers of bacteria. One critical characteristic of Francisella is its ability to dampen or subvert the host immune response. Previous work has shown that monocytes infected with highly virulent F. tularensis subsp. tularensis strain Schu S4 responded with a general pattern of quantitatively reduced pro-inflammatory signaling pathway genes and cytokine production in comparison to those infected with the less virulent related F. novicida. However, it has been unclear whether the virulent Schu S4 was merely evading or actively suppressing monocyte responses. By using mixed infection assays with F. tularensis and F. novicida, we show that F. tularensis actively suppresses monocyte pro-inflammatory responses. Additional experiments show that this suppression occurs in a dose-dependent manner and is dependent upon the viability of F. tularensis. Importantly, F. tularensis was able to suppress pro-inflammatory responses to earlier infections with F. novicida. These results lend support that F. tularensis actively dampens human monocyte responses and this likely contributes to its enhanced pathogenicity.

  8. Host-pathogen interactions between Francisella tularensis and Drosophila melanogaster

    OpenAIRE

    Vonkavaara, Malin

    2012-01-01

    Francisella tularensis is a highly virulent Gram-negative bacterium causing the zoonotic disease tularemia. Arthropod-borne transmission plays an important role in transferring the disease to humans. F. tularensis induces very low amounts of pro-inflammatory cytokines during infection, due to inhibition of immune signaling pathways and an unusual structure of its lipopolysaccharide (LPS). To date, there is no vaccine available that is approved for public use, although an attenuated live vacci...

  9. Live Vaccine Strain Francisella tularensis is Detectable at the Inoculation Site but Not in Blood after Vaccination Against Tularemia

    National Research Council Canada - National Science Library

    Hepburn, Matthew J; Purcell, Bret K; Lawler, James V; Coyne, Susan R; Petitt, Patricia L; Sellers, Karen D; Norwood, David A; Ulrich, Melanie P

    2006-01-01

    ...) for the detection of F. tularensis in human clinical samples. Methods. Blood and skin swab samples were prospectively collected from volunteers who received the LVS tularemia vaccine at baseline (negative controls...

  10. Francisella tularensis endocarditis: two case reports and a literature review.

    Science.gov (United States)

    Gaci, Rostane; Alauzet, Corentine; Selton-Suty, Christine; Lozniewski, Alain; Pulcini, Céline; May, Thierry; Goehringer, François

    2017-02-01

    We report the first two cases of infective endocarditis caused by Francisella tularensis in Europe (two cases have previously been reported outside Europe). We suggest clinicians should consider tularemia as a possible diagnosis in endemic regions in cases of culture-negative endocarditis.

  11. The Role and Mechanism of Erythrocyte Invasion by Francisella tularensis

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    Deanna M. Schmitt

    2017-05-01

    Full Text Available Francisella tularensis is an extremely virulent bacterium that can be transmitted naturally by blood sucking arthropods. During mammalian infection, F. tularensis infects numerous types of host cells, including erythrocytes. As erythrocytes do not undergo phagocytosis or endocytosis, it remains unknown how F. tularensis invades these cells. Furthermore, the consequence of inhabiting the intracellular space of red blood cells (RBCs has not been determined. Here, we provide evidence indicating that residing within an erythrocyte enhances the ability of F. tularensis to colonize ticks following a blood meal. Erythrocyte residence protected F. tularensis from a low pH environment similar to that of gut cells of a feeding tick. Mechanistic studies revealed that the F. tularensis type VI secretion system (T6SS was required for erythrocyte invasion as mutation of mglA (a transcriptional regulator of T6SS genes, dotU, or iglC (two genes encoding T6SS machinery severely diminished bacterial entry into RBCs. Invasion was also inhibited upon treatment of erythrocytes with venom from the Blue-bellied black snake (Pseudechis guttatus, which aggregates spectrin in the cytoskeleton, but not inhibitors of actin polymerization and depolymerization. These data suggest that erythrocyte invasion by F. tularensis is dependent on spectrin utilization which is likely mediated by effectors delivered through the T6SS. Our results begin to elucidate the mechanism of a unique biological process facilitated by F. tularensis to invade erythrocytes, allowing for enhanced colonization of ticks.

  12. Interactions of Francisella tularensis with Alveolar Type II Epithelial Cells and the Murine Respiratory Epithelium.

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    Matthew Faron

    Full Text Available Francisella tularensis is classified as a Tier 1 select agent by the CDC due to its low infectious dose and the possibility that the organism can be used as a bioweapon. The low dose of infection suggests that Francisella is unusually efficient at evading host defenses. Although ~50 cfu are necessary to cause human respiratory infection, the early interactions of virulent Francisella with the lung environment are not well understood. To provide additional insights into these interactions during early Francisella infection of mice, we performed TEM analysis on mouse lungs infected with F. tularensis strains Schu S4, LVS and the O-antigen mutant Schu S4 waaY::TrgTn. For all three strains, the majority of the bacteria that we could detect were observed within alveolar type II epithelial cells at 16 hours post infection. Although there were no detectable differences in the amount of bacteria within an infected cell between the three strains, there was a significant increase in the amount of cellular debris observed in the air spaces of the lungs in the Schu S4 waaY::TrgTn mutant compared to either the Schu S4 or LVS strain. We also studied the interactions of Francisella strains with human AT-II cells in vitro by characterizing the ability of these three strains to invade and replicate within these cells. Gentamicin assay and confocal microscopy both confirmed that F. tularensis Schu S4 replicated robustly within these cells while F. tularensis LVS displayed significantly lower levels of growth over 24 hours, although the strain was able to enter these cells at about the same level as Schu S4 (1 organism per cell, as determined by confocal imaging. The Schu S4 waaY::TrgTn mutant that we have previously described as attenuated for growth in macrophages and mouse virulence displayed interesting properties as well. This mutant induced significant airway inflammation (cell debris and had an attenuated growth phenotype in the human AT-II cells. These

  13. Russian isolates enlarge the known geographic diversity of Francisella tularensis subsp. mediasiatica.

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    Vitalii Timofeev

    Full Text Available Francisella tularensis, a small Gram-negative bacterium, is capable of infecting a wide range of animals, including humans, and causes a plague-like disease called tularemia-a highly contagious disease with a high mortality rate. Because of these characteristics, F. tularensis is considered a potential agent of biological terrorism. Currently, F. tularensis is divided into four subspecies, which differ in their virulence and geographic distribution. Two of them, subsp. tularensis (primarily found in North America and subsp. holarctica (widespread across the Northern Hemisphere, are responsible for tularemia in humans. Subsp. novicida is almost avirulent in humans. The fourth subspecies, subsp. mediasiatica, is the least studied because of its limited distribution and impact in human health. It is found only in sparsely populated regions of Central Asia. In this report, we describe the first focus of naturally circulating F. tularensis subsp. mediasiatica in Russia. We isolated and characterized 18 strains of this subspecies in the Altai region. All strains were highly virulent in mice. The virulence of subsp. mediasiatica in a vaccinated mouse model is intermediate between that of subsp. tularensis and subsp. holarctica. Based on a multiple-locus variable number tandem repeat analysis (MLVA, we show that the Altaic population of F. tularensis subsp. mediasiatica is genetically distinct from the classical Central Asian population, and probably is endemic to Southern Siberia. We propose to subdivide the mediasiatica subspecies into three phylogeographic groups, M.I, M.II and M.III.

  14. A novel nanoprobe for the sensitive detection of Francisella tularensis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji-eun; Seo, Youngmin; Jeong, Yoon [Department of Bionano Technology, Graduate School, Hanyang University, Seoul 133-791 (Korea, Republic of); Hwang, Mintai P. [Center for Biomaterials, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Hwang, Jangsun [Department of Bionano Technology, Graduate School, Hanyang University, Seoul 133-791 (Korea, Republic of); Choo, Jaebum; Hong, Jong Wook [Department of Bionano Technology, Graduate School, Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Bionano Engineering, Hanyang University ERICA, Ansan 426-791 (Korea, Republic of); Jeon, Jun Ho; Rhie, Gi-eun [Division of High-risk Pathogen Research, Center for Infectious Disease, Korea National Institute of Health, Cheongju 363-951 (Korea, Republic of); Choi, Jonghoon, E-mail: jonghchoi@hanyang.ac.kr [Department of Bionano Technology, Graduate School, Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Bionano Engineering, Hanyang University ERICA, Ansan 426-791 (Korea, Republic of)

    2015-11-15

    Highlights: • We prepare apoferritin nanoprobes decorated with antibodies and nanoparticles. • We examine nanoprobes for the sensitive detection of Francisella tularensis. • 10-fold decrease of minimum concentration of pathogen was achieved. • Simultaneous detection of multiple high-risk pathogens was obtained. - Abstract: Francisella tularensis is a human zoonotic pathogen and the causative agent of tularemia, a severe infectious disease. Given the extreme infectivity of F. tularensis and its potential to be used as a biological warfare agent, a fast and sensitive detection method is highly desirable. Herein, we construct a novel detection platform composed of two units: (1) Magnetic beads conjugated with multiple capturing antibodies against F. tularensis for its simple and rapid separation and (2) Genetically-engineered apoferritin protein constructs conjugated with multiple quantum dots and a detection antibody against F. tularensis for the amplification of signal. We demonstrate a 10-fold increase in the sensitivity relative to traditional lateral flow devices that utilize enzyme-based detection methods. We ultimately envision the use of our novel nanoprobe detection platform in future applications that require the highly-sensitive on-site detection of high-risk pathogens.

  15. A novel nanoprobe for the sensitive detection of Francisella tularensis

    International Nuclear Information System (INIS)

    Kim, Ji-eun; Seo, Youngmin; Jeong, Yoon; Hwang, Mintai P.; Hwang, Jangsun; Choo, Jaebum; Hong, Jong Wook; Jeon, Jun Ho; Rhie, Gi-eun; Choi, Jonghoon

    2015-01-01

    Highlights: • We prepare apoferritin nanoprobes decorated with antibodies and nanoparticles. • We examine nanoprobes for the sensitive detection of Francisella tularensis. • 10-fold decrease of minimum concentration of pathogen was achieved. • Simultaneous detection of multiple high-risk pathogens was obtained. - Abstract: Francisella tularensis is a human zoonotic pathogen and the causative agent of tularemia, a severe infectious disease. Given the extreme infectivity of F. tularensis and its potential to be used as a biological warfare agent, a fast and sensitive detection method is highly desirable. Herein, we construct a novel detection platform composed of two units: (1) Magnetic beads conjugated with multiple capturing antibodies against F. tularensis for its simple and rapid separation and (2) Genetically-engineered apoferritin protein constructs conjugated with multiple quantum dots and a detection antibody against F. tularensis for the amplification of signal. We demonstrate a 10-fold increase in the sensitivity relative to traditional lateral flow devices that utilize enzyme-based detection methods. We ultimately envision the use of our novel nanoprobe detection platform in future applications that require the highly-sensitive on-site detection of high-risk pathogens

  16. Adaptive Immunity to Francisella tularensis and Considerations for Vaccine Development

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    Lydia M. Roberts

    2018-04-01

    Full Text Available Francisella tularensis is an intracellular bacterium that causes the disease tularemia. There are several subspecies of F. tularensis whose ability to cause disease varies in humans. The most virulent subspecies, tularensis, is a Tier One Select Agent and a potential bioweapon. Although considerable effort has made to generate efficacious tularemia vaccines, to date none have been licensed for use in the United States. Despite the lack of a tularemia vaccine, we have learned a great deal about the adaptive immune response the underlies protective immunity. Herein, we detail the animal models commonly used to study tularemia and their recapitulation of human disease, the field's current understanding of vaccine-mediated protection, and discuss the challenges associated with new vaccine development.

  17. CpG oligodeoxyribonucleotides protect mice from Burkholderia pseudomallei but not Francisella tularensis Schu S4 aerosols.

    Science.gov (United States)

    Rozak, David A; Gelhaus, Herbert C; Smith, Mark; Zadeh, Mojgan; Huzella, Louis; Waag, David; Adamovicz, Jeffrey J

    2010-02-05

    Studies have shown that CpG oligodeoxyribonucleotides (ODN) protect mice from various bacterial pathogens, including Burkholderia pseudomallei and Francisella tularensis live vaccine strain (LVS), when administered before parenteral challenge. Given the potential to develop CpG ODN as a pre-treatment for multiple bacterial biological warfare agents, we examined survival, histopathology, and cytokine data from CpG ODN-treated C57BL/6 mice to determine whether previously-reported protection extended to aerosolized B. pseudomallei 1026b and highly virulent F. tularensis Schu S4 infections. We found that, although CpG ODN protected mice from aerosolized B. pseudomallei challenges, the immunostimulant failed to benefit the animals exposed to F. tularensis Schu S4 aerosols. Our results, which contrast with earlier F. tularensis LVS studies, highlight potential differences in Francisella species pathogenesis and underscore the need to evaluate immunotherapies against human pathogenic species.

  18. Amblyomma americanum as a Bridging Vector for Human Infection with Francisella tularensis.

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    Rinosh J Mani

    Full Text Available The γ-proteobacterium Francisella tularensis causes seasonal tick-transmitted tularemia outbreaks in natural rabbit hosts and incidental infections in humans in the south-central United States. Although Dermacentor variabilis is considered a primary vector for F. tularensis, Amblyomma americanum is the most abundant tick species in this endemic region. A systematic study of F. tularensis colonization of A. americanum was undertaken to better understand its potential to serve as an overwintering reservoir for F. tularensis and as a bridging vector for human infections. Colony-reared A. americanum were artificially fed F. tularensis subspecies holarctica strain LVS via glass capillaries and colonization levels determined. Capillary-fed larva and nymph were initially infected with 10(4 CFU/tick which declined prior to molting for both stages, but rebounded post-molting in nymphs and persisted in 53% at 10(3 to 10(8 CFU/nymph at 168 days post-capillary feeding (longest sampling time in the study. In contrast, only 18% of adults molted from colonized nymphs maintained LVS colonization at 10(1 to 10(5 CFU/adult at 168 days post-capillary feeding (longest sampling time. For adults, LVS initially colonized the gut and disseminated to salivary glands by 24 h and had an ID50 of <5CFU in mice. Francisella tularensis infected the ovaries of gravid females, but transmission to eggs was infrequent and transovarial transmission to hatched larvae was not observed. The prolonged persistence of F. tularensis in A. americanum nymphs supports A. americanum as an overwintering reservoir for F. tularensis from which seasonal epizootics may originate; however, although the rapid dissemination of F. tularensis from gut to salivary glands in adults A. americanum is compatible with intermittent feeding adult males acting as bridging vectors for incidental F. tularensis infections of humans, acquisition of F. tularensis by adults may be unlikely based on adult feeding

  19. Rapid high resolution genotyping of Francisella tularensis by whole genome sequence comparison of annotated genes ("MLST+".

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    Markus H Antwerpen

    Full Text Available The zoonotic disease tularemia is caused by the bacterium Francisella tularensis. This pathogen is considered as a category A select agent with potential to be misused in bioterrorism. Molecular typing based on DNA-sequence like canSNP-typing or MLVA has become the accepted standard for this organism. Due to the organism's highly clonal nature, the current typing methods have reached their limit of discrimination for classifying closely related subpopulations within the subspecies F. tularensis ssp. holarctica. We introduce a new gene-by-gene approach, MLST+, based on whole genome data of 15 sequenced F. tularensis ssp. holarctica strains and apply this approach to investigate an epidemic of lethal tularemia among non-human primates in two animal facilities in Germany. Due to the high resolution of MLST+ we are able to demonstrate that three independent clones of this highly infectious pathogen were responsible for these spatially and temporally restricted outbreaks.

  20. Live attenuated Francisella novicida vaccine protects against Francisella tularensis pulmonary challenge in rats and non-human primates.

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    Ping Chu

    2014-10-01

    Full Text Available Francisella tularensis causes the disease tularemia. Human pulmonary exposure to the most virulent form, F. tularensis subsp. tularensis (Ftt, leads to high morbidity and mortality, resulting in this bacterium being classified as a potential biothreat agent. However, a closely-related species, F. novicida, is avirulent in healthy humans. No tularemia vaccine is currently approved for human use. We demonstrate that a single dose vaccine of a live attenuated F. novicida strain (Fn iglD protects against subsequent pulmonary challenge with Ftt using two different animal models, Fischer 344 rats and cynomolgus macaques (NHP. The Fn iglD vaccine showed protective efficacy in rats, as did a Ftt iglD vaccine, suggesting no disadvantage to utilizing the low human virulent Francisella species to induce protective immunity. Comparison of specific antibody profiles in vaccinated rat and NHP sera by proteome array identified a core set of immunodominant antigens in vaccinated animals. This is the first report of a defined live attenuated vaccine that demonstrates efficacy against pulmonary tularemia in a NHP, and indicates that the low human virulence F. novicida functions as an effective tularemia vaccine platform.

  1. The Effect of Interferon-γ and Lipopolysaccharide on the Growth of Francisella tularensis LVS in Murine Macrophage-like Cell Line J774

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    Monika Holická

    2009-01-01

    Full Text Available Background: Francisella tularensis, a causative agent of human tularemia, displaying the ability to proliferate inside the human cells. Aims: To evaluate the growth potential of F. tularensis LVS strain in macrophage-like cell line J774 modulated by recombinant interferon γ and E. coli derived lipopolysaccharide. Results: Stimulation of J774 cells either by interferon-γ or lipopolysaccharide alone, or especially in combination before infection F. tularensis, revealed protective effects. Higher concentrations of stimulating agents were needed to inhibit ongoing F. tularensis infection. Conclusions: Stimulation of J774 cell line by combination of interferon-γ with lipopolysaccharide inhibits the intracellular growth of F. tularensis.

  2. TLR-dependent control of Francisella tularensis infection and host inflammatory responses.

    Directory of Open Access Journals (Sweden)

    Allison L Abplanalp

    2009-11-01

    Full Text Available Francisella tularensis is the causative agent of tularemia and is classified as a Category A select agent. Recent studies have implicated TLR2 as a critical element in the host protective response to F. tularensis infection, but questions remain about whether TLR2 signaling dominates the response in all circumstances and with all species of Francisella and whether F. tularensis PAMPs are predominantly recognized by TLR2/TLR1 or TLR2/TLR6. To address these questions, we have explored the role of Toll-like receptors (TLRs in the host response to infections with F. tularensis Live Vaccine Strain (LVS and F. tularensis subspecies (subsp. novicida in vivo.C57BL/6 (B6 control mice and TLR- or MyD88-deficient mice were infected intranasally (i.n. or intradermally (i.d. with F. tularensis LVS or with F. tularensis subsp. novicida. B6 mice survived >21 days following infection with LVS by both routes and survival of TLR1(-/-, TLR4(-/-, and TLR6(-/- mice infected i.n. with LVS was equivalent to controls. Survival of TLR2(-/- and MyD88(-/- mice, however, was significantly reduced compared to B6 mice, regardless of the route of infection or the subspecies of F. tularensis. TLR2(-/- and MyD88(-/- mice also showed increased bacterial burdens in lungs, liver, and spleen compared to controls following i.n. infection. Primary macrophages from MyD88(-/- and TLR2(-/- mice were significantly impaired in the ability to secrete TNF and other pro-inflammatory cytokines upon ex vivo infection with LVS. TNF expression was also impaired in vivo as demonstrated by analysis of bronchoalveolar lavage fluid and by in situ immunofluorescent staining.We conclude from these studies that TLR2 and MyD88, but not TLR4, play critical roles in the innate immune response to F. tularensis infection regardless of the route of infection or the subspecies. Moreover, signaling through TLR2 does not depend exclusively on TLR1 or TLR6 during F. tularensis LVS infection.

  3. Characterization of a Francisella tularensis-Caenorhabditis elegans Pathosystem for the Evaluation of Therapeutic Compounds

    Science.gov (United States)

    Jayamani, Elamparithi; Tharmalingam, Nagendran; Rajamuthiah, Rajmohan; Kim, Wooseong; Okoli, Ikechukwu; Hernandez, Ana M.; Lee, Kiho; Nau, Gerard J.; Ausubel, Frederick M.

    2017-01-01

    ABSTRACT Francisella tularensis is a highly infectious Gram-negative intracellular pathogen that causes tularemia. Because of its potential as a bioterrorism agent, there is a need for new therapeutic agents. We therefore developed a whole-animal Caenorhabditis elegans-F. tularensis pathosystem for high-throughput screening to identify and characterize potential therapeutic compounds. We found that the C. elegans p38 mitogen-activate protein (MAP) kinase cascade is involved in the immune response to F. tularensis, and we developed a robust F. tularensis-mediated C. elegans killing assay with a Z′ factor consistently of >0.5, which was then utilized to screen a library of FDA-approved compounds that included 1,760 small molecules. In addition to clinically used antibiotics, five FDA-approved drugs were also identified as potential hits, including the anti-inflammatory drug diflunisal that showed anti-F. tularensis activity in vitro. Moreover, the nonsteroidal anti-inflammatory drug (NSAID) diflunisal, at 4× MIC, blocked the replication of an F. tularensis live vaccine strain (LVS) in primary human macrophages and nonphagocytic cells. Diflunisal was nontoxic to human erythrocytes and HepG2 human liver cells at concentrations of ≥32 μg/ml. Finally, diflunisal exhibited synergetic activity with the antibiotic ciprofloxacin in both a checkerboard assay and a macrophage infection assay. In conclusion, the liquid C. elegans-F. tularensis LVS assay described here allows screening for anti-F. tularensis compounds and suggests that diflunisal could potentially be repurposed for the management of tularemia. PMID:28652232

  4. Characterization of a Francisella tularensis-Caenorhabditis elegans Pathosystem for the Evaluation of Therapeutic Compounds.

    Science.gov (United States)

    Jayamani, Elamparithi; Tharmalingam, Nagendran; Rajamuthiah, Rajmohan; Coleman, Jeffrey J; Kim, Wooseong; Okoli, Ikechukwu; Hernandez, Ana M; Lee, Kiho; Nau, Gerard J; Ausubel, Frederick M; Mylonakis, Eleftherios

    2017-09-01

    Francisella tularensis is a highly infectious Gram-negative intracellular pathogen that causes tularemia. Because of its potential as a bioterrorism agent, there is a need for new therapeutic agents. We therefore developed a whole-animal Caenorhabditis elegans - F. tularensis pathosystem for high-throughput screening to identify and characterize potential therapeutic compounds. We found that the C. elegans p38 mitogen-activate protein (MAP) kinase cascade is involved in the immune response to F. tularensis , and we developed a robust F. tularensis -mediated C. elegans killing assay with a Z' factor consistently of >0.5, which was then utilized to screen a library of FDA-approved compounds that included 1,760 small molecules. In addition to clinically used antibiotics, five FDA-approved drugs were also identified as potential hits, including the anti-inflammatory drug diflunisal that showed anti- F. tularensis activity in vitro Moreover, the nonsteroidal anti-inflammatory drug (NSAID) diflunisal, at 4× MIC, blocked the replication of an F. tularensis live vaccine strain (LVS) in primary human macrophages and nonphagocytic cells. Diflunisal was nontoxic to human erythrocytes and HepG2 human liver cells at concentrations of ≥32 μg/ml. Finally, diflunisal exhibited synergetic activity with the antibiotic ciprofloxacin in both a checkerboard assay and a macrophage infection assay. In conclusion, the liquid C. elegans - F. tularensis LVS assay described here allows screening for anti- F. tularensis compounds and suggests that diflunisal could potentially be repurposed for the management of tularemia. Copyright © 2017 American Society for Microbiology.

  5. Indigenous Infection with Francisella tularensis holarctica in The Netherlands

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    Boulos Maraha

    2013-01-01

    Full Text Available We report here the first case of indigenous tularemia detected in The Netherlands, a nonendemic country, since 1953. Whole genome DNA sequence analysis assigned the isolate BD11-00177 to the genomic group B.FTNF002-00, which previously has been exclusively reported from Spain, France, Italy, Switzerland, and Germany. The patient had not been abroad for years, which implies that this is an indigenous infection. The current case might predict an upcoming distribution of Francisella tularensis holarctica genomic group B.FTNF002-00 in Europe.

  6. Natural Selection in Virulence Genes of Francisella tularensis.

    Science.gov (United States)

    Gunnell, Mark K; Robison, Richard A; Adams, Byron J

    2016-06-01

    A fundamental tenet of evolution is that alleles that are under negative selection are often deleterious and confer no evolutionary advantage. Negatively selected alleles are removed from the gene pool and are eventually extinguished from the population. Conversely, alleles under positive selection do confer an evolutionary advantage and lead to an increase in the overall fitness of the organism. These alleles increase in frequency until they eventually become fixed in the population. Francisella tularensis is a zoonotic pathogen and a potential biothreat agent. The most virulent type of F. tularensis, Type A, is distributed across North America with Type A.I occurring mainly in the east and Type A.II appearing mainly in the west. F. tularensis is thought to be a genome in decay (losing genes) because of the relatively large number of pseudogenes present in its genome. We hypothesized that the observed frequency of gene loss/pseudogenes may be an artifact of evolution in response to a changing environment, and that genes involved in virulence should be under strong positive selection. To test this hypothesis, we sequenced and compared whole genomes of Type A.I and A.II isolates. We analyzed a subset of virulence and housekeeping genes from several F. tularensis subspecies genomes to ascertain the presence and extent of positive selection. Eleven previously identified virulence genes were screened for positive selection along with 10 housekeeping genes. Analyses of selection yielded one housekeeping gene and 7 virulence genes which showed significant evidence of positive selection at loci implicated in cell surface structures and membrane proteins, metabolism and biosynthesis, transcription, translation and cell separation, and substrate binding and transport. Our results suggest that while the loss of functional genes through disuse could be accelerated by negative selection, the genome decay in Francisella could also be the byproduct of adaptive evolution

  7. TaqMan real-time PCR assays for single-nucleotide polymorphisms which identify Francisella tularensis and its subspecies and subpopulations.

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    Dawn N Birdsell

    Full Text Available Francisella tularensis, the etiologic agent of tularemia and a Class A Select Agent, is divided into three subspecies and multiple subpopulations that differ in virulence and geographic distribution. Given these differences, there is a need to rapidly and accurately determine if a strain is F. tularensis and, if it is, assign it to subspecies and subpopulation. We designed TaqMan real-time PCR genotyping assays using eleven single nucleotide polymorphisms (SNPs that were potentially specific to closely related groups within the genus Francisella, including numerous subpopulations within F. tularensis species. We performed extensive validation studies to test the specificity of these SNPs to particular populations by screening the assays across a set of 565 genetically and geographically diverse F. tularensis isolates and an additional 21 genetic near-neighbor (outgroup isolates. All eleven assays correctly determined the genetic groups of all 565 F. tularensis isolates. One assay differentiates F. tularensis, F. novicida, and F. hispaniensis from the more genetically distant F. philomiragia and Francisella-like endosymbionts. Another assay differentiates F. tularensis isolates from near neighbors. The remaining nine assays classify F. tularensis-confirmed isolates into F. tularensis subspecies and subpopulations. The genotyping accuracy of these nine assays diminished when tested on outgroup isolates (i.e. non F. tularensis, therefore a hierarchical approach of assay usage is recommended wherein the F. tularensis-specific assay is used before the nine downstream assays. Among F. tularensis isolates, all eleven assays were highly sensitive, consistently amplifying very low concentrations of DNA. Altogether, these eleven TaqMan real-time PCR assays represent a highly accurate, rapid, and sensitive means of identifying the species, subspecies, and subpopulation of any F. tularensis isolate if used in a step-wise hierarchical scheme. These assays

  8. Role of pathogenicity determinant protein C (PdpC in determining the virulence of the Francisella tularensis subspecies tularensis SCHU.

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    Akihiko Uda

    Full Text Available Francisella tularensis subspecies tularensis, the etiological agent of tularemia, is highly pathogenic to humans and animals. However, the SCHU strain of F. tularensis SCHU P0 maintained by passaging in artificial media has been found to be attenuated. To better understand the molecular mechanisms behind the pathogenicity of F. tularensis SCHU, we attempted to isolate virulent bacteria by serial passages in mice. SCHU P5 obtained after 5th passages in mice remained avirulent, while SCHU P9 obtained after 9th passages was completely virulent in mice. Moreover, SCHU P9 grew more efficiently in J774.1 murine macrophages compared with that in the less pathogenic SCHU P0 and P5. Comparison of the nucleotide sequences of the whole genomes of SCHU P0, P5, and P9 revealed only 1 nucleotide difference among P0, P5 and P9 in 1 of the 2 copies of pathogenicity determinant protein C (pdpC gene. An adenine residue deletion was observed in the pdpC1 gene of SCHU P0, P5, and P9 and in the pdpC2 gene of SCHU P0, and P5, while P9 was characterized by the wild type pdpC2 gene. Thus, SCHU P0 and P5 expressed only truncated forms of PdpC protein, while SCHU P9 expressed both wild type and truncated versions. To validate the pathogenicity of PdpC, both copies of the pdpC gene in SCHU P9 have been inactivated by Targetron mutagenesis. SCHU P9 mutants with inactivated pdpC gene showed low intracellular growth in J774.1 cells and did not induce severe disease in experimentally infected mice, while virulence of the mutants was restored by complementation with expression of the intact PdpC. These results demonstrate that PdpC is crucial in determining the virulence of F. tularensis SCHU.

  9. Entry of Francisella tularensis into Murine B Cells: The Role of B Cell Receptors and Complement Receptors.

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    Lenka Plzakova

    Full Text Available Francisella tularensis, the etiological agent of tularemia, is an intracellular pathogen that dominantly infects and proliferates inside phagocytic cells but can be seen also in non-phagocytic cells, including B cells. Although protective immunity is known to be almost exclusively associated with the type 1 pathway of cellular immunity, a significant role of B cells in immune responses already has been demonstrated. Whether their role is associated with antibody-dependent or antibody-independent B cell functions is not yet fully understood. The character of early events during B cell-pathogen interaction may determine the type of B cell response regulating the induction of adaptive immunity. We used fluorescence microscopy and flow cytometry to identify the basic requirements for the entry of F. tularensis into B cells within in vivo and in vitro infection models. Here, we present data showing that Francisella tularensis subsp. holarctica strain LVS significantly infects individual subsets of murine peritoneal B cells early after infection. Depending on a given B cell subset, uptake of Francisella into B cells is mediated by B cell receptors (BCRs with or without complement receptor CR1/2. However, F. tularensis strain FSC200 ΔiglC and ΔftdsbA deletion mutants are defective in the ability to enter B cells. Once internalized into B cells, F. tularensis LVS intracellular trafficking occurs along the endosomal pathway, albeit without significant multiplication. The results strongly suggest that BCRs alone within the B-1a subset can ensure the internalization process while the BCRs on B-1b and B-2 cells need co-signaling from the co receptor containing CR1/2 to initiate F. tularensis engulfment. In this case, fluidity of the surface cell membrane is a prerequisite for the bacteria's internalization. The results substantially underline the functional heterogeneity of B cell subsets in relation to F. tularensis.

  10. Signatures of T cells as correlates of immunity to Francisella tularensis.

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    Kjell Eneslätt

    Full Text Available Tularemia or vaccination with the live vaccine strain (LVS of Francisella tularensis confers long-lived cell-mediated immunity. We hypothesized that this immunity depends on polyfunctional memory T cells, i.e., CD4(+ and/or CD8(+ T cells with the capability to simultaneously express several functional markers. Multiparametric flow cytometry, measurement of secreted cytokines, and analysis of lymphocyte proliferation were used to characterize in vitro recall responses of peripheral blood mononuclear cells (PBMC to killed F. tularensis antigens from the LVS or Schu S4 strains. PBMC responses were compared between individuals who had contracted tularemia, had been vaccinated, or had not been exposed to F. tularensis (naïve. Significant differences were detected between either of the immune donor groups and naïve individuals for secreted levels of IL-5, IL-6, IL-10, IL-12, IL-13, IFN-γ, MCP-1, and MIP-1β. Expression of IFN-γ, MIP-1β, and CD107a by CD4(+CD45RO(+ or CD8(+CD45RO(+ T cells correlated to antigen concentrations. In particular, IFN-γ and MIP-1β strongly discriminated between immune and naïve individuals. Only one cytokine, IL-6, discriminated between the two groups of immune individuals. Notably, IL-2- or TNF-α-secretion was low. Our results identify functional signatures of T cells that may serve as correlates of immunity and protection against F. tularensis.

  11. Glutathione provides a source of cysteine essential for intracellular multiplication of Francisella tularensis.

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    Khaled Alkhuder

    2009-01-01

    Full Text Available Francisella tularensis is a highly infectious bacterium causing the zoonotic disease tularemia. Its ability to multiply and survive in macrophages is critical for its virulence. By screening a bank of HimarFT transposon mutants of the F. tularensis live vaccine strain (LVS to isolate intracellular growth-deficient mutants, we selected one mutant in a gene encoding a putative gamma-glutamyl transpeptidase (GGT. This gene (FTL_0766 was hence designated ggt. The mutant strain showed impaired intracellular multiplication and was strongly attenuated for virulence in mice. Here we present evidence that the GGT activity of F. tularensis allows utilization of glutathione (GSH, gamma-glutamyl-cysteinyl-glycine and gamma-glutamyl-cysteine dipeptide as cysteine sources to ensure intracellular growth. This is the first demonstration of the essential role of a nutrient acquisition system in the intracellular multiplication of F. tularensis. GSH is the most abundant source of cysteine in the host cytosol. Thus, the capacity this intracellular bacterial pathogen has evolved to utilize the available GSH, as a source of cysteine in the host cytosol, constitutes a paradigm of bacteria-host adaptation.

  12. Cellular and humoral immunity are synergistic in protection against types A and B Francisella tularensis.

    Science.gov (United States)

    Sebastian, Shite; Pinkham, Jessica T; Lynch, Jillian G; Ross, Robin A; Reinap, Barbara; Blalock, Leeann T; Conlan, J Wayne; Kasper, Dennis L

    2009-01-22

    Herein we report studies with a novel combination vaccine that, when administered to mice, conferred protection against highly virulent strains of Francisella tularensis by stimulating both arms of the immune system. Our earlier studies with Ft.LVS::wbtA, an O-polysaccharide (OPS)-negative mutant derived from the available live vaccine strain of F. tularensis (Ft.LVS), elucidated the role of antibodies to the OPS - a key virulence determinant - in protection against virulent type A organisms. However, when expressed on the organism, the OPS enhances virulence. In contrast, in purified form, the OPS is completely benign. We hypothesized that a novel combination vaccine containing both a component that induces humoral immunity and a component that induces cellular immunity to this intracellular microbe would have an enhanced protective capacity over either component alone and would be much safer than the LVS vaccine. Thus we developed a combination vaccine containing both OPS (supplied in an OPS-tetanus toxoid glycoconjugate) to induce a humoral antibody response and strain Ft.LVS::wbtA (which is markedly attenuated by its lack of OPS) to induce a cell-mediated protective response. This vaccine protected mice against otherwise-lethal intranasal and intradermal challenge with wild-type F. tularensis strains Schu S4 (type A) and FSC 108 (type B). These results represent a significant advance in our understanding of immunity to F. tularensis and provide important insight into the development of a safer vaccine effective against infections caused by clinical type A and B strains of F. tularensis.

  13. Towards Development of Improved Serodiagnostics for Tularemia by Use of Francisella tularensis Proteome Microarrays.

    Science.gov (United States)

    Nakajima, Rie; Escudero, Raquel; Molina, Douglas M; Rodríguez-Vargas, Manuela; Randall, Arlo; Jasinskas, Algis; Pablo, Jozelyn; Felgner, Philip L; AuCoin, David P; Anda, Pedro; Davies, D Huw

    2016-07-01

    Tularemia in humans is caused mainly by two subspecies of the Gram-negative facultative anaerobe Francisella tularensis: F. tularensis subsp. tularensis (type A) and F. tularensis subsp. holarctica (type B). The current serological test for tularemia is based on agglutination of whole organisms, and the reactive antigens are not well understood. Previously, we profiled the antibody responses in type A and B tularemia cases in the United States using a proteome microarray of 1,741 different proteins derived from the type A strain Schu S4. Fifteen dominant antigens able to detect antibodies to both types of infection were identified, although these were not validated in a different immunoassay format. Since type A and B subspecies are closely related, we hypothesized that Schu S4 antigens would also have utility for diagnosing type B tularemia caused by strains from other geographic locations. To test this, we probed the Schu S4 array with sera from 241 type B tularemia cases in Spain. Despite there being no type A strains in Spain, we confirmed the responses against some of the same potential serodiagnostic antigens reported previously, as well as determined the responses against additional potential serodiagnostic antigens. Five potential serodiagnostic antigens were evaluated on immunostrips, and two of these (FTT1696/GroEL and FTT0975/conserved hypothetical protein) discriminated between the Spanish tularemia cases and healthy controls. We conclude that antigens from the type A strain Schu S4 are suitable for detection of antibodies from patients with type B F. tularensis infections and that these can be used for the diagnosis of tularemia in a deployable format, such as the immunostrip. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  14. Inhibition of AcpA phosphatase activity with ascorbate attenuates Francisella tularensis intramacrophage survival.

    Science.gov (United States)

    McRae, Steven; Pagliai, Fernando A; Mohapatra, Nrusingh P; Gener, Alejandro; Mahmou, Asma Sayed Abdelgeliel; Gunn, John S; Lorca, Graciela L; Gonzalez, Claudio F

    2010-02-19

    Acid phosphatase activity in the highly infectious intracellular pathogen Francisella tularensis is directly related with the ability of these bacteria to survive inside host cells. Pharmacological inactivation of acid phosphatases could potentially help in the treatment of tularemia or even be utilized to neutralize the infection. In the present work, we report inhibitory compounds for three of the four major acid phosphatases produced by F. tularensis SCHU4: AcpA, AcpB, and AcpC. The inhibitors were identified using a catalytic screen from a library of chemicals approved for use in humans. The best results were obtained against AcpA. The two compounds identified, ascorbate (K(i) = 380 +/- 160 microM) and 2-phosphoascorbate (K(i) = 3.2 +/- 0.85 microM) inhibit AcpA in a noncompetitive, nonreversible fashion. A potential ascorbylation site in the proximity of the catalytic pocket of AcpA was identified using site-directed mutagenesis. The effects of the inhibitors identified in vitro were evaluated using bioassays determining the ability of F. tularensis to survive inside infected cells. The presence of ascorbate or 2-phosphoascorbate impaired the intramacrophage survival of F. tularensis in an AcpA-dependent manner as it was probed using knockout strains. The evidence presented herein indicated that ascorbate could be a good alternative to be used clinically to improve treatments against tularemia.

  15. An original case of Francisella tularensis subsp. holarctica bacteremia after a near-drowning accident.

    Science.gov (United States)

    Ughetto, Estelle; Héry-Arnaud, Geneviève; Cariou, Marie-Estelle; Pelloux, Isabelle; Maurin, Max; Caillon, Jocelyne; Moreau, Philippe; Ygout, Jean-François; Corvec, Stéphane

    2015-08-01

    We report the first case of Francisella tularensis subsp. holarctica bacteremia after water contamination in France. A 75-year-old man developed septic pneumonic tularemia after a near-drowning accident. We highlight the need for a longer incubation time for isolation of F. tularensis from blood cultures.

  16. A method for functional trans-complementation of intracellular Francisella tularensis.

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    Shaun Steele

    Full Text Available Francisella tularensis is a highly infectious bacterial pathogen that invades and replicates within numerous host cell types. After uptake, F. tularensis bacteria escape the phagosome, replicate within the cytosol, and suppress cytokine responses. However, the mechanisms employed by F. tularensis to thrive within host cells are mostly unknown. Potential F. tularensis mutants involved in host-pathogen interactions are typically discovered by negative selection screens for intracellular replication or virulence. Mutants that fulfill these criteria fall into two categories: mutants with intrinsic intracellular growth defects and mutants that fail to modify detrimental host cell processes. It is often difficult and time consuming to discriminate between these two possibilities. We devised a method to functionally trans-complement and thus identify mutants that fail to modify the host response. In this assay, host cells are consistently and reproducibly infected with two different F. tularensis strains by physically tethering the bacteria to antibody-coated beads. To examine the efficacy of this protocol, we tested phagosomal escape, cytokine suppression, and intracellular replication for F. tularensis ΔripA and ΔpdpC. ΔripA has an intracellular growth defect that is likely due to an intrinsic defect and fails to suppress IL-1β secretion. In the co-infection model, ΔripA was unable to replicate in the host cell when wild-type bacteria infected the same cell, but cytokine suppression was rescued. Therefore, ΔripA intracellular growth is due to an intrinsic bacterial defect while cytokine secretion results from a failed host-pathogen interaction. Likewise, ΔpdpC is deficient for phagosomal escape, intracellular survival and suppression of IL-1β secretion. Wild-type bacteria that entered through the same phagosome as ΔpdpC rescued all of these phenotypes, indicating that ΔpdpC failed to properly manipulate the host. In summary, functional

  17. Biochemical responses and oxidative stress in Francisella tularensis infection: a European brown hare model

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    Treml Frantisek

    2011-01-01

    Full Text Available Abstract Background The aim of the present study was to investigate biochemical and oxidative stress responses to experimental F. tularensis infection in European brown hares, an important source of human tularemia infections. Methods For these purposes we compared the development of an array of biochemical parameters measured in blood plasma using standard procedures of dry chemistry as well as electrochemical devices following a subcutaneous infection with a wild Francisella tularensis subsp. holarctica strain (a single dose of 2.6 × 109 CFU pro toto. Results Subcutaneous inoculation of a single dose with 2.6 × 109 colony forming units of a wild F. tularensis strain pro toto resulted in the death of two out of five hares. Plasma chemistry profiles were examined on days 2 to 35 post-infection. When compared to controls, the total protein, urea, lactate dehydrogenase, aspartate aminotransferase and alanine aminotransferase were increased, while albumin, glucose and amylase were decreased. Both uric and ascorbic acids and glutathione dropped on day 2 and then increased significantly on days 6 to 12 and 6 to 14 post-inoculation, respectively. There was a two-fold increase in lipid peroxidation on days 4 to 8 post-inoculation. Conclusions Contrary to all expectations, the present study demonstrates that the European brown hare shows relatively low susceptibility to tularemia. Therefore, the circumstances of tularemia in hares under natural conditions should be further studied.

  18. Crystallization of a newly discovered histidine acid phosphatase from Francisella tularensis

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    Felts, Richard L. [Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211 (United States); Reilly, Thomas J. [Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri-Columbia, Columbia, Missouri 65212 (United States); Veterinary Medical Diagnostic Laboratory, College of Veterinary Medicine, University of Missouri-Columbia, Columbia, Missouri 65212 (United States); Calcutt, Michael J. [Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri-Columbia, Columbia, Missouri 65212 (United States); Tanner, John J., E-mail: tannerjj@missouri.edu [Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211 (United States); Department of Biochemistry, University of Missouri-Columbia, Columbia, Missouri 65211 (United States)

    2006-01-01

    A histidine acid phosphatase from the CDC Category A pathogen F. tularensis has been crystallized in space group P4{sub 1}2{sub 1}2, with unit-cell parameters a = 61.96, c = 210.78 Å. A 1.75 Å resolution data set was collected at Advanced Light Source beamline 4.2.2. Francisella tularensis is a highly infectious bacterial pathogen that is considered by the Centers for Disease Control and Prevention to be a potential bioterrorism weapon. Here, the crystallization of a 37.2 kDa phosphatase encoded by the genome of F. tularensis subsp. holarctica live vaccine strain is reported. This enzyme shares 41% amino-acid sequence identity with Legionella pneumophila major acid phosphatase and contains the RHGXRXP motif that is characteristic of the histidine acid phosphatase family. Large diffraction-quality crystals were grown in the presence of Tacsimate, HEPES and PEG 3350. The crystals belong to space group P4{sub 1}2{sub 1}2, with unit-cell parameters a = 61.96, c = 210.78 Å. The asymmetric unit is predicted to contain one protein molecule, with a solvent content of 53%. A 1.75 Å resolution native data set was recorded at beamline 4.2.2 of the Lawrence Berkeley National Laboratory Advanced Light Source. Molecular-replacement trials using the human prostatic acid phosphatase structure as the search model (28% amino-acid sequence identity) did not produce a satisfactory solution. Therefore, the structure of F. tularensis histidine acid phosphatase will be determined by multiwavelength anomalous dispersion phasing using a selenomethionyl derivative.

  19. Crystallization of a newly discovered histidine acid phosphatase from Francisella tularensis

    International Nuclear Information System (INIS)

    Felts, Richard L.; Reilly, Thomas J.; Calcutt, Michael J.; Tanner, John J.

    2005-01-01

    A histidine acid phosphatase from the CDC Category A pathogen F. tularensis has been crystallized in space group P4 1 2 1 2, with unit-cell parameters a = 61.96, c = 210.78 Å. A 1.75 Å resolution data set was collected at Advanced Light Source beamline 4.2.2. Francisella tularensis is a highly infectious bacterial pathogen that is considered by the Centers for Disease Control and Prevention to be a potential bioterrorism weapon. Here, the crystallization of a 37.2 kDa phosphatase encoded by the genome of F. tularensis subsp. holarctica live vaccine strain is reported. This enzyme shares 41% amino-acid sequence identity with Legionella pneumophila major acid phosphatase and contains the RHGXRXP motif that is characteristic of the histidine acid phosphatase family. Large diffraction-quality crystals were grown in the presence of Tacsimate, HEPES and PEG 3350. The crystals belong to space group P4 1 2 1 2, with unit-cell parameters a = 61.96, c = 210.78 Å. The asymmetric unit is predicted to contain one protein molecule, with a solvent content of 53%. A 1.75 Å resolution native data set was recorded at beamline 4.2.2 of the Lawrence Berkeley National Laboratory Advanced Light Source. Molecular-replacement trials using the human prostatic acid phosphatase structure as the search model (28% amino-acid sequence identity) did not produce a satisfactory solution. Therefore, the structure of F. tularensis histidine acid phosphatase will be determined by multiwavelength anomalous dispersion phasing using a selenomethionyl derivative

  20. Characterization of a Francisella tularensis-Caenorhabditis elegans Pathosystem for the Evaluation of Therapeutic Compounds

    OpenAIRE

    Jayamani, Elamparithi; Tharmalingam, Nagendran; Rajamuthiah, Rajmohan; Coleman, Jeffrey J.; Kim, Wooseong; Okoli, Ikechukwu; Hernandez, Ana M.; Lee, Kiho; Nau, Gerard J.; Ausubel, Frederick M.; Mylonakis, Eleftherios

    2017-01-01

    Francisella tularensis is a highly infectious Gram-negative intracellular pathogen that causes tularemia. Because of its potential as a bioterrorism agent, there is a need for new therapeutic agents. We therefore developed a whole-animal Caenorhabditis elegans-F. tularensis pathosystem for high-throughput screening to identify and characterize potential therapeutic compounds. We found that the C. elegans p38 mitogen-activate protein (MAP) kinase cascade is involved in the immune response to F...

  1. Mouse models of aerosol-acquired tularemia caused by Francisella tularensis types A and B.

    Science.gov (United States)

    Fritz, David L; England, Marilyn J; Miller, Lynda; Waag, David M

    2014-10-01

    After preliminary assessment of virulence in AKR/J, DBA/1, BALB/c, and C57BL/6 mice, we investigated histopathologic changes in BALB/c and C57BL/6 mice infected with type A (strain SCHU S4) or type B (strain 425) Francisella tularensis by aerosol exposure. In mice exposed to type A infection, changes in histologic presentation were not apparent until day 3 after infection, when pyogranulomatous inflammation was detected in spleens and livers of BALB/c mice, and in lungs and spleens of C57BL/6 mice. Histopathologic changes were most severe and widespread in both mouse strains on day 5 after infection and seemed to completely resolve within 22 d of challenge. BALB/c mice were more resistant than C57BL/6 mice in lethal-dose calculations, but C57BL/6 mice cleared the infection more rapidly. Mice similarly challenged with type B F. tularensis also developed histopathologic signs of infection beginning on day 3. The most severe changes were noted on day 8 and were characterized by granulomatous or pyogranulomatous infiltrations of the lungs. Unlike type A infection, lesions due to type B did not resolve over time and remained 3 wk after infection. In type B, but not type A, infection we noted extensive inflammation of the heart muscle. Although no microorganisms were found in tissues of type A survivors beyond 9 d after infection, mice surviving strain 425 infection had a low level of residual infection at 3 wk after challenge. The histopathologic presentation of tularemia caused by F. tularensis types A and B in BALB/c and C57BL/6 mice bears distinct similarities to tularemia in humans.

  2. The potential for flower nectar to allow mosquito to mosquito transmission of Francisella tularensis.

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    Adam Kenney

    Full Text Available Francisella tularensis is disseminated in nature by biting arthropods such as mosquitoes. The relationship between mosquitoes and F. tularensis in nature is highly ambiguous, due in part to the fact that mosquitoes have caused significant tularemia outbreaks despite being classified as a mechanical vector of F. tularensis. One possible explanation for mosquitoes being a prominent, yet mechanical vector is that these insects feed on flower nectar between blood meals, allowing for transmission of F. tularensis between mosquitoes. Here, we aimed to assess whether F. tularensis could survive in flower nectar. Moreover, we examined if mosquitoes could interact with or ingest and transmit F. tularensis from one source of nectar to another. F. tularensis exhibited robust survivability in flower nectar with concentrations of viable bacteria remaining consistent with the rich growth medium. Furthermore, F. tularensis was able to survive (albeit to a lesser extent in 30% sucrose (a nectar surrogate over a period of time consistent with that of a typical flower bloom. Although we observed diminished bacterial survival in the nectar surrogate, mosquitoes that fed on this material became colonized with F. tularensis. Finally, colonized mosquitoes were capable of transferring F. tularensis to a sterile nectar surrogate. These data suggest that flower nectar may be capable of serving as a temporary source of F. tularensis that could contribute to the amplification of outbreaks. Mosquitoes that feed on an infected mammalian host and subsequently feed on flower nectar could deposit some F. tularensis bacteria into the nectar in the process. Mosquitoes subsequently feeding on this nectar source could potentially become colonized by F. tularensis. Thus, the possibility exists that flower nectar may allow for vector-vector transmission of F. tularensis.

  3. The potential for flower nectar to allow mosquito to mosquito transmission of Francisella tularensis.

    Science.gov (United States)

    Kenney, Adam; Cusick, Austin; Payne, Jessica; Gaughenbaugh, Anna; Renshaw, Andrea; Wright, Jenna; Seeber, Roger; Barnes, Rebecca; Florjanczyk, Aleksandr; Horzempa, Joseph

    2017-01-01

    Francisella tularensis is disseminated in nature by biting arthropods such as mosquitoes. The relationship between mosquitoes and F. tularensis in nature is highly ambiguous, due in part to the fact that mosquitoes have caused significant tularemia outbreaks despite being classified as a mechanical vector of F. tularensis. One possible explanation for mosquitoes being a prominent, yet mechanical vector is that these insects feed on flower nectar between blood meals, allowing for transmission of F. tularensis between mosquitoes. Here, we aimed to assess whether F. tularensis could survive in flower nectar. Moreover, we examined if mosquitoes could interact with or ingest and transmit F. tularensis from one source of nectar to another. F. tularensis exhibited robust survivability in flower nectar with concentrations of viable bacteria remaining consistent with the rich growth medium. Furthermore, F. tularensis was able to survive (albeit to a lesser extent) in 30% sucrose (a nectar surrogate) over a period of time consistent with that of a typical flower bloom. Although we observed diminished bacterial survival in the nectar surrogate, mosquitoes that fed on this material became colonized with F. tularensis. Finally, colonized mosquitoes were capable of transferring F. tularensis to a sterile nectar surrogate. These data suggest that flower nectar may be capable of serving as a temporary source of F. tularensis that could contribute to the amplification of outbreaks. Mosquitoes that feed on an infected mammalian host and subsequently feed on flower nectar could deposit some F. tularensis bacteria into the nectar in the process. Mosquitoes subsequently feeding on this nectar source could potentially become colonized by F. tularensis. Thus, the possibility exists that flower nectar may allow for vector-vector transmission of F. tularensis.

  4. Revisiting Francisella tularensis subsp. holarctica, Causative Agent of Tularemia in Germany With Bioinformatics: New Insights in Genome Structure, DNA Methylation and Comparative Phylogenetic Analysis

    Directory of Open Access Journals (Sweden)

    Anne Busch

    2018-03-01

    Full Text Available Francisella (F. tularensis is a highly virulent, Gram-negative bacterial pathogen and the causative agent of the zoonotic disease tularemia. Here, we generated, analyzed and characterized a high quality circular genome sequence of the F. tularensis subsp. holarctica strain 12T0050 that caused fatal tularemia in a hare. Besides the genomic structure, we focused on the analysis of oriC, unique to the Francisella genus and regulating replication in and outside hosts and the first report on genomic DNA methylation of a Francisella strain. The high quality genome was used to establish and evaluate a diagnostic whole genome sequencing pipeline. A genotyping strategy for F. tularensis was developed using various bioinformatics tools for genotyping. Additionally, whole genome sequences of F. tularensis subsp. holarctica isolates isolated in the years 2008–2015 in Germany were generated. A phylogenetic analysis allowed to determine the genetic relatedness of these isolates and confirmed the highly conserved nature of F. tularensis subsp. holarctica.

  5. Rapid countermeasure discovery against Francisella tularensis based on a metabolic network reconstruction.

    Directory of Open Access Journals (Sweden)

    Sidhartha Chaudhury

    Full Text Available In the future, we may be faced with the need to provide treatment for an emergent biological threat against which existing vaccines and drugs have limited efficacy or availability. To prepare for this eventuality, our objective was to use a metabolic network-based approach to rapidly identify potential drug targets and prospectively screen and validate novel small-molecule antimicrobials. Our target organism was the fully virulent Francisella tularensis subspecies tularensis Schu S4 strain, a highly infectious intracellular pathogen that is the causative agent of tularemia and is classified as a category A biological agent by the Centers for Disease Control and Prevention. We proceeded with a staggered computational and experimental workflow that used a strain-specific metabolic network model, homology modeling and X-ray crystallography of protein targets, and ligand- and structure-based drug design. Selected compounds were subsequently filtered based on physiological-based pharmacokinetic modeling, and we selected a final set of 40 compounds for experimental validation of antimicrobial activity. We began screening these compounds in whole bacterial cell-based assays in biosafety level 3 facilities in the 20th week of the study and completed the screens within 12 weeks. Six compounds showed significant growth inhibition of F. tularensis, and we determined their respective minimum inhibitory concentrations and mammalian cell cytotoxicities. The most promising compound had a low molecular weight, was non-toxic, and abolished bacterial growth at 13 µM, with putative activity against pantetheine-phosphate adenylyltransferase, an enzyme involved in the biosynthesis of coenzyme A, encoded by gene coaD. The novel antimicrobial compounds identified in this study serve as starting points for lead optimization, animal testing, and drug development against tularemia. Our integrated in silico/in vitro approach had an overall 15% success rate in terms of

  6. Innate immune recognition of Francisella tularensis: activation of type-I interferons and the inflammasome

    Directory of Open Access Journals (Sweden)

    Jonathan Wiley Jones

    2011-02-01

    Full Text Available Francisella tularensis is an intracellular pathogen that can cause severe disease in a wide range of mammalian hosts. Primarily residing in host macrophages, F. tularensis escapes phagosomal degradation, and replicates in the macrophage cytosol. The macrophage uses a series of pattern recognition receptors to detect conserved microbial molecules from invading pathogens, and initiates an appropriate host response. In the cytosol, F. tularensis is recognized by the inflammasome, a multiprotein complex responsible for the activation of the cysteine protease caspase-1. Caspase-1 activation leads to processing and release of proinflammatory cytokines and host cell death. Here we review recent work on the molecular mechanisms of inflammasome activation by F. tularensis, and its consequences both in vitro and in vivo. Finally, we discuss the coordination between the inflammasome and other cytosolic host responses, and the evidence for F. tularensis virulence factors that suppress inflammasome activation.

  7. Insights to genetic characterization tools for epidemiological tracking of Francisella tularensis in Sweden.

    Directory of Open Access Journals (Sweden)

    Tara Wahab

    Full Text Available Tularaemia, caused by the bacterium Francisella tularensis, is endemic in Sweden and is poorly understood. The aim of this study was to evaluate the effectiveness of three different genetic typing systems to link a genetic type to the source and place of tularemia infection in Sweden. Canonical single nucleotide polymorphisms (canSNPs, MLVA including five variable number of tandem repeat loci and PmeI-PFGE were tested on 127 F. tularensis positive specimens collected from Swedish case-patients. All three typing methods identified two major genetic groups with near-perfect agreement. Higher genetic resolution was obtained with canSNP and MLVA compared to PFGE; F. tularensis samples were first assigned into ten phylogroups based on canSNPs followed by 33 unique MLVA types. Phylogroups were geographically analysed to reveal complex phylogeographic patterns in Sweden. The extensive phylogenetic diversity found within individual counties posed a challenge to linking specific genetic types with specific geographic locations. Despite this, a single phylogroup (B.22, defined by a SNP marker specific to a lone Swedish sequenced strain, did link genetic type with a likely geographic place. This result suggests that SNP markers, highly specific to a particular reference genome, may be found most frequently among samples recovered from the same location where the reference genome originated. This insight compels us to consider whole-genome sequencing (WGS as the appropriate tool for effectively linking specific genetic type to geography. Comparing the WGS of an unknown sample to WGS databases of archived Swedish strains maximizes the likelihood of revealing those rare geographically informative SNPs.

  8. Tick salivary gland extract accelerates proliferation of Francisella tularensis in the host

    Czech Academy of Sciences Publication Activity Database

    Kročová, Z.; Macela, A.; Hernychová, L.; Kroča, M.; Pechová, Jitka; Kopecký, Jan

    2003-01-01

    Roč. 89, č. 1 (2003), s. 14-20 ISSN 0022-3395 R&D Projects: GA ČR GA524/02/0901; GA MZd NI4700 Institutional research plan: CEZ:AV0Z6022909 Keywords : salivary gland extract * tick * Francisella tularensis Subject RIV: EC - Immunology Impact factor: 1.137, year: 2003

  9. A combined enrichment and aptamer pulldown assay for francisella tularensis detection in food and environmental matrices

    NARCIS (Netherlands)

    Lamont, Elise A.; Wang, Ping; Enomoto, Shinichiro; Borewicz, Klaudyna; Abdallah, Ahmed; Isaacson, Richard E.; Sreevatsan, Srinand; Kourentzi, Katerina

    2014-01-01

    Francisella tularensis, a Gram-negative bacterium and causative agent of tularemia, is categorized as a Class A select agent by the Centers for Disease Control and Prevention due to its ease of dissemination and ability to cause disease. Oropharyngeal and gastrointestinal tularemia may occur due

  10. Border Patrol Gone Awry: Lung NKT Cell Activation by Francisella tularensis Exacerbates Tularemia-Like Disease.

    Science.gov (United States)

    Hill, Timothy M; Gilchuk, Pavlo; Cicek, Basak B; Osina, Maria A; Boyd, Kelli L; Durrant, Douglas M; Metzger, Dennis W; Khanna, Kamal M; Joyce, Sebastian

    2015-06-01

    The respiratory mucosa is a major site for pathogen invasion and, hence, a site requiring constant immune surveillance. The type I, semi-invariant natural killer T (NKT) cells are enriched within the lung vasculature. Despite optimal positioning, the role of NKT cells in respiratory infectious diseases remains poorly understood. Hence, we assessed their function in a murine model of pulmonary tularemia--because tularemia is a sepsis-like proinflammatory disease and NKT cells are known to control the cellular and humoral responses underlying sepsis. Here we show for the first time that respiratory infection with Francisella tularensis live vaccine strain resulted in rapid accumulation of NKT cells within the lung interstitium. Activated NKT cells produced interferon-γ and promoted both local and systemic proinflammatory responses. Consistent with these results, NKT cell-deficient mice showed reduced inflammatory cytokine and chemokine response yet they survived the infection better than their wild type counterparts. Strikingly, NKT cell-deficient mice had increased lymphocytic infiltration in the lungs that organized into tertiary lymphoid structures resembling induced bronchus-associated lymphoid tissue (iBALT) at the peak of infection. Thus, NKT cell activation by F. tularensis infection hampers iBALT formation and promotes a systemic proinflammatory response, which exacerbates severe pulmonary tularemia-like disease in mice.

  11. Protective Immunity against Tularemia Provided by an Adenovirus-Vectored Vaccine Expressing Tul4 of Francisella tularensis

    OpenAIRE

    Kaur, Ravinder; Chen, Shan; Arévalo, Maria T.; Xu, Qingfu; Chen, Yanping; Zeng, Mingtao

    2012-01-01

    Francisella tularensis, a category A bioterrorism agent, is a highly infectious organism that is passed on via skin contact and inhalation routes. A live attenuated vaccine strain (LVS) has been developed, but it has not been licensed for public use by the FDA due to safety concerns. Thus, there exists a need for a safer and improved vaccine. In this study, we have constructed a replication-incompetent adenovirus, Ad/opt-Tul4, carrying a codon-optimized gene for expression of a membrane prote...

  12. Inactivation of Francisella tularensis Gene Encoding Putative ABC Transporter Has a Pleiotropic Effect upon Production of Various Glycoconjugates

    Czech Academy of Sciences Publication Activity Database

    Daňková, V.; Balonová, L.; Link, M.; Strašková, Adéla; Sheshko, V .; Stulík, J.

    2016-01-01

    Roč. 15, č. 2 (2016), s. 510-524 ISSN 1535-3893 Institutional support: RVO:61388971 Keywords : Francisella tularensis * glycosylation * lipopolysaccharide Subject RIV: EE - Microbiology, Virology Impact factor: 4.268, year: 2016

  13. Adaptation of Francisella tularensis to the Mammalian Environment Is Governed by Cues Which Can Be Mimicked In Vitro▿ †

    OpenAIRE

    Hazlett, Karsten R. O.; Caldon, Seth D.; McArthur, Debbie G.; Cirillo, Kerry A.; Kirimanjeswara, Girish S.; Magguilli, Micheal L.; Malik, Meenakshi; Shah, Aaloki; Broderick, Scott; Golovliov, Igor; Metzger, Dennis W.; Rajan, Krishna; Sellati, Timothy J.; Loegering, Daniel J.

    2008-01-01

    The intracellular bacterium Francisella tularensis survives in mammals, arthropods, and freshwater amoeba. It was previously established that the conventional media used for in vitro propagation of this microbe do not yield bacteria that mimic those harvested from infected mammals; whether these in vitro-cultivated bacteria resemble arthropod- or amoeba-adapted Francisella is unknown. As a foundation for our goal of identifying F. tularensis outer membrane proteins which are expressed during ...

  14. Molecular evolutionary consequences of niche restriction in Francisella tularensis, a facultative intracellular pathogen.

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    Pär Larsson

    2009-06-01

    Full Text Available Francisella tularensis is a potent mammalian pathogen well adapted to intracellular habitats, whereas F. novicida and F. philomiragia are less virulent in mammals and appear to have less specialized lifecycles. We explored adaptations within the genus that may be linked to increased host association, as follows. First, we determined the genome sequence of F. tularensis subsp. mediasiatica, the only subspecies that had not been previously sequenced. This genome, and those of 12 other F. tularensis isolates, were then compared to the genomes of F. novicida (three isolates and F. philomiragia (one isolate. Signs of homologous recombination were found in approximately 19.2% of F. novicida and F. philomiragia genes, but none among F. tularensis genomes. In addition, random insertions of insertion sequence elements appear to have provided raw materials for secondary adaptive mutations in F. tularensis, e.g. for duplication of the Francisella Pathogenicity Island and multiplication of a putative glycosyl transferase gene. Further, the five major genetic branches of F. tularensis seem to have converged along independent routes towards a common gene set via independent losses of gene functions. Our observations suggest that despite an average nucleotide identity of >97%, F. tularensis and F. novicida have evolved as two distinct population lineages, the former characterized by clonal structure with weak purifying selection, the latter by more frequent recombination and strong purifying selection. F. tularensis and F. novicida could be considered the same bacterial species, given their high similarity, but based on the evolutionary analyses described in this work we propose retaining separate species names.

  15. Novel engineered cationic antimicrobial peptides display broad-spectrum activity against Francisella tularensis, Yersinia pestis and Burkholderia pseudomallei.

    Science.gov (United States)

    Abdelbaqi, Suha; Deslouches, Berthony; Steckbeck, Jonathan; Montelaro, Ronald; Reed, Douglas S

    2016-02-01

    Broad-spectrum antimicrobials are needed to effectively treat patients infected in the event of a pandemic or intentional release of a pathogen prior to confirmation of the pathogen's identity. Engineered cationic antimicrobial peptides (eCAPs) display activity against a number of bacterial pathogens including multi-drug-resistant strains. Two lead eCAPs, WLBU2 and WR12, were compared with human cathelicidin (LL-37) against three highly pathogenic bacteria: Francisella tularensis, Yersinia pestis and Burkholderia pseudomallei. Both WLBU2 and WR12 demonstrated bactericidal activity greater than that of LL-37, particularly against F. tularensis and Y. pestis. Only WLBU2 had bactericidal activity against B. pseudomallei. WLBU2, WR12 and LL-37 were all able to inhibit the growth of the three bacteria in vitro. Because these bacteria can be facultative intracellular pathogens, preferentially infecting macrophages and dendritic cells, we evaluated the activity of WLBU2 against F. tularensis in an ex vivo infection model with J774 cells, a mouse macrophage cell line. In that model WLBU2 was able to achieve greater than 50% killing of F. tularensis at a concentration of 12.5 μM. These data show the therapeutic potential of eCAPs, particularly WLBU2, as a broad-spectrum antimicrobial for treating highly pathogenic bacterial infections.

  16. Proteomic analysis of bronchoalveolar lavage fluid proteins from mice infected with Francisella tularensis ssp novicida

    Energy Technology Data Exchange (ETDEWEB)

    Varnum, Susan M.; Webb-Robertson, Bobbie-Jo M.; Pounds, Joel G.; Moore, Ronald J.; Smith, Richard D.; Frevert, Charles; Skerret, Shawn J.; Wunschel, David S.

    2012-07-06

    Francisella tularensis causes the zoonosis tularemia in humans and is one of the most virulent bacterial pathogens. We utilized a global proteomic approach to characterize protein changes in bronchoalveolar lavage fluid from mice exposed to one of three organisms, F. tularensis ssp. novicida, an avirulent mutant of F. tularensis ssp. novicida (F.t. novicida-ΔmglA); and Pseudomonas aeruginosa. The composition of BALF proteins was altered following infection, including proteins involved in neutrophil activation, oxidative stress and inflammatory responses. Components of the innate immune response were induced including the acute phase response and the complement system, however the timing of their induction varied. Francisella tularensis ssp. novicida infected mice do not appear to have an effective innate immune response in the first hours of infection, however within 24 hours they show an upregulation of innate immune response proteins. This delayed response is in contrast to P. aeruginosa infected animals which show an early innate immune response. Likewise, F.t. novicida-ΔmglA infection initiates an early innate immune response, however this response is dimished by 24 hours. Finally, this study identifies several candidate biomarkers, including Chitinase 3-like-1 (CHI3L1 or YKL-40) and peroxiredoxin 1, that are associated with F. tularensis ssp. novicida but not P. aeruginosa infection.

  17. Francisella tularensis Catalase Restricts Immune Function by Impairing TRPM2 Channel Activity.

    Science.gov (United States)

    Shakerley, Nicole L; Chandrasekaran, Akshaya; Trebak, Mohamed; Miller, Barbara A; Melendez, J Andrés

    2016-02-19

    As an innate defense mechanism, macrophages produce reactive oxygen species that weaken pathogens and serve as secondary messengers involved in immune function. The Gram-negative bacterium Francisella tularensis utilizes its antioxidant armature to limit the host immune response, but the mechanism behind this suppression is not defined. Here we establish that F. tularensis limits Ca(2+) entry in macrophages, thereby limiting actin reorganization and IL-6 production in a redox-dependent fashion. Wild type (live vaccine strain) or catalase-deficient F. tularensis (ΔkatG) show distinct profiles in their H2O2 scavenging rates, 1 and 0.015 pm/s, respectively. Murine alveolar macrophages infected with ΔkatG display abnormally high basal intracellular Ca(2+) concentration that did not increase further in response to H2O2. Additionally, ΔkatG-infected macrophages displayed limited Ca(2+) influx in response to ionomycin, as a result of ionophore H2O2 sensitivity. Exogenously added H2O2 or H2O2 generated by ΔkatG likely oxidizes ionomycin and alters its ability to transport Ca(2+). Basal increases in cytosolic Ca(2+) and insensitivity to H2O2-mediated Ca(2+) entry in ΔkatG-infected cells are reversed by the Ca(2+) channel inhibitors 2-aminoethyl diphenylborinate and SKF-96365. 2-Aminoethyl diphenylborinate but not SKF-96365 abrogated ΔkatG-dependent increases in macrophage actin remodeling and IL-6 secretion, suggesting a role for H2O2-mediated Ca(2+) entry through the transient receptor potential melastatin 2 (TRPM2) channel in macrophages. Indeed, increases in basal Ca(2+), actin polymerization, and IL-6 production are reversed in TRPM2-null macrophages infected with ΔkatG. Together, our findings provide compelling evidence that F. tularensis catalase restricts reactive oxygen species to temper macrophage TRPM2-mediated Ca(2+) signaling and limit host immune function. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  18. Francisella tularensis detection using magnetic labels and a magnetic biosensor based on frequency mixing

    International Nuclear Information System (INIS)

    Meyer, Martin H.F.; Krause, Hans-Joachim; Hartmann, Markus; Miethe, Peter; Oster, Juergen; Keusgen, Michael

    2007-01-01

    A biosensor that uses resonant coils with a special frequency-mixing technique and magnetic beads as detectable labels has been established for the detection of Francisella tularensis, the causative agent for tularemia. The detection principle is based on a sandwich immunoassay using an anti-Ft antibody for immunofiltration immobilized to ABICAP[reg] polyethylene filters, and biotinylated with streptavidin-coated magnetic beads as labels. The linear detection range of this biosensor was found to be 10 4 -10 6 cfu F. tularensis lipopolysaccharide (LPS) per ml. Tested sample matrices were physiological PBS buffer and rabbit serum

  19. Francisella tularensis detection using magnetic labels and a magnetic biosensor based on frequency mixing

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Martin H.F. [Institute for Pharmaceutical Chemistry, Philipps-Universitaet Marburg (Germany); Krause, Hans-Joachim [Institute of Bio-and Nanosystems (IBN-2), Research Center Juelich (Germany); Hartmann, Markus [Institute for Pharmaceutical Chemistry, Philipps-Universitaet Marburg (Germany); Miethe, Peter [SENOVA GmbH, Jena (Germany); Oster, Juergen [chemagen GmbH, Baesweiler (Germany); Keusgen, Michael [Institute for Pharmaceutical Chemistry, Philipps-Universitaet Marburg (Germany)]. E-mail: Keusgen@staff.uni-marburg.de

    2007-04-15

    A biosensor that uses resonant coils with a special frequency-mixing technique and magnetic beads as detectable labels has been established for the detection of Francisella tularensis, the causative agent for tularemia. The detection principle is based on a sandwich immunoassay using an anti-Ft antibody for immunofiltration immobilized to ABICAP[reg] polyethylene filters, and biotinylated with streptavidin-coated magnetic beads as labels. The linear detection range of this biosensor was found to be 10{sup 4}-10{sup 6} cfu F. tularensis lipopolysaccharide (LPS) per ml. Tested sample matrices were physiological PBS buffer and rabbit serum.

  20. Francisella tularensis subsp. tularensis induces a unique pulmonary inflammatory response: role of bacterial gene expression in temporal regulation of host defense responses.

    Directory of Open Access Journals (Sweden)

    Kathie-Anne Walters

    Full Text Available Pulmonary exposure to Francisella tularensis is associated with severe lung pathology and a high mortality rate. The lack of induction of classical inflammatory mediators, including IL1-β and TNF-α, during early infection has led to the suggestion that F. tularensis evades detection by host innate immune surveillance and/or actively suppresses inflammation. To gain more insight into the host response to Francisella infection during the acute stage, transcriptomic analysis was performed on lung tissue from mice exposed to virulent (Francisella tularensis ssp tularensis SchuS4. Despite an extensive transcriptional response in the lungs of animals as early as 4 hrs post-exposure, Francisella tularensis was associated with an almost complete lack of induction of immune-related genes during the initial 24 hrs post-exposure. This broad subversion of innate immune responses was particularly evident when compared to the pulmonary inflammatory response induced by other lethal (Yersinia pestis and non-lethal (Legionella pneumophila, Pseudomonas aeruginosa pulmonary infections. However, the unique induction of a subset of inflammation-related genes suggests a role for dysregulation of lymphocyte function and anti-inflammatory pathways in the extreme virulence of Francisella. Subsequent activation of a classical inflammatory response 48 hrs post-exposure was associated with altered abundance of Francisella-specific transcripts, including those associated with bacterial surface components. In summary, virulent Francisella induces a unique pulmonary inflammatory response characterized by temporal regulation of innate immune pathways correlating with altered bacterial gene expression patterns. This study represents the first simultaneous measurement of both host and Francisella transcriptome changes that occur during in vivo infection and identifies potential bacterial virulence factors responsible for regulation of host inflammatory pathways.

  1. Protective immunity against tularemia provided by an adenovirus-vectored vaccine expressing Tul4 of Francisella tularensis.

    Science.gov (United States)

    Kaur, Ravinder; Chen, Shan; Arévalo, Maria T; Xu, Qingfu; Chen, Yanping; Zeng, Mingtao

    2012-03-01

    Francisella tularensis, a category A bioterrorism agent, is a highly infectious organism that is passed on via skin contact and inhalation routes. A live attenuated vaccine strain (LVS) has been developed, but it has not been licensed for public use by the FDA due to safety concerns. Thus, there exists a need for a safer and improved vaccine. In this study, we have constructed a replication-incompetent adenovirus, Ad/opt-Tul4, carrying a codon-optimized gene for expression of a membrane protein, Tul4, of F. tularensis LVS. Its ability to protect against lethal challenge and its immunogenicity were evaluated in a murine model. An intramuscular injection of a single dose (1 × 10(7) PFU) of Ad/opt-Tul4 elicited a robust Tul4-specific antibody response. Assays suggest a Th1-driven response. A single dose elicited 20% protection against challenge with 100 × 50% lethal dose (LD(50)) F. tularensis LVS; two additional booster shots resulted in 60% protection. In comparison, three doses of 5 μg recombinant Tul4 protein did not elicit significant protection against challenge. Therefore, the Ad/opt-Tul4 vaccine was more effective than the protein vaccine, and protection was dose dependent. Compared to LVS, the protection rate is lower, but an adenovirus-vectored vaccine may be more attractive due to its enhanced safety profile and mucosal route of delivery. Furthermore, simple genetic modification of the vaccine may potentially produce antibodies protective against a fully virulent strain of F. tularensis. Our data support the development and further research of an adenovirus-vectored vaccine against Tul4 of F. tularensis LVS.

  2. Complete genome sequence of Francisella tularensis subspecies holarctica FTNF002-00.

    Directory of Open Access Journals (Sweden)

    Ravi D Barabote

    Full Text Available Francisella tularensis subspecies holarctica FTNF002-00 strain was originally obtained from the first known clinical case of bacteremic F. tularensis pneumonia in Southern Europe isolated from an immunocompetent individual. The FTNF002-00 complete genome contains the RD(23 deletion and represents a type strain for a clonal population from the first epidemic tularemia outbreak in Spain between 1997-1998. Here, we present the complete sequence analysis of the FTNF002-00 genome. The complete genome sequence of FTNF002-00 revealed several large as well as small genomic differences with respect to two other published complete genome sequences of F. tularensis subsp. holarctica strains, LVS and OSU18. The FTNF002-00 genome shares >99.9% sequence similarity with LVS and OSU18, and is also approximately 5 MB smaller by comparison. The overall organization of the FTNF002-00 genome is remarkably identical to those of LVS and OSU18, except for a single 3.9 kb inversion in FTNF002-00. Twelve regions of difference ranging from 0.1-1.5 kb and forty-two small insertions and deletions were identified in a comparative analysis of FTNF002-00, LVS, and OSU18 genomes. Two small deletions appear to inactivate two genes in FTNF002-00 causing them to become pseudogenes; the intact genes encode a protein of unknown function and a drug:H(+ antiporter. In addition, we identified ninety-nine proteins in FTNF002-00 containing amino acid mutations compared to LVS and OSU18. Several non-conserved amino acid replacements were identified, one of which occurs in the virulence-associated intracellular growth locus subunit D protein. Many of these changes in FTNF002-00 are likely the consequence of direct selection that increases the fitness of this subsp. holarctica clone within its endemic population. Our complete genome sequence analyses lay the foundation for experimental testing of these possibilities.

  3. Nasal Acai Polysaccharides Potentiate Innate Immunity to Protect against Pulmonary Francisella tularensis and Burkholderia pseudomallei Infections

    OpenAIRE

    Skyberg, Jerod A.; Rollins, MaryClare F.; Holderness, Jeff S.; Marlenee, Nicole L.; Schepetkin, Igor A.; Goodyear, Andrew; Dow, Steven W.; Jutila, Mark A.; Pascual, David W.

    2012-01-01

    Pulmonary Francisella tularensis and Burkholderia pseudomallei infections are highly lethal in untreated patients, and current antibiotic regimens are not always effective. Activating the innate immune system provides an alternative means of treating infection and can also complement antibiotic therapies. Several natural agonists were screened for their ability to enhance host resistance to infection, and polysaccharides derived from the Acai berry (Acai PS) were found to have potent abilitie...

  4. Tularemia vaccine: Safety, reactogenicity, "Take" skin reactions, and antibody responses following vaccination with a new lot of the Francisella tularensis live vaccine strain - A phase 2 randomized clinical Trial.

    Science.gov (United States)

    Mulligan, Mark J; Stapleton, Jack T; Keitel, Wendy A; Frey, Sharon E; Chen, Wilbur H; Rouphael, Nadine; Edupuganti, Srilatha; Beck, Allison; Winokur, Patricia L; El Sahly, Hana M; Patel, Shital M; Atmar, Robert L; Graham, Irene; Anderson, Edwin; El-Kamary, Samer S; Pasetti, Marcela F; Sztein, Marcelo B; Hill, Heather; Goll, Johannes B

    2017-08-24

    Tularemia is caused by Francisella tularensis, a gram-negative bacterium that has been weaponized as an aerosol. For protection of personnel conducting biodefense research, the United States Army required clinical evaluation of a new lot of tularemia live vaccine strain manufactured in accordance with Current Good Manufacturing Practices. A phase 2 randomized clinical trial compared the new lot (DVC-LVS) to the existing vaccine that has been in use for decades (USAMRIID-LVS). The vaccines were delivered by scarification to 228 participants. Safety, reactogenicity, take and/or antibody levels were assessed on days 0, 1, 2, 8, 14, 28, 56, and 180. Both vaccines were safe and had acceptable reactogenicity profiles during six months of follow-up. There were no serious or grade 3 and 4 laboratory adverse events. Moderate systemic reactogenicity (mostly headache or feeling tired) was reported by ∼23% of participants receiving either vaccine. Injection site reactogenicity was mostly mild itchiness and pain. The frequencies of vaccine take skin reactions were 73% (95% CI, 64, 81) for DVC-LVS and 80% (95% CI, 71, 87) for USAMRIID-LVS. The 90% CI for the difference in proportions was -6.9% (-16.4, 2.6). The rates of seroconversion measured by microagglutination assay on days 28 or 56 were 94% (95% CI, 88, 98; n=98/104) for DVC-LVS and 94% (95% CI, 87, 97; n=103/110) for USAMRIID-LVS (p=1.00). Day 14 sera revealed more rapid seroconversion for DVC-LVS relative to USAMRIID-LVS: 82% (95% CI, 73, 89) versus 55% (95% CI, 45, 65), respectively (p<0.0001). The DVC-LVS vaccine had similar safety, reactogenicity, take and antibody responses compared to the older USAMRIID vaccine, and was superior for early (day 14) antibody production. Vaccination take was not a sensitive surrogate for seroconversion in a multi-center study where personnel at five research clinics performed assessments. ClinicalTrials.gov identifier NCT01150695. Copyright © 2017 The Authors. Published by Elsevier

  5. From the Outside-In: the Francisella tularensis Envelope and Virulence

    Directory of Open Access Journals (Sweden)

    Hannah M. Rowe

    2015-12-01

    Full Text Available Francisella tularensis is a highly-infectious bacterium that causes the rapid, and often lethal disease, tularemia. Many studies have been performed to identify and characterize the virulence factors that F. tularensis uses to infect a wide variety of hosts and host cell types, evade immune defenses, and induce severe disease and death. This review focuses on the virulence factors that are present in the F. tularensis envelope, including capsule, LPS, outer membrane, periplasm, inner membrane, secretion systems, and various molecules in each of aforementioned sub-compartments. Whereas no single bacterial molecule or molecular complex single-handedly controls F. tularensis virulence, we review here how diverse bacterial systems work in conjunction to subvert the immune system, attach to and invade host cells, alter phagosome/lysosome maturation pathways, replicate in host cells without being detected, inhibit apoptosis, and induce host cell death for bacterial release and infection of adjacent cells. Given that the F. tularensis envelope is the outermost layer of the bacterium, we highlight herein how many of these molecules directly interact with the host to promote infection and disease. These and future envelope studies are important to advance our collective understanding of F. tularensis virulence mechanisms and offer targets for future vaccine development efforts.

  6. The involvement of IL-17A in the murine response to sub-lethal inhalational infection with Francisella tularensis.

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    Gal Markel

    2010-06-01

    Full Text Available Francisella tularensis is an intercellular bacterium often causing fatal disease when inhaled. Previous reports have underlined the role of cell-mediated immunity and IFNgamma in the host response to Francisella tularensis infection.Here we provide evidence for the involvement of IL-17A in host defense to inhalational tularemia, using a mouse model of intranasal infection with the Live Vaccine Strain (LVS. We demonstrate the kinetics of IL-17A production in lavage fluids of infected lungs and identify the IL-17A-producing lymphocytes as pulmonary gammadelta and Th17 cells. The peak of IL-17A production appears early during sub-lethal infection, it precedes the peak of immune activation and the nadir of the disease, and then subsides subsequently. Exogenous airway administration of IL-17A or of IL-23 had a limited yet consistent effect of delaying the onset of death from a lethal dose of LVS, implying that IL-17A may be involved in restraining the infection. The protective role for IL-17A was directly demonstrated by in vivo neutralization of IL-17A. Administration of anti IL-17A antibodies concomitantly to a sub-lethal airway infection with 0.1xLD(50 resulted in a fatal disease.In summary, these data characterize the involvement and underline the protective key role of the IL-17A axis in the lungs from inhalational tularemia.

  7. Generation of a convalescent model of virulent Francisella tularensis infection for assessment of host requirements for survival of tularemia.

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    Deborah D Crane

    Full Text Available Francisella tularensis is a facultative intracellular bacterium and the causative agent of tularemia. Development of novel vaccines and therapeutics for tularemia has been hampered by the lack of understanding of which immune components are required to survive infection. Defining these requirements for protection against virulent F. tularensis, such as strain SchuS4, has been difficult since experimentally infected animals typically die within 5 days after exposure to as few as 10 bacteria. Such a short mean time to death typically precludes development, and therefore assessment, of immune responses directed against virulent F. tularensis. To enable identification of the components of the immune system that are required for survival of virulent F. tularensis, we developed a convalescent model of tularemia in C57Bl/6 mice using low dose antibiotic therapy in which the host immune response is ultimately responsible for clearance of the bacterium. Using this model we demonstrate αβTCR(+ cells, γδTCR(+ cells, and B cells are necessary to survive primary SchuS4 infection. Analysis of mice deficient in specific soluble mediators shows that IL-12p40 and IL-12p35 are essential for survival of SchuS4 infection. We also show that IFN-γ is required for survival of SchuS4 infection since mice lacking IFN-γR succumb to disease during the course of antibiotic therapy. Finally, we found that both CD4(+ and CD8(+ cells are the primary producers of IFN-γand that γδTCR(+ cells and NK cells make a minimal contribution toward production of this cytokine throughout infection. Together these data provide a novel model that identifies key cells and cytokines required for survival or exacerbation of infection with virulent F. tularensis and provides evidence that this model will be a useful tool for better understanding the dynamics of tularemia infection.

  8. The orange spotted cockroach (Blaptica dubia, Serville 1839) is a permissive experimental host for Francisella tularensis

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    Eklund, Bridget E.; Mahdi, Osama; Huntley, Jason F.; Collins, Elliot; Martin, Caleb; Horzempa, Joseph; Fisher, Nathan A.

    2018-01-01

    Francisella tularensis is a zoonotic bacterial pathogen that causes severe disease in a wide range of host animals, including humans. Well-developed murine models of F. tularensis pathogenesis are available, but they do not meet the needs of all investigators. However, researchers are increasingly turning to insect host systems as a cost-effective alternative that allows greater increased experimental throughput without the regulatory requirements associated with the use of mammals in biomedical research. Unfortunately, the utility of previously-described insect hosts is limited because of temperature restriction, short lifespans, and concerns about the immunological status of insects mass-produced for other purposes. Here, we present a novel host species, the orange spotted (OS) cockroach (Blaptica dubia), that overcomes these limitations and is readily infected by F. tularensis. Intrahemocoel inoculation was accomplished using standard laboratory equipment and lethality was directly proportional to the number of bacteria injected. Progression of infection differed in insects housed at low and high temperatures and F. tularensis mutants lacking key virulence components were attenuated in OS cockroaches. Finally, antibiotics were delivered to infected OS cockroaches by systemic injection and controlled feeding; in the latter case, protection correlated with oral bioavailability in mammals. Collectively, these results demonstrate that this new host system provides investigators with a new tool capable of interrogating F. tularensis virulence and immune evasion in situations where mammalian models are not available or appropriate, such as undirected screens of large mutant libraries. PMID:29578544

  9. Evidence Suggesting That Francisella tularensis O-Antigen Capsule Contains a Lipid A-Like Molecule That Is Structurally Distinct from the More Abundant Free Lipid A.

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    Jason H Barker

    Full Text Available Francisella tularensis, the Gram-negative bacterium that causes tularemia, produces a high molecular weight capsule that is immunologically distinct from Francisella lipopolysaccharide but contains the same O-antigen tetrasaccharide. To pursue the possibility that the capsule of Francisella live vaccine strain (LVS has a structurally unique lipid anchor, we have metabolically labeled Francisella with [14C]acetate to facilitate highly sensitive compositional analysis of capsule-associated lipids. Capsule was purified by two independent methods and yielded similar results. Autoradiographic and immunologic analysis confirmed that this purified material was largely devoid of low molecular weight LPS and of the copious amounts of free lipid A that the Francisellae accumulate. Chemical hydrolysis yielded [14C]-labeled free fatty acids characteristic of Francisella lipid A but with a different molar ratio of 3-OH C18:0 to 3-OH C16:0 and different composition of non-hydroxylated fatty acids (mainly C14:0 rather than C16:0 than that of free Francisella lipid A. Mild acid hydrolysis to induce selective cleavage of KDO-lipid A linkage yielded a [14C]-labeled product that partitioned during Bligh/Dyer extraction and migrated during thin-layer chromatography like lipid A. These findings suggest that the O-antigen capsule of Francisella contains a covalently linked and structurally distinct lipid A species. The presence of a discrete lipid A-like molecule associated with capsule raises the possibility that Francisella selectively exploits lipid A structural heterogeneity to regulate synthesis, transport, and stable bacterial surface association of the O-antigen capsular layer.

  10. Phylogeography of Francisella tularensis from Tibet, China: Evidence for an asian origin and radiation of holarctica-type Tularemia.

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    Lu, Yongfeng; Yu, Yonghui; Feng, Le; Li, Yanwei; He, Jun; Zhu, Hong; Duan, Qing; Song, Lihua

    2016-07-01

    The geographical origin and radiation of holarctica-type tularemia, which has spread across the northern hemisphere, is open to scientific debate. Here, through phylogenetics, we show that five Tibetan Francisella tularensis isolates subsp. holarctica cluster between basal-positioned Japanese isolates and all other subspecies strains in the world, providing evidence for a previously unknown intermediate lineage next to the Japanese isolates. Importantly, identification of this new intermediate lineage complements current knowledge of tularemia epidemiology, supporting a geographical origin and radiation of the subsp. holarctica in Asia. In addition, thirteen Tibetan isolates belonging to a clade previously found only in North America and Scandinavia, further increases the diversity of holarctica strains in Asia. In summary, this study provides evidence for an Asian origin and radiation of holarctica-type tularemia. Copyright © 2016 Elsevier GmbH. All rights reserved.

  11. Isolation and mutagenesis of a capsule-like complex (CLC from Francisella tularensis, and contribution of the CLC to F. tularensis virulence in mice.

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    Aloka B Bandara

    Full Text Available BACKGROUND: Francisella tularensis is a category-A select agent and is responsible for tularemia in humans and animals. The surface components of F. tularensis that contribute to virulence are not well characterized. An electron-dense capsule has been postulated to be present around F. tularensis based primarily on electron microscopy, but this specific antigen has not been isolated or characterized. METHODS AND FINDINGS: A capsule-like complex (CLC was effectively extracted from the cell surface of an F. tularensis live vaccine strain (LVS lacking O-antigen with 0.5% phenol after 10 passages in defined medium broth and growth on defined medium agar for 5 days at 32°C in 7% CO₂. The large molecular size CLC was extracted by enzyme digestion, ethanol precipitation, and ultracentrifugation, and consisted of glucose, galactose, mannose, and Proteinase K-resistant protein. Quantitative reverse transcriptase PCR showed that expression of genes in a putative polysaccharide locus in the LVS genome (FTL_1432 through FTL_1421 was upregulated when CLC expression was enhanced. Open reading frames FTL_1423 and FLT_1422, which have homology to genes encoding for glycosyl transferases, were deleted by allelic exchange, and the resulting mutant after passage in broth (LVSΔ1423/1422_P10 lacked most or all of the CLC, as determined by electron microscopy, and CLC isolation and analysis. Complementation of LVSΔ1423/1422 and subsequent passage in broth restored CLC expression. LVSΔ1423/1422_P10 was attenuated in BALB/c mice inoculated intranasally (IN and intraperitoneally with greater than 80 times and 270 times the LVS LD₅₀, respectively. Following immunization, mice challenged IN with over 700 times the LD₅₀ of LVS remained healthy and asymptomatic. CONCLUSIONS: Our results indicated that the CLC may be a glycoprotein, FTL_1422 and -FTL_1423 were involved in CLC biosynthesis, the CLC contributed to the virulence of F. tularensis LVS, and a CLC

  12. Francisella tularensis: No Evidence for Transovarial Transmission in the Tularemia Tick Vectors Dermacentor reticulatus and Ixodes ricinus

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    Genchi, Marco; Prati, Paola; Vicari, Nadia; Manfredini, Andrea; Sacchi, Luciano; Clementi, Emanuela; Bandi, Claudio; Epis, Sara; Fabbi, Massimo

    2015-01-01

    Background Tularemia is a zoonosis caused by the Francisella tularensis, a highly infectious Gram-negative coccobacillus. Due to easy dissemination, multiple routes of infection, high environmental contamination and morbidity and mortality rates, Francisella is considered a potential bioterrorism threat and classified as a category A select agent by the CDC. Tick bites are among the most prevalent modes of transmission, and ticks have been indicated as a possible reservoir, although their reservoir competence has yet to be defined. Tick-borne transmission of F. tularensis was recognized in 1923, and transstadial transmission has been demonstrated in several tick species. Studies on transovarial transmission, however, have reported conflicting results. Objective The aim of this study was to evaluate the role of ticks as reservoirs for Francisella, assessing the transovarial transmission of F. tularensis subsp. holarctica in ticks, using experimentally-infected females of Dermacentor reticulatus and Ixodes ricinus. Results Transmission electron microscopy and fluorescence in situ hybridization showed F. tularensis within oocytes. However, cultures and bioassays of eggs and larvae were negative; in addition, microscopy techniques revealed bacterial degeneration/death in the oocytes. Conclusions These results suggest that bacterial death might occur in oocytes, preventing the transovarial transmission of Francisella. We can speculate that Francisella does not have a defined reservoir, but that rather various biological niches (e.g. ticks, rodents), that allow the bacterium to persist in the environment. Our results, suggesting that ticks are not competent for the bacterium vertical transmission, are congruent with this view. PMID:26244842

  13. Francisella tularensis: No Evidence for Transovarial Transmission in the Tularemia Tick Vectors Dermacentor reticulatus and Ixodes ricinus.

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    Marco Genchi

    Full Text Available Tularemia is a zoonosis caused by the Francisella tularensis, a highly infectious Gram-negative coccobacillus. Due to easy dissemination, multiple routes of infection, high environmental contamination and morbidity and mortality rates, Francisella is considered a potential bioterrorism threat and classified as a category A select agent by the CDC. Tick bites are among the most prevalent modes of transmission, and ticks have been indicated as a possible reservoir, although their reservoir competence has yet to be defined. Tick-borne transmission of F. tularensis was recognized in 1923, and transstadial transmission has been demonstrated in several tick species. Studies on transovarial transmission, however, have reported conflicting results.The aim of this study was to evaluate the role of ticks as reservoirs for Francisella, assessing the transovarial transmission of F. tularensis subsp. holarctica in ticks, using experimentally-infected females of Dermacentor reticulatus and Ixodes ricinus.Transmission electron microscopy and fluorescence in situ hybridization showed F. tularensis within oocytes. However, cultures and bioassays of eggs and larvae were negative; in addition, microscopy techniques revealed bacterial degeneration/death in the oocytes.These results suggest that bacterial death might occur in oocytes, preventing the transovarial transmission of Francisella. We can speculate that Francisella does not have a defined reservoir, but that rather various biological niches (e.g. ticks, rodents, that allow the bacterium to persist in the environment. Our results, suggesting that ticks are not competent for the bacterium vertical transmission, are congruent with this view.

  14. Phylogeographical pattern of Francisella tularensis in a nationwide outbreak of tularaemia in Norway, 2011.

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    Afset, J E; Larssen, K W; Bergh, K; Larkeryd, A; Sjodin, A; Johansson, A; Forsman, M

    2015-05-14

    In 2011, a nationwide outbreak of tularaemia occurred in Norway with 180 recorded cases. It was associated with the largest peak in lemming density seen in 40 years. Francisella tularensis was isolated from 18 patients. To study the geographical distribution of F.tularensis genotypes in Norway and correlate genotype with epidemiology and clinical presentation,we performed whole genome sequencing of patient isolates. All 18 genomes from the outbreak carried genetic signatures of F. tularensis subsp. holarctica and were assigned to genetic clades using canonical single nucleotide polymorphisms. Ten isolates were assigned to major genetic clade B.6 (subclade B.7),seven to clade B.12, and one to clade B.4. The B.6 subclade B.7 was most common in southern and central Norway, while clade B.12 was evenly distributed between the southern, central and northern parts of the country. There was no association between genotype and clinical presentation of tularaemia, time of year or specimen type. We found extensive sequence similarity with F. tularensis subsp. holarctica genomes from high-endemic tularaemia areas in Sweden.Finding nearly identical genomes across large geographical distances in Norway and Sweden imply a life cycle of the bacterium without replication between the outbreaks and raise new questions about long-range migration mechanisms.

  15. Comparison of virulence of Francisella tularensis ssp. holarctica genotypes B.12 and B.FTNF002-00.

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    Kreizinger, Zsuzsa; Erdélyi, Károly; Felde, Orsolya; Fabbi, Massimo; Sulyok, Kinga M; Magyar, Tibor; Gyuranecz, Miklós

    2017-02-10

    Two main genetic groups (B.12 and B.FTNF002-00) of Francisella tularensis ssp. holarctica are endemic in Europe. The B.FTNF002-00 group proved to be dominant in Western European countries, while strains of the B.12 group were isolated mainly in Northern, Central and Eastern Europe. The clinical course of tularemia in the European brown hare (Lepus europaeus) also shows distinct patterns according to the geographical area. Acute course of the disease is observed in hares in Western European countries, while signs of sub-acute or chronic infection are more frequently detected in the eastern part of the continent. The aim of the present study was to examine whether there is any difference in the virulence of the strains belonging to the B.FTNF002-00 and B.12 genetic clades. Experimental infection of Fischer 344 rats was performed by intra-peritoneal injection of three dilutions of a Hungarian (B.12 genotype) and an Italian (B.FTNF002-00 genotype) F. tularensis ssp. holarctica strain. Moderate difference was observed in the virulence of the two genotypes. Significant differences were observed in total weight loss values and scores of clinical signs between the two genotypes with more rats succumbing to tularemia in groups infected with the B.FTNF002-00 genotype. Results of the experimental infection are consistent with previous clinical observations and pathological studies suggesting that F. tularensis ssp. holarctica genotype B.FTNF002-00 has higher pathogenic potential than the B.12 genotype.

  16. The Multiple Localized Glyceraldehyde-3-Phosphate Dehydrogenase Contributes to the Attenuation of the Francisella tularensis dsbA Deletion Mutant

    Czech Academy of Sciences Publication Activity Database

    Pavkova, I.; Kopečková, M.; Klimentová, J.; Schmidt, M.; Sheshko, V.; Sobol, Margaryta; Žáková, J.; Hozák, Pavel; Stulík, J.

    2017-01-01

    Roč. 7, zima (2017), č. článku 503. ISSN 2235-2988 Institutional support: RVO:68378050 Keywords : DsbA * SILAC * glyceraldehyde-3-phosphate dehydrogenase * Francisella tularensis * moonlighting Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Biochemistry and molecular biology Impact factor: 4.300, year: 2016

  17. An outbreak of respiratory tularemia caused by diverse clones of Francisella tularensis.

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    Johansson, Anders; Lärkeryd, Adrian; Widerström, Micael; Mörtberg, Sara; Myrtännäs, Kerstin; Ohrman, Caroline; Birdsell, Dawn; Keim, Paul; Wagner, David M; Forsman, Mats; Larsson, Pär

    2014-12-01

    The bacterium Francisella tularensis is recognized for its virulence, infectivity, genetic homogeneity, and potential as a bioterrorism agent. Outbreaks of respiratory tularemia, caused by inhalation of this bacterium, are poorly understood. Such outbreaks are exceedingly rare, and F. tularensis is seldom recovered from clinical specimens. A localized outbreak of tularemia in Sweden was investigated. Sixty-seven humans contracted laboratory-verified respiratory tularemia. F. tularensis subspecies holarctica was isolated from the blood or pleural fluid of 10 individuals from July to September 2010. Using whole-genome sequencing and analysis of single-nucleotide polymorphisms (SNPs), outbreak isolates were compared with 110 archived global isolates. There were 757 SNPs among the genomes of the 10 outbreak isolates and the 25 most closely related archival isolates (all from Sweden/Finland). Whole genomes of outbreak isolates were >99.9% similar at the nucleotide level and clustered into 3 distinct genetic clades. Unexpectedly, high-sequence similarity grouped some outbreak and archival isolates that originated from patients from different geographic regions and up to 10 years apart. Outbreak and archival genomes frequently differed by only 1-3 of 1 585 229 examined nucleotides. The outbreak was caused by diverse clones of F. tularensis that occurred concomitantly, were widespread, and apparently persisted in the environment. Multiple independent acquisitions of F. tularensis from the environment over a short time period suggest that natural outbreaks of respiratory tularemia are triggered by environmental cues. The findings additionally caution against interpreting genome sequence identity for this pathogen as proof of a direct epidemiological link. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  18. Vaccine-Mediated Mechanisms Controlling Replication of Francisella tularensis in Human Peripheral Blood Mononuclear Cells Using a Co-culture System

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    Kjell Eneslätt

    2018-02-01

    Full Text Available Cell-mediated immunity (CMI is normally required for efficient protection against intracellular infections, however, identification of correlates is challenging and they are generally lacking. Francisella tularensis is a highly virulent, facultative intracellular bacterium and CMI is critically required for protection against the pathogen, but how this is effectuated in humans is poorly understood. To understand the protective mechanisms, we established an in vitro co-culture assay to identify how control of infection of F. tularensis is accomplished by human cells and hypothesized that the model will mimic in vivo immune mechanisms. Non-adherent peripheral blood mononuclear cells (PBMCs were expanded with antigen and added to cultures with adherent PBMC infected with the human vaccine strain, LVS, or the highly virulent SCHU S4 strain. Intracellular numbers of F. tularensis was followed for 72 h and secreted and intracellular cytokines were analyzed. Addition of PBMC expanded from naïve individuals, i.e., those with no record of immunization to F. tularensis, generally resulted in little or no control of intracellular bacterial growth, whereas addition of PBMC from a majority of F. tularensis-immune individuals executed static and sometimes cidal effects on intracellular bacteria. Regardless of infecting strain, statistical differences between the two groups were significant, P < 0.05. Secretion of 11 cytokines was analyzed after 72 h of infection and significant differences with regard to secretion of IFN-γ, TNF, and MIP-1β was observed between immune and naïve individuals for LVS-infected cultures. Also, in LVS-infected cultures, CD4 T cells from vaccinees, but not CD8 T cells, showed significantly higher expression of IFN-γ, MIP-1β, TNF, and CD107a than cells from naïve individuals. The co-culture system appears to identify correlates of immunity that are relevant for the understanding of mechanisms of the protective host immunity to

  19. Automated microfluidically controlled electrochemical biosensor for the rapid and highly sensitive detection of Francisella tularensis.

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    Dulay, Samuel B; Gransee, Rainer; Julich, Sandra; Tomaso, Herbert; O'Sullivan, Ciara K

    2014-09-15

    Tularemia is a highly infectious zoonotic disease caused by a Gram-negative coccoid rod bacterium, Francisella tularensis. Tularemia is considered as a life-threatening potential biological warfare agent due to its high virulence, transmission, mortality and simplicity of cultivation. In the work reported here, different electrochemical immunosensor formats for the detection of whole F. tularensis bacteria were developed and their performance compared. An anti-Francisella antibody (FB11) was used for the detection that recognises the lipopolysaccharide found in the outer membrane of the bacteria. In the first approach, gold-supported self-assembled monolayers of a carboxyl terminated bipodal alkanethiol were used to covalently cross-link with the FB11 antibody. In an alternative second approach F(ab) fragments of the FB11 antibody were generated and directly chemisorbed onto the gold electrode surface. The second approach resulted in an increased capture efficiency and higher sensitivity. Detection limits of 4.5 ng/mL for the lipopolysaccharide antigen and 31 bacteria/mL for the F. tularensis bacteria were achieved. Having demonstrated the functionality of the immunosensor, an electrode array was functionalised with the antibody fragment and integrated with microfluidics and housed in a tester set-up that facilitated complete automation of the assay. The only end-user intervention is sample addition, requiring less than one-minute hands-on time. The use of the automated microfluidic set-up not only required much lower reagent volumes but also the required incubation time was considerably reduced and a notable increase of 3-fold in assay sensitivity was achieved with a total assay time from sample addition to read-out of less than 20 min. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. The Multiple Localized Glyceraldehyde-3-Phosphate Dehydrogenase Contributes to the Attenuation of the Francisella tularensis dsbA Deletion Mutant

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    Ivona Pavkova

    2017-12-01

    Full Text Available The DsbA homolog of Francisella tularensis was previously demonstrated to be required for intracellular replication and animal death. Disruption of the dsbA gene leads to a pleiotropic phenotype that could indirectly affect a number of different cellular pathways. To reveal the broad effects of DsbA, we compared fractions enriched in membrane proteins of the wild-type FSC200 strain with the dsbA deletion strain using a SILAC-based quantitative proteomic analysis. This analysis enabled identification of 63 proteins with significantly altered amounts in the dsbA mutant strain compared to the wild-type strain. These proteins comprise a quite heterogeneous group including hypothetical proteins, proteins associated with membrane structures, and potential secreted proteins. Many of them are known to be associated with F. tularensis virulence. Several proteins were selected for further studies focused on their potential role in tularemia's pathogenesis. Of them, only the gene encoding glyceraldehyde-3-phosphate dehydrogenase, an enzyme of glycolytic pathway, was found to be important for full virulence manifestations both in vivo and in vitro. We next created a viable mutant strain with deleted gapA gene and analyzed its phenotype. The gapA mutant is characterized by reduced virulence in mice, defective replication inside macrophages, and its ability to induce a protective immune response against systemic challenge with parental wild-type strain. We also demonstrate the multiple localization sites of this protein: In addition to within the cytosol, it was found on the cell surface, outside the cells, and in the culture medium. Recombinant GapA was successfully obtained, and it was shown that it binds host extracellular serum proteins like plasminogen, fibrinogen, and fibronectin.

  1. The human-bacterial pathogen protein interaction networks of Bacillus anthracis, Francisella tularensis, and Yersinia pestis.

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    Matthew D Dyer

    2010-08-01

    Full Text Available Bacillus anthracis, Francisella tularensis, and Yersinia pestis are bacterial pathogens that can cause anthrax, lethal acute pneumonic disease, and bubonic plague, respectively, and are listed as NIAID Category A priority pathogens for possible use as biological weapons. However, the interactions between human proteins and proteins in these bacteria remain poorly characterized leading to an incomplete understanding of their pathogenesis and mechanisms of immune evasion.In this study, we used a high-throughput yeast two-hybrid assay to identify physical interactions between human proteins and proteins from each of these three pathogens. From more than 250,000 screens performed, we identified 3,073 human-B. anthracis, 1,383 human-F. tularensis, and 4,059 human-Y. pestis protein-protein interactions including interactions involving 304 B. anthracis, 52 F. tularensis, and 330 Y. pestis proteins that are uncharacterized. Computational analysis revealed that pathogen proteins preferentially interact with human proteins that are hubs and bottlenecks in the human PPI network. In addition, we computed modules of human-pathogen PPIs that are conserved amongst the three networks. Functionally, such conserved modules reveal commonalities between how the different pathogens interact with crucial host pathways involved in inflammation and immunity.These data constitute the first extensive protein interaction networks constructed for bacterial pathogens and their human hosts. This study provides novel insights into host-pathogen interactions.

  2. Nonrandom distribution of vector ticks (Dermacentor variabilis infected by Francisella tularensis.

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    Heidi K Goethert

    2009-02-01

    Full Text Available The island of Martha's Vineyard, Massachusetts, is the site of a sustained outbreak of tularemia due to Francisella tularensis tularensis. Dog ticks, Dermacentor variabilis, appear to be critical in the perpetuation of the agent there. Tularemia has long been characterized as an agent of natural focality, stably persisting in characteristic sites of transmission, but this suggestion has never been rigorously tested. Accordingly, we sought to identify a natural focus of transmission of the agent of tularemia by mapping the distribution of PCR-positive ticks. From 2004 to 2007, questing D. variabilis were collected from 85 individual waypoints along a 1.5 km transect in a field site on Martha's Vineyard. The positions of PCR-positive ticks were then mapped using ArcGIS. Cluster analysis identified an area approximately 290 meters in diameter, 9 waypoints, that was significantly more likely to yield PCR-positive ticks (relative risk 3.3, P = 0.001 than the rest of the field site. Genotyping of F. tularensis using variable number tandem repeat (VNTR analysis on PCR-positive ticks yielded 13 different haplotypes, the vast majority of which was one dominant haplotype. Positive ticks collected in the cluster were 3.4 times (relative risk = 3.4, P<0.0001 more likely to have an uncommon haplotype than those collected elsewhere from the transect. We conclude that we have identified a microfocus where the agent of tularemia stably perpetuates and that this area is where genetic diversity is generated.

  3. Lymphotoxin-α Plays Only a Minor Role in Host Resistance to Respiratory Infection with Virulent Type A Francisella tularensis in Mice

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    Deng Zhang

    2008-01-01

    Full Text Available This study examined the role of lymphotoxin (LT-α in host defense against airborne infection with Francisella tularensis, a gram-negative facultative intracellular bacterium and the causative agent of tularemia. Following a low-dose aerosol infection with the highly virulent type A strain of F. tularensis, mice deficient in LT α (LTα−/− consistently harbored approximately 10-fold fewer bacteria in their spleens at day 2 and 10-fold more bacteria in their lungs at day 4 than LTα+/+ mice. However, the mortality and median time to death were indistinguishable between the two mouse strains. In addition, the inflammatory responses to the infection, as reflected by the cytokine levels and leukocyte influx in the bronchoalveolar lavage fluid and histopathological analysis, were generally similar between LTα−/− and LTα+/+ mice. These data suggest that although LTα does not contribute significantly to the resistance and host responses of mice to airborne type A F. tularensis infection, it does play a subtle role in the multiplication/dissemination of F. tularensis.

  4. Serological evidence of Francisella tularensis in febrile patients seeking treatment at remote hospitals, northeastern Kenya, 2014–2015

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    J. Njeru

    2017-09-01

    Full Text Available Tularaemia is a highly contagious infectious zoonosis caused by the bacterial agent Francisella tularensis. The aim of this study was to investigate the presence of antibodies to F. tularensis in febrile patients in northeastern Kenya. During 2014–2015, 730 patients were screened for anti-F. tularensis antibodies using a combination of ELISA and Western blot. Twenty-seven (3.7% individuals were positive for F. tularensis. Tularaemia was not suspected by the treating clinicians in any of them. Our results suggest that tularaemia may be present in Kenya but remain unreported, and emphasizes the need for local clinicians to broaden their diagnostic repertoire when evaluating patients with undifferentiated febrile illness.

  5. Host-adaptation of Francisella tularensis alters the bacterium's surface-carbohydrates to hinder effectors of innate and adaptive immunity.

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    Tiffany M Zarrella

    Full Text Available The gram-negative bacterium Francisella tularensis survives in arthropods, fresh water amoeba, and mammals with both intracellular and extracellular phases and could reasonably be expected to express distinct phenotypes in these environments. The presence of a capsule on this bacterium has been controversial with some groups finding such a structure while other groups report that no capsule could be identified. Previously we reported in vitro culture conditions for this bacterium which, in contrast to typical methods, yielded a bacterial phenotype that mimics that of the bacterium's mammalian, extracellular phase.SDS-PAGE and carbohydrate analysis of differentially-cultivated F. tularensis LVS revealed that bacteria displaying the host-adapted phenotype produce both longer polymers of LPS O-antigen (OAg and additional HMW carbohydrates/glycoproteins that are reduced/absent in non-host-adapted bacteria. Analysis of wildtype and OAg-mutant bacteria indicated that the induced changes in surface carbohydrates involved both OAg and non-OAg species. To assess the impact of these HMW carbohydrates on the access of outer membrane constituents to antibody we used differentially-cultivated bacteria in vitro to immunoprecipitate antibodies directed against outer membrane moieties. We observed that the surface-carbohydrates induced during host-adaptation shield many outer membrane antigens from binding by antibody. Similar assays with normal mouse serum indicate that the induced HMW carbohydrates also impede complement deposition. Using an in vitro macrophage infection assay, we find that the bacterial HMW carbohydrate impedes TLR2-dependent, pro-inflammatory cytokine production by macrophages. Lastly we show that upon host-adaptation, the human-virulent strain, F. tularensis SchuS4 also induces capsule production with the effect of reducing macrophage-activation and accelerating tularemia pathogenesis in mice.F. tularensis undergoes host-adaptation which

  6. Further Characterization of the Capsule-Like Complex (CLC Produced by Francisella tularensis Subspecies tularensis: Protective Efficacy and Similarity to Outer Membrane Vesicles

    Directory of Open Access Journals (Sweden)

    Anna E. Champion

    2018-06-01

    Full Text Available Francisella tularensis is the etiologic agent of tularemia, and subspecies tularensis (type A is the most virulent subspecies. The live vaccine strain (LVS of subspecies holarctica produces a capsule-like complex (CLC that consists of a large variety of glycoproteins. Expression of the CLC is greatly enhanced when the bacteria are subcultured in and grown on chemically defined medium. Deletion of two genes responsible for CLC glycosylation in LVS results in an attenuated mutant that is protective against respiratory tularemia in a mouse model. We sought to further characterize the CLC composition and to determine if a type A CLC glycosylation mutant would be attenuated in mice. The CLCs isolated from LVS extracted with 0.5% phenol or 1 M urea were similar, as determined by gel electrophoresis and Western blotting, but the CLC extracted with urea was more water-soluble. The CLC extracted with either 0.5% phenol or 1 M urea from type A strains was also similar to the CLC of LVS in antigenic properties, electrophoretic profile, and by transmission electron microscopy (TEM. The solubility of the CLC could be further enhanced by fractionation with Triton X-114 followed by N-Lauroylsarcosine detergents; the largest (>250 kDa molecular size component appeared to be an aggregate of smaller components. Outer membrane vesicles/tubules (OMV/T isolated by differential centrifugation and micro-filtration appeared similar to the CLC by TEM, and many of the proteins present in the OMV/T were also identified in soluble and insoluble fractions of the CLC. Further investigation is warranted to assess the relationship between OMV/T and the CLC. The CLC conjugated to keyhole limpet hemocyanin or flagellin was highly protective against high-dose LVS intradermal challenge and partially protective against intranasal challenge. A protective response was associated with a significant rise in cytokines IL-12, IL-10, and IFN-γ. However, a type A CLC glycosylation mutant

  7. Re-emergence of tularemia in Germany: Presence of Francisella tularensis in different rodent species in endemic areas

    Directory of Open Access Journals (Sweden)

    Pfeffer Martin

    2008-11-01

    Full Text Available Abstract Background Tularemia re-emerged in Germany starting in 2004 (with 39 human cases from 2004 to 2007 after over 40 years of only sporadic human infections. The reasons for this rise in case numbers are unknown as is the possible reservoir of the etiologic agent Francisella (F. tularensis. No systematic study on the reservoir situation of F. tularensis has been published for Germany so far. Methods We investigated three areas six to ten months after the initial tularemia outbreaks for the presence of F. tularensis among small mammals, ticks/fleas and water. The investigations consisted of animal live-trapping, serologic testing, screening by real-time-PCR and cultivation. Results A total of 386 small mammals were trapped. F. tularensis was detected in five different rodent species with carrier rates of 2.04, 6.94 and 10.87% per trapping area. None of the ticks or fleas (n = 432 tested positive for F. tularensis. We were able to demonstrate F. tularensis-specific DNA in one of 28 water samples taken in one of the outbreak areas. Conclusion The findings of our study stress the need for long-term surveillance of natural foci in order to get a better understanding of the reasons for the temporal and spatial patterns of tularemia in Germany.

  8. IL-23 p19 knockout mice exhibit minimal defects in responses to primary and secondary infection with Francisella tularensis LVS.

    Directory of Open Access Journals (Sweden)

    Sherry L Kurtz

    Full Text Available Our laboratory's investigations into mechanisms of protective immunity against Francisella tularensis Live Vaccine Strain (LVS have uncovered mediators important in host defense against primary infection, as well as those correlated with successful vaccination. One such potential correlate was IL-12p40, a pleiotropic cytokine that promotes Th1 T cell function as part of IL-12p70. LVS-infected IL-12p40 deficient knockout (KO mice maintain a chronic infection, but IL-12p35 KO mice clear LVS infection; thus the role that IL-12p40 plays in immunity to LVS is independent of the IL-12p70 heterodimer. IL-12p40 can also partner with IL-23p19 to create the heterodimeric cytokine IL-23. Here, we directly tested the role of IL-23 in LVS resistance, and found IL-23 to be largely dispensable for immunity to LVS following intradermal or intranasal infection. IL-23p19 KO splenocytes were fully competent in controlling intramacrophage LVS replication in an in vitro overlay assay. Further, antibody responses in IL-23p19 KO mice were similar to those of normal wild type mice after LVS infection. IL-23p19 KO mice or normal wild type mice that survived primary LVS infection survived maximal doses of LVS secondary challenge. Thus p40 has a novel role in clearance of LVS infection that is unrelated to either IL-12 or IL-23.

  9. Human Dose-Response Data for Francisella tularensis and a Dose- and Time-Dependent Mathematical Model of Early-Phase Fever Associated with Tularemia After Inhalation Exposure.

    Science.gov (United States)

    McClellan, Gene; Coleman, Margaret; Crary, David; Thurman, Alec; Thran, Brandolyn

    2018-04-25

    Military health risk assessors, medical planners, operational planners, and defense system developers require knowledge of human responses to doses of biothreat agents to support force health protection and chemical, biological, radiological, nuclear (CBRN) defense missions. This article reviews extensive data from 118 human volunteers administered aerosols of the bacterial agent Francisella tularensis, strain Schu S4, which causes tularemia. The data set includes incidence of early-phase febrile illness following administration of well-characterized inhaled doses of F. tularensis. Supplemental data on human body temperature profiles over time available from de-identified case reports is also presented. A unified, logically consistent model of early-phase febrile illness is described as a lognormal dose-response function for febrile illness linked with a stochastic time profile of fever. Three parameters are estimated from the human data to describe the time profile: incubation period or onset time for fever; rise time of fever; and near-maximum body temperature. Inhaled dose-dependence and variability are characterized for each of the three parameters. These parameters enable a stochastic model for the response of an exposed population through incorporation of individual-by-individual variability by drawing random samples from the statistical distributions of these three parameters for each individual. This model provides risk assessors and medical decisionmakers reliable representations of the predicted health impacts of early-phase febrile illness for as long as one week after aerosol exposures of human populations to F. tularensis. © 2018 Society for Risk Analysis.

  10. Lipids Derived from Virulent Francisella tularensis Broadly Inhibit Pulmonary Inflammation via Toll-Like Receptor 2 and Peroxisome Proliferator-Activated Receptor α

    Science.gov (United States)

    Crane, Deborah D.; Ireland, Robin; Alinger, Joshua B.; Small, Pamela

    2013-01-01

    Francisella tularensis is a Gram-negative facultative intracellular pathogen that causes an acute lethal respiratory disease in humans. The heightened virulence of the pathogen is linked to its unique ability to inhibit Toll-like receptor (TLR)-mediated inflammatory responses. The bacterial component and mechanism of this inhibition are unknown. Here we show that lipids isolated from virulent but not attenuated strains of F. tularensis are not detected by host cells, inhibit production of proinflammatory cytokines by primary macrophages in response to known TLR ligands, and suppress neutrophil recruitment in vivo. We further show that lipid-mediated inhibition of inflammation is dependent on TLR2, MyD88, and the nuclear hormone and fatty acid receptor peroxisome proliferator-activated receptor α (PPARα). Pathogen lipid-mediated interference with inflammatory responses through the engagement of TLR2 and PPARα represents a novel manipulation of host signaling pathways consistent with the ability of highly virulent F. tularensis to efficiently evade host immune responses. PMID:23925884

  11. Detection of Francisella tularensis-Specific Antibodies in Patients with Tularemia by a Novel Competitive Enzyme-Linked Immunosorbent Assay

    Science.gov (United States)

    Sharma, Neekun; Hotta, Akitoyo; Yamamoto, Yoshie; Fujita, Osamu; Uda, Akihiko; Morikawa, Shigeru; Yamada, Akio

    2013-01-01

    A novel competitive enzyme-linked immunosorbent assay (cELISA) was developed and evaluated for detection of antibodies against Francisella tularensis in humans. The assay is based on the ability of serum antibodies to inhibit the binding of monoclonal antibodies (MAbs) directed against F. tularensis lipopolysaccharide antigens. The assay was evaluated using serum samples of tularemia patients, inactivated F. tularensis-immunized rabbits, and F. tularensis-infected mice. Antibodies against F. tularensis were successfully detected in serum samples of tularemia patients as well as the immunized and infected animals. The cELISA method was compared to indirect ELISA (iELISA) and the commonly used microagglutination test (MA) using serum samples of 19 tularemia patients and 50 healthy individuals. The sensitivity and specificity of cELISA were 93.9 and 96.1%, respectively, in comparison to the iELISA. MA was less sensitive than cELISA with a sensitivity and specificity of only 81.8 and 98.0%, respectively. A high degree of correlation (R2 = 0.8226) was observed between cELISA and iELISA results. The novel cELISA developed in this study appears to be highly sensitive and specific for serodiagnosis of human tularemia. The potential of the MAb-based cELISA to be used in both human and animal samples emphasizes its usefulness for serological survey of tularemia among multiple animal species. PMID:23114700

  12. A Spontaneous Mutation in kdsD, a Biosynthesis Gene for 3-Deoxy-D-manno-Octulosonic Acid, Occurred in a Ciprofloxacin Resistant Strain of Francisella tularensis and Causes a High Level of Attenuation in Murine Models of Tularemia

    Science.gov (United States)

    2016-08-30

    often associated with areas of tissue necrosis . These random 339 areas of neutrophilic inflammation are consistent with embolic ( vascular ) spread of F...colonization of tissues and associated tissue necrosis . For mice on day 5 post-exposure, 342 classic lesions consistent with acute to subacute infection...with F. tularensis were observed (Fig. 8). These 343 lesions consisted of random foci of lytic necrosis in the liver, spleen, lungs, and lymph nodes

  13. About three cases of ulceroglandular tularemia, is this the re-emergence of Francisella tularensis in Belgium?

    Science.gov (United States)

    Dupont, E; Van Eeckhoudt, S; Thissen, X; Ausselet, N; Fretin, D; Stefanescu, I; Glupczynski, Y; Delaere, B

    2015-10-01

    Tularemia is a zoonosis caused by Francisella tularensis that can be transmitted by several ways to human being and cause different clinical manifestations. We report three clinical cases of tularemia with ulceroglandular presentation in young males acquired during outdoor activities in Southern Belgium. Confirmation of the diagnosis was established by serology. Only three cases of tularemia have been reported in Belgium between 1950 and 2012 by the National Reference Laboratory CODA-CERVA (Ref Lab CODA-CERVA) but re-emergence of tularemia is established in several European countries and F. tularensis is also well known to be present in animal reservoirs and vectors in Belgium. The diagnosis of tularemia has to be considered in case of suggestive clinical presentation associated with epidemiological risk factors.

  14. Quantitative Proteomics Analysis of Macrophage-Derived Lipid Rafts Reveals Induction of Autophagy Pathway at the Early Time of Francisella tularensis LVS Infection

    Czech Academy of Sciences Publication Activity Database

    Hartlová, A.; Link, M.; Balounová, Jana; Benešová, Martina; Resch, U.; Strašková, A.; Sobol, Margaryta; Filimonenko, Anatolij; Hozák, Pavel; Krocová, Z.; Gekara, N.; Filipp, Dominik; Stulík, J.

    2014-01-01

    Roč. 13, č. 2 (2014), s. 796-804 ISSN 1535-3893 R&D Projects: GA MO(CZ) OVUOFVZ200808 Institutional support: RVO:68378050 Keywords : innate immune response * bacterial infection * lipid rafts * Francisella tularensis * phagocytosis * autophagy Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.245, year: 2014

  15. FmvB: A Francisella tularensis Magnesium-Responsive Outer Membrane Protein that Plays a Role in Virulence.

    Directory of Open Access Journals (Sweden)

    Xiaojun Wu

    Full Text Available Francisella tularensis is the causative agent of the lethal disease tularemia. Despite decades of research, little is understood about why F. tularensis is so virulent. Bacterial outer membrane proteins (OMPs are involved in various virulence processes, including protein secretion, host cell attachment, and intracellular survival. Many pathogenic bacteria require metals for intracellular survival and OMPs often play important roles in metal uptake. Previous studies identified three F. tularensis OMPs that play roles in iron acquisition. In this study, we examined two previously uncharacterized proteins, FTT0267 (named fmvA, for Francisella metal and virulence and FTT0602c (fmvB, which are homologs of the previously studied F. tularensis iron acquisition genes and are predicted OMPs. To study the potential roles of FmvA and FmvB in metal acquisition and virulence, we first examined fmvA and fmvB expression following pulmonary infection of mice, finding that fmvB was upregulated up to 5-fold during F. tularensis infection of mice. Despite sequence homology to previously-characterized iron-acquisition genes, FmvA and FmvB do not appear to be involved iron uptake, as neither fmvA nor fmvB were upregulated in iron-limiting media and neither ΔfmvA nor ΔfmvB exhibited growth defects in iron limitation. However, when other metals were examined in this study, magnesium-limitation significantly induced fmvB expression, ΔfmvB was found to express significantly higher levels of lipopolysaccharide (LPS in magnesium-limiting medium, and increased numbers of surface protrusions were observed on ΔfmvB in magnesium-limiting medium, compared to wild-type F. tularensis grown in magnesium-limiting medium. RNA sequencing analysis of ΔfmvB revealed the potential mechanism for increased LPS expression, as LPS synthesis genes kdtA and wbtA were significantly upregulated in ΔfmvB, compared with wild-type F. tularensis. To provide further evidence for the potential

  16. Azithromycin effectiveness against intracellular infections of Francisella

    Directory of Open Access Journals (Sweden)

    Mann Barbara J

    2010-04-01

    Full Text Available Abstract Background Macrolide antibiotics are commonly administered for bacterial respiratory illnesses. Azithromycin (Az is especially noted for extremely high intracellular concentrations achieved within macrophages which is far greater than the serum concentration. Clinical strains of Type B Francisella (F. tularensis have been reported to be resistant to Az, however our laboratory Francisella strains were found to be sensitive. We hypothesized that different strains/species of Francisella (including Type A may have different susceptibilities to Az, a widely used and well-tolerated antibiotic. Results In vitro susceptibility testing of Az confirmed that F. tularensis subsp. holarctica Live Vaccine Strain (LVS (Type B was not sensitive while F. philomiragia, F. novicida, and Type A F. tularensis (NIH B38 and Schu S4 strain were susceptible. In J774A.1 mouse macrophage cells infected with F. philomiragia, F. novicida, and F. tularensis LVS, 5 μg/ml Az applied extracellularly eliminated intracellular Francisella infections. A concentration of 25 μg/ml Az was required for Francisella-infected A549 human lung epithelial cells, suggesting that macrophages are more effective at concentrating Az than epithelial cells. Mutants of RND efflux components (tolC and ftlC in F. novicida demonstrated less sensitivity to Az by MIC than the parental strain, but the tolC disc-inhibition assay demonstrated increased sensitivity, indicating a complex role for the outer-membrane transporter. Mutants of acrA and acrB mutants were less sensitive to Az than the parental strain, suggesting that AcrAB is not critical for the efflux of Az in F. novicida. In contrast, F. tularensis Schu S4 mutants ΔacrB and ΔacrA were more sensitive than the parental strain, indicating that the AcrAB may be important for Az efflux in F. tularensis Schu S4. F. novicida LPS O-antigen mutants (wbtN, wbtE, wbtQ and wbtA were found to be less sensitive in vitro to Az compared to the wild

  17. A Molecular Survey for Francisella tularensis and Rickettsia spp. in Haemaphysalis leporispalustris (Acari: Ixodidae) in Northern California.

    Science.gov (United States)

    Roth, Tara; Lane, Robert S; Foley, Janet

    2017-03-01

    Francisella tularensis and Rickettsia spp. have been cultured from Haemaphysalis leporispalustris Packard, but their prevalence in this tick has not been determined using modern molecular methods. We collected H. leporispalustris by flagging vegetation and leaf litter and from lagomorphs (Lepus californicus Gray and Sylvilagus bachmani (Waterhouse)) in northern California. Francisella tularensis DNA was not detected in any of 1,030 ticks tested by polymerase chain reaction (PCR), whereas 0.4% of larvae tested in pools, 0 of 117 individual nymphs, and 2.3% of 164 adult ticks were PCR-positive for Rickettsia spp. Positive sites were Laurel Canyon Trail in Tilden Regional Park in Alameda Contra Costa County, with a Rickettsia spp. prevalence of 0.6% in 2009, and Hopland Research and Extension Center in Mendocino County, with a prevalence of 4.2% in 1988. DNA sequencing revealed R. felis, the agent of cat-flea typhus, in two larval pools from shaded California bay and live oak leaf litter in Contra Costa County and one adult tick from a L. californicus in chaparral in Mendocino County. The R. felis in unfed, questing larvae demonstrates that H. leporispalustris can transmit this rickettsia transovarially. Although R. felis is increasingly found in diverse arthropods and geographical regions, prior literature suggests a typical epidemiological cycle involving mesocarnivores and the cat flea, Ctenocephalides felis. To our knowledge, this is the first report of R. felis in H. leporispalustris. Natural infection and transovarial transmission of this pathogen in the tick indicate the existence of a previously undocumented wild-lands transmission cycle that may intersect mesocarnivore-reservoired cycles and collectively affect human health risk. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. 3-Substituted Indole Inhibitors Against Francisella tularensis FabI Identified by Structure-Based Virtual Screening

    Science.gov (United States)

    2013-07-01

    and incubation at 35 ± 2 °C on agar plates using starting samples removed from freezer stocks of each strain. Chocolate agar was used for F. tularensis...potential massive use of antimicrobial agents as prophylaxis or therapy of a bioterrorist attack. Clin. Microbiol. Infect. 2002, 8, 534−539. (11) Loveless, B

  19. Structure of the Francisella tularensis enoyl-acyl carrier protein reductase (FabI) in complex with NAD+ and triclosan

    International Nuclear Information System (INIS)

    Mehboob, Shahila; Truong, Kent; Santarsiero, Bernard D.; Johnson, Michael E.

    2010-01-01

    Structure of the ternary complex of F. tularensis enoyl-acyl carrier protein reductase reveals the structure of the substrate binding loop whose electron density was missing in an earlier structure, and demonstrates a shift in the position of the NAD + cofactor. Enoyl-acyl carrier protein reductase (FabI) catalyzes the last rate-limiting step in the elongation cycle of the fatty-acid biosynthesis pathway and has been validated as a potential antimicrobial drug target in Francisella tularensis. The development of new antibiotic therapies is important both to combat potential drug-resistant bioweapons and to address the broader societal problem of increasing antibiotic resistance among many pathogenic bacteria. The crystal structure of FabI from F. tularensis (FtuFabI) in complex with the inhibitor triclosan and the cofactor NAD + has been solved to a resolution of 2.1 Å. Triclosan is known to effectively inhibit FabI from different organisms. Precise characterization of the mode of triclosan binding is required to develop highly specific inhibitors. Comparison of our structure with the previously determined FtuFabI structure which is bound to only NAD + reveals the conformation of the substrate-binding loop, electron density for which was missing in the earlier structure, and demonstrates a shift in the conformation of the NAD + cofactor. This shift in the position of the phosphate groups allows more room in the active site for substrate or inhibitor to bind and be better accommodated. This information will be crucial for virtual screening studies to identify novel scaffolds for development into new active inhibitors

  20. Historical distribution and host-vector diversity of Francisella tularensis, the causative agent of tularemia, in Ukraine.

    Science.gov (United States)

    Hightower, Jake; Kracalik, Ian T; Vydayko, Nataliya; Goodin, Douglas; Glass, Gregory; Blackburn, Jason K

    2014-10-16

    Francisella tularensis, the causative agent of tularemia, is a zoonotic agent that remains across much of the northern hemisphere, where it exists in enzootic cycles. In Ukraine, tularemia has a long history that suggests a need for sustained surveillance in natural foci. To better characterize the host-vector diversity and spatial distribution of tularemia, we analyzed historical data from field collections carried out from 1941 to 2008. We analyzed the spatial-temporal distribution of bacterial isolates collected from field samples. Isolates were characterized by source and dominant land cover type. To identify environmental persistence and spatial variation in the source of isolation, we used the space-time permutation and multinomial models in SaTScan. A total of 3,086 positive isolates were taken from 1,084 geographic locations. Isolation of F. tularensis was more frequent among arthropods [n = 2,045 (66.3%)] followed by mammals [n = 619 (20.1%)], water [n = 393 (12.7%)], and farm produce [n = 29 (0.94%)], respectively. Four areas of persistent bacterial isolation were identified. Water and farm produce as sources of bacterial isolation were clustered. Our findings confirm the presence of long-standing natural foci of F. tularensis in Ukraine. Given the history of tularemia as well as its environmental persistence there exists a possibility of (re)emergence in human populations. Heterogeneity in the distribution of tularemia isolate recovery related to land cover type supports the theory of natural nidality and clusters identify areas to target potential sources of the pathogen and improve surveillance.

  1. Environmental Monitoring and Surveillance of Rodents and Vectors for Francisella tularensis Following Outbreaks of Human Tularemia in Georgia.

    Science.gov (United States)

    Elashvili, Eka; Kracalik, Ian; Burjanadze, Irma; Datukishvili, Sophio; Chanturia, Gvantsa; Tsertsvadze, Nikoloz; Beridze, Levan; Shavishvili, Merab; Dzneladze, Archil; Grdzelidze, Marina; Imnadze, Paata; Pearson, Andrew; Blackburn, Jason K

    2015-10-01

    Tularemia is a re-emerging bacterial zoonosis, broadly distributed across the northern hemisphere. In Georgia, there is a history of human tularemia outbreaks dating back to the 1940s. In response to outbreaks, health officials initiated long-term field surveillance and environmental monitoring. The objective of our study was to obtain information from 57 years of field surveys to identify species that play a role in the occurrence Francisella tularensis subsp. holarctica in the environment in Georgia. We collected historical data on human outbreaks, field collections, population dynamics of the common vole (Microtus arvalis), and conducted surveys on small mammals and vectors from five regions in Georgia during 1956-2012. Bacterial isolation was conducted using standard culturing techniques, and isolation rates for species were obtained for a subset of years. We used a Spearman rank correlation to test for associations between the density of the common vole and isolation rates. From 1956 through 2012, there were four recorded outbreaks of human tularemia (362 cases). A total of 465 bacterial isolates of F. tularensis subsp. holarctica were obtained from 27 species and environmental samples. The number of isolations was highest in the common vole (M. arvalis; 149 isolates; 32%) and Dermacentor marginatus ticks (132 isolates; 28%); isolation rates ranged between 0-0.91% and 0-0.47%, respectively. Population dynamics of the common vole were not correlated with the isolation rate. Given the history of tularemia re-emergence in Georgia, continued field surveys and environmental monitoring may provide an early indication of outbreak risk in humans. In conclusion, our findings provide evidence of long-standing foci of F. tularensis subsp. holarctica that are likely maintained by the common vole-tick cycle.

  2. Diversity of Francisella tularensis Schu4 antigens recognized by T lymphocytes after natural infections in humans: identification of candidate epitopes for inclusion in a rationally designed tularemia vaccine

    DEFF Research Database (Denmark)

    McMurry, Julie A; Gregory, Stephen H; Moise, Leonard

    2007-01-01

    The T lymphocyte antigens, which may have a role in protection against tularemia, were predicted by immunoinformatics analysis of Francisella tularensis Schu4. Twenty-seven class II putative promiscuous epitopes and 125 putative class I supertype epitopes were chosen for synthesis; peptides were...... responded to pools of 25 A2, A24, and B7 peptides, respectively. These data can aid in the development of novel epitope-based and subunit tularemia vaccines....

  3. The Early Dendritic Cell Signaling Induced by Virulent Francisella tularensis Strain Occurs in Phases and Involves the Activation of Extracellular Signal-Regulated Kinases (ERKs) and p38 In the Later Stage

    Czech Academy of Sciences Publication Activity Database

    Fabrik, I.; Link, M.; Putzova, D.; Plzakova, L.; Lubovska, Zuzana; Philimonenko, Vlada; Pavkova, I.; Řehulka, P.; Krocová, Z.; Hozák, Pavel; Santic, M.; Stulík, J.

    2018-01-01

    Roč. 17, č. 1 (2018), s. 95-108 ISSN 1535-9476 R&D Projects: GA MŠk(CZ) LM2015062 Institutional support: RVO:68378050 Keywords : factor-alpha production * live vaccine strain * phosphorylation sites * negative regulator * innate immunity * lvs infection * pathway * identification * reveals * mapk Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Cell biology Impact factor: 6.540, year: 2016

  4. Evaluation of an Immunochromatographic Test for Rapid and Reliable Serodiagnosis of Human Tularemia and Detection of Francisella tularensis-Specific Antibodies in Sera from Different Mammalian Species ▿

    Science.gov (United States)

    Splettstoesser, W.; Guglielmo-Viret, V.; Seibold, E.; Thullier, P.

    2010-01-01

    Tularemia is a highly contagious infectious zoonosis caused by the bacterial agent Francisella tularensis. Serology is still considered to be a cornerstone in tularemia diagnosis due to the low sensitivity of bacterial culture and the lack of standardization in PCR methodology for the direct identification of the pathogen. We developed a novel immunochromatographic test (ICT) to efficiently detect F. tularensis-specific antibodies in sera from humans and other mammalian species (nonhuman primate, pig, and rabbit). This new tool requires none or minimal laboratory equipment, and the results are obtained within 15 min. When compared to the method of microagglutination, which was shown to be more specific than the enzyme-linked immunosorbent assay, the ICT had a sensitivity of 98.3% (58 positive sera were tested) and a specificity of 96.5% (58 negative sera were tested) on human sera. On animal sera, the overall sensitivity was 100% (22 positive sera were tested) and specificity was also 100% (70 negative sera were tested). This rapid test preferentially detects IgG antibodies that may occur early in the course of human tularemia, but further evaluation with human sera is important to prove that the ICT can be a valuable field test to support a presumptive diagnosis of tularemia. The ICT can also be a useful tool to monitor successful vaccination with subunit vaccines or live vaccine strains containing lipopolysaccharide (e.g., LVS) and to detect seropositive individuals or animals in outbreak situations or in the context of epidemiologic surveillance programs in areas of endemicity as recently recommended by the World Health Organization. PMID:20220165

  5. Complement Receptor 3-Mediated Inhibition of Inflammasome Priming by Ras GTPase-Activating Protein During Francisella tularensis Phagocytosis by Human Mononuclear Phagocytes

    Directory of Open Access Journals (Sweden)

    Ky V. Hoang

    2018-03-01

    Full Text Available Francisella tularensis is a remarkably infectious facultative intracellular bacterium of macrophages that causes tularemia. Early evasion of host immune responses contributes to the success of F. tularensis as a pathogen. F. tularensis entry into human monocytes and macrophages is mediated by the major phagocytic receptor, complement receptor 3 (CR3, CD11b/CD18. We recently determined that despite a significant increase in macrophage uptake following C3 opsonization of the virulent Type A F. tularensis spp. tularensis Schu S4, this phagocytic pathway results in limited pro-inflammatory cytokine production. Notably, MAP kinase/ERK activation is suppressed immediately during C3-opsonized Schu S4-CR3 phagocytosis. A mathematical model of CR3-TLR2 crosstalk predicted early involvement of Ras GTPase-activating protein (RasGAP in immune suppression by CR3. Here, we link CR3-mediated uptake of opsonized Schu S4 by human monocytes and macrophages with inhibition of early signal 1 inflammasome activation, evidenced by limited caspase-1 cleavage and IL-18 release. This inhibition is due to increased RasGAP activity, leading to a reduction in the Ras-ERK signaling cascade upstream of the early inflammasome activation event. Thus, our data uncover a novel signaling pathway mediated by CR3 following engagement of opsonized virulent F. tularensis to limit inflammasome activation in human phagocytic cells, thereby contributing to evasion of the host innate immune system.

  6. Cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of macrophage growth locus A (MglA) protein from Francisella tularensis

    International Nuclear Information System (INIS)

    Subburaman, Priadarsini; Austin, Brian P.; Shaw, Gary X.; Waugh, David S.; Ji, Xinhua

    2010-01-01

    The macrophage growth locus A (MglA) protein from F. tularensis crystallized in the hexagonal space group P6 1 or P6 5 , with unit-cell parameters a = b = 125, c = 54 Å. Francisella tularensis, a potential bioweapon, causes a rare infectious disease called tularemia in humans and animals. The macrophage growth locus A (MglA) protein from F. tularensis associates with RNA polymerase to positively regulate the expression of multiple virulence factors that are required for its survival and replication within macrophages. The MglA protein was overproduced in Escherichia coli, purified and crystallized. The crystals diffracted to 7.5 Å resolution at the Advanced Photon Source, Argonne National Laboratory and belonged to the hexagonal space group P6 1 or P6 5 , with unit-cell parameters a = b = 125, c = 54 Å

  7. Mucosal immunization with live attenuated Francisella novicida U112ΔiglB protects against pulmonary F. tularensis SCHU S4 in the Fischer 344 rat model.

    Directory of Open Access Journals (Sweden)

    Aimee L Signarovitz

    Full Text Available The need for an efficacious vaccine against Francisella tularensis is a consequence of its low infectious dose and high mortality rate if left untreated. This study sought to characterize a live attenuated subspecies novicida-based vaccine strain (U112ΔiglB in an established second rodent model of pulmonary tularemia, namely the Fischer 344 rat using two distinct routes of vaccination (intratracheal [i.t.] and oral. Attenuation was verified by comparing replication of U112ΔiglB with wild type parental strain U112 in F344 primary alveolar macrophages. U112ΔiglB exhibited an LD(50>10(7 CFU compared to the wild type (LD(50 = 5 × 10(6 CFU i.t.. Immunization with 10(7 CFU U112ΔiglB by i.t. and oral routes induced antigen-specific IFN-γ and potent humoral responses both systemically (IgG2a>IgG1 in serum and at the site of mucosal vaccination (respiratory/intestinal compartment. Importantly, vaccination with U112ΔiglB by either i.t. or oral routes provided equivalent levels of protection (50% survival in F344 rats against a subsequent pulmonary challenge with ~25 LD(50 (1.25 × 10(4 CFU of the highly human virulent strain SCHU S4. Collectively, these results provide further evidence on the utility of a mucosal vaccination platform with a defined subsp. novicida U112ΔiglB vaccine strain in conferring protective immunity against pulmonary tularemia.

  8. Rapid Countermeasure Discovery against Francisella tularensis Based on a Metabolic Network Reconstruction

    Science.gov (United States)

    2013-05-21

    growth inhibition [13]. These modeling frameworks can also be used to identify synergistic effects that arise from combination therapies that inhibit...addition of the compound. Briefly, scrapings from F. tularensis Schu S4 in 25% glycerol stock were streaked onto a chocolate agar plate and incubated...at 37uC for 2 days until clearly formed colonies appeared. A single colony from the chocolate agar plate was used to inoculate 3 ml Chamberlain’s

  9. Population Genomics of Francisella tularensis subsp. holarctica and its Implication on the Eco-Epidemiology of Tularemia in Switzerland.

    Science.gov (United States)

    Wittwer, Matthias; Altpeter, Ekkehard; Pilo, Paola; Gygli, Sebastian M; Beuret, Christian; Foucault, Frederic; Ackermann-Gäumann, Rahel; Karrer, Urs; Jacob, Daniela; Grunow, Roland; Schürch, Nadia

    2018-01-01

    Whole genome sequencing (WGS) methods provide new possibilities in the field of molecular epidemiology. This is particularly true for monomorphic organisms where the discriminatory power of traditional methods (e.g., restriction enzyme length polymorphism typing, multi locus sequence typing etc.) is inadequate to elucidate complex disease transmission patterns, as well as resolving the phylogeny at high resolution on a micro-geographic scale. In this study, we present insights into the population structure of Francisella tularensis subsp. holarctica , the causative agent of tularemia in Switzerland. A total of 59 Fth isolates were obtained from castor bean ticks ( Ixodes ricinus) , animals and humans and a high resolution phylogeny was inferred using WGS methods. The majority of the Fth population in Switzerland belongs to the west European B.11 clade and shows an extraordinary genetic diversity underlining the old evolutionary history of the pathogen in the alpine region. Moreover, a new B.11 subclade was identified which was not described so far. The combined analysis of the epidemiological data of human tularemia cases with the whole genome sequences of the 59 isolates provide evidence that ticks play a pivotal role in transmitting Fth to humans and other vertebrates in Switzerland. This is further underlined by the correlation of disease risk estimates with climatic and ecological factors influencing the survival of ticks.

  10. Population Genomics of Francisella tularensis subsp. holarctica and its Implication on the Eco-Epidemiology of Tularemia in Switzerland

    Science.gov (United States)

    Wittwer, Matthias; Altpeter, Ekkehard; Pilo, Paola; Gygli, Sebastian M.; Beuret, Christian; Foucault, Frederic; Ackermann-Gäumann, Rahel; Karrer, Urs; Jacob, Daniela; Grunow, Roland; Schürch, Nadia

    2018-01-01

    Whole genome sequencing (WGS) methods provide new possibilities in the field of molecular epidemiology. This is particularly true for monomorphic organisms where the discriminatory power of traditional methods (e.g., restriction enzyme length polymorphism typing, multi locus sequence typing etc.) is inadequate to elucidate complex disease transmission patterns, as well as resolving the phylogeny at high resolution on a micro-geographic scale. In this study, we present insights into the population structure of Francisella tularensis subsp. holarctica, the causative agent of tularemia in Switzerland. A total of 59 Fth isolates were obtained from castor bean ticks (Ixodes ricinus), animals and humans and a high resolution phylogeny was inferred using WGS methods. The majority of the Fth population in Switzerland belongs to the west European B.11 clade and shows an extraordinary genetic diversity underlining the old evolutionary history of the pathogen in the alpine region. Moreover, a new B.11 subclade was identified which was not described so far. The combined analysis of the epidemiological data of human tularemia cases with the whole genome sequences of the 59 isolates provide evidence that ticks play a pivotal role in transmitting Fth to humans and other vertebrates in Switzerland. This is further underlined by the correlation of disease risk estimates with climatic and ecological factors influencing the survival of ticks. PMID:29623260

  11. Cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of intracellular growth locus E (IglE) protein from Francisella tularensis subsp. novicida

    International Nuclear Information System (INIS)

    Robb, Craig S.; Nano, Francis E.; Boraston, Alisdair B.

    2010-01-01

    The F. tularensis protein IglE from the FPI, which is a component of the type VI-like secretion system, has been crystallized and preliminary X-ray data have been collected. Tularaemia is an uncommon but potentially dangerous zoonotic disease caused by the bacterium Francisella tularensis. As few as ten bacterial cells are sufficient to cause disease in a healthy human, making this one of the most infectious disease agents known. The virulence of this organism is dependent upon a genetic locus known as the Francisella pathogenicity island (FPI), which encodes components of a secretion system that is related to the type VI secretion system. Here, the cloning, expression, purification and preliminary X-ray diffraction statistics of the FPI-encoded protein IglE are presented. This putative lipoprotein is required for intra-macrophage growth and is thought to be a constituent of the periplasmic portion of the type VI-like protein complex that is responsible for the secretion of critical virulence factors in Francisella

  12. Proteogenomic biomarkers for identification of Francisella species and subspecies by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry.

    Science.gov (United States)

    Durighello, Emie; Bellanger, Laurent; Ezan, Eric; Armengaud, Jean

    2014-10-07

    Francisella tularensis is the causative agent of tularemia. Because some Francisella strains are very virulent, this species is considered by the Centers for Disease Control and Prevention to be a potential category A bioweapon. A mass spectrometry method to quickly and robustly distinguish between virulent and nonvirulent Francisella strains is desirable. A combination of shotgun proteomics and whole-cell matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry on the Francisella tularensis subsp. holarctica LVS defined three protein biomarkers that allow such discrimination: the histone-like protein HU form B, the 10 kDa chaperonin Cpn10, and the 50S ribosomal protein L24. We established that their combined detection by whole-cell MALDI-TOF spectrum could enable (i) the identification of Francisella species, and (ii) the prediction of their virulence level, i.e., gain of a taxonomical level with the identification of Francisella tularensis subspecies. The detection of these biomarkers by MALDI-TOF mass spectrometry is straightforward because of their abundance and the absence of other abundant protein species closely related in terms of m/z. The predicted molecular weights for the three biomarkers and their presence as intense peaks were confirmed with MALDI-TOF/MS spectra acquired on Francisella philomiragia ATCC 25015 and on Francisella tularensis subsp. tularensis CCUG 2112, the most virulent Francisella subspecies.

  13. Downmodulation of Vaccine-Induced Immunity and Protection against the Intracellular Bacterium Francisella tularensis by the Inhibitory Receptor FcγRIIB

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    Brian J. Franz

    2015-01-01

    Full Text Available Fc gamma receptor IIB (FcγRIIB is the only Fc gamma receptor (FcγR which negatively regulates the immune response, when engaged by antigen- (Ag- antibody (Ab complexes. Thus, the generation of Ag-specific IgG in response to infection or immunization has the potential to downmodulate immune protection against infection. Therefore, we sought to determine the impact of FcγRIIB on immune protection against Francisella tularensis (Ft, a Category A biothreat agent. We utilized inactivated Ft (iFt as an immunogen. Naïve and iFt-immunized FcγRIIB knockout (KO or wildtype (WT mice were challenged with Ft-live vaccine strain (LVS. While no significant difference in survival between naïve FcγRIIB KO versus WT mice was observed, iFt-immunized FcγRIIB KO mice were significantly better protected than iFt-immunized WT mice. Ft-specific IgA in serum and bronchial alveolar lavage, as well as IFN-γ, IL-10, and TNF-α production by splenocytes harvested from iFt-immunized FcγRIIB KO, were also significantly elevated. In addition, iFt-immunized FcγRIIB KO mice exhibited a reduction in proinflammatory cytokine levels in vivo at 5 days after challenge, which correlates with increased survival following Ft-LVS challenge in published studies. Thus, these studies demonstrate for the first time the ability of FcγRIIB to regulate vaccine-induced IgA production and downmodulate immunity and protection. The immune mechanisms behind the above observations and their potential impact on vaccine development are discussed.

  14. Francisella tularensis elicits IL-10 via a PGE₂-inducible factor, to drive macrophage MARCH1 expression and class II down-regulation.

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    Danielle Hunt

    Full Text Available Francisella tularensis is a bacterial pathogen that uses host-derived PGE₂ to subvert the host's adaptive immune responses in multiple ways. Francisella-induced PGE₂ acts directly on CD4 T cells to blunt production of IFN-γ. Francisella-induced PGE₂ can also elicit production of a >10 kDa soluble host factor termed FTMØSN (F. tularensismacrophage supernatant, which acts on IFN-γ pre-activated MØ to down-regulate MHC class II expression via a ubiquitin-dependent mechanism, blocking antigen presentation to CD4 T cells. Here, we report that FTMØSN-induced down-regulation of MØ class II is the result of the induction of MARCH1, and that MØ expressing MARCH1 "resistant" class II molecules are resistant to FTMØSN-induced class II down-regulation. Since PGE₂ can induce IL-10 production and IL-10 is the only reported cytokine able to induce MARCH1 expression in monocytes and dendritic cells, these findings suggested that IL-10 is the active factor in FTMØSN. However, use of IL-10 knockout MØ established that IL-10 is not the active factor in FTMØSN, but rather that Francisella-elicited PGE₂ drives production of a >10 kDa host factor distinct from IL-10. This factor then drives MØ IL-10 production to induce MARCH1 expression and the resultant class II down-regulation. Since many human pathogens such as Salmonella typhi, Mycobacterium tuberculosis and Legionella pneumophila also induce production of host PGE₂, these results suggest that a yet-to-be-identified PGE₂-inducible host factor capable of inducing IL-10 is central to the immune evasion mechanisms of multiple important human pathogens.

  15. Discordant results obtained with Francisella tularensis during in vitro and in vivo immunological studies are attributable to compromised bacterial structural integrity.

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    Anju Singh

    Full Text Available Francisella tularensis (Ft is a highly infectious intracellular pathogen and the causative agent of tularemia. Because Ft can be dispersed via small droplet-aerosols and has a very low infectious dose it is characterized as a category A Select Agent of biological warfare. Respiratory infection with the attenuated Live Vaccine Strain (LVS and the highly virulent SchuS4 strain of Ft engenders intense peribronchiolar and perivascular inflammation, but fails to elicit select pro-inflammatory mediators (e.g., TNF, IL-1β, IL-6, IL-12, and IFN-γ within the first ~72 h. This in vivo finding is discordant with the principally TH1-oriented response to Ft frequently observed in cell-based studies wherein the aforementioned cytokines are produced. An often overlooked confounding factor in the interpretation of experimental results is the influence of environmental cues on the bacterium's capacity to elicit certain host responses. Herein, we reveal that adaptation of Ft to its mammalian host imparts an inability to elicit select pro-inflammatory mediators throughout the course of infection. Furthermore, in vitro findings that non-host adapted Ft elicits such a response from host cells reflect aberrant recognition of the DNA of structurally-compromised bacteria by AIM2-dependent and -independent host cell cytosolic DNA sensors. Growth of Ft in Muller-Hinton Broth or on Muller-Hinton-based chocolate agar plates or genetic mutation of Ft was found to compromise the structural integrity of the bacterium thus rendering it capable of aberrantly eliciting pro-inflammatory mediators (e.g., TNF, IL-1β, IL-6, IL-12, and IFN-γ. Our studies highlight the profound impact of different growth conditions on host cell response to infection and demonstrate that not all in vitro-derived findings may be relevant to tularemia pathogenesis in the mammalian host. Rational development of a vaccine and immunotherapeutics can only proceed from a foundation of knowledge based upon

  16. Monitoring of Francisella tularensis and Yersinia pseudotuberculosis in Danish hares (Lepus europaeus) by fluorescent in-situ hybridization

    DEFF Research Database (Denmark)

    Hansen, Mette Sif; Chriél, Mariann; Larsen, Gitte

    . pseudotuberculosis has a wide host range and causes high mortality in hares. When it comes to zoonotic potential F. tularensis poses the major risk for humans, where it causes tularemia - a potentially deadly disease. FISH is an easy, cheap and not at least safe method for monitoring F. tularensis and Y...

  17. Inhibition of expression in Escherichia coli of a virulence regulator MglB of Francisella tularensis using external guide sequence technology.

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    Gaoping Xiao

    Full Text Available External guide sequences (EGSs have successfully been used to inhibit expression of target genes at the post-transcriptional level in both prokaryotes and eukaryotes. We previously reported that EGS accessible and cleavable sites in the target RNAs can rapidly be identified by screening random EGS (rEGS libraries. Here the method of screening rEGS libraries and a partial RNase T1 digestion assay were used to identify sites accessible to EGSs in the mRNA of a global virulence regulator MglB from Francisella tularensis, a Gram-negative pathogenic bacterium. Specific EGSs were subsequently designed and their activities in terms of the cleavage of mglB mRNA by RNase P were tested in vitro and in vivo. EGS73, EGS148, and EGS155 in both stem and M1 EGS constructs induced mglB mRNA cleavage in vitro. Expression of stem EGS73 and EGS155 in Escherichia coli resulted in significant reduction of the mglB mRNA level coded for the F. tularensis mglB gene inserted in those cells.

  18. Antibodies to Both Terminal and Internal B-Cell Epitopes of Francisella tularensis O-Polysaccharide Produced by Patients with Tularemia

    Science.gov (United States)

    Lu, Zhaohua; Perkins, Hillary M.

    2014-01-01

    Francisella tularensis, the Gram-negative bacterium that causes tularemia, is considered a potential bioterrorism threat due to its low infectivity dose and the high morbidity and mortality from respiratory disease. We previously characterized two mouse monoclonal antibodies (MAbs) specific for the O-polysaccharide (O antigen [OAg]) of F. tularensis lipopolysaccharide (LPS): Ab63, which targets a terminal epitope at the nonreducing end of OAg, and Ab52, which targets a repeating internal OAg epitope. These two MAbs were protective in a mouse model of respiratory tularemia. To determine whether these epitope types are also targeted by humans, we tested the ability of each of 18 blood serum samples from 11 tularemia patients to inhibit the binding of Ab63 or Ab52 to F. tularensis LPS in a competition enzyme-linked immunosorbent assay (ELISA). Although all serum samples had Ab63- and Ab52-inhibitory activities, the ratios of Ab63 to Ab52 inhibitory potencies varied 75-fold. However, the variation was only 2.3-fold for sequential serum samples from the same patient, indicating different distributions of terminal- versus internal-binding antibodies in different individuals. Western blot analysis using class-specific anti-human Ig secondary antibodies showed that both terminal- and internal-binding OAg antibodies were of the IgG, IgM, and IgA isotypes. These results support the use of a mouse model to discover protective B-cell epitopes for tularemia vaccines or prophylactic/therapeutic antibodies, and they present a general strategy for interrogating the antibody responses of patients and vaccinees to microbial carbohydrate epitopes that have been characterized in experimental animals. PMID:24351753

  19. Identification of Ciprofloxacin Resistance by SimpleProbe (trademark), High Resolution Melt and Pyrosequencing (trademark) Nucleic Acid Analysis in Biothreat Agents: Bacillus anthracis, Yersinia pestis and Francisella tularensis

    Science.gov (United States)

    2010-01-01

    tularensis strain Schu4 following standardmicrobiological techniques to develop antibiotic resistance. Colonies from an original chocolate agar culture...35 C for two weeks. Growth in broth containing 16 mg/ml ciprofloxacin was transferred to chocolate agar plates containing 64 mg/ml ciprofloxacin and...expeditious therapy , the three PCR technologies described in this study were evaluated for the ability to accurately differentiate wt B. anthracis, Y

  20. FEASIBILITY OF THE AEROSOL-TO-LIQUID PARTICLE EXTRACTION SYSTEM (ALPES) FOR COLLECTION OF VIABLE FRANCISELLA SP.

    Energy Technology Data Exchange (ETDEWEB)

    Heitkamp, M

    2006-08-07

    Several Biowatch monitoring sites in the Houston area have tested positive for Francisella tularensis and there is a need to determine whether natural occurring Francisella-related microorganism(s) may be responsible for these observed positive reactions. The collection, culturing and characterization of Francisella-related natural microorganisms will provide the knowledge base to improve the future selectivity of Biowatch monitoring for Francisella. The aerosol-to-liquid particle extraction system (ALPES) is a high-efficiency, dual mechanism collection system that utilizes a liquid collection medium for capture of airborne microorganisms. Since the viability of microorganisms is preserved better in liquid medium than on air filters, this project was undertaken to determine whether Francisella philomiragia and Francisella tularensis LVS maintain acceptable viability in the continuous liquid recirculation, high direct current voltage and residual ozone concentrations which occur during ALPES operation. Throughout a series of preliminary trial runs with representative gram-negative and gram-positive microorganisms, several design modifications and improvements to the ALPES optimized liquid handling, electrical stability, sampling and overall performance for biological sampling. Initial testing with Francisella philomiragia showed viability was preserved better in PBS buffer than HBSS buffer. Trial runs at starting cell concentrations of 1.8 x 10{sup 6} and 2.5 x 10{sup 4} CFU/L showed less than a 1-log decrease in viability for F. philomiragia after 24 h in the ALPES. Francisella tularensis LVS (live vaccine strain) was used as a surrogate for virulent F. tularensis in ALPES trial runs conducted at starting cell concentrations of 10{sup 4}, 10{sup 5} and 10{sup 6} CFU/L. F. tularensis LVS was slow-growing and required highly selective growth media to prevent overgrowth by collected airborne microorganisms. In addition, one ALPES unit intake was HEPA filtered during

  1. M-Cells Contribute to the Entry of an Oral Vaccine but Are Not Essential for the Subsequent Induction of Protective Immunity against Francisella tularensis.

    Directory of Open Access Journals (Sweden)

    Aimee L Cunningham

    Full Text Available M-cells (microfold cells are thought to be a primary conduit of intestinal antigen trafficking. Using an established neutralizing anti-RANKL (Receptor Activator of NF-κB Ligand antibody treatment to transiently deplete M-cells in vivo, we sought to determine whether intestinal M-cells were required for the effective induction of protective immunity following oral vaccination with ΔiglB (a defined live attenuated Francisella novicida mutant. M-cell depleted, ΔiglB-vaccinated mice exhibited increased (but not significant morbidity and mortality following a subsequent homotypic or heterotypic pulmonary F. tularensis challenge. No significant differences in splenic IFN-γ, IL-2, or IL-17 or serum antibody (IgG1, IgG2a, IgA production were observed compared to non-depleted, ΔiglB-vaccinated animals suggesting complementary mechanisms for ΔiglB entry. Thus, we examined other possible routes of gastrointestinal antigen sampling following oral vaccination and found that ΔiglB co-localized to villus goblet cells and enterocytes. These results provide insight into the role of M-cells and complementary pathways in intestinal antigen trafficking that may be involved in the generation of optimal immunity following oral vaccination.

  2. Francisella novicida bacteremia after a near-drowning accident.

    Science.gov (United States)

    Brett, Meghan; Doppalapudi, Avanthi; Respicio-Kingry, Laurel B; Myers, Debra; Husband, Brigitte; Pollard, Kerry; Mead, Paul; Petersen, Jeannine M; Whitener, Cynthia J

    2012-08-01

    We describe a rare case of Francisella novicida bacteremia following a near-drowning event in seawater. We highlight the challenges associated with laboratory identification of F. novicida and differences in the epidemiology of F. novicida and Francisella tularensis infections.

  3. Benzimidazole-Based Antibacterial Agents Against F. tularensis

    Science.gov (United States)

    Kumar, Kunal; Awasthi, Divya; Lee, Seung-Yub; Cummings, Jason E.; Knudson, Susan E.; Slayden, Richard A.; Ojima, Iwao

    2013-01-01

    Francisella tularensis is a highly virulent pathogenic bacterium. In order to identify novel potential antibacterial agents against F. tularensis, libraries of trisubstituted benzimidazoles were screened against F. tularensis LVS strain. In a preliminary screening assay, remarkably, 23 of 2,5,6- and 2,5,7-trisubstituted benzimidazoles showed excellent activity exhibiting greater than 90 % growth inhibition at 1 µg/mL. Among those hits, 21 compounds showed MIC90 values in the range of 0.35–48.6 µg/mL after accurate MIC determination. In ex-vivo efficacy assays, four of these compounds exhibited 2–3 Log reduction in colony forming units (CFU) per mL at concentrations of 10 and 50 µg/mL. PMID:23623254

  4. AR-13, a Celecoxib Derivative, Directly Kills Francisella In Vitro and Aids Clearance and Mouse Survival In Vivo

    Directory of Open Access Journals (Sweden)

    Ky V. Hoang

    2017-09-01

    Full Text Available Francisella tularensis (F. tularensis is the causative agent of tularemia and is classified as a Tier 1 select agent. No licensed vaccine is currently available in the United States and treatment of tularemia is confined to few antibiotics. In this study, we demonstrate that AR-13, a derivative of the cyclooxygenase-2 inhibitor celecoxib, exhibits direct in vitro bactericidal killing activity against Francisella including a type A strain of F. tularensis (SchuS4 and the live vaccine strain (LVS, as well as toward the intracellular proliferation of LVS in macrophages, without causing significant host cell toxicity. Identification of an AR-13-resistant isolate indicates that this compound has an intracellular target(s and that efflux pumps can mediate AR-13 resistance. In the mouse model of tularemia, AR-13 treatment protected 50% of the mice from lethal LVS infection and prolonged survival time from a lethal dose of F. tularensis SchuS4. Combination of AR-13 with a sub-optimal dose of gentamicin protected 60% of F. tularensis SchuS4-infected mice from death. Taken together, these data support the translational potential of AR-13 as a lead compound for the further development of new anti-Francisella agents.

  5. Live Attenuated Tularemia Vaccines for Protection Against Respiratory Challenge With Virulent F. tularensis subsp. tularensis

    Science.gov (United States)

    Jia, Qingmei; Horwitz, Marcus A.

    2018-01-01

    Francisella tularensis is the causative agent of tularemia and a Tier I bioterrorism agent. In the 1900s, several vaccines were developed against tularemia including the killed “Foshay” vaccine, subunit vaccines comprising F. tularensis protein(s) or lipoproteins(s) in an adjuvant formulation, and the F. tularensis Live Vaccine Strain (LVS); none were licensed in the U.S.A. or European Union. The LVS vaccine retains toxicity in humans and animals—especially mice—but has demonstrated efficacy in humans, and thus serves as the current gold standard for vaccine efficacy studies. The U.S.A. 2001 anthrax bioterrorism attack spawned renewed interest in vaccines against potential biowarfare agents including F. tularensis. Since live attenuated—but not killed or subunit—vaccines have shown promising efficacy and since vaccine efficacy against respiratory challenge with less virulent subspecies holarctica or F. novicida, or against non-respiratory challenge with virulent subsp. tularensis (Type A) does not reliably predict vaccine efficacy against respiratory challenge with virulent subsp. tularensis, the route of transmission and species of greatest concern in a bioterrorist attack, in this review, we focus on live attenuated tularemia vaccine candidates tested against respiratory challenge with virulent Type A strains, including homologous vaccines derived from mutants of subsp. holarctica, F. novicida, and subsp. tularensis, and heterologous vaccines developed using viral or bacterial vectors to express F. tularensis immunoprotective antigens. We compare the virulence and efficacy of these vaccine candidates with that of LVS and discuss factors that can significantly impact the development and evaluation of live attenuated tularemia vaccines. Several vaccines meet what we would consider the minimum criteria for vaccines to go forward into clinical development—safety greater than LVS and efficacy at least as great as LVS, and of these, several meet the

  6. Identification of Francisella novicida mutants that fail to induce prostaglandin E2 synthesis by infected macrophages.

    Directory of Open Access Journals (Sweden)

    Matthew Dale Woolard

    2013-02-01

    Full Text Available Francisella tularensis is the causative agent of tularemia. We have previously shown that infection with F. tularensis Live Vaccine Strain (LVS induces macrophages to synthesize prostaglandin E2 (PGE2. Synthesis of PGE2 by F. tularensis infected macrophages results in decreased T cell proliferation in vitro and increased bacterial survival in vivo. Although we understand some of the biological consequences of F. tularensis induced PGE2 synthesis by macrophages, we do not understand the cellular pathways (neither host nor bacterial that result in up-regulation of the PGE2 biosynthetic pathway in F. tularensis infected macrophages. We took a genetic approach to begin to understand the molecular mechanisms of bacterial induction of PGE2 synthesis from infected macrophages. To identify F. tularensis genes necessary for the induction of PGE2 in primary macrophages, we infected cells with individual mutants from the closely related strain Francisella tularensis subspecies novicida U112 (U112 two allele mutant library. Twenty genes were identified that when disrupted resulted in U112 mutant strains unable to induce the synthesis of PGE2 by infected macrophages. Fourteen of the genes identified are located within the Francisella pathogenicity island (FPI. Genes in the FPI are required for F. tularensis to escape from the phagosome and replicate in the cytosol, which might account for the failure of U112 with transposon insertions within the FPI to induce PGE2. This implies that U112 mutant strains that do not grow intracellularly would also not induce PGE2. We found that U112 clpB::Tn grows within macrophages yet fails to induce PGE2, while U112 pdpA::Tn does not grow yet does induce PGE2. We also found that U112 iglC::Tn neither grows nor induces PGE2. These findings indicate that there is dissociation between intracellular growth and the ability of F. tularensis to induce PGE2 synthesis. These mutants provide a critical entrée into the pathways used

  7. Rapid differentiation of Francisella species and subspecies by fluorescent in situ hybridization targeting the 23S rRNA

    Directory of Open Access Journals (Sweden)

    Trebesius Karlheinz

    2010-03-01

    Full Text Available Abstract Background Francisella (F. tularensis is the causative agent of tularemia. Due to its low infectious dose, ease of dissemination and high case fatality rate, F. tularensis was the subject in diverse biological weapons programs and is among the top six agents with high potential if misused in bioterrorism. Microbiological diagnosis is cumbersome and time-consuming. Methods for the direct detection of the pathogen (immunofluorescence, PCR have been developed but are restricted to reference laboratories. Results The complete 23S rRNA genes of representative strains of F. philomiragia and all subspecies of F. tularensis were sequenced. Single nucleotide polymorphisms on species and subspecies level were confirmed by partial amplification and sequencing of 24 additional strains. Fluorescent In Situ Hybridization (FISH assays were established using species- and subspecies-specific probes. Different FISH protocols allowed the positive identification of all 4 F. philomiragia strains, and more than 40 F. tularensis strains tested. By combination of different probes, it was possible to differentiate the F. tularensis subspecies holarctica, tularensis, mediasiatica and novicida. No cross reactivity with strains of 71 clinically relevant bacterial species was observed. FISH was also successfully applied to detect different F. tularensis strains in infected cells or tissue samples. In blood culture systems spiked with F. tularensis, bacterial cells of different subspecies could be separated within single samples. Conclusion We could show that FISH targeting the 23S rRNA gene is a rapid and versatile method for the identification and differentiation of F. tularensis isolates from both laboratory cultures and clinical samples.

  8. Inflammasome priming is similar for francisella species that differentially induce inflammasome activation.

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    Mohammed G Ghonime

    Full Text Available Inflammasome activation is a two-step process where step one, priming, prepares the inflammasome for its subsequent activation, by step two. Classically step one can be induced by LPS priming followed by step two, high dose ATP. Furthermore, when IL-18 processing is used as the inflammasome readout, priming occurs before new protein synthesis. In this context, how intracellular pathogens such as Francisella activate the inflammasome is incompletely understood, particularly regarding the relative importance of priming versus activation steps. To better understand these events we compared Francisella strains that differ in virulence and ability to induce inflammasome activation for their relative effects on step one vs. step two. When using the rapid priming model, i.e., 30 min priming by live or heat killed Francisella strains (step 1, followed by ATP (step 2, we found no difference in IL-18 release, p20 caspase-1 release and ASC oligomerization between Francisella strains (F. novicida, F. holarctica -LVS and F. tularensis Schu S4. This priming is fast, independent of bacteria viability, internalization and phagosome escape, but requires TLR2-mediated ERK phosphorylation. In contrast to their efficient priming capacity, Francisella strains LVS and Schu S4 were impaired in inflammasome triggering compared to F. novicida. Thus, observed differences in inflammasome activation by F. novicida, LVS and Schu S4 depend not on differences in priming but rather on their propensity to trigger the primed inflammasome.

  9. Construction of a New Phage Integration Vector pFIV-Val for Use in Different Francisella Species

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    Hana Tlapák

    2018-03-01

    Full Text Available We recently identified and described a putative prophage on the genomic island FhaGI-1 located within the genome of Francisella hispaniensis AS02-814 (F. tularensis subsp. novicida-like 3523. In this study, we constructed two variants of a Francisella phage integration vector, called pFIV1-Val and pFIV2-Val (Francisella Integration Vector-tRNAVal-specific, using the attL/R-sites and the site-specific integrase (FN3523_1033 of FhaGI-1, a chloramphenicol resistance cassette and a sacB gene for counter selection of transformants against the vector backbone. We inserted the respective sites and genes into vector pUC57-Kana to allow for propagation in Escherichia coli. The constructs generated a circular episomal form in E. coli which could be used to transform Francisella spp. where FIV-Val stably integrated site specifically into the tRNAVal gene of the genome, whereas pUC57-Kana is lost due to counter selection. Functionality of the new vector was demonstrated by the successfully complementation of a Francisella mutant strain. The vectors were stable in vitro and during host-cell infection without selective pressure. Thus, the vectors can be applied as a further genetic tool in Francisella research, expanding the present genetic tools by an integrative element. This new element is suitable to perform long-term experiments with different Francisella species.

  10. MiR-155 induction by F. novicida but not the virulent F. tularensis results in SHIP down-regulation and enhanced pro-inflammatory cytokine response.

    Directory of Open Access Journals (Sweden)

    Thomas J Cremer

    2009-12-01

    Full Text Available The intracellular gram-negative bacterium Francisella tularensis causes the disease tularemia and is known for its ability to subvert host immune responses. Previous work from our laboratory identified the PI3K/Akt pathway and SHIP as critical modulators of host resistance to Francisella. Here, we show that SHIP expression is strongly down-regulated in monocytes and macrophages following infection with F. tularensis novicida (F.n.. To account for this negative regulation we explored the possibility that microRNAs (miRs that target SHIP may be induced during infection. There is one miR that is predicted to target SHIP, miR-155. We tested for induction and found that F.n. induced miR-155 both in primary monocytes/macrophages and in vivo. Using luciferase reporter assays we confirmed that miR-155 led to down-regulation of SHIP, showing that it specifically targets the SHIP 3'UTR. Further experiments showed that miR-155 and BIC, the gene that encodes miR-155, were induced as early as four hours post-infection in primary human monocytes. This expression was dependent on TLR2/MyD88 and did not require inflammasome activation. Importantly, miR-155 positively regulated pro-inflammatory cytokine release in human monocytes infected with Francisella. In sharp contrast, we found that the highly virulent type A SCHU S4 strain of Francisella tularensis (F.t. led to a significantly lower miR-155 response than the less virulent F.n. Hence, F.n. induces miR-155 expression and leads to down-regulation of SHIP, resulting in enhanced pro-inflammatory responses. However, impaired miR-155 induction by SCHU S4 may help explain the lack of both SHIP down-regulation and pro-inflammatory response and may account for the virulence of Type A Francisella.

  11. Long-Lasting Fever and Lymphadenitis: Think about F. tularensis

    Directory of Open Access Journals (Sweden)

    Maria Vittoria Longo

    2015-01-01

    Full Text Available We report the case of glandular tularemia that developed in a man supposedly infected by a tick bite in Western Switzerland. Francisella tularensis (F. tularensis was identified. In Europe tularemia most commonly manifests itself as ulcero-glandular or glandular disease; the diagnosis of tularemia may be delayed in glandular form where skin or mucous lesion is absent, particularly in areas which are assumed to have a low incidence of the disease.

  12. Screening for bacterial DNA in the hard tick Hyalomma marginatum (Ixodidae from Socotra Island (Yemen: detection of Francisella-like endosymbiont

    Directory of Open Access Journals (Sweden)

    M. Montagna

    2012-12-01

    Full Text Available Thirty-four adult ticks collected from livestock on Socotra Island (Yemen were identified as Hyalomma marginatum using traditional morphological characteristics. Morphological identification was confirmed for all the collected specimens using a molecular approach targeting a fragment of the mitochondrial gene 12S rRNA. All the specimens were examined for the presence of tick-borne pathogens and the tick endosymbiont Candidatus Midichloria mitochondrii using polymerase chain reaction. Three specimens out of the 34 analyzed tested positive to the presence of Francisella spp. leading to the first detection of these bacteria in H. marginatum on Socotra Island. The phylogenetic analyses conducted on a 660 bp fragment of the ribosomal gene 16S rRNA of Francisella spp. (including F. philomiragia as outgroup, the four subspecies of F. tularensis and the Francisella-like endosymbiont of ticks confirm that the newly detected Francisella strains cluster into the Francisella-like endosymbionts of ticks. Interestingly, the detected Francisella-like endosymbiont, shows a different genotype to that previously isolated from H. marginatum collected in Bulgaria. No specimen was positive for the presence of Rickettsia spp., Coxiella burnetii, Borrelia burgdorferi or M. mitochondrii.

  13. Macrophage replication screen identifies a novel Francisella hydroperoxide resistance protein involved in virulence.

    Directory of Open Access Journals (Sweden)

    Anna C Llewellyn

    Full Text Available Francisella tularensis is a gram-negative facultative intracellular pathogen and the causative agent of tularemia. Recently, genome-wide screens have identified Francisella genes required for virulence in mice. However, the mechanisms by which most of the corresponding proteins contribute to pathogenesis are still largely unknown. To further elucidate the roles of these virulence determinants in Francisella pathogenesis, we tested whether each gene was required for replication of the model pathogen F. novicida within macrophages, an important virulence trait. Fifty-three of the 224 genes tested were involved in intracellular replication, including many of those within the Francisella pathogenicity island (FPI, validating our results. Interestingly, over one third of the genes identified are annotated as hypothetical, indicating that F. novicida likely utilizes novel virulence factors for intracellular replication. To further characterize these virulence determinants, we selected two hypothetical genes to study in more detail. As predicted by our screen, deletion mutants of FTN_0096 and FTN_1133 were attenuated for replication in macrophages. The mutants displayed differing levels of attenuation in vivo, with the FTN_1133 mutant being the most attenuated. FTN_1133 has sequence similarity to the organic hydroperoxide resistance protein Ohr, an enzyme involved in the bacterial response to oxidative stress. We show that FTN_1133 is required for F. novicida resistance to, and degradation of, organic hydroperoxides as well as resistance to the action of the NADPH oxidase both in macrophages and mice. Furthermore, we demonstrate that F. holarctica LVS, a strain derived from a highly virulent human pathogenic species of Francisella, also requires this protein for organic hydroperoxide resistance as well as replication in macrophages and mice. This study expands our knowledge of Francisella's largely uncharacterized intracellular lifecycle and

  14. Medical Countermeasure Models. Volume 4. Francisella tularensis

    Science.gov (United States)

    2013-04-12

    abscess complicating ulceroglandular tularemia." Canadian Medical Association Journal. 129(12). 1983. 191 Hanna C and Lyford J. "Tularemia...administration of another antibiotic (TMP/SMX) 3 3 Lung infiltrate Cefazolin 6 7 Streptomycin 13 7 Relapsed 1 week after therapy with a...course. 1 patient was not treated with antibiotics and subsequently died. 2 46 Lung infiltrates Isoniazid Streptomycin 3 11

  15. Identification of genes required for secretion of the Francisella oxidative burst-inhibiting acid phosphatase AcpA

    Directory of Open Access Journals (Sweden)

    John S Gunn

    2016-04-01

    Full Text Available Francisella tularensis is a Tier 1 bioterror threat and the intracellular pathogen responsible for tularemia in humans and animals. Upon entry into the host, Francisella uses multiple mechanisms to evade killing. Our previous studies have shown that after entering its primary cellular host, the macrophage, Francisella immediately suppresses the oxidative burst by secreting a series of acid phosphatases including AcpA-B-C and HapA, thereby evading the innate immune response of the macrophage and enhancing survival and further infection. However, the mechanism of acid phosphatase secretion by Francisella is still unknown. In this study, we screened for genes required for AcpA secretion in Francisella. We initially demonstrated that the known secretion systems, the putative Francisella-pathogenicity island (FPI-encoded Type VI secretion system and the Type IV pili, do not secrete AcpA. Using random transposon mutagenesis in conjunction with ELISA, Western blotting and acid phosphatase enzymatic assays, a transposon library of 5450 mutants was screened for strains with a minimum 1.5-fold decrease in secreted (culture supernatant AcpA, but no defect in cytosolic AcpA. Three mutants with decreased supernatant AcpA were identified. The transposon insertion sites of these mutants were revealed by direct genomic sequencing or inverse-PCR and sequencing. One of these mutants has a severe defect in AcpA secretion (at least 85% decrease and is a predicted hypothetical inner membrane protein. Interestingly, this mutant also affected the secretion of the FPI-encoded protein, VgrG. Thus, this screen identified novel protein secretion factors involved in the subversion of host defenses.

  16. Evasion of IFN-γ signaling by Francisella novicida is dependent upon Francisella outer membrane protein C.

    Directory of Open Access Journals (Sweden)

    Kalyan C Nallaparaju

    2011-03-01

    Full Text Available Francisella tularensis is a Gram-negative facultative intracellular bacterium and the causative agent of the lethal disease tularemia. An outer membrane protein (FTT0918 of F. tularensis subsp. tularensis has been identified as a virulence factor. We generated a F. novicida (F. tularensis subsp. novicida FTN_0444 (homolog of FTT0918 fopC mutant to study the virulence-associated mechanism(s of FTT0918.The ΔfopC strain phenotype was characterized using immunological and biochemical assays. Attenuated virulence via the pulmonary route in wildtype C57BL/6 and BALB/c mice, as well as in knockout (KO mice, including MHC I, MHC II, and µmT (B cell deficient, but not in IFN-γ or IFN-γR KO mice was observed. Primary bone marrow derived macrophages (BMDM prepared from C57BL/6 mice treated with rIFN-γ exhibited greater inhibition of intracellular ΔfopC than wildtype U112 strain replication; whereas, IFN-γR KO macrophages showed no IFN-γ-dependent inhibition of ΔfopC replication. Moreover, phosphorylation of STAT1 was downregulated by the wildtype strain, but not the fopC mutant, in rIFN-γ treated macrophages. Addition of NG-monomethyl-L-arginine, an NOS inhibitor, led to an increase of ΔfopC replication to that seen in the BMDM unstimulated with rIFN-γ. Enzymatic screening of ΔfopC revealed aberrant acid phosphatase activity and localization. Furthermore, a greater abundance of different proteins in the culture supernatants of ΔfopC than that in the wildtype U112 strain was observed.F. novicida FopC protein facilitates evasion of IFN-γ-mediated immune defense(s by down-regulation of STAT1 phosphorylation and nitric oxide production, thereby promoting virulence. Additionally, the FopC protein also may play a role in maintaining outer membrane stability (integrity facilitating the activity and localization of acid phosphatases and other F. novicida cell components.

  17. New species in the genus Francisella (Gammaproteobacteria; Francisellaceae); Francisella piscicida sp. nov. isolated from cod (Gadus morhua)

    DEFF Research Database (Denmark)

    Ottem, Karl F; Nylund, Are; Karlsbakk, Egil

    2007-01-01

    A Francisella strain, GM2212, previously isolated from moribund farmed Atlantic cod (Gadus morhua) in Norway, is closely related to Francisella philomiragia among Francisella spp. according to its complete 16S rDNA, 16S-23S intergenic spacer, 23S rDNA, 23S-5S intergenic spacer, 5S rDNA, Fop...

  18. Type IV pili in Francisella – A virulence trait in an intracellular pathogen

    Directory of Open Access Journals (Sweden)

    Emelie eNäslund Salomonsson

    2011-02-01

    Full Text Available 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 summarise 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 adaption 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.

  19. Understanding Virulence in the Brucellae and Francisellae: Towards Efficacious Treatments for Two Potential Biothreat Agents

    Energy Technology Data Exchange (ETDEWEB)

    Rasley, A; Parsons, D A; El-Etr, S; Roux, C; Tsolis, R

    2009-12-30

    Francisella tularensis, Yersinia pestis and Brucellae species are highly infectious pathogens classified as select agents by the Centers for Disease Control and Prevention (CDC) with the potential for use in bioterrorism attacks. These organisms are known to be facultative intracellular pathogens that preferentially infect human monocytes. As such, understanding how the host responds to infection with these organisms is paramount in detecting and combating human disease. We have compared the ability of fully virulent strains of each pathogen and their non-pathogenic near neighbors to enter and survive inside the human monocytic cell line THP-1 and have quantified the cellular response to infection with the goal of identifying both unique and common host response patterns. We expanded the scope of these studies to include experiments with pathogenic and non-pathogenic strains of Y. pestis, the causative agent of plague. Nonpathogenic strains of each organism were impaired in their ability to survive intracellularly compared with their pathogenic counterparts. Furthermore, infection of THP-1 cells with pathogenic strains of Y. pestis and F. tularensis resulted in marked increases in the secretion of the inflammatory chemokines IL-8, RANTES, and MIP-1{beta}. In contrast, B. melitensis infection failed to elicit any significant increases in a panel of cytokines tested. These differences may underscore distinct strategies in pathogenic mechanisms employed by these pathogens.

  20. Characterization of Francisella species isolated from the cooling water of an air conditioning system.

    Science.gov (United States)

    Gu, Quan; Li, Xunde; Qu, Pinghua; Hou, Shuiping; Li, Juntao; Atwill, Edward R; Chen, Shouyi

    2015-01-01

    Strains of Francisella spp. were isolated from cooling water from an air conditioning system in Guangzhou, China. These strains are Gram negative, coccobacilli, non-motile, oxidase negative, catalase negative, esterase and lipid esterase positive. In addition, these bacteria grow on cysteine-supplemented media at 20 °C to 40 °C with an optimal growth temperature of 30 °C. Analysis of 16S rRNA gene sequences revealed that these strains belong to the genus Francisella. Biochemical tests and phylogenetic and BLAST analyses of 16S rRNA, rpoB and sdhA genes indicated that one strain was very similar to Francisella philomiragia and that the other strains were identical or highly similar to the Francisella guangzhouensis sp. nov. strain 08HL01032 we previously described. Biochemical and molecular characteristics of these strains demonstrated that multiple Francisella species exist in air conditioning systems.

  1. Clinical Characterization of Aerosolized Francisella tularensis Infection in Cynomolgus macaques

    Science.gov (United States)

    2016-11-21

    All airflows, environmental monitoring, and system balancing were configured, controlled, and recorded through the institute standard automated...were used as a baseline to fit an autoregressive integrated moving average (ARIMA) model. Temperature elevations exceeding three standard deviations...supervision of a pathologist board certified by the American College of Veterinary Pathologist in a biosafety level (BSL) 3 necropsy facility. Tissues

  2. Indigenous infection with Francisella tularensis holarctica in The Netherlands

    NARCIS (Netherlands)

    Maraha, B.; Hajer, G.F.; Sjödin, A.; Forsman, M.; Paauw, A.; Roeselers, G.; Verspui, E.; Frenay, H.M.E.; Notermans, D.W.; Vries, M.C. de; Reubsaet, F.A.G.

    2013-01-01

    We report here the first case of indigenous tularemia detected inTheNetherlands, a nonendemic country, since 1953.Whole genome DNAsequence analysis assigned the isolate BD11-00177 to the genomic group B.FTNF002-00,which previously has been exclusively reported from Spain, France, Italy, Switzerland,

  3. Francisella guangzhouensis sp. nov., isolated from air-conditioning systems.

    Science.gov (United States)

    Qu, Ping-Hua; Chen, Shou-Yi; Scholz, Holger C; Busse, Hans-Jürgen; Gu, Quan; Kämpfer, Peter; Foster, Jeffrey T; Glaeser, Stefanie P; Chen, Cha; Yang, Zhi-Chong

    2013-10-01

    Four strains (08HL01032(T), 09HG994, 10HP82-6 and 10HL1960) were isolated from water of air-conditioning systems of various cooling towers in Guangzhou city, China. Cells were Gram-stain-negative coccobacilli without flagella, catalase-positive and oxidase-negative, showing no reduction of nitrate, no hydrolysis of urea and no production of H2S. Growth was characteristically enhanced in the presence of l-cysteine, which was consistent with the properties of members of the genus Francisella. The quinone system was composed of ubiquinone Q-8 with minor amounts of Q-9. The polar lipid profile consisted of the predominant lipids phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, two unidentified phospholipids (PL2, PL3), an unidentified aminophospholipid and an unidentified glycolipid (GL2). The polyamine pattern consisted of the major compounds spermidine, cadaverine and spermine. The major cellular fatty acids were C10 : 0, C14 : 0, C16 : 0, C18 : 1ω9c and C18 : 1 3-OH. A draft whole-genome sequence of the proposed type strain 08HL01032(T) was generated. Comparative sequence analysis of the complete 16S and 23S rRNA genes confirmed affiliation to the genus Francisella, with 95 % sequence identity to the closest relatives in the database, the type strains of Francisella philomiragia and Francisella noatunensis subsp. orientalis. Full-length deduced amino acid sequences of various housekeeping genes, recA, gyrB, groEL, dnaK, rpoA, rpoB, rpoD, rpoH, fopA and sdhA, exhibited similarities of 67-92 % to strains of other species of the genus Francisella. Strains 08HL01032(T), 09HG994, 10HP82-6 and 10HL1960 exhibited highly similar pan-genome PCR profiles. Both the phenotypic and molecular data support the conclusion that the four strains belong to the genus Francisella but exhibit considerable divergence from all recognized Francisella species. Therefore, we propose the name Francisella guangzhouensis sp

  4. Francisella subverts innate immune signaling: Focus on PI3K/Akt

    Directory of Open Access Journals (Sweden)

    Thomas John Cremer

    2011-02-01

    Full Text Available Intracellular bacterial pathogens exploit host cells as a part of their lifecycle, and they do so by manipulating host cell signaling events. Many such bacteria are known to produce effector proteins that promote cell invasion, alter membrane trafficking and disrupt signaling cascades. This review highlights recent advances in our understanding of signaling pathways involved in host cell responses to Francisella tularensis, a facultative Gram-negative intracellular pathogen that causes tularemia. We highlight several key pathways that are targeted by Francisella, with a focus on the PI3K/Akt pathway. Lastly, we discuss the emerging role of microRNAs, specifically miR-155, as a key regulator of host signaling and defense.

  5. Manipulation of host membranes by the bacterial pathogens Listeria, Francisella, Shigella and Yersinia.

    Science.gov (United States)

    Pizarro-Cerdá, Javier; Charbit, Alain; Enninga, Jost; Lafont, Frank; Cossart, Pascale

    2016-12-01

    Bacterial pathogens display an impressive arsenal of molecular mechanisms that allow survival in diverse host niches. Subversion of plasma membrane and cytoskeletal functions are common themes associated to infection by both extracellular and intracellular pathogens. Moreover, intracellular pathogens modify the structure/stability of their membrane-bound compartments and escape degradation from phagocytic or autophagic pathways. Here, we review the manipulation of host membranes by Listeria monocytogenes, Francisella tularensis, Shigella flexneri and Yersinia spp. These four bacterial model pathogens exemplify generalized strategies as well as specific features observed during bacterial infection processes. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  6. New species in the genus Francisella (Gammaproteobacteria; Francisellaceae); Francisella piscicida sp. nov. isolated from cod (Gadus morhua)

    DEFF Research Database (Denmark)

    Ottem, Karl F; Nylund, Are; Karlsbakk, Egil

    2007-01-01

    A, lipoprotein TUL4 (LpnA), malate dehydrogenase and hypothetical lipoprotein (LpnB) sequences. A comparison between GM2212 and the type strain of Francisella philomiragia were performed by DNA-DNA hybridization and fatty acid analysis. The DNA-DNA hybridization showed a 70% similarity. The fatty acid analysis...

  7. Respiratory and oral vaccination improves protection conferred by the live vaccine strain against pneumonic tularemia in the rabbit model.

    Science.gov (United States)

    Stinson, Elizabeth; Smith, Le'Kneitah P; Cole, Kelly Stefano; Barry, Eileen M; Reed, Douglas S

    2016-10-01

    Tularemia is a severe, zoonotic disease caused by a gram-negative bacterium, Francisella tularensis We have previously shown that rabbits are a good model of human pneumonic tularemia when exposed to aerosols containing a virulent, type A strain, SCHU S4. We further demonstrated that the live vaccine strain (LVS), an attenuated type B strain, extended time to death when given by scarification. Oral or aerosol vaccination has been previously shown in humans to offer superior protection to parenteral vaccination against respiratory tularemia challenge. Both oral and aerosol vaccination with LVS were well tolerated in the rabbit with only minimal fever and no weight loss after inoculation. Plasma antibody titers against F. tularensis were higher in rabbits that were vaccinated by either oral or aerosol routes compared to scarification. Thirty days after vaccination, all rabbits were challenged with aerosolized SCHU S4. LVS given by scarification extended time to death compared to mock-vaccinated controls. One orally vaccinated rabbit did survive aerosol challenge, however, only aerosol vaccination extended time to death significantly compared to scarification. These results further demonstrate the utility of the rabbit model of pneumonic tularemia in replicating what has been reported in humans and macaques as well as demonstrating the utility of vaccination by oral and respiratory routes against an aerosol tularemia challenge. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  8. Nanolipoprotein Particles (NLPs) as Versatile Vaccine Platforms for Co-delivery of Multiple Adjuvants with Subunit Antigens from Burkholderia spp. and F. tularensis - Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, N. O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-01-13

    The goal of this proposal is to demonstrate that colocalization of protein subunit antigens and adjuvants on nanolipoprotein particles (NLPs) can increase the protective efficacy of subunit antigens from Burkholderia spp. and Francisella tularensis against an aerosol challenge. In the third quarter of the third year, F344 rats vaccinated with adjuvanted NLP formulations were challenged with F. tularensis SCHU S4 at Battelle. Preliminary data indicate that up to 65% of females vaccinated intranasally with an NLP-based formulation survived this challenge, compared to only 20% survival of naïve animals. In addition, NLPs were successfully formulated with Burkholderia protein antigens. IACUC approval for immunological assessments in BALB/c mice was received and we anticipate that these assessments will begin by March 2015, pending ACURO approval.

  9. Nanolipoprotein Particles (NLPs) as Versatile Vaccine Platforms for Co-delivery of Multiple Adjuvants with Subunit Antigens from Burkholderia spp. and F. tularensis - Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, N. O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-01-06

    The goal of this proposal is to demonstrate that colocalization of protein subunit antigens and adjuvants on nanolipoprotein particles (NLPs) can increase the protective efficacy of subunit antigens from Burkholderia spp. and Francisella tularensis against an aerosol challenge. In the second quarter of the third year, LLNL finalized all immunological assessments of NLP vaccine formulations in the F344 model. Battelle has immunized rats with three unique NLP formulations by either intramuscular or intranasal administration. All inoculations have been completed, and protective efficacy against an aerosolized challenge will begin at the end of October, 2014.

  10. DotU and VgrG, core components of type VI secretion systems, are essential for Francisella LVS pathogenicity.

    Directory of Open Access Journals (Sweden)

    Jeanette E Bröms

    Full Text Available The Gram-negative bacterium Francisella tularensis causes tularemia, a disease which requires bacterial escape from phagosomes of infected macrophages. Once in the cytosol, the bacterium rapidly multiplies, inhibits activation of the inflammasome and ultimately causes death of the host cell. Of importance for these processes is a 33-kb gene cluster, the Francisella pathogenicity island (FPI, which is believed to encode a type VI secretion system (T6SS. In this study, we analyzed the role of the FPI-encoded proteins VgrG and DotU, which are conserved components of type VI secretion (T6S clusters. We demonstrate that in F. tularensis LVS, VgrG was shown to form multimers, consistent with its suggested role as a trimeric membrane puncturing device in T6SSs, while the inner membrane protein DotU was shown to stabilize PdpB/IcmF, another T6SS core component. Upon infection of J774 cells, both ΔvgrG and ΔdotU mutants did not escape from phagosomes, and subsequently, did not multiply or cause cytopathogenicity. They also showed impaired activation of the inflammasome and marked attenuation in the mouse model. Moreover, all of the DotU-dependent functions investigated here required the presence of three residues that are essentially conserved among all DotU homologues. Thus, in agreement with a core function in T6S clusters, VgrG and DotU play key roles for modulation of the intracellular host response as well as for the virulence of F. tularensis.

  11. Macrophage pro-inflammatory response to Francisella novicida infection is regulated by SHIP.

    Directory of Open Access Journals (Sweden)

    Kishore V L Parsa

    2006-07-01

    Full Text Available Francisella tularensis, a Gram-negative facultative intracellular pathogen infecting principally macrophages and monocytes, is the etiological agent of tularemia. Macrophage responses to F. tularensis infection include the production of pro-inflammatory cytokines such as interleukin (IL-12, which is critical for immunity against infection. Molecular mechanisms regulating production of these inflammatory mediators are poorly understood. Herein we report that the SH2 domain-containing inositol phosphatase (SHIP is phosphorylated upon infection of primary murine macrophages with the genetically related F. novicida, and negatively regulates F. novicida-induced cytokine production. Analyses of the molecular details revealed that in addition to activating the MAP kinases, F. novicida infection also activated the phosphatidylinositol 3-kinase (PI3K/Akt pathway in these cells. Interestingly, SHIP-deficient macrophages displayed enhanced Akt activation upon F. novicida infection, suggesting elevated PI3K-dependent activation pathways in absence of SHIP. Inhibition of PI3K/Akt resulted in suppression of F. novicida-induced cytokine production through the inhibition of NFkappaB. Consistently, macrophages lacking SHIP displayed enhanced NFkappaB-driven gene transcription, whereas overexpression of SHIP led to decreased NFkappaB activation. Thus, we propose that SHIP negatively regulates F. novicida-induced inflammatory cytokine response by antagonizing the PI3K/Akt pathway and suppressing NFkappaB-mediated gene transcription. A detailed analysis of phosphoinositide signaling may provide valuable clues for better understanding the pathogenesis of tularemia.

  12. Francisella philomiragia Adenitis and Pulmonary Nodules in a Child with Chronic Granulomatous Disease

    Directory of Open Access Journals (Sweden)

    Timothy Mailman

    2005-01-01

    Full Text Available Francisella philomiragia is a rare and opportunistic pathogen capable of producing invasive infection in patients with compromised neutrophil function and in patients that have survived a near-drowning. A case of F philomiragia adenitis and lung nodules, refractory to cephalosporin therapy, is reported in a 10-year-old boy with chronic granulomatous disease following a facial abrasion from a saltwater crab. To the authors' knowledge, this is the first Canadian clinical isolate to be reported. Genus and species identification was confirmed via 16S ribosomal RNA sequence analysis. A literature review revealed three groups at risk of F philomiragia infection: young patients with chronic granulomatous disease; adults with hematogenous malignancy; and near-drowning patients. Pneumonia, fever without an apparent source and sepsis are the main clinical presentations. Invasive procedures may be required to isolate this organism and ensure appropriate antimicrobial therapy. Limited awareness of F philomiragia has led to delayed identification, patient death and misidentification as Francisella tularensis - a biosafety level three pathogen and potential bioterrorism agent.

  13. Francisella tularensis prevalence and load in Dermacentor reticulatus ticks in an endemic area in Central Europe

    Czech Academy of Sciences Publication Activity Database

    Hubálek, Zdeněk; Rudolf, Ivo

    2017-01-01

    Roč. 31, č. 2 (2017), s. 234-239 ISSN 0269-283X Institutional support: RVO:68081766 Keywords : Ixodid ticks * pathogen load * Tularaemia Subject RIV: FN - Epidemiology, Contagious Diseases ; Clinical Immunology OBOR OECD: Epidemiology Impact factor: 1.809, year: 2016

  14. Biofilm formation of Francisella noatunensis subsp. orientalis

    Science.gov (United States)

    Soto, Esteban; Halliday-Wimmonds, Iona; Francis , Stewart; Kearney, Michael T.; Hansen, John D.

    2015-01-01

    Francisella noatunensis subsp. orientalis (Fno) is an emergent fish pathogen in both marine and fresh water environments. The bacterium is suspected to persist in the environment even without the presence of a suitable fish host. In the present study, the influence of different abiotic factors such as salinity and temperature were used to study the biofilm formation of different isolates of Fno including intracellular growth loci C (iglC)and pathogenicity determinant protein A (pdpA) knockout strains. Finally, we compared the susceptibility of planktonic and biofilm to three disinfectants used in the aquaculture and ornamental fish industry, namely Virkon®, bleach and hydrogen peroxide. The data indicates that Fno is capable of producing biofilms within 24 h where both salinity as well as temperature plays a role in the growth and biofilm formation of Fno. Mutations in theiglC or pdpA, both known virulence factors, do not appear to affect the capacity of Fno to produce biofilms, and the minimum inhibitory concentration, and minimum biocidal concentration for the three disinfectants were lower than the minimum biofilm eradication concentration values. This information needs to be taken into account if trying to eradicate the pathogen from aquaculture facilities or aquariums.

  15. Nanolipoprotein Particles (NLPs) as Versatile Vaccine Platforms for Co-delivery of Multiple Adjuvants with Subunit Antigens from Burkholderia spp. and F. tularensis - Annual Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, N. O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-04-16

    The goal of this proposal is to demonstrate that co-localization of protein subunit antigens and adjuvants on nanolipoprotein particles (NLPs) can increase the protective efficacy of recombinant subunit antigens from Burkholderia spp. and Francisella tularensis against an aerosol challenge. NLPs are are biocompatible, high-density lipoprotein mimetics that are amenable to the incorporation of multiple, chemically-disparate adjuvant and antigen molecules. We hypothesize that the ability to co-localize optimized adjuvant formulations with subunit antigens within a single particle will enhance the stimulation and activation of key immune effector cells, increasing the protective efficacy of subunit antigen-based vaccines. While Burkholderia spp. and F. tularensis subunit antigens are the focus of this proposal, we anticipate that this approach is applicable to a wide range of DOD-relevant biothreat agents. The F344 rat aerosol challenge model for F. tularensis has been successfully established at Battelle under this contract, and Year 3 efficacy studies performed at Battelle demonstrated that an NLP vaccine formulation was able to enhance survival of female F344 rats relative to naïve animals. In addition, Year 3 focused on the incorporation of multiple Burkholderia antigens (both polysaccharides and proteins) onto adjuvanted NLPs, with immunological analysis poised to begin in the next quarter.

  16. Structure of the Francisella response regulator QseB receiver domain, and characterization of QseB inhibition by antibiofilm 2-aminoimidazole-based compounds: Inhibition of response regulator QseB by antibiofilm compounds

    Energy Technology Data Exchange (ETDEWEB)

    Milton, Morgan E.; Allen, C. Leigh; Feldmann, Erik A.; Bobay, Benjamin G.; Jung, David K.; Stephens, Matthew D.; Melander, Roberta J.; Theisen, Kelly E.; Zeng, Daina; Thompson, Richele J.; Melander, Christian; Cavanagh, John (NCSU)

    2017-08-16

    With antibiotic resistance increasing at alarming rates, targets for new antimicrobial therapies must be identified. A particularly promising target is the bacterial two-component system. Two-component systems allow bacteria to detect, evaluate and protect themselves against changes in the environment, such as exposure to antibiotics and also to trigger production of virulence factors. Drugs that target the response regulator portion of two-component systems represent a potent new approach so far unexploited. Here, we focus efforts on the highly virulent bacterium Francisella tularensis tularensis. Francisella contains only three response regulators, making it an ideal system to study. In this study, we initially present the structure of the N-terminal domain of QseB, the response regulator responsible for biofilm formation. Subsequently, using binding assays, computational docking and cellular studies, we show that QseB interacts with2-aminoimidazole based compounds that impede its function. This information will assist in tailoring compounds to act as adjuvants that will enhance the effect of antibiotics.

  17. NCBI nr-aa BLAST: CBRC-TTRU-01-0103 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-TTRU-01-0103 ref|YP_169727.1| serine transporter [Francisella tularensis subsp.... tularensis SCHU S4] ref|YP_666859.1| serine transporter [Francisella tularensis subsp. tularensis FSC198] ...ref|ZP_03665376.1| serine transporter [Francisella tularensis subsp. tularensis MA00-2987] ref|ZP_04986333.1...5247354.1| serine transporter [Francisella tularensis subsp. tularensis MA00-2987] emb|CAG45345.1| serine transporter [Fran...cisella tularensis subsp. tularensis SCHU S4] emb|CAL08728.1| serine transporter [Francisella

  18. Immunoproteomic analysis of the human antibody response to natural tularemia infection with Type A or Type B strains or LVS vaccination

    Science.gov (United States)

    Fulton, Kelly M.; Zhao, Xigeng; Petit, Mireille D.; Kilmury, Sara L.N; Wolfraim, Lawrence A.; House, Robert V.; Sjostedt, Anders; Twine, Susan M.

    2011-01-01

    Francisella tularensis is pathogenic for many mammalian species including humans, causing a spectrum of diseases called tularemia. The highly virulent Type A strains have associated mortality rates of up to 60% if inhaled. An attenuated live vaccine strain (LVS) is the only vaccine to show efficacy in humans, but suffers several barriers to licensure, including the absence of a correlate of protection. An immunoproteomics approach was used to survey the repertoire of antibodies in sera from individuals who had contracted tularemia during two outbreaks and individuals from two geographical areas who had been vaccinated with NDBR Lot 11 or Lot 17 LVS. These data showed a large overlap in the antibodies generated in response to tularemia infection or LVS vaccination. A total of seven proteins were observed to be reactive with 60 % or more sera from vaccinees and convalescents. A further four proteins were recognised by 30–60 % of the sera screened. These proteins have the potential to serve as markers of vaccination or candidates for subunit vaccines. PMID:21873113

  19. NCBI nr-aa BLAST: CBRC-TTRU-01-0084 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-TTRU-01-0084 ref|ZP_03665674.1| amino acid permease [Francisella tularensis su...bsp. tularensis MA00-2987] ref|ZP_04986598.1| amino acid permease [Francisella tularensis subsp. tularensis ...FSC033] ref|ZP_05247618.1| amino acid permease [Francisella tularensis subsp. tularensis MA00-2987] gb|EDN34...490.1| amino acid permease [Francisella tularensis subsp. tularensis FSC033] gb|E...ET19343.1| amino acid permease [Francisella tularensis subsp. tularensis MA00-2987] ZP_03665674.1 0.22 27% ...

  20. DESTRUCTION OF FRANCISELLA TULARENSIS AND YERSINIA PESTIS PERSISTENCE OF BACILLUS ANTHRACIS SPORES AND CLOSTRIDIUM BOTULINUM IN MUNICIPAL SOLID LANDFILL LEACHATES

    Science.gov (United States)

    The United States Environmental Protection Agency Office of Research and Development National Homeland Security Research Center (NHSRC) in collaboration with the Department of Defense Edgewood Chemical Biological Center (ECBC) are evaluating the permanence of biological and chemi...

  1. Lipophilic prodrugs of FR900098 are antimicrobial against Francisella novicida in vivo and in vitro and show GlpT independent efficacy.

    Directory of Open Access Journals (Sweden)

    Elizabeth S McKenney

    Full Text Available Bacteria, plants, and algae produce isoprenoids through the methylerythritol phosphate (MEP pathway, an attractive pathway for antimicrobial drug development as it is present in prokaryotes and some lower eukaryotes but absent from human cells. The first committed step of the MEP pathway is catalyzed by 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR/MEP synthase. MEP pathway genes have been identified in many biothreat agents, including Francisella, Brucella, Bacillus, Burkholderia, and Yersinia. The importance of the MEP pathway to Francisella is demonstrated by the fact that MEP pathway mutations are lethal. We have previously established that fosmidomycin inhibits purified MEP synthase (DXR from F. tularensis LVS. FR900098, the acetyl derivative of fosmidomycin, was found to inhibit the activity of purified DXR from F. tularensis LVS (IC(50=230 nM. Fosmidomycin and FR900098 are effective against purified DXR from Mycobacterium tuberculosis as well, but have no effect on whole cells because the compounds are too polar to penetrate the thick cell wall. Fosmidomycin requires the GlpT transporter to enter cells, and this is absent in some pathogens, including M. tuberculosis. In this study, we have identified the GlpT homologs in F. novicida and tested transposon insertion mutants of glpT. We showed that FR900098 also requires GlpT for full activity against F. novicida. Thus, we synthesized several FR900098 prodrugs that have lipophilic groups to facilitate their passage through the bacterial cell wall and bypass the requirement for the GlpT transporter. One compound, that we termed "compound 1," was found to have GlpT-independent antimicrobial activity. We tested the ability of this best performing prodrug to inhibit F. novicida intracellular infection of eukaryotic cell lines and the caterpillar Galleria mellonella as an in vivo infection model. As a lipophilic GlpT-independent DXR inhibitor, compound 1 has the potential to be a broad

  2. Characterization of Francisella sp., GM2212, the first Francisella isolate from marine fish, Atlantic cod (Gadus morhua)

    DEFF Research Database (Denmark)

    Ottem, Karl F; Nylund, Are; Karlsbakk, Egil

    2007-01-01

    from F. tularensis and F. philomiragia. GM2212(T) is catalase-positive, indole positive, oxidase-negative, do not produce H(2)S in Triple Sugar Iron agar, and does not hydrolyze gelatin, is resistant to erythromycin and susceptible to ceftazidime, the latter five characteristics separating it from F...

  3. A Polyphasic Approach for Phenotypic and Genetic Characterization of the Fastidious Aquatic Pathogen Francisella noatunensis subsp. orientalis

    Directory of Open Access Journals (Sweden)

    José G. Ramírez-Paredes

    2017-12-01

    Full Text Available Francisella noatunensis subsp. orientalis (Fno is the causative agent of piscine francisellosis, an emerging infectious disease in Asia and Latin America. In this study two outbreaks of francisellosis were diagnosed in the UK on the basis of histopathology, electron microscopy, PCR, bacterial isolation and fulfillment of Koch's postulates. Furthermore, a phenotypic fingerprint based on biochemical analyses, metabolic activity, chemotaxonomic composition, and antimicrobial assays was generated for the novel isolates, the Fno type strain Ehime-1 from Asia and other Fno from Latin America. The genetic relatedness between the novel Fno and other Francisellaceae species was investigated by sequencing and comparing the 16SrRNA gene, 8 housekeeping genes (individually and concatenated and the 16SrRNA-ITS-23SrRNA sequence. The phenotypic profiling indicated a high degree of similarity among the Fno strains as all were able to metabolize dextrin, N-acetyl-D glucosamine, D-fructose, α-D-glucose, D-mannose, methyl pyruvate, acetic acid, α-keto butyric acid, L-alaninamide, L-alanine, L-alanylglycine, L-asparagine, L-glutamic acid, L-proline, L-serine, L-threonine, inosine, uridine, glycerol, D L-α-glycerol phosphate, glucose-1-phosphate, and glucose-6-phosphate. The chemotaxonomic analyses indicated that 24:1 (20.3%, 18:1n-9 (16.9%, 24:0 (13.1% 14:0 (10.9%, 22:0 (7.8%, 16:0 (7.6%, and 18:0 (5.5% were the predominant structural fatty acids in Fno. The antimicrobial assays showed little variation between the isolates and high susceptibility to enrofloxacin, gentamicin, neomycin, streptomycin, amikacin, ciprofloxacin, gatifloxacin, nitrofurantoin, tobramycin, kanamycin, tetracycline, oxytetracycline, florfenicol, oxolinic acid, and streptomycin in all the Fno analyzed. In all the phylogenetic trees the Fno strains clustered together in independent branches confirming a high degree of homogeneity. Interestingly in five of the 11 trees i.e., mutS, putA, rpo

  4. Characterization of Francisella sp., GM2212, the first Francisella isolate from marine fish, Atlantic cod (Gadus morhua)

    DEFF Research Database (Denmark)

    Ottem, Karl F; Nylund, Are; Karlsbakk, Egil

    2007-01-01

    A Francisella sp., isolate GM2212(T), previously isolated from diseased farmed Atlantic cod Gadus morhua in Norway is characterized. The complete 16S rDNA, 16S-23S intergenic spacer, 23S rDNA, 23S-5S intergenic spacer, 5S rDNA, FopA, lipoprotein TUL4 (LpnA), malate dehydrogenase and a hypothetica...

  5. NCBI nr-aa BLAST: CBRC-CBRI-05-0288 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-CBRI-05-0288 ref|YP_512974.1| Acyltransferase [Francisella tularensis subsp. h...olarctica] ref|YP_762841.1| acyltransferase [Francisella tularensis subsp. holarctica OSU18] ref|YP_001427626.1| acyltransferase [Fra...ncisella tularensis subsp. holarctica FTA] emb|CAJ78620.1| Acyltransferase [Francis...ella tularensis subsp. holarctica LVS] gb|ABI82204.1| acyltransferase [Francisell...a tularensis subsp. holarctica OSU18] gb|EBA51928.1| acyltransferase [Francisella tularensis subsp. holarcti

  6. Re-sensitizing Multidrug Resistant Bacteria to Antibiotics by Targeting Bacterial Response Regulators: Characterization and Comparison of Interactions between 2-Aminoimidazoles and the Response Regulators BfmR from Acinetobacter baumannii and QseB from Francisella spp.

    Directory of Open Access Journals (Sweden)

    Morgan E. Milton

    2018-02-01

    Full Text Available 2-aminoimidazole (2-AI compounds inhibit the formation of bacterial biofilms, disperse preformed biofilms, and re-sensitize multidrug resistant bacteria to antibiotics. 2-AIs have previously been shown to interact with bacterial response regulators, but the mechanism of interaction is still unknown. Response regulators are one part of two-component systems (TCS. TCSs allow cells to respond to changes in their environment, and are used to trigger quorum sensing, virulence factors, and antibiotic resistance. Drugs that target the TCS signaling process can inhibit pathogenic behavior, making this a potent new therapeutic approach that has not yet been fully exploited. We previously laid the groundwork for the interaction of the Acinetobacter baumannii response regulator BfmR with an early 2-AI derivative. Here, we further investigate the response regulator/2-AI interaction and look at a wider library of 2-AI compounds. By combining molecular modeling with biochemical and cellular studies, we expand on a potential mechanism for interaction between response regulators and 2-AIs. We also establish that Francisella tularensis/novicida, encoding for only three known response regulators, can be a model system to study the interaction between 2-AIs and response regulators. We show that knowledge gained from studying Francisella can be applied to the more complex A. baumannii system, which contains over 50 response regulators. Understanding the impact of 2-AIs on response regulators and their mechanism of interaction will lead to the development of more potent compounds that will serve as adjuvant therapies to broad-range antibiotics.

  7. Host immune response and acute disease in a zebrafish model of francisella pathogenesis

    Science.gov (United States)

    Vojtech, L.N.; Sanders, G.E.; Conway, C.; Ostland, V.; Hansen, J.D.

    2009-01-01

    Members of the bacterial genus Francisella are highly virulent and infectious pathogens. New models to study Francisella pathogenesis in evolutionarily distinct species are needed to provide comparative insight, as the mechanisms of host resistance and pathogen virulence are not well understood. We took advantage of the recent discovery of a novel species of Francisella to establish a zebrafish/Francisella comparative model of pathogenesis and host immune response. Adult zebraflsh were susceptible to acute Francisella-induced disease and suffered mortality in a dose-dependent manner. Using immunohistochemical analysis, we localized bacterial antigens primarily to lymphoid tissues and livers of zebraflsh following infection by intraperitoneal injection, which corresponded to regions of local cellular necrosis. Francisella sp. bacteria replicated rapidly in these tissues beginning 12 h postinfection, and bacterial titers rose steadily, leveled off, and then decreased by 7 days postinfection. Zebraflsh mounted a significant tissue-specific proinflammatory response to infection as measured by the upregulation of interleukin-l?? (IL-1??), gamma interferon, and tumor necrosis factor alpha mRNA beginning by 6 h postinfection and persisting for up to 7 days postinfection. In addition, exposure of zebraflsh to heat-killed bacteria demonstrated that the significant induction of IL-?? was highly specific to live bacteria. Taken together, the pathology and immune response to acute Francisella infection in zebraflsh share many features with those in mammals, highlighting the usefulness of this new model system for addressing both general and specific questions about Francisella host-pathogen interactions via an evolutionary approach. Copyright ?? 2009, American Society for Microbiology. All Rights Reserved.

  8. First identification of Francisella noatunensis subsp. orientalis causing mortality in Mexican tilapia Oreochromis spp.

    Science.gov (United States)

    Ortega, Cesar; Mancera, Gerardo; Enríquez, Ricardo; Vargas, Augusto; Martínez, Simón; Fajardo, Raúl; Avendaño-Herrera, Ruben; Navarrete, María José; Romero, Alex

    2016-08-09

    Francisellosis, an emerging disease in tilapia Oreochromis spp., is caused by the facultative, intracellular bacterium Francisella noatunensis subsp. orientalis, which is present in various countries where tilapia farming is commercially important. We confirmed the presence of francisellosis in Mexican tilapia cultures in association with an outbreak during the second semester of 2012. Broodstock fish presented a mortality rate of approximately 40%, and disease was characterized by histologically classified granulomas, or whitish nodules, in different organs, mainly the spleen and kidney. Through DNA obtained from infected tissue and pure cultures in a cysteine heart medium supplemented with hemoglobin, F. noatunensis subsp. orientalis was initially confirmed through the amplification and analysis of the 16S rRNA gene and the internal transcribed spacer region. Phylogenetic analysis of these genes demonstrated close similarity with previously reported F. noatunensis subsp. orientalis sequences obtained from infected tilapia from various countries. The identification of this subspecies as the causative agent of the outbreak was confirmed using the iglC gene as a target sequence, which showed 99.5% identity to 2 F. noatunensis subsp. orientalis strains (Ethime-1 and Toba04). These findings represent the first documented occurrence of francisellosis in Mexican tilapia cultures, which highlights the importance of establishing preventative measures to minimize the spread of this disease within the Mexican aquaculture industry.

  9. Immunotherapy for tularemia

    Science.gov (United States)

    Skyberg, Jerod A.

    2013-01-01

    Francisella tularensis is a gram-negative bacterium that causes the zoonotic disease tularemia. Francisella is highly infectious via the respiratory route (~10 CFUs) and pulmonary infections due to type A strains of F. tularensis are highly lethal in untreated patients (>30%). In addition, no vaccines are licensed to prevent tularemia in humans. Due to the high infectivity and mortality of pulmonary tularemia, F. tularensis has been weaponized, including via the introduction of antibiotic resistance, by several countries. Because of the lack of efficacious vaccines, and concerns about F. tularensis acquiring resistance to antibiotics via natural or illicit means, augmentation of host immunity, and humoral immunotherapy have been investigated as countermeasures against tularemia. This manuscript will review advances made and challenges in the field of immunotherapy against tularemia. PMID:23959031

  10. Francisella marina sp. nov., etiologic agent of systemic disease in cultured spotted rose snapper (Lutjanus guttatus) in Central America

    Science.gov (United States)

    Historically, piscine francisellosis in various warm, temperate and coldwater fish hosts has been attributed to Francisella noatunensis. From 2015-2016, an undescribed Francisella sp. was recovered during mortality events in cultured spotted rose snapper (Lutjanus guttatus) off the Pacific coast of ...

  11. NCBI nr-aa BLAST: CBRC-TTRU-01-0103 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-TTRU-01-0103 ref|YP_514171.1| serine transporter [Francisella tularensis subsp.... holarctica] ref|YP_001429039.1| hypothetical protein FTA_1608 [Francisella tularensis subsp. holarctica FT...NF002-00] ref|ZP_02274778.1| serine permease [Francisella tularensis subsp. holarctica FSC200] ref|ZP_049841...11.1| serine transporter [Francisella tularensis subsp. holarctica 257] emb|CAJ79...963.1| serine transporter [Francisella tularensis subsp. holarctica LVS] gb|EBA52995.1| serine transporter [Fran

  12. Molecular detection of Rickettsia, Anaplasma, Coxiella and Francisella bacteria in ticks collected from Artiodactyla in Thailand.

    Science.gov (United States)

    Sumrandee, Chalao; Baimai, Visut; Trinachartvanit, Wachareeporn; Ahantarig, Arunee

    2016-07-01

    A total of 79 ticks collected from Sambar deer (Cervus unicolor), Barking deer (Muntiacus muntjak) and Wild boar (Sus scrofa) were examined by PCR for the presence of Rickettsia, Anaplasma, Coxiella, and Francisella bacteria. Of the 79 ticks, 13% tested positive for Rickettsia, 15% tested positive for Anaplasma, 4% tested positive for Coxiella, and 3% tested positive for Francisella. Interestingly, triple infection with Anaplasma, Rickettsia and Francisella was determined in a Dermacentor auratus tick. Moreover, another triple infection with Rickettsia, Anaplasma, and Coxiella was found in a Haemaphysalis lagrangei tick. Double infection of Rickettsia with Coxiella was also detected in another H. lagrangei tick. From the phylogenetic analyses, we found a Rickettsia sp. with a close evolutionary relationship to Rickettsia bellii in the H. lagrangei tick. We also found the first evidence of a Rickettsia sp. that is closely related to Rickettsia tamurae in Rhipicephalus (Boophilus) microplus ticks from Thailand. H. lagrangei and Haemaphysalis obesa ticks collected from Sambar deer tested positive for Anaplasma species form the same clade with Anaplasma bovis. In contrast, other H. lagrangei ticks collected from Sambar deer and D. auratus ticks collected from Wild boar were also reported for the first time to be infected with an Anaplasma species that is closely related to Anaplasma platys. The phylogenetic analysis of the 16S rRNA gene of Coxiella bacteria revealed that Coxiella symbionts from H. lagrangei formed a distinctly different lineage from Coxiella burnetii (a human pathogen). Additionally, Francisella bacteria identified in D. auratus ticks were found to be distantly related to a group of pathogenic Francisella species. The identification of these bacteria in several feeding ticks suggests the risk of various emerging tick-borne diseases and endosymbionts in humans, wildlife, and domestic animals in Thailand. Copyright © 2016 Elsevier GmbH. All rights

  13. Testing and Validation of High Density Resequencing Microarray for Broad Range Biothreat Agents Detection

    Science.gov (United States)

    2009-08-11

    concentration of the virus was expressed in plaque forming units (pfu). For synthetic DNA templates, the DNA concentration was used to calculate the...cells ATCC Escherichia coli O157:H7 ATCC 43985 (CDC EDL933) Nucleic acid ATCC Francisella tularensis SHU4 Nucleic acid AFIP Leptospira interrogans ATCC...2% on the nucleotide level and 0.6% on the protein level. Similar strain discrimination was obtained in case of Machupo virus strains Carvallo and

  14. Problems in identification of Francisella philomiragia associated with fatal bacteremia in a patient with chronic granulomatous disease

    DEFF Research Database (Denmark)

    Friis-Møller, Alice; Lemming, L E; Valerius, Niels Henrik

    2004-01-01

    Francisella philomiragia is a rare gram-negative, halophilic coccobacillus with bizarre spherical forms on primary isolation. A case of F. philomiragia bacteremia in a 24-year-old patient with chronic granulomatous disease is reported. Identification of F. philomiragia was problematic with conven......Francisella philomiragia is a rare gram-negative, halophilic coccobacillus with bizarre spherical forms on primary isolation. A case of F. philomiragia bacteremia in a 24-year-old patient with chronic granulomatous disease is reported. Identification of F. philomiragia was problematic...

  15. Immunochromatographic Assays for Identification of Biological Agents: NATO SIBCA Exercise I

    National Research Council Canada - National Science Library

    Fulton, R

    2000-01-01

    ...: Bacillus anthracis, Yersinia pestis, Vibrio cholerae, Venezuelan Equine Encephalitis (VEE) virus, Francisella tularensis, Brucella melitensis, Burkholderia mallei, Yellow Fever virus, Vaccinia virus, or Coxiella burnetii...

  16. Unique Structural Modifications Are Present in the Lipopolysaccharide from Colistin-Resistant Strains of Acinetobacter baumannii

    Science.gov (United States)

    2013-10-01

    Selected reaction monitoring (SRM) studies were performed on a Thermo TSQ Quantum Ultra Triple Stage quadrupole mass spectrometer. The scans of the...well as a PmrC-dependent pEtN addition to the lipid A of E. coli O157:H7 (39). Surprisingly, the canine pathogen Capnocytophaga canimorsus and plant...variety of novel lipid A structures obtained from Francisella tula- rensis live vaccine strain. Innate Immun. 18:268 –278. 44. Balaji V, Jeremiah SS

  17. Problems in identification of Francisella philomiragia associated with fatal bacteremia in a patient with chronic granulomatous disease

    DEFF Research Database (Denmark)

    Friis-Møller, Alice; Lemming, L E; Valerius, Niels Henrik

    2004-01-01

    Francisella philomiragia is a rare gram-negative, halophilic coccobacillus with bizarre spherical forms on primary isolation. A case of F. philomiragia bacteremia in a 24-year-old patient with chronic granulomatous disease is reported. Identification of F. philomiragia was problematic...

  18. Phylogenetic relationships of Francisella-like endosymbionts detected in two species of Amblyomma from snakes in Thailand

    Czech Academy of Sciences Publication Activity Database

    Sumrandee, C.; Hirunkanokpun, S.; Grubhoffer, Libor; Baimai, V.; Trinachartvanit, W.; Ahantarig, A.

    2014-01-01

    Roč. 5, č. 1 (2014), s. 29-32 ISSN 1877-959X Institutional support: RVO:60077344 Keywords : tick * Francisella-like endosymbiont * Amblyomma varanense * Amblyomma helvolum * snake * Thailand Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.718, year: 2014

  19. NCBI nr-aa BLAST: CBRC-DNOV-01-2151 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DNOV-01-2151 ref|YP_897819.1| competence protein [Francisella tularensis subsp.... novicida U112] gb|ABK89065.1| competence protein [Francisella tularensis subsp. novicida U112] YP_897819.1 0.005 24% ...

  20. NCBI nr-aa BLAST: CBRC-DNOV-01-2378 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DNOV-01-2378 ref|YP_897819.1| competence protein [Francisella tularensis subsp.... novicida U112] gb|ABK89065.1| competence protein [Francisella tularensis subsp. novicida U112] YP_897819.1 0.12 24% ...

  1. NCBI nr-aa BLAST: CBRC-SARA-01-0900 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-SARA-01-0900 ref|YP_898010.1| phosphatidylserine synthase [Francisella tularen...sis subsp. novicida U112] gb|ABK89256.1| phosphatidylserine synthase [Francisella tularensis subsp. novicida U112] YP_898010.1 3.0 27% ...

  2. NCBI nr-aa BLAST: CBRC-TTRU-01-0103 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-TTRU-01-0103 ref|YP_763917.1| HAAAP family serine permease [Francisella tulare...nsis subsp. holarctica OSU18] gb|ABI83280.1| HAAAP family serine permease [Francisella tularensis subsp. holarctica OSU18] YP_763917.1 0.077 25% ...

  3. Development of a Multivalent Subunit Vaccine against Tularemia Using Tobacco Mosaic Virus (TMV Based Delivery System.

    Directory of Open Access Journals (Sweden)

    Sukalyani Banik

    Full Text Available Francisella tularensis is a facultative intracellular pathogen, and is the causative agent of a fatal human disease known as tularemia. F. tularensis is classified as a Category A Biothreat agent by the CDC based on its use in bioweapon programs by several countries in the past and its potential to be used as an agent of bioterrorism. No licensed vaccine is currently available for prevention of tularemia. In this study, we used a novel approach for development of a multivalent subunit vaccine against tularemia by using an efficient tobacco mosaic virus (TMV based delivery platform. The multivalent subunit vaccine was formulated to contain a combination of F. tularensis protective antigens: OmpA-like protein (OmpA, chaperone protein DnaK and lipoprotein Tul4 from the highly virulent F. tularensis SchuS4 strain. Two different vaccine formulations and immunization schedules were used. The immunized mice were challenged with lethal (10xLD100 doses of F. tularensis LVS on day 28 of the primary immunization and observed daily for morbidity and mortality. Results from this study demonstrate that TMV can be used as a carrier for effective delivery of multiple F. tularensis antigens. TMV-conjugate vaccine formulations are safe and multiple doses can be administered without causing any adverse reactions in immunized mice. Immunization with TMV-conjugated F. tularensis proteins induced a strong humoral immune response and protected mice against respiratory challenges with very high doses of F. tularensis LVS. This study provides a proof-of-concept that TMV can serve as a suitable platform for simultaneous delivery of multiple protective antigens of F. tularensis. Refinement of vaccine formulations coupled with TMV-targeting strategies developed in this study will provide a platform for development of an effective tularemia subunit vaccine as well as a vaccination approach that may broadly be applicable to many other bacterial pathogens.

  4. Francisella-Like Endosymbionts and Rickettsia Species in Local and Imported Hyalomma Ticks.

    Science.gov (United States)

    Azagi, Tal; Klement, Eyal; Perlman, Gidon; Lustig, Yaniv; Mumcuoglu, Kosta Y; Apanaskevich, Dmitry A; Gottlieb, Yuval

    2017-09-15

    Hyalomma ticks (Acari: Ixodidae) are hosts for Francisella -like endosymbionts (FLE) and may serve as vectors of zoonotic disease agents. This study aimed to provide an initial characterization of the interaction between Hyalomma and FLE and to determine the prevalence of pathogenic Rickettsia in these ticks. Hyalomma marginatum , Hyalomma rufipes , Hyalomma dromedarii , Hyalomma aegyptium , and Hyalomma excavatum ticks, identified morphologically and molecularly, were collected from different hosts and locations representing the distribution of the genus Hyalomma in Israel, as well as from migratory birds. A high prevalence of FLE was found in all Hyalomma species (90.6%), as well as efficient maternal transmission of FLE (91.8%), and the localization of FLE in Malpighian tubules, ovaries, and salivary glands in H. marginatum Furthermore, we demonstrated strong cophylogeny between FLE and their host species. Contrary to FLE, the prevalence of Rickettsia ranged from 2.4% to 81.3% and was significantly different between Hyalomma species, with a higher prevalence in ticks collected from migratory birds. Using ompA gene sequences, most of the Rickettsia spp. were similar to Rickettsia aeschlimannii , while a few were similar to Rickettsia africae of the spotted fever group (SFG). Given their zoonotic importance, 249 ticks were tested for Crimean Congo hemorrhagic fever virus infection, and all were negative. The results imply that Hyalomma and FLE have obligatory symbiotic interactions, indicating a potential SFG Rickettsia zoonosis risk. A further understanding of the possible influence of FLE on Hyalomma development, as well as on its infection with Rickettsia pathogens, may lead to novel ways to control tick-borne zoonoses. IMPORTANCE This study shows that Francisella -like endosymbionts were ubiquitous in Hyalomma , were maternally transmitted, and cospeciated with their hosts. These findings imply that the interaction between FLE and Hyalomma is of an obligatory

  5. Roles of inflammatory caspases during processing of zebrafish interleukin-1β in Francisella noatunensis infection

    Science.gov (United States)

    Vojtech, Lucia N.; Scharping, Nichole; Woodson, James C.; Hansen, John D.

    2012-01-01

    The interleukin-1 family of cytokines are essential for the control of pathogenic microbes but are also responsible for devastating autoimmune pathologies. Consequently, tight regulation of inflammatory processes is essential for maintaining homeostasis. In mammals, interleukin-1 beta (IL-1β) is primarily regulated at two levels, transcription and processing. The main pathway for processing IL-1β is the inflammasome, a multiprotein complex that forms in the cytosol and which results in the activation of inflammatory caspase (caspase 1) and the subsequent cleavage and secretion of active IL-1β. Although zebrafish encode orthologs of IL-1β and inflammatory caspases, the processing of IL-1β by activated caspase(s) has never been examined. Here, we demonstrate that in response to infection with the fish-specific bacterial pathogen Francisella noatunensis, primary leukocytes from adult zebrafish display caspase-1-like activity that results in IL-1β processing. Addition of caspase 1 or pancaspase inhibitors considerably abrogates IL-1β processing. As in mammals, this processing event is concurrent with the secretion of cleaved IL-1β into the culture medium. Furthermore, two putative zebrafish inflammatory caspase orthologs, caspase A and caspase B, are both able to cleave IL-1β, but with different specificities. These results represent the first demonstration of processing and secretion of zebrafish IL-1β in response to a pathogen, contributing to our understanding of the evolutionary processes governing the regulation of inflammation.                   

  6. Revisiting the Gram-negative lipoprotein paradigm.

    Science.gov (United States)

    LoVullo, Eric D; Wright, Lori F; Isabella, Vincent; Huntley, Jason F; Pavelka, Martin S

    2015-05-01

    The processing of lipoproteins (Lpps) in Gram-negative bacteria is generally considered an essential pathway. Mature lipoproteins in these bacteria are triacylated, with the final fatty acid addition performed by Lnt, an apolipoprotein N-acyltransferase. The mature lipoproteins are then sorted by the Lol system, with most Lpps inserted into the outer membrane (OM). We demonstrate here that the lnt gene is not essential to the Gram-negative pathogen Francisella tularensis subsp. tularensis strain Schu or to the live vaccine strain LVS. An LVS Δlnt mutant has a small-colony phenotype on sucrose medium and increased susceptibility to globomycin and rifampin. We provide data indicating that the OM lipoprotein Tul4A (LpnA) is diacylated but that it, and its paralog Tul4B (LpnB), still sort to the OM in the Δlnt mutant. We present a model in which the Lol sorting pathway of Francisella has a modified ABC transporter system that is capable of recognizing and sorting both triacylated and diacylated lipoproteins, and we show that this modified system is present in many other Gram-negative bacteria. We examined this model using Neisseria gonorrhoeae, which has the same Lol architecture as that of Francisella, and found that the lnt gene is not essential in this organism. This work suggests that Gram-negative bacteria fall into two groups, one in which full lipoprotein processing is essential and one in which the final acylation step is not essential, potentially due to the ability of the Lol sorting pathway in these bacteria to sort immature apolipoproteins to the OM. This paper describes the novel finding that the final stage in lipoprotein processing (normally considered an essential process) is not required by Francisella tularensis or Neisseria gonorrhoeae. The paper provides a potential reason for this and shows that it may be widespread in other Gram-negative bacteria. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  7. Expansion and retention of pulmonary CD4+ T cells after prime boost vaccination correlates with improved longevity and strength of immunity against tularemia.

    Science.gov (United States)

    Roberts, Lydia M; Wehrly, Tara D; Crane, Deborah D; Bosio, Catharine M

    2017-05-02

    Francisella tularensis subsp. tularensis strain SchuS4 (Ftt) is a highly virulent intracellular bacterium. Inhalation of 10 or fewer organisms results in an acute and potentially lethal disease called pneumonic tularemia. Ftt infections occur naturally in the U.S. and Ftt was developed as a bioweapon. Thus, there is a need for vaccines that protect against this deadly pathogen. Although a live vaccine strain of Francisella tularensis (LVS) exists, LVS fails to generate long-lived protective immunity against modest challenge doses of Ftt. We recently identified an important role for high avidity CD4 + T cells in short-term protection and hypothesized that expanding this pool of cells would improve overall vaccine efficacy with regard to longevity and challenge dose. In support of our hypothesis, application of a prime/boost vaccination strategy increased the pool of high avidity CD4 + T cells which correlated with improved survival following challenge with either increased doses of virulent Ftt or at late time points after vaccination. In summary, we demonstrate that both epitope selection and vaccination strategies that expand antigen-specific T cells correlate with superior immunity to Ftt as measured by survival. Copyright © 2017. Published by Elsevier Ltd.

  8. Decontamination of materials contaminated with Francisella philomiragia or MS2 bacteriophage using PES-Solid, a solid source of peracetic acid.

    Science.gov (United States)

    Buhr, T L; Young, A A; Johnson, C A; Minter, Z A; Wells, C M

    2014-08-01

    The aim of the study was to develop test methods and evaluate survival of Francisella philomiragia cells and MS2 bacteriophage after exposure to PES-Solid (a solid source of peracetic acid) formulations with or without surfactants. Francisella philomiragia cells (≥7·6 log10 CFU) or MS2 bacteriophage (≥6·8 log10 PFU) were deposited on seven different test materials and treated with three different PES-Solid formulations, three different preneutralized samples and filter controls at room temperature for 15 min. There were 0-1·3 log10 CFU (6 log10 CFU/PFU F. philomiragia cells and/or MS2 bacteriophage on different materials. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  9. Customizable PCR-microplate array for differential identification of multiple pathogens.

    Science.gov (United States)

    Woubit, Abdela; Yehualaeshet, Teshome; Roberts, Sherrelle; Graham, Martha; Kim, Moonil; Samuel, Temesgen

    2013-11-01

    Customizable PCR-microplate arrays were developed for the rapid identification of Salmonella Typhimurium, Salmonella Saintpaul, Salmonella Typhi, Shigella dysenteriae, Escherichia coli O157:H7, Francisella tularensis subsp. tularensis, Francisella tularensis subsp. novicida, Vibrio cholerae, Vibrio parahaemolyticus, Yersinia pestis, and Yersinia pseudotuberculosis. Previously, we identified highly specific primers targeting each of these pathogens. Here, we report the development of customizable PCR-microplate arrays for simultaneous identification of the pathogens using the primers identified. A mixed aliquot of genomic DNA from 38 strains was used to validate three PCR-microplate array formats. Identical PCR conditions were used to run all the samples on the three formats. Specific amplifications were obtained on all three custom plates. In preliminary tests performed to evaluate the sensitivity of these assays in samples inoculated in the laboratory with Salmonella Typhimurium, amplifications were obtained from 1 g of beef hot dog inoculated at as low as 9 CFU/ml or from milk inoculated at as low as 78 CFU/ml. Such microplate arrays could be valuable tools for initial identification or secondary confirmation of contamination by these pathogens.

  10. Transmission of tularemia from a water source by transstadial maintenance in a mosquito vector

    Science.gov (United States)

    Bäckman, Stina; Näslund, Jonas; Forsman, Mats; Thelaus, Johanna

    2015-01-01

    Mosquitoes are thought to function as mechanical vectors of Francisella tularensis subspecies holarctica (F. t. holarctica) causing tularemia in humans. We investigated the clinical relevance of transstadially maintained F. t. holarctica in mosquitoes. Aedes egypti larvae exposed to a fully virulent F. t. holarctica strain for 24 hours, were allowed to develop into adults when they were individually homogenized. Approximately 24% of the homogenates tested positive for F. t. DNA in PCR. Mice injected with the mosquito homogenates acquired tularemia within 5 days. This novel finding demonstrates the possibility of transmission of bacteria by adult mosquitoes having acquired the pathogen from their aquatic larval habitats.

  11. CHLORINE INACTIVATION OF CATEGORY "A" BIO-TERRORISM AGENTS

    Science.gov (United States)

    This poster presents information on the inactivation of select bioterrorist agents. Information will be presented on chlorine disinfection of vegetative cells of Brucella suis, Brucella melitensis, Burkholderia mallei, Burkholderia pseudomallei, Francisella tularensis and endos...

  12. Elisa-Like Format for Comparing DNA Capture Elements (Aptamers) to Antibody in Diagnostic Efficacy

    National Research Council Canada - National Science Library

    Kiel, Johnathan L; Holwitt, Eric A; Vivekananda, Jeevalatha; Franz, Veronica

    2004-01-01

    .... For this purpose, the microtiter, heterologous phase, ELISAlike sandwich assay test was chosen. The antigen of choice was the standard antigen used in commercially available agglutination tests for Francisella tularensis (tularemia bacterium...

  13. Tularemia blood test

    Science.gov (United States)

    Tularemia test; Serology for Francisella tularensis ... This blood test is done when tularemia is suspected. ... Elsevier; 2017:chap 44. Chernecky CC, Berger BJ. Tularemia agglutinins - serum. In: Chernecky CC, Berger BJ, eds. ...

  14. Flåtbårne infektioner i Danmark

    DEFF Research Database (Denmark)

    Jensen, Bo Bødker; Ocias, Lukas Frans; Andersen, Nanna Skaarup

    2017-01-01

    The castor bean tick, Ixodes ricinus, is common in woodlands in most of Denmark. Besides Borrelia burgdorferi, it can harbour a number of pathogenic microorganisms such as tick-borne encephalitis virus, Anaplasma phagocytophilum, Rickettsia helvetica, Francisella tularensis, Candidatus Neoehrlichia...

  15. 76 FR 56099 - Implementation of a Decision Adopted Under the Australia Group (AG) Intersessional Silent...

    Science.gov (United States)

    2011-09-12

    ... virus; a.22. Marburg virus; a.23. Monkey pox virus; a.24. Murray Valley encephalitis virus; a.25. Nipah... serotypes; c.11. Francisella tularensis; c.12. Salmonella typhi; c.13. Shigella dysenteriae; c.14. Vibrio...

  16. Natural coinfection by Streptococcus agalactiae and Francisella noatunensis subsp. orientalis in farmed Nile tilapia (Oreochromis niloticus L.).

    Science.gov (United States)

    Assis, G B N; Tavares, G C; Pereira, F L; Figueiredo, H C P; Leal, C A G

    2017-01-01

    Streptococcus agalactiae and Francisella noatunensis subsp. orientalis (Fno) are important pathogens for farm-raised tilapia worldwide. There are no reports of coinfection caused by S. agalactiae and Fno in fish. This study aimed to determine the aetiology of atypical mortalities in a cage farm of Nile tilapia and to characterize the genetic diversity of the isolates. Fifty-two fish were sampled and subjected to parasitological and bacteriological examination. The S. agalactiae and Fno isolates were genotyped using MLST and REP-PCR, respectively. Whole-genome sequencing was performed to confirm the MLST results. Seven fish were shown coinfected by S. agalactiae and Fno. Chronic hypoxia and a reduction in the water temperature were determined as risk factors for coinfection. Fno isolates were shown clonally related in REP-PCR. The MLST analysis revealed that the S. agalactiae isolates from seven coinfected fish were negative for the glcK gene; however, these were determined to be members of clonal complex CC-552. This is the first description of coinfection by S. agalactiae and Fno in farm-raised Nile tilapia. The coinfection was predisposed by chronic hypoxia and was caused by the main genotypes of S. agalactiae and Fno reported in Brazil. Finally, a new S. agalactiae genotype with glcK gene partially deleted was described. © 2016 John Wiley & Sons Ltd.

  17. Bronchus-associated lymphoid tissue (BALT and survival in a vaccine mouse model of tularemia.

    Directory of Open Access Journals (Sweden)

    Damiana Chiavolini

    2010-06-01

    Full Text Available Francisella tularensis causes severe pulmonary disease, and nasal vaccination could be the ideal measure to effectively prevent it. Nevertheless, the efficacy of this type of vaccine is influenced by the lack of an effective mucosal adjuvant.Mice were immunized via the nasal route with lipopolysaccharide isolated from F. tularensis and neisserial recombinant PorB as an adjuvant candidate. Then, mice were challenged via the same route with the F. tularensis attenuated live vaccine strain (LVS. Mouse survival and analysis of a number of immune parameters were conducted following intranasal challenge. Vaccination induced a systemic antibody response and 70% of mice were protected from challenge as showed by their improved survival and weight regain. Lungs from mice recovering from infection presented prominent lymphoid aggregates in peribronchial and perivascular areas, consistent with the location of bronchus-associated lymphoid tissue (BALT. BALT areas contained proliferating B and T cells, germinal centers, T cell infiltrates, dendritic cells (DCs. We also observed local production of antibody generating cells and homeostatic chemokines in BALT areas.These data indicate that PorB might be an optimal adjuvant candidate for improving the protective effect of F. tularensis antigens. The presence of BALT induced after intranasal challenge in vaccinated mice might play a role in regulation of local immunity and long-term protection, but more work is needed to elucidate mechanisms that lead to its formation.

  18. Determination of the Persistence of Non-Spore-Forming ...

    Science.gov (United States)

    Report This report presents the results of an investigation to evaluate the persistence (or natural attenuation) of Yersinia pestis (Y. pestis), Francisella tularensis (F. tularensis), and Burkholderia mallei (B. mallei) on glass and soil under multiple environmental conditions and time points.

  19. First case of severe pneumonic tularemia in an immunocompetent patient in the Netherlands

    NARCIS (Netherlands)

    Sigaloff, K.C.E.; Chung, P.K.; Koopmans, J.; Notermans, D.W.; Rijckevorsel, Van G.G.C.; Koene, M.; Sprengers, R.W.; Gooskens, J.; Stalenhoef, J.E.

    2017-01-01

    Tularemia is a zoonosis caused by different subspecies of the Gram-negative bacterium Francisella tularensis. We report the first case in the Netherlands of pneumonic tularemia caused by the F. tularensis subspecies holarctica after probable occupational inhalation of contaminated aerosols.

  20. First case of severe pneumonic tularemia in an immunocompetent patient in the Netherlands.

    NARCIS (Netherlands)

    Sigaloff, K C E; Chung, P K; Koopmans, J; Notermans, D W; van Rijckevorsel, G G C; Koene, M; Sprengers, R W; Gooskens, J; Stalenhoef, J E

    Tularemia is a zoonosis caused by different subspecies of the Gram-negative bacterium Francisella tularensis. We report the first case in the Netherlands of pneumonic tularemia caused by the F. tularensis subspecies holarctica after probable occupational inhalation of contaminated aerosols.

  1. Environmental surveillance during an outbreak of tularaemia in hares, the Netherlands, 2015.

    NARCIS (Netherlands)

    Janse, Ingmar; Maas, Miriam; Rijks, Jolianne M; Koene, Miriam; van der Plaats, Rozemarijn Qj; Engelsma, Marc; van der Tas, Peter; Braks, Marieta; Stroo, Arjan; Notermans, Daan W; de Vries, Maaike C; Reubsaet, Frans; Fanoy, Ewout; Swaan, Corien; Kik, Marja Jl; IJzer, Jooske; Jaarsma, Ryanne I; van Wieren, Sip; de Roda-Husman, Ana Maria; van Passel, Mark; Roest, Hendrik-Jan; van der Giessen, Joke

    2017-01-01

    Tularaemia, a disease caused by the bacterium Francisella tularensis, is a re-emerging zoonosis in the Netherlands. After sporadic human and hare cases occurred in the period 2011 to 2014, a cluster of F. tularensis-infected hares was recognised in a region in the north of the Netherlands from

  2. Buse_Francisella Medium

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset contains colony forming unit and qPCR data. This dataset is associated with the following publication: Morris, B., H. Buse, N. Adcock, and E. Rice. A...

  3. [The epizootic characteristics of tularemia in the Crimea].

    Science.gov (United States)

    Alekseev, A F; Chirniĭ, V I; Bogatyreva, L M; Tovpinets, N N; Evstaf'ev, I L; Markeshin, S Ia; Kovin, V V; Evstratov, Iu V; Zakharova, T F; Galushko, V I

    1996-01-01

    Cases of tularemia were registered in the Crimea both before and after planned immunization. In 1981-1993 in 4.000 localities 35,100 mammals, 27,400 ectoparasites, 8,800 feces left by birds of prey and foxes and 900 environmental specimens were studied. 137 Francisella tularensis strains were isolated. Field mapping of the spread of F.tularensis and places of habitation of small mammals was carried out. The active polyhostal natural focus of tularemia was found to exist on the Kerch Peninsula, less affected by anthropogenic factors, where tularemia morbidity among humans, and tularemia epizootic coincided with the maximum rises in the number of myomorphs. The core of the focus constituted 2.4% of its area and were characterized by the stable complex of Ixodes ticks and the preservation of F. tularensis in the environment. In other regions of the flat part of the Crimea with considerable anthropogenic transformations of the landscape rises in tularemia epizootics and tularemia morbidity in humans were rare. In the mountainous part of the Crimea tularemia epizootics were registered only by the detection of specific antibodies and antigens.

  4. MglA/SspA complex interactions are modulated by inorganic polyphosphate.

    Science.gov (United States)

    Wrench, Algevis P; Gardner, Christopher L; Siegel, Sara D; Pagliai, Fernando A; Malekiha, Mahsa; Gonzalez, Claudio F; Lorca, Graciela L

    2013-01-01

    The transcription factors MglA and SspA of Francisella tularensis form a heterodimer complex and interact with the RNA polymerase to regulate the expression of the Francisella pathogenicity island (FPI) genes. These genes are essential for this pathogen's virulence and survival within host cells. Our goal was to determine if an intracellular metabolite modulate these protein/protein interactions. In this study, we identified inorganic polyphosphate (polyP) as a signal molecule that promotes the interaction of MglA and SspA from F. tularensis SCHU S4. Analysis of the Mgla/SspA interaction was carried out using a two-hybrid system. The Escherichia coli reporter strain contained a deletion on the ppK-ppX operon, inhibiting polyP synthesis. The interaction between MglA and SspA was significantly impaired, as was the interaction between the MglA/SspA complex and the regulatory protein, FevR, indicating the stabilizing effect of polyP. In F. tularensis, chromatin immune precipitation studies revealed that in the absence of polyP, binding of the MglA/SspA complex to the promoter region of the pdpD, iglA, fevR and ppK genes is decreased. Isothermal titration calorimetry (ITC) indicated that polyP binds directly to the MglA/SspA complex with high affinity (KD = 0.3 µM). These observations directly correlated with results obtained from calorimetric scans (DSC), where a strong shift in the mid-transition temperature (Tm) of the MglA/SspA complex was observed in the presence of polyP.

  5. MglA/SspA complex interactions are modulated by inorganic polyphosphate.

    Directory of Open Access Journals (Sweden)

    Algevis P Wrench

    Full Text Available The transcription factors MglA and SspA of Francisella tularensis form a heterodimer complex and interact with the RNA polymerase to regulate the expression of the Francisella pathogenicity island (FPI genes. These genes are essential for this pathogen's virulence and survival within host cells. Our goal was to determine if an intracellular metabolite modulate these protein/protein interactions. In this study, we identified inorganic polyphosphate (polyP as a signal molecule that promotes the interaction of MglA and SspA from F. tularensis SCHU S4. Analysis of the Mgla/SspA interaction was carried out using a two-hybrid system. The Escherichia coli reporter strain contained a deletion on the ppK-ppX operon, inhibiting polyP synthesis. The interaction between MglA and SspA was significantly impaired, as was the interaction between the MglA/SspA complex and the regulatory protein, FevR, indicating the stabilizing effect of polyP. In F. tularensis, chromatin immune precipitation studies revealed that in the absence of polyP, binding of the MglA/SspA complex to the promoter region of the pdpD, iglA, fevR and ppK genes is decreased. Isothermal titration calorimetry (ITC indicated that polyP binds directly to the MglA/SspA complex with high affinity (KD = 0.3 µM. These observations directly correlated with results obtained from calorimetric scans (DSC, where a strong shift in the mid-transition temperature (Tm of the MglA/SspA complex was observed in the presence of polyP.

  6. Metabolic network analysis-based identification of antimicrobial drug targets in category A bioterrorism agents.

    Directory of Open Access Journals (Sweden)

    Yong-Yeol Ahn

    Full Text Available The 2001 anthrax mail attacks in the United States demonstrated the potential threat of bioterrorism, hence driving the need to develop sophisticated treatment and diagnostic protocols to counter biological warfare. Here, by performing flux balance analyses on the fully-annotated metabolic networks of multiple, whole genome-sequenced bacterial strains, we have identified a large number of metabolic enzymes as potential drug targets for each of the three Category A-designated bioterrorism agents including Bacillus anthracis, Francisella tularensis and Yersinia pestis. Nine metabolic enzymes- belonging to the coenzyme A, folate, phosphatidyl-ethanolamine and nucleic acid pathways common to all strains across the three distinct genera were identified as targets. Antimicrobial agents against some of these enzymes are available. Thus, a combination of cross species-specific antibiotics and common antimicrobials against shared targets may represent a useful combinatorial therapeutic approach against all Category A bioterrorism agents.

  7. Susceptibility of Select Agents to Predation by Predatory Bacteria

    Directory of Open Access Journals (Sweden)

    Riccardo Russo

    2015-12-01

    Full Text Available Select Agents are microorganisms and toxins considered to be exploitable as biological weapons. Although infections by many Select Agents can be treated by conventional antibiotics, the risk of an emerging or engineered drug resistant strain is of great concern. One group of microorganisms that is showing potential to control drug resistant Gram-negative bacteria are the predatory bacteria from the genera Bdellovibrio spp. and Micavibrio spp. In this study, we have examined the ability of Bdellovibrio bacteriovorus (B. bacteriovorus strain 109J, HD100 and Micavibrio aeruginosavorus (M. aeruginosavorus ARL-13 to prey on a variety of Select Agents. Our findings demonstrate that B. bacteriovorus and M. aeruginosavorus are able to prey efficiently on Yersinia pestis and Burkholderia mallei. Modest predation was also measured in co-cultures of B. bacteriovorus and Francisella tularensis. However, neither of the predators showed predation when Burkholderia pseudomallei and Brucella melitensis were used as prey.

  8. Harepest hos jaeger

    DEFF Research Database (Denmark)

    Edfors, Robert; Smith, Birgitte; Lillebaek, Troels

    2010-01-01

    "Rabbit fever" (Francisella Tularensis) is a rare infection in Denmark. It was first described in Denmark in 1987. It is most likely to affect people who come into close contact with infected animals or ticks, such as hunters, butchers and veterinarians. The diagnosis should be suspected in such ......"Rabbit fever" (Francisella Tularensis) is a rare infection in Denmark. It was first described in Denmark in 1987. It is most likely to affect people who come into close contact with infected animals or ticks, such as hunters, butchers and veterinarians. The diagnosis should be suspected...

  9. IFN-γ extends the immune functions of Guanylate Binding Proteins to inflammasome-independent antibacterial activities during Francisella novicida infection.

    Directory of Open Access Journals (Sweden)

    Pierre Wallet

    2017-10-01

    Full Text Available Guanylate binding proteins (GBPs are interferon-inducible proteins involved in the cell-intrinsic immunity against numerous intracellular pathogens. The molecular mechanisms underlying the potent antibacterial activity of GBPs are still unclear. GBPs have been functionally linked to the NLRP3, the AIM2 and the caspase-11 inflammasomes. Two opposing models are currently proposed to explain the GBPs-inflammasome link: i GBPs would target intracellular bacteria or bacteria-containing vacuoles to increase cytosolic PAMPs release ii GBPs would directly facilitate inflammasome complex assembly. Using Francisella novicida infection, we investigated the functional interactions between GBPs and the inflammasome. GBPs, induced in a type I IFN-dependent manner, are required for the F. novicida-mediated AIM2-inflammasome pathway. Here, we demonstrate that GBPs action is not restricted to the AIM2 inflammasome, but controls in a hierarchical manner the activation of different inflammasomes complexes and apoptotic caspases. IFN-γ induces a quantitative switch in GBPs levels and redirects pyroptotic and apoptotic pathways under the control of GBPs. Furthermore, upon IFN-γ priming, F. novicida-infected macrophages restrict cytosolic bacterial replication in a GBP-dependent and inflammasome-independent manner. Finally, in a mouse model of tularemia, we demonstrate that the inflammasome and the GBPs are two key immune pathways functioning largely independently to control F. novicida infection. Altogether, our results indicate that GBPs are the master effectors of IFN-γ-mediated responses against F. novicida to control antibacterial immune responses in inflammasome-dependent and independent manners.

  10. The Atypical Occurrence of Two Biotin Protein Ligases in Francisella novicida Is Due to Distinct Roles in Virulence and Biotin Metabolism

    Science.gov (United States)

    Feng, Youjun; Chin, Chui-Yoke; Chakravartty, Vandana; Gao, Rongsui; Crispell, Emily K.

    2015-01-01

    ABSTRACT The physiological function of biotin requires biotin protein ligase activity in order to attach the coenzyme to its cognate proteins, which are enzymes involved in central metabolism. The model intracellular pathogen Francisella novicida is unusual in that it encodes two putative biotin protein ligases rather than the usual single enzyme. F. novicida BirA has a ligase domain as well as an N-terminal DNA-binding regulatory domain, similar to the prototypical BirA protein in E. coli. However, the second ligase, which we name BplA, lacks the N-terminal DNA binding motif. It has been unclear why a bacterium would encode these two disparate biotin protein ligases, since F. novicida contains only a single biotinylated protein. In vivo complementation and enzyme assays demonstrated that BirA and BplA are both functional biotin protein ligases, but BplA is a much more efficient enzyme. BirA, but not BplA, regulated transcription of the biotin synthetic operon. Expression of bplA (but not birA) increased significantly during F. novicida infection of macrophages. BplA (but not BirA) was required for bacterial replication within macrophages as well as in mice. These data demonstrate that F. novicida has evolved two distinct enzymes with specific roles; BplA possesses the major ligase activity, whereas BirA acts to regulate and thereby likely prevent wasteful synthesis of biotin. During infection BplA seems primarily employed to maximize the efficiency of biotin utilization without limiting the expression of biotin biosynthetic genes, representing a novel adaptation strategy that may also be used by other intracellular pathogens. PMID:26060274

  11. Molecular Investigation of Tularemia Outbreaks, Spain, 1997–2008

    Science.gov (United States)

    Ariza-Miguel, Jaime; Johansson, Anders; Fernández-Natal, María Isabel; Martínez-Nistal, Carmen; Orduña, Antonio; Rodríguez-Ferri, Elías F.; Hernández, Marta

    2014-01-01

    Tularemia outbreaks occurred in northwestern Spain in 1997–1998 and 2007–2008 and affected >1,000 persons. We assessed isolates involved in these outbreaks by using pulsed-field gel electrophoresis with 2 restriction enzymes and multilocus variable number tandem repeat analysis of 16 genomic loci of Francisella tularensis, the cause of this disease. Isolates were divided into 3 pulsotypes by pulsed-field gel electrophoresis and 8 allelic profiles by multilocus variable number tandem repeat analysis. Isolates obtained from the second tularemia outbreak had the same genotypes as isolates obtained from the first outbreak. Both outbreaks were caused by genotypes of genetic subclade B.Br:FTNF002–00, which is widely distributed in countries in central and western Europe. Thus, reemergence of tularemia in Spain was not caused by the reintroduction of exotic strains, but probably by persistence of local reservoirs of infection. PMID:24750848

  12. Strain-Modulated Epitaxy

    National Research Council Canada - National Science Library

    Brown, April

    1999-01-01

    Strain-Modulated Epitaxy (SME) is a novel approach, invented at Georgia Tech, to utilize subsurface stressors to control strain and therefore material properties and growth kinetics in the material above the stressors...

  13. Hamstring strain - aftercare

    Science.gov (United States)

    Pulled hamstring muscle; Sprain - hamstring ... There are 3 levels of hamstring strains: Grade 1 -- mild muscle strain or pull Grade 2 -- partial muscle tear Grade 3 -- complete muscle tear Recovery time depends ...

  14. A strain gauge

    DEFF Research Database (Denmark)

    2016-01-01

    The invention relates to a strain gauge of a carrier layer and a meandering measurement grid positioned on the carrier layer, wherein the strain gauge comprises two reinforcement members positioned on the carrier layer at opposite ends of the measurement grid in the axial direction....... The reinforcement members are each placed within a certain axial distance to the measurement grid with the axial distance being equal to or smaller than a factor times the grid spacing. The invention further relates to a multi-axial strain gauge such as a bi-axial strain gauge or a strain gauge rosette where each...... of the strain gauges comprises reinforcement members. The invention further relates to a method for manufacturing a strain gauge as mentioned above....

  15. Environmental surveillance during an outbreak of tularaemia in hares, the Netherlands, 2015.

    Science.gov (United States)

    Janse, Ingmar; Maas, Miriam; Rijks, Jolianne M; Koene, Miriam; van der Plaats, Rozemarijn Qj; Engelsma, Marc; van der Tas, Peter; Braks, Marieta; Stroo, Arjan; Notermans, Daan W; de Vries, Maaike C; Reubsaet, Frans; Fanoy, Ewout; Swaan, Corien; Kik, Marja Jl; IJzer, Jooske; Jaarsma, Ryanne I; van Wieren, Sip; de Roda-Husman, Ana Maria; van Passel, Mark; Roest, Hendrik-Jan; van der Giessen, Joke

    2017-08-31

    Tularaemia, a disease caused by the bacterium Francisella tularensis, is a re-emerging zoonosis in the Netherlands. After sporadic human and hare cases occurred in the period 2011 to 2014, a cluster of F. tularensis-infected hares was recognised in a region in the north of the Netherlands from February to May 2015. No human cases were identified, including after active case finding. Presence of F. tularensis was investigated in potential reservoirs and transmission routes, including common voles, arthropod vectors and surface waters. F. tularensis was not detected in common voles, mosquito larvae or adults, tabanids or ticks. However, the bacterium was detected in water and sediment samples collected in a limited geographical area where infected hares had also been found. These results demonstrate that water monitoring could provide valuable information regarding F. tularensis spread and persistence, and should be used in addition to disease surveillance in wildlife. This article is copyright of The Authors, 2017.

  16. Three dimensional strained semiconductors

    Science.gov (United States)

    Voss, Lars; Conway, Adam; Nikolic, Rebecca J.; Leao, Cedric Rocha; Shao, Qinghui

    2016-11-08

    In one embodiment, an apparatus includes a three dimensional structure comprising a semiconductor material, and at least one thin film in contact with at least one exterior surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the three dimensional structure. In another embodiment, a method includes forming a three dimensional structure comprising a semiconductor material, and depositing at least one thin film on at least one surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the structure.

  17. Strain measurement technique

    International Nuclear Information System (INIS)

    1987-01-01

    The 10 contributions are concerned with selected areas of application, such as strain measurements in wood, rubber/metal compounds, sets of strain measurements on buildings, reinforced concrete structures without gaps, pipes buried in the ground and measurements of pressure fluctuations. To increase the availability and safety of plant, stress analyses were made on gas turbine rotors with HT-DMS or capacitive HT-DMS (high temperature strain measurements). (DG) [de

  18. Strained Silicon Photonics

    Directory of Open Access Journals (Sweden)

    Ralf B. Wehrspohn

    2012-05-01

    Full Text Available A review of recent progress in the field of strained silicon photonics is presented. The application of strain to waveguide and photonic crystal structures can be used to alter the linear and nonlinear optical properties of these devices. Here, methods for the fabrication of strained devices are summarized and recent examples of linear and nonlinear optical devices are discussed. Furthermore, the relation between strain and the enhancement of the second order nonlinear susceptibility is investigated, which may enable the construction of optically active photonic devices made of silicon.

  19. Tularemia induces different biochemical responses in BALB/c mice and common voles

    Directory of Open Access Journals (Sweden)

    Vitula Frantisek

    2009-06-01

    Full Text Available Abstract Background Both BALB/c mice and common voles (Microtus arvalis are considered highly susceptible to tularemia. However, the common vole is reported to harbour Francisella tularensis in European habitats as well as to survive longer with chronic shedding of the bacterium. The purpose of the present study was to compare the response of these two rodents to a wild Francisella tularensis subsp. holarctica strain infection. Methods Rodents were evaluated for differences in the total antioxidant capacity derived from low-molecular-weight antioxidants, biochemistry including lipid metabolism, tissue bacterial burdens and histopathology following experimental intraperitoneal infection with 160 colony forming units (CFU pro toto. Results Bacterial burdens in common voles started to develop later post-exposure and amounted to lower levels than in BALB/c mice. Elevation of liver function enzymes was more pronounced in mice than common voles and there were marked differences in lipid metabolism in the course of tularemia in these two species. Hypertriglyceridemia and hypercholesterolemia developed in mice, while physiologically higher levels of triglycerides and cholesterol showed a decreasing tendency in common voles. On the other hand, the total plasma antioxidant capacity gradually dropped to 81.5% in mice on day 5 post-infection, while it increased to 130% on day 6 post-infection in common voles. Significant correlations between tissue bacterial burdens and several biochemical parameters were found. Conclusion As differences in lipid metabolism and the total antioxidant capacity of highly susceptible rodent species were demonstrated, the role of triglycerides, cholesterol and antioxidants in tularemic sepsis should be further investigated.

  20. Dicty_cDB: Contig-U15463-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 40 |pid:none) Bazzania tayloriana voucher NSW712... 248 3e-64 DQ406895_1( DQ406895 |pid:none) Sabia sp. Qiu ...248 3e-64 CP000439_1615( CP000439 |pid:none) Francisella tularensis subsp. n... 248 3e-64 EF101040_1( EF1010

  1. A strain gauge

    DEFF Research Database (Denmark)

    2017-01-01

    The invention relates to a strain gauge of a carrier layer and a meandering measurement grid (101) positioned on the carrier layer, wherein the measurement grid comprises a number of measurement grid sections placed side by side with gaps in between, and a number of end loops (106) interconnecting...... relates to a method for manufacturing a strain gauge as mentioned above....

  2. Internally Mounting Strain Gages

    Science.gov (United States)

    Jett, J. R., Jr.

    1984-01-01

    Technique for mounting strain gages inside bolt or cylinder simultaneously inserts gage, attached dowel segment, and length of expandable tubing. Expandable tubing holds gage in place while adhesive cures, assuring even distribution of pressure on gage and area gaged.

  3. Running Title: Strained Yoghurts

    African Journals Online (AJOL)

    USER

    2012-09-27

    Sep 27, 2012 ... ever, the traditional method of producing strained yoghurt ... Food market studies have the essential function of providing ..... Communication No: 2001/21. ... fermented foods and beverages of Turkey. Crit. Rev. Food. Sci. Nutr.

  4. Flexible piezotronic strain sensor.

    Science.gov (United States)

    Zhou, Jun; Gu, Yudong; Fei, Peng; Mai, Wenjie; Gao, Yifan; Yang, Rusen; Bao, Gang; Wang, Zhong Lin

    2008-09-01

    Strain sensors based on individual ZnO piezoelectric fine-wires (PFWs; nanowires, microwires) have been fabricated by a simple, reliable, and cost-effective technique. The electromechanical sensor device consists of a single electrically connected PFW that is placed on the outer surface of a flexible polystyrene (PS) substrate and bonded at its two ends. The entire device is fully packaged by a polydimethylsiloxane (PDMS) thin layer. The PFW has Schottky contacts at its two ends but with distinctly different barrier heights. The I- V characteristic is highly sensitive to strain mainly due to the change in Schottky barrier height (SBH), which scales linear with strain. The change in SBH is suggested owing to the strain induced band structure change and piezoelectric effect. The experimental data can be well-described by the thermionic emission-diffusion model. A gauge factor of as high as 1250 has been demonstrated, which is 25% higher than the best gauge factor demonstrated for carbon nanotubes. The strain sensor developed here has applications in strain and stress measurements in cell biology, biomedical sciences, MEMS devices, structure monitoring, and more.

  5. Exploiting a natural auxotrophy for genetic selection.

    Science.gov (United States)

    Ramage, Elizabeth; Gallagher, Larry; Manoil, Colin

    2012-08-01

    We exploited the natural histidine auxotrophy of Francisella species to develop hisD (encodes histidinol dehydrogenase) as a positive selection marker. A shuttle plasmid (pBR103) carrying Escherichia coli hisD and designed for cloning of PCR fragments replicated in both attenuated and highly virulent Francisella strains. During this work, we formulated a simplified defined growth medium for Francisella novicida.

  6. Distinct Bacterial Composition Associated with Different Laboratory-cultured Aiptasia Strains Across Two Thermal Conditions

    KAUST Repository

    Ahmed, Hanin

    2018-05-01

    Coral reefs are crucial for the ecological sustainability of the oceans, yet, increasing sea surface temperature is threatening these ecosystems globally. Microbial communities associated with corals have become a recent research focus, as the associated microbiome may contribute to coral resilience to environmental stressors, e.g., heat stress. However, research in this area is hampered by the difficulty of working with corals. This study aims to use Aiptasia, a sea anemone, as a tractable laboratory model system to study the role of the coral microbiome. Analyses of the bacterial compositions associated with different Aiptasia strains across two temperatures (25 °C and 32 °C), based on 16S rRNA gene sequencing. This study aims also to identify a “core” microbiome associated with heat stress acclimation, as well as host-specific differences. In general, results showed that bacterial composition associated with Aiptasia strains differs significantly with temperature. Higher bacterial diversity and richness were observed when all Aiptasia strains were placed under heat stress. Moreover, results showed an increase in beta diversity and dispersion of bacterial communities in response to heat stress. These changes in the bacterial composition are in line with the recently described “Anna Karenina principle” for animal microbiomes, which suggests that the microbiomes of unhealthy individuals vary more than healthy and stable individuals. This study further shows that while temperature had the greatest effect on structuring the bacterial compositions, there were some variations better attributed to batch and host effects. This suggests that technical aspects have to be carefully addressed in the framework of microbiome studies. Members of a putative “core” microbiome associated with 32 °C Aiptasia have been identified as indicator species of heat stress (i.e., Francisella sp.,). Previous reports have shown that these indicator taxa are associated with

  7. Strains and Sprains

    Science.gov (United States)

    ... lot of pressure on a muscle or you push it too far, such as when lifting a heavy object. Strains may be more likely to happen if you haven't warmed up first to get blood circulating to the muscles. They're also common for someone returning to a sport after the off-season. That first time playing ...

  8. Multiple-Locus VNTR Analysis (MLVA) for Bacterial Strain Identification - Quarterly Progress Report for the period 7/1/00 to 10/30/00

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Paul Keim

    2000-11-07

    Multiple locus VNTR analysis (MLVA) systems are being developed for B. anthracis, Y. pestis and F. tularensis. These are high resolution DNA fingerprinting systems that will allow for molecular epidemiology and forensic analysis of these pathogens.

  9. Multiple-Locus VNTR Analysis (MLVA) for Bacterial Strain Identification - Quarterly Progress Report for the period 7/1/00 to 10/30/00

    International Nuclear Information System (INIS)

    Dr. Paul Keim

    2000-01-01

    Multiple locus VNTR analysis (MLVA) systems are being developed for B. anthracis, Y. pestis and F. tularensis. These are high resolution DNA fingerprinting systems that will allow for molecular epidemiology and forensic analysis of these pathogens

  10. Multiple-Locus VNTR Analysis (MLVA) for Bacterial Strain Identification - Quarterly Progress Report for the Period 4/1/00 to 6/30/00

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Paul Keim

    2000-11-07

    Multiple locus VNTR analysis (MLVA) systems are being developed for B. anthracis, Y. pestis and F. tularensis. These are high resolution DNA fingerprinting systems that will allow for molecular epidemiology and forensic analysis of these pathogens.

  11. Multiple-Locus VNTR Analysis (MLVA) for Bacterial Strain Identification - Quarterly Progress Report for the Period 4/1/00 to 6/30/00

    International Nuclear Information System (INIS)

    Dr. Paul Keim

    2000-01-01

    Multiple locus VNTR analysis (MLVA) systems are being developed for B. anthracis, Y. pestis and F. tularensis. These are high resolution DNA fingerprinting systems that will allow for molecular epidemiology and forensic analysis of these pathogens

  12. Tularemia in Alaska, 1938 - 2010

    Directory of Open Access Journals (Sweden)

    Hansen Cristina M

    2011-11-01

    Full Text Available Abstract Tularemia is a serious, potentially life threatening zoonotic disease. The causative agent, Francisella tularensis, is ubiquitous in the Northern hemisphere, including Alaska, where it was first isolated from a rabbit tick (Haemophysalis leporis-palustris in 1938. Since then, F. tularensis has been isolated from wildlife and humans throughout the state. Serologic surveys have found measurable antibodies with prevalence ranging from F. tularensis isolates from Alaska were analyzed using canonical SNPs and a multi-locus variable-number tandem repeats (VNTR analysis (MLVA system. The results show that both F. t. tularensis and F. t. holarctica are present in Alaska and that subtype A.I, the most virulent type, is responsible for most recently reported human clinical cases in the state.

  13. YopP-expressing variant of Y. pestis activates a potent innate immune response affording cross-protection against yersiniosis and tularemia [corrected].

    Directory of Open Access Journals (Sweden)

    Ayelet Zauberman

    Full Text Available Plague, initiated by Yersinia pestis infection, is a rapidly progressing disease with a high mortality rate if not quickly treated. The existence of antibiotic-resistant Y. pestis strains emphasizes the need for the development of novel countermeasures against plague. We previously reported the generation of a recombinant Y. pestis strain (Kim53ΔJ+P that over-expresses Y. enterocolitica YopP. When this strain was administered subcutaneously to mice, it elicited a fast and effective protective immune response in models of bubonic, pneumonic and septicemic plague. In the present study, we further characterized the immune response induced by the Kim53ΔJ+P recombinant strain. Using a panel of mouse strains defective in specific immune functions, we observed the induction of a prompt protective innate immune response that was interferon-γ dependent. Moreover, inoculation of mice with Y. pestis Kim53ΔJ+P elicited a rapid protective response against secondary infection by other bacterial pathogens, including the enteropathogen Y. enterocolitica and the respiratory pathogen Francisella tularensis. Thus, the development of new therapies to enhance the innate immune response may provide an initial critical delay in disease progression following the exposure to highly virulent bacterial pathogens, extending the time window for successful treatment.

  14. Strains in general relativity

    International Nuclear Information System (INIS)

    Bini, Donato; Felice, Fernando de; Geralico, Andrea

    2006-01-01

    The definition of relative accelerations and strains among a set of comoving particles is studied in connection with the geometric properties of the frame adapted to a 'fiducial observer'. We find that a relativistically complete and correct definition of strains must take into account the transport law of the chosen spatial triad along the observer's congruence. We use special congruences of (accelerated) test particles in some familiar spacetimes to elucidate such a point. The celebrated idea of Szekeres' compass of inertia, arising when studying geodesic deviation among a set of free-falling particles, is here generalized to the case of accelerated particles. In doing so we have naturally contributed to the theory of relativistic gravity gradiometer. Moreover, our analysis was made in an observer-dependent form, a fact that would be very useful when thinking about general relativistic tests on space stations orbiting compact objects like black holes and also in other interesting gravitational situations

  15. Strain Induced Adatom Correlations

    OpenAIRE

    Kappus, Wolfgang

    2012-01-01

    A Born-Green-Yvon type model for adatom density correlations is combined with a model for adatom interactions mediated by the strain in elastic anisotropic substrates. The resulting nonlinear integral equation is solved numerically for coverages from zero to a limit given by stability constraints. W, Nb, Ta and Au surfaces are taken as examples to show the effects of different elastic anisotropy regions. Results of the calculation are shown by appropriate plots and discussed. A mapping to sup...

  16. Ratchetting strain prediction

    International Nuclear Information System (INIS)

    Noban, Mohammad; Jahed, Hamid

    2007-01-01

    A time-efficient method for predicting ratchetting strain is proposed. The ratchetting strain at any cycle is determined by finding the ratchetting rate at only a few cycles. This determination is done by first defining the trajectory of the origin of stress in the deviatoric stress space and then incorporating this moving origin into a cyclic plasticity model. It is shown that at the beginning of the loading, the starting point of this trajectory coincides with the initial stress origin and approaches the mean stress, displaying a power-law relationship with the number of loading cycles. The method of obtaining this trajectory from a standard uniaxial asymmetric cyclic loading is presented. Ratchetting rates are calculated with the help of this trajectory and through the use of a constitutive cyclic plasticity model which incorporates deviatoric stresses and back stresses that are measured with respect to this moving frame. The proposed model is used to predict the ratchetting strain of two types of steels under single- and multi-step loadings. Results obtained agree well with the available experimental measurements

  17. Strain measurement based battery testing

    Science.gov (United States)

    Xu, Jeff Qiang; Steiber, Joe; Wall, Craig M.; Smith, Robert; Ng, Cheuk

    2017-05-23

    A method and system for strain-based estimation of the state of health of a battery, from an initial state to an aged state, is provided. A strain gauge is applied to the battery. A first strain measurement is performed on the battery, using the strain gauge, at a selected charge capacity of the battery and at the initial state of the battery. A second strain measurement is performed on the battery, using the strain gauge, at the selected charge capacity of the battery and at the aged state of the battery. The capacity degradation of the battery is estimated as the difference between the first and second strain measurements divided by the first strain measurement.

  18. Studies on Drosophila radiosensitive strains

    International Nuclear Information System (INIS)

    Varentsova, E.P.; Zakharov, I.A.

    1976-01-01

    45 of radiosensitive strains of Drosophila melanogaster were isolated by Curly/Lobe technique after EMS treatment of Livadia population males. The lethality of non-Curly late larvae after gamma-irradiation (4000r) characterized radiosensitivity strains. Most of them exhibited higher frequency of the spontaneous dominant lethals (up to 69%). The males of 6 strains were semi-sterile. 5 of these strains exhibited higher frequency of X-chromosome non-disjunction

  19. Strain induced adatom correlations

    Science.gov (United States)

    Kappus, Wolfgang

    2012-12-01

    A Born-Green-Yvon type model for adatom density correlations is combined with a model for adatom interactions mediated by the strain in elastic anisotropic substrates. The resulting nonlinear integral equation is solved numerically for coverages from zero to a limit given by stability constraints. W, Nb, Ta and Au surfaces are taken as examples to show the effects of different elastic anisotropy regions. Results of the calculation are shown by appropriate plots and discussed. A mapping to superstructures is tried. Corresponding adatom configurations from Monte Carlo simulations are shown.

  20. Strain actuated aeroelastic control

    Science.gov (United States)

    Lazarus, Kenneth B.

    1992-01-01

    Viewgraphs on strain actuated aeroelastic control are presented. Topics covered include: structural and aerodynamic modeling; control law design methodology; system block diagram; adaptive wing test article; bench-top experiments; bench-top disturbance rejection: open and closed loop response; bench-top disturbance rejection: state cost versus control cost; wind tunnel experiments; wind tunnel gust alleviation: open and closed loop response at 60 mph; wind tunnel gust alleviation: state cost versus control cost at 60 mph; wind tunnel command following: open and closed loop error at 60 mph; wind tunnel flutter suppression: open loop flutter speed; and wind tunnel flutter suppression: closed loop state cost curves.

  1. Colony Dimorphism in Bradyrhizobium Strains

    Science.gov (United States)

    Sylvester-Bradley, Rosemary; Thornton, Philip; Jones, Peter

    1988-01-01

    Ten isolates of Bradyrhizobium spp. which form two colony types were studied; the isolates originated from a range of legume species. The two colony types differed in the amount of gum formed or size or both, depending on the strain. Whole 7-day-old colonies of each type were subcultured to determine the proportion of cells which had changed to the other type. An iterative computerized procedure was used to determine the rate of switching per generation between the two types and to predict proportions reached at equilibrium for each strain. The predicted proportions of the wetter (more gummy) or larger colony type at equilibrium differed significantly between strains, ranging from 0.9999 (strain CIAT 2383) to 0.0216 (strain CIAT 2469), because some strains switched faster from dry to wet (or small to large) and others switched faster from wet to dry (or large to small). Predicted equilibrium was reached after about 140 generations in strain USDA 76. In all but one strain (CIAT 3030) the growth rate of the wetter colony type was greater than or similar to that of the drier type. The mean difference in generation time between the two colony types was 0.37 h. Doubling times calculated for either colony type after 7 days of growth on the agar surface ranged from 6.0 to 7.3 h. The formation of two persistent colony types by one strain (clonal or colony dimorphism) may be a common phenomenon among Bradyrhizobium strains. Images PMID:16347599

  2. Towards an understanding of the perpetuation of the agent of tularemia

    Directory of Open Access Journals (Sweden)

    Sam eTelford

    2011-01-01

    Full Text Available The epidemiology of tularemia has influenced, perhaps incorrectly skewed, our views on the ecology of the agent of tularemia. In particular, the central role of lagomorphs needs to be reexamined. Diverse observations, some incidental, and some that are more generally reproducible, have not been synthesized so that the critical elements of the perpetuation of Francisella tularensis can be identified. Developing a quantitative model of the basic reproduction number (BRN of F. tularensis may require separate treatments for Type A and Type B given the fundamental differences in their ecology.

  3. Strain Pattern in Supercooled Liquids

    Science.gov (United States)

    Illing, Bernd; Fritschi, Sebastian; Hajnal, David; Klix, Christian; Keim, Peter; Fuchs, Matthias

    2016-11-01

    Investigations of strain correlations at the glass transition reveal unexpected phenomena. The shear strain fluctuations show an Eshelby-strain pattern [˜cos (4 θ ) /r2 ], characteristic of elastic response, even in liquids, at long times. We address this using a mode-coupling theory for the strain fluctuations in supercooled liquids and data from both video microscopy of a two-dimensional colloidal glass former and simulations of Brownian hard disks. We show that the long-ranged and long-lived strain signatures follow a scaling law valid close to the glass transition. For large enough viscosities, the Eshelby-strain pattern is visible even on time scales longer than the structural relaxation time τ and after the shear modulus has relaxed to zero.

  4. Hydrogen production from microbial strains

    Science.gov (United States)

    Harwood, Caroline S; Rey, Federico E

    2012-09-18

    The present invention is directed to a method of screening microbe strains capable of generating hydrogen. This method involves inoculating one or more microbes in a sample containing cell culture medium to form an inoculated culture medium. The inoculated culture medium is then incubated under hydrogen producing conditions. Once incubating causes the inoculated culture medium to produce hydrogen, microbes in the culture medium are identified as candidate microbe strains capable of generating hydrogen. Methods of producing hydrogen using one or more of the microbial strains identified as well as the hydrogen producing strains themselves are also disclosed.

  5. Asymptomatic bacteriuria Escherichia coli strains

    DEFF Research Database (Denmark)

    Hancock, Viktoria; Nielsen, E.M.; Klemm, Per

    2006-01-01

    Urinary tract infections (UTIs) affect millions of people each year. Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU) in humans. Persons affected by ABU may carry a particular E. coli strain for extended periods of time without any symptoms. In contrast...... to uropathogenic E. coli (UPEC) that cause symptomatic UTI, very little is known about the mechanisms by which these strains colonize the urinary tract. Here, we have investigated the growth characteristics in human urine as well as adhesin repertoire of nine ABU strains; the ability of ABU strains to compete...

  6. TL transgenic mouse strains

    International Nuclear Information System (INIS)

    Obata, Y.; Matsudaira, Y.; Hasegawa, H.; Tamaki, H.; Takahashi, T.; Morita, A.; Kasai, K.

    1993-01-01

    As a result of abnormal development of the thymus of these mice, TCR αβ lineage of the T cell differentiation is disturbed and cells belonging to the TCR γδ CD4 - CD8 - double negative (DN) lineage become preponderant. The γδ DN cells migrate into peripheral lymphoid organs and constitute nearly 50% of peripheral T cells. Immune function of the transgenic mice is severely impaired, indicating that the γδ cells are incapable of participating in these reactions. Molecular and serological analyses of T-cell lymphomas reveal that they belong to the γδ lineage. Tg.Tla a -3-1 mice should be useful in defining the role of TL in normal and abnormal T cell differentiation as well as in the development of T-cell lymphomas, and further they should facilitate studies on the differentiation and function of γδ T cells. We isolated T3 b -TL gene from B6 mice and constructed a chimeric gene in which T3 b -TL is driven by the promoter of H-2K b . With the chimeric gene, two transgenic mouse strains, Tg. Con.3-1 and -2 have been derived in C3H background. Both strains express TL antigen in various tissues including skin. The skin graft of transgenic mice on C3H and (B6 X C3H)F 1 mice were rejected. In the mice which rejected the grafts, CD8 + TCRαβ cytotoxic T cells (CTL) against TL antigens were recognized. The recognition of TL by CTL did not require the antigen presentation by H-2 molecules. The results indicated that TL antigen in the skin becomes a transplantation antigen and behaves like a typical allogeneic MHC class I antigen. The facts that (B6 X C3H)F 1 mice rejected the skin expressing T3 b -TL antigen and induced CTL that killed TL + lymphomas of B6 origin revealed that TL antigen encoded by T3 b -TL is recognized as non-self in B6 mice. Experiments are now extended to analyze immune responses to TL antigen expressed on autochthonous T cell lymphomas. (J.P.N.)

  7. Nutritionally fastidious Ruminococct $ flovefociens : strains

    African Journals Online (AJOL)

    than those obtained in a medium containing rumen fluid. Growth of all strains was remarkably uniform. Where the same inoculum was used, differences in the qualitative com- position of the medium usually had little effect on growth. In contrast, the R. f/avefaciens strains were much more variable in their growth responses.

  8. Haldane model under nonuniform strain

    Science.gov (United States)

    Ho, Yen-Hung; Castro, Eduardo V.; Cazalilla, Miguel A.

    2017-10-01

    We study the Haldane model under strain using a tight-binding approach, and compare the obtained results with the continuum-limit approximation. As in graphene, nonuniform strain leads to a time-reversal preserving pseudomagnetic field that induces (pseudo-)Landau levels. Unlike a real magnetic field, strain lifts the degeneracy of the zeroth pseudo-Landau levels at different valleys. Moreover, for the zigzag edge under uniaxial strain, strain removes the degeneracy within the pseudo-Landau levels by inducing a tilt in their energy dispersion. The latter arises from next-to-leading order corrections to the continuum-limit Hamiltonian, which are absent for a real magnetic field. We show that, for the lowest pseudo-Landau levels in the Haldane model, the dominant contribution to the tilt is different from graphene. In addition, although strain does not strongly modify the dispersion of the edge states, their interplay with the pseudo-Landau levels is different for the armchair and zigzag ribbons. Finally, we study the effect of strain in the band structure of the Haldane model at the critical point of the topological transition, thus shedding light on the interplay between nontrivial topology and strain in quantum anomalous Hall systems.

  9. Pin clad strains in Phenix

    International Nuclear Information System (INIS)

    Languille, A.

    1979-07-01

    The Phenix reactor has operated for 4 years in a satisfactory manner. The first 2 sub-assembly loadings contained pins clad in solution treated 316. The principal pin strains are: diametral strain (swelling and irradiation creep), ovality and spiral bending of the pin (interaction of wire and pin cluster and wrapper). A pin cluster irradiated to a dose of 80 dpa F reached a pin diameter strain of 5%. This strain is principally due to swelling (low fission gas pressure). The principal parameters governing the swelling are instantaneous dose, time and temperature for a given type of pin cladding. Other types of steel are or will be irradiated in Phenix. In particular, cold-worked titanium stabilised 316 steel should contribute towards a reduction in the pin clad strains and increase the target burn-up in this reactor. (author)

  10. Strain expansion-reduction approach

    Science.gov (United States)

    Baqersad, Javad; Bharadwaj, Kedar

    2018-02-01

    Validating numerical models are one of the main aspects of engineering design. However, correlating million degrees of freedom of numerical models to the few degrees of freedom of test models is challenging. Reduction/expansion approaches have been traditionally used to match these degrees of freedom. However, the conventional reduction/expansion approaches are only limited to displacement, velocity or acceleration data. While in many cases only strain data are accessible (e.g. when a structure is monitored using strain-gages), the conventional approaches are not capable of expanding strain data. To bridge this gap, the current paper outlines a reduction/expansion technique to reduce/expand strain data. In the proposed approach, strain mode shapes of a structure are extracted using the finite element method or the digital image correlation technique. The strain mode shapes are used to generate a transformation matrix that can expand the limited set of measurement data. The proposed approach can be used to correlate experimental and analytical strain data. Furthermore, the proposed technique can be used to expand real-time operating data for structural health monitoring (SHM). In order to verify the accuracy of the approach, the proposed technique was used to expand the limited set of real-time operating data in a numerical model of a cantilever beam subjected to various types of excitations. The proposed technique was also applied to expand real-time operating data measured using a few strain gages mounted to an aluminum beam. It was shown that the proposed approach can effectively expand the strain data at limited locations to accurately predict the strain at locations where no sensors were placed.

  11. Roll bonding of strained aluminium

    DEFF Research Database (Denmark)

    Staun, Jakob M.

    2003-01-01

    This report investigates roll bonding of pre-strained (å ~ 4) aluminium sheets to produce high strain material from high purity aluminium (99.996%) and commercial pure aluminium (99.6%). The degree of bonding is investigated by optical microscopy and ultrasonic scanning. Under the right...... of the cross rolled volume fraction is found. To further asses this effect, and the anisotropy, it is necessary to acquire knowledge about both texture and microstructure, e.g. by TEM. Roll bonding of pre-strained aluminium is found to be a possible alternative to ARB in the quest for ultra-fine grained...

  12. Strain fluctuations and elastic constants

    Energy Technology Data Exchange (ETDEWEB)

    Parrinello, M.; Rahman, A.

    1982-03-01

    It is shown that the elastic strain fluctuations are a direct measure of elastic compliances in a general anisotropic medium; depending on the ensemble in which the fluctuation is measured either the isothermal or the adiabatic compliances are obtained. These fluctuations can now be calculated in a constant enthalpy and pressure, and hence, constant entropy, ensemble due to recent develpments in the molecular dynamics techniques. A calculation for a Ni single crystal under uniform uniaxial 100 tensile or compressive load is presented as an illustration of the relationships derived between various strain fluctuations and the elastic modulii. The Born stability criteria and the behavior of strain fluctuations are shown to be related.

  13. Strain accumulation in quasicrystalline solids

    International Nuclear Information System (INIS)

    Nori, F.; Ronchetti, M.; Elser, V.

    1988-01-01

    We study the relaxation of 2D quasicrystalline elastic networks when their constituent bonds are perturbed homogeneously. Whereas ideal, quasiperiodic networks are stable against such perturbations, we find significant accumulations of strain in a class of disordered networks generated by a growth process. The grown networks are characterized by root mean square phason fluctuations which grow linearly with system size. The strain accumulation we observe in these networks also grows linearly with system size. Finally, we find a dependence of strain accumulation on cooling rate

  14. The distribution and spreading pattern of Dermacentor reticulatus over its threshold area in the Czech Republic—How much is range of this vector expanding?

    Czech Academy of Sciences Publication Activity Database

    Široký, P.; Kubelová, M.; Bednář, M.; Modrý, David; Hubálek, Zdeněk; Tkadlec, Emil

    2011-01-01

    Roč. 183, 1/2 (2011), s. 130-135 ISSN 0304-4017 Grant - others:GA ČR(CZ) GA524/09/0715 Institutional research plan: CEZ:AV0Z60220518; CEZ:AV0Z60930519 Keywords : Moravia * tick-borne diseases * Babesia canis * Francisella tularensis Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 2.579, year: 2011

  15. Descriptive Summaries of the Research, Development, Test and Evaluation, Army Appropriation. Supporting Data FY 1994, Budget Estimates Submitted to Congress, April 1993

    Science.gov (United States)

    1993-04-01

    Investigate the genetics and physiology of Yersinia pestis, Brucella Sp., Q-fever, Vibrio cholerae , Francisella tularensis and Bacillus anthracis "* (U) Conduct...New Mexico State University, NM; Optimetrics, Inc., Ann Arbor, MI; Massachusetts Institute of Technology. Cambridge, MA; Mission Research Corporation...Laboratory (ARL), Adelphi, MD. Contractors include: New Mexico Institute of Mining and Technology, Socorro, NM; Dynamic Sciences, Inc., Phoenix, AZ; Honeywell

  16. A More Flexible Lipoprotein Sorting Pathway

    Science.gov (United States)

    Chahales, Peter

    2015-01-01

    Lipoprotein biogenesis in Gram-negative bacteria occurs by a conserved pathway, each step of which is considered essential. In contrast to this model, LoVullo and colleagues demonstrate that the N-acyl transferase Lnt is not required in Francisella tularensis or Neisseria gonorrhoeae. This suggests the existence of a more flexible lipoprotein pathway, likely due to a modified Lol transporter complex, and raises the possibility that pathogens may regulate lipoprotein processing to modulate interactions with the host. PMID:25755190

  17. Prevalence and distribution of soil-borne zoonotic pathogens in Lahore district of Pakistan

    OpenAIRE

    Shabbir, Muhammad Z.; Jamil, Tariq; Ali, Asad A.; Ahmad, Arfan; Naeem, Muhammad; Chaudhary, Muhammad H.; Bilal, Muhammad; Ali, Muhammad A.; Muhammad, Khushi; Yaqub, Tahir; Bano, Asghari; Mirza, Ali I.; Shabbir, Muhammad A. B.; McVey, Walter R.; Patel, Ketan

    2015-01-01

    A multidisciplinary, collaborative project was conducted to determine the prevalence and distribution of soil-borne zoonotic pathogens in Lahore district of Pakistan and ascertain its Public Health Significance. Using a grid-based sampling strategy, soil samples (n = 145) were collected from villages (n = 29, 5 samples/village) and examined for Bacillus anthracis, Burkholderia mallei/pseudomallei, Coxiella burnetii, Francisella tularensis, and Yersinia pestis using real time PCR assays. Chemi...

  18. Public Health Surveillance: A Local Health Department Perspective

    Science.gov (United States)

    2002-04-03

    vomiting – Diarrhea (+/-bloody) • Rash and fever – Vesicular – Petechial • Neurologic – cranial nerve palsies, HA, fever , confusion • Septic Shock...Francisella tularensis (tularemia) • Viral hemorrhagic fever Agents of Concern: CDC Category B • Coxiella burnetti (Q fever ) • Brucella species...Concern: CDC Category C • Nipah virus • hantaviruses • tickborne hemorrhagic fever viruses • yellow fever • multidrug-resistant tuberculosis

  19. New England Bioterrorism Preparedness Workshop

    Science.gov (United States)

    2002-04-04

    Hypoxia • GI – Fever – Nausea/vomiting – Diarrhea (+/-bloody) • Rash and fever – Vesicular – Petechial • Neurologic – cranial nerve palsies, HA...plague) • variola major (smallpox) • Francisella tularensis (tularemia) • Viral hemorrhagic fever Agents of Concern: CDC Category B • Coxiella...burnetti (Q fever ) • Brucella species (brucellosis) • Burkholderia mallei (glanders) • ricin toxin from Ricinus communis (castor beans) • epsilon toxin of

  20. Strain localisation in granular media

    OpenAIRE

    Desrues , Jacques

    1984-01-01

    This study is devoted to strain localisation in Granular materials. Both experimental and theoretical results have been obtained.The first part of the thesis is a review of the methods and theories about rupture in sols mechanics and more generally, in solid mechanics. The classical framework of Shear Band analysis is presented, and the main results available for different classes of materials are discussed.The second part describes an experimental study of strain localisation in sand specime...

  1. Performance of seven serological assays for diagnosing tularemia

    Science.gov (United States)

    2014-01-01

    Background Tularemia is a rare zoonotic disease caused by the Gram-negative bacterium Francisella tularensis. Serology is frequently the preferred diagnostic approach, because the pathogen is highly infectious and difficult to cultivate. The aim of this retrospective study was to determine the diagnostic accuracy of tularemia specific tests. Methods The Serazym®Anti-Francisella tularensis ELISA, Serion ELISA classic Francisella tularensis IgG/IgM, an in-house ELISA, the VIRapid® Tularemia immunochromatographic test, an in-house antigen microarray, and a Western Blot (WB) assay were evaluated. The diagnosis tularemia was established using a standard micro-agglutination assay. In total, 135 sera from a series of 110 consecutive tularemia patients were tested. Results The diagnostic sensitivity and diagnostic specificity of the tests were VIRapid (97.0% and 84.0%), Serion IgG (96.3% and 96.8%), Serion IgM (94.8% and 96.8%), Serazym (97.0% and 91.5%), in-house ELISA (95.6% and 76.6%), WB (93.3% and 83.0%), microarray (91.1% and 97.9%). Conclusions The diagnostic value of the commercial assays was proven, because the diagnostic accuracy was >90%. The diagnostic sensitivity of the in-house ELISA and the WB were acceptable, but the diagnostic accuracy was <90%. Interestingly, the antigen microarray test was very specific and had a very good positive predictive value. PMID:24885274

  2. Landscape Epidemiology of Tularemia Outbreaks in Sweden

    Science.gov (United States)

    Svensson, Kerstin; Bäck, Erik; Eliasson, Henrik; Berglund, Lennart; Granberg, Malin; Karlsson, Linda; Larsson, Pär; Forsman, Mats

    2009-01-01

    Summer outbreaks of tularemia that occurred from 1995 through 2005 in 2 locations in Sweden affected 441 persons. We performed an epidemiologic investigation of these outbreaks using a novel strategy, involving high-resolution genotyping of Francisella tularensis isolates obtained from 136 patients (using 18 genetic markers developed from 6 F. tularensis genome sequences) and interviews with the patients. Strong spatial associations were found between F. tularensis subpopulations and the places of disease transmission; infection by some subpopulations occurred within areas as small as 2 km2, indicating unidentified environmental point sources of tularemia. In both locations, disease clusters were associated with recreational areas beside water, and genetic subpopulations were present throughout the tularemia season and persisted over years. High-resolution genotyping in combination with patients’ statements about geographic places of disease transmission provided valuable indications of likely sources of infection and the causal genotypes during these tularemia outbreaks. PMID:19961673

  3. Job strain and male fertility.

    Science.gov (United States)

    Hjollund, Niels Henrik I; Bonde, Jens Peter E; Henriksen, Tine Brink; Giwercman, Aleksander; Olsen, Jørn

    2004-01-01

    Job strain, defined as high job demands and low job control, has not previously been explored as a possible determinant of male fertility. We collected prospective data on job strain among men, and describe the associations with semen quality and probability of conceiving a clinical pregnancy during a menstrual cycle. Danish couples (N = 399) who were trying to become pregnant for the first time were followed for up to 6 menstrual periods. All men collected semen samples, and a blood sample was drawn from both partners. Job demand and job control were measured by a self-administered questionnaire at entry, and in each cycle the participants recorded changes in job control or job demand during the previous 30 days. In adjusted analyses, no associations were found between any semen characteristic or sexual hormones and any job strain variable. The odds for pregnancy were not associated with job strain. Psychologic job strain encountered in normal jobs in Denmark does not seem to affect male reproductive function.

  4. Crack tip stress and strain

    International Nuclear Information System (INIS)

    Francois, D.

    1975-01-01

    The study of potential energy variations in a loaded elastic solid containing a crack leads to determination of the crack driving force G. Generalization of this concept to cases other than linear elasticity leads to definition of the integral J. In a linear solid, the crack tip stress field is characterized by a single parameter: the stress-intensity factor K. When the crack tip plastic zone size is confined to the elastic singularity J=G, it is possible to establish relationship between these parameters and plastic strain (and in particular the crack tip opening displacement delta). The stress increases because of the triaxiality effect. This overload rises with increasing strain hardening. When the plastic zone size expands, using certain hypotheses, delta can be calculated. The plastic strain intensity is exclusively dependent on parameter J [fr

  5. Management of digital eye strain.

    Science.gov (United States)

    Coles-Brennan, Chantal; Sulley, Anna; Young, Graeme

    2018-05-23

    Digital eye strain, an emerging public health issue, is a condition characterised by visual disturbance and/or ocular discomfort related to the use of digital devices and resulting from a range of stresses on the ocular environment. This review aims to provide an overview of the extensive literature on digital eye strain research with particular reference to the clinical management of symptoms. As many as 90 per cent of digital device users experience symptoms of digital eye strain. Many studies suggest that the following factors are associated with digital eye strain: uncorrected refractive error (including presbyopia), accommodative and vergence anomalies, altered blinking pattern (reduced rate and incomplete blinking), excessive exposure to intense light, closer working distance, and smaller font size. Since a symptom may be caused by one or more factors, a holistic approach should be adopted. The following management strategies have been suggested: (i) appropriate correction of refractive error, including astigmatism and presbyopia; (ii) management of vergence anomalies, with the aim of inducing or leaving a small amount of heterophoria (~1.5 Δ Exo); (iii) blinking exercise/training to maintain normal blinking pattern; (iv) use of lubricating eye drops (artificial tears) to help alleviate dry eye-related symptoms; (v) contact lenses with enhanced comfort, particularly at end-of-day and in challenging environments; (vi) prescription of colour filters in all vision correction options, especially blue light-absorbing filters; and (vii) management of accommodative anomalies. Prevention is the main strategy for management of digital eye strain, which involves: (i) ensuring an ergonomic work environment and practice (through patient education and the implementation of ergonomic workplace policies); and (ii) visual examination and eye care to treat visual disorders. Special consideration is needed for people at a high risk of digital eye strain, such as computer

  6. Taxonomy of oxalotrophic Methylobacterium strains

    Science.gov (United States)

    Sahin, Nurettin; Kato, Yuko; Yilmaz, Ferah

    2008-10-01

    Most of the oxalotrophic bacteria are facultative methylotrophs and play important ecological roles in soil fertility and cycling of elements. This study gives a detailed picture of the taxonomy and diversity of these bacteria and provides new information about the taxonomical variability within the genus Methylobacterium. Twelve mesophilic, pink-pigmented, and facultatively methylotrophic oxalate-oxidizing strains were included in this work that had been previously isolated from the soil and some plant tissues by the potassium oxalate enrichment method. The isolates were characterized using biochemical tests, cellular lipid profiles, spectral characteristics of carotenoid pigments, G+C content of the DNA, and 16S rDNA sequencing. The taxonomic similarities among the strains were analyzed using the simple matching ( S SM) and Jaccard ( S J) coefficients, and the UPGMA clustering algorithm. The phylogenetic position of the strains was inferred by the neighbor-joining method on the basis of the 16S rDNA sequences. All isolates were Gram-negative, facultatively methylotrophic, oxidase and catalase positive, and required no growth factors. Based on the results of numerical taxonomy, the strains formed four closely related clusters sharing ≥85% similarity. Analysis of the 16S rDNA sequences demonstrated that oxalotrophic, pink-pigmented, and facultatively methylotrophic strains could be identified as members of the genus Methylobacterium. Except for M. variabile and M. aquaticum, all of the Methylobacterium type strains tested had the ability of oxalate utilization. Our results indicate that the capability of oxalate utilization seems to be an uncommon trait and could be used as a valuable taxonomic criterion for differentiation of Methylobacterium species.

  7. Noncontacting-optical-strain device

    Science.gov (United States)

    Silver, R. H.

    1970-01-01

    Noncontacting-strain-measuring gauge and extensometer remotely measures the mechanical displacement along the entire length of a test specimen. Measurement is accomplished by continuous scanning of a reflected light from reflective bench markings or stripes previously affixed to the specimen.

  8. Job strain and tobacco smoking

    DEFF Research Database (Denmark)

    Heikkilä, Katriina; Nyberg, Solja T; Fransson, Eleonor I

    2012-01-01

    Tobacco smoking is a major contributor to the public health burden and healthcare costs worldwide, but the determinants of smoking behaviours are poorly understood. We conducted a large individual-participant meta-analysis to examine the extent to which work-related stress, operationalised as job...... strain, is associated with tobacco smoking in working adults....

  9. Strain effects in oxide superconductors

    International Nuclear Information System (INIS)

    Wada, H.; Kuroda, T.; Sekine, H.; Yuyama, M.; Itoh, K.

    1991-01-01

    Strain sensitivities of superconducting properties are critical to high magnetic field applications of superconductors, since critical temperature, T c , upper critical field, H c2 , and critical current (density), I c (J c ), are all degraded under strains. Oxide superconductors so far known are all very fragile, thus requiring to be fabricated in the form of composite. In the case of practical metallic superconductors, such as Nb 3 Sn and V 3 Ga, the so-called bronze method has been developed where these superconducting intermetallics are enveloped in a ductile metallic sheath. Recently, a fabrication method similar to the bronze method has been developed for the Bi 2 Sr 2 Ca 2 Cu 3 O x superconductors using Ag tubes as sheath. In the present study mono- and multicore BiPbSrCaCuO tape conductors were prepared by means of this Ag-sheath composite method, and examined in terms of strain sensitivity by measuring their T c and I c (J c ) under bending or tensile strains. (orig.)

  10. Mobilomics in Saccharomyces cerevisiae strains.

    Science.gov (United States)

    Menconi, Giulia; Battaglia, Giovanni; Grossi, Roberto; Pisanti, Nadia; Marangoni, Roberto

    2013-03-20

    Mobile Genetic Elements (MGEs) are selfish DNA integrated in the genomes. Their detection is mainly based on consensus-like searches by scanning the investigated genome against the sequence of an already identified MGE. Mobilomics aims at discovering all the MGEs in a genome and understanding their dynamic behavior: The data for this kind of investigation can be provided by comparative genomics of closely related organisms. The amount of data thus involved requires a strong computational effort, which should be alleviated. Our approach proposes to exploit the high similarity among homologous chromosomes of different strains of the same species, following a progressive comparative genomics philosophy. We introduce a software tool based on our new fast algorithm, called regender, which is able to identify the conserved regions between chromosomes. Our case study is represented by a unique recently available dataset of 39 different strains of S.cerevisiae, which regender is able to compare in few minutes. By exploring the non-conserved regions, where MGEs are mainly retrotransposons called Tys, and marking the candidate Tys based on their length, we are able to locate a priori and automatically all the already known Tys and map all the putative Tys in all the strains. The remaining putative mobile elements (PMEs) emerging from this intra-specific comparison are sharp markers of inter-specific evolution: indeed, many events of non-conservation among different yeast strains correspond to PMEs. A clustering based on the presence/absence of the candidate Tys in the strains suggests an evolutionary interconnection that is very similar to classic phylogenetic trees based on SNPs analysis, even though it is computed without using phylogenetic information. The case study indicates that the proposed methodology brings two major advantages: (a) it does not require any template sequence for the wanted MGEs and (b) it can be applied to infer MGEs also for low coverage genomes

  11. Mobilomics in Saccharomyces cerevisiae strains

    Science.gov (United States)

    2013-01-01

    Background Mobile Genetic Elements (MGEs) are selfish DNA integrated in the genomes. Their detection is mainly based on consensus–like searches by scanning the investigated genome against the sequence of an already identified MGE. Mobilomics aims at discovering all the MGEs in a genome and understanding their dynamic behavior: The data for this kind of investigation can be provided by comparative genomics of closely related organisms. The amount of data thus involved requires a strong computational effort, which should be alleviated. Results Our approach proposes to exploit the high similarity among homologous chromosomes of different strains of the same species, following a progressive comparative genomics philosophy. We introduce a software tool based on our new fast algorithm, called regender, which is able to identify the conserved regions between chromosomes. Our case study is represented by a unique recently available dataset of 39 different strains of S.cerevisiae, which regender is able to compare in few minutes. By exploring the non–conserved regions, where MGEs are mainly retrotransposons called Tys, and marking the candidate Tys based on their length, we are able to locate a priori and automatically all the already known Tys and map all the putative Tys in all the strains. The remaining putative mobile elements (PMEs) emerging from this intra–specific comparison are sharp markers of inter–specific evolution: indeed, many events of non–conservation among different yeast strains correspond to PMEs. A clustering based on the presence/absence of the candidate Tys in the strains suggests an evolutionary interconnection that is very similar to classic phylogenetic trees based on SNPs analysis, even though it is computed without using phylogenetic information. Conclusions The case study indicates that the proposed methodology brings two major advantages: (a) it does not require any template sequence for the wanted MGEs and (b) it can be applied to

  12. A NEW STRAIN OF TRANSMISSIBLE LEUCEMIA IN FOWLS (STRAIN H).

    Science.gov (United States)

    Ellermann, V

    1921-03-31

    1. A new strain of fowl leucosis has been transmitted through twelve generations of fowls. 2. An increase in virulence was observed during its passage. This was shown in a shortening of the interval between inoculation and death. The increase in virulence does not affect the number of successful inoculations, which remains approximately constant in from 20 to 40 per cent of the birds employed. 3. As with former strains, the disease manifests itself in various forms; i.e., myeloid and intravascular lymphoid types. A single lymphatic case was observed. 4. In several intravascular cases a diminution in the hemolytic power of the serum was established. This phenomenon was absent in a number of myeloid cases. 5. Active immunization cannot be produced by means of the subcutaneous injection of virulent material. 6. The finding of previous experiments that the virus is filterable has been confirmed. 7. The inoculation of human leucemic material into fowls gave negative results.

  13. Computational strain gradient crystal plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2014-01-01

    A numerical method for viscous strain gradient crystal plasticity theory is presented, which incorporates both energetic and dissipative gradient effects. The underlying minimum principles are discussed as well as convergence properties of the proposed finite element procedure. Three problems...... of plane crystal plasticity are studied: pure shear of a single crystal between rigid platens as well as plastic deformation around cylindrical voids in hexagonal close packed and face centered cubic crystals. Effective in-plane constitutive slip parameters for plane strain deformation of specifically...... oriented face centered cubic crystals are developed in terms of the crystallographic slip parameters. The effect on geometrically necessary dislocation structures introduced by plastic deformation is investigated as a function of the ratio of void radius to plasticity length scale....

  14. Strain-Detecting Composite Materials

    Science.gov (United States)

    Wallace, Terryl A. (Inventor); Smith, Stephen W. (Inventor); Piascik, Robert S. (Inventor); Horne, Michael R. (Inventor); Messick, Peter L. (Inventor); Alexa, Joel A. (Inventor); Glaessgen, Edward H. (Inventor); Hailer, Benjamin T. (Inventor)

    2016-01-01

    A composite material includes a structural material and a shape-memory alloy embedded in the structural material. The shape-memory alloy changes crystallographic phase from austenite to martensite in response to a predefined critical macroscopic average strain of the composite material. In a second embodiment, the composite material includes a plurality of particles of a ferromagnetic shape-memory alloy embedded in the structural material. The ferromagnetic shape-memory alloy changes crystallographic phase from austenite to martensite and changes magnetic phase in response to the predefined critical macroscopic average strain of the composite material. A method of forming a composite material for sensing the predefined critical macroscopic average strain includes providing the shape-memory alloy having an austenite crystallographic phase, changing a size and shape of the shape-memory alloy to thereby form a plurality of particles, and combining the structural material and the particles at a temperature of from about 100-700.degree. C. to form the composite material.

  15. Nutrient content of sorghum beer strainings

    African Journals Online (AJOL)

    Sorghum beer strainings were analysed for starch, protein, fat, crude fibre, ash, minerals and ... The importance of minerals in animal nutrition has been recognized for many ..... strainings is probably due to yeast activity during fermentation ...

  16. Yeast strains and methods of use thereof

    OpenAIRE

    Goddard, Matthew Robert; Gardner, Richard Clague; Anfang, Nicole

    2013-01-01

    The present invention relates to yeast strains and, in particular, to yeast stains for use in fermentation processes. The invention also relates to methods of fermentation using the yeast strains of the invention either alone or in combination with other yeast strains. The invention thither relates to methods for the selection of yeast strains suitable for fermentation cultures by screening for various metabolic products and the use of specific nutrient sources.

  17. Development of Industrial Yeast Platform Strains

    DEFF Research Database (Denmark)

    Bergdahl, Basti; Dato, Laura; Förster, Jochen

    2014-01-01

    Most of the current metabolic engineering projects are carried out using laboratory strains as the starting host. Although such strains are easily manipulated genetically, their robustness does not always meet the requirements set by industrial fermentation conditions. In such conditions, the cells...... screening of the 36 industrial and laboratory yeast strains. In addition, progress in the development of molecular biology methods for generating the new strains will be presented....

  18. STRAINED OFF BREAST MILK: PRO AND CONTRA

    Directory of Open Access Journals (Sweden)

    O.L. Lukoyanova

    2010-01-01

    Full Text Available The questions of feeding of children with strained off breast milk are discussed in this article. Author presents medical indications to such type of feeding, peculiarities and rules of storage of strained off milk. There is a brief literature review on the influence of different factors on the composition of strained off breast milk.Key words: strained milk, breast feeding, pasteurization, freezing.(Voprosy sovremennoi pediatrii — Current Pediatrics. 2010;9(2:70-73

  19. Haemophilus ducreyi Cutaneous Ulcer Strains Are Nearly Identical to Class I Genital Ulcer Strains.

    Directory of Open Access Journals (Sweden)

    Dharanesh Gangaiah

    Full Text Available Although cutaneous ulcers (CU in the tropics is frequently attributed to Treponema pallidum subspecies pertenue, the causative agent of yaws, Haemophilus ducreyi has emerged as a major cause of CU in yaws-endemic regions of the South Pacific islands and Africa. H. ducreyi is generally susceptible to macrolides, but CU strains persist after mass drug administration of azithromycin for yaws or trachoma. H. ducreyi also causes genital ulcers (GU and was thought to be exclusively transmitted by microabrasions that occur during sex. In human volunteers, the GU strain 35000HP does not infect intact skin; wounds are required to initiate infection. These data led to several questions: Are CU strains a new variant of H. ducreyi or did they evolve from GU strains? Do CU strains contain additional genes that could allow them to infect intact skin? Are CU strains susceptible to azithromycin?To address these questions, we performed whole-genome sequencing and antibiotic susceptibility testing of 5 CU strains obtained from Samoa and Vanuatu and 9 archived class I and class II GU strains. Except for single nucleotide polymorphisms, the CU strains were genetically almost identical to the class I strain 35000HP and had no additional genetic content. Phylogenetic analysis showed that class I and class II strains formed two separate clusters and CU strains evolved from class I strains. Class I strains diverged from class II strains ~1.95 million years ago (mya and CU strains diverged from the class I strain 35000HP ~0.18 mya. CU and GU strains evolved under similar selection pressures. Like 35000HP, the CU strains were highly susceptible to antibiotics, including azithromycin.These data suggest that CU strains are derivatives of class I strains that were not recognized until recently. These findings require confirmation by analysis of CU strains from other regions.

  20. Strain gradient effects in surface roughening

    DEFF Research Database (Denmark)

    Borg, Ulrik; Fleck, N.A.

    2007-01-01

    evidence for strain gradient effects. Numerical analyses of a bicrystal undergoing in-plane tensile deformation are also studied using a strain gradient crystal plasticity theory and also by using a strain gradient plasticity theory for an isotropic solid. Both theories include an internal material length...

  1. Engineering piezoresistivity using biaxially strained silicon

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Richter, Jacob; Brandbyge, Mads

    2008-01-01

    of the piezocoefficient on temperature and dopant density is altered qualitatively for strained silicon. In particular, we find that a vanishing temperature coefficient may result for silicon with grown-in biaxial tensile strain. These results suggest that strained silicon may be used to engineer the iezoresistivity...

  2. drug resistant strains of Salmonella enterica

    African Journals Online (AJOL)

    Conclusions: The aqueous extract of Thonningia sanguinea can provide an alternative therapy for the treatment of salmonellosis, mainly for typhoid fever caused by MDR strains of S. Typhi.The extract also inhibits S.Hadar a MDR emerging strain in Ivory Coast. Keywords: Thonningia sanguinea; Salmonella, MDR strains, ...

  3. Development of high temperature strain gage, (5)

    International Nuclear Information System (INIS)

    Yuuki, Hiroshi; Kobayashi, Yukio; Kanai, Kenji; Yamaura, Yoshio

    1976-01-01

    Development and improvement of resistance wire type strain gages usable for experimental measurement of thermal strains generated at high temperature in various structures and equipments that consist of a Fast Breeder Reactor have been carried out, and various characteristics of the strain gages have been investigated. Based on the results obtained up to now, development and research of this time mainly aim to improve strain and fatigue characteristics. As the results, characteristics of strain gages with sensing elements of nichrome V are improved, specifically mechanical hysteresis is decreased, strain limit is increased, etc. Also, improvement is recognized in thermal output, and it becomes clear that dummy gages work effectively. However, a filling method of MgO and an inserting method of active-dummy elements are selected as primary objects to improve strain characteristics, and many hours are taken for these objects, so confirmations of characteristics of platinum-tungsten strain gages, strain sensing elements of which are troublesome to produce, have not been completely done, though the performance of the gages has been improved in several points. As to nichrome V strain gages, there is a fair prospect of obtaining ones, specifications of which are quite close to the goal, though problems in manufacturing technics remain for future. As to platinum-tungsten strain gages, it is expected that similar strain gages to nichrome V are obtainable by improvement in manufacturing of sensing elements. (auth.)

  4. Strain path dependency in metal plasticity

    NARCIS (Netherlands)

    Viatkina, E.M.; Brekelmans, W.A.M.; Geers, M.G.D.

    2003-01-01

    A change in strain path has a significant effect on the mechanical response of metals. Strain path change effects physically originate from a complex microstructure evolution. This paper deals with the contribution of cell structure evolution to the strain path change effect. The material with cells

  5. Stress and strain measurements in solids

    International Nuclear Information System (INIS)

    Askegaard, V.

    1978-01-01

    A design basis is given for stress- and strain cells to be used in a solid either externally loaded or with a stressfree strain field (for example shrinkage). A stress- and a strain cell has been designed for use in granular materials. Calibration tests show either good or reasonably good correspondance with calculated values. (orig.) [de

  6. Spontaneous abortion and physical strain around implantation

    DEFF Research Database (Denmark)

    Hjollund, N H; Jensen, Tina Kold; Bonde, Jens Peter

    2000-01-01

    pregnancy the women recorded physical strain prospectively in a structured diary. Physical strain around the time of implantation was associated with later spontaneous abortion. The adjusted risk ratio for women who reported physical strain higher than average at day 6 to 9 after the estimated date...

  7. Strain engineering of van der Waals heterostructures

    NARCIS (Netherlands)

    Vermeulen, Paul A.; Mulder, Jefta; Momand, Jamo; Kooi, Bart J.

    2018-01-01

    Modifying the strain state of solids allows control over a plethora of functional properties. The weak interlayer bonding in van der Waals (vdWaals) materials such as graphene, hBN, MoS2, and Bi2Te3 might seem to exclude strain engineering, since strain would immediately relax at the vdWaals

  8. Evaluation of In-House and Commercial Serological Tests for Diagnosis of Human Tularemia

    Science.gov (United States)

    Yanes, Hadjila; Hennebique, Aurélie; Pelloux, Isabelle; Boisset, Sandrine; Bicout, Dominique J.; Caspar, Yvan

    2017-01-01

    ABSTRACT Tularemia is a zoonosis caused by the bacterium Francisella tularensis. Its specific diagnosis remains based on serological methods, while F. tularensis is rarely detected in clinical samples by culture or PCR. The aim of the present study was to evaluate the performance of the Serion enzyme-linked immunosorbent assay (ELISA) classic Francisella tularensis IgG and IgM tests (Virion/Serion GmbH Institute, Würzburg, Germany) and the VIRapid tularemia immunochromatographic test (ICT) (Vircell, Granada, Spain) compared to that of the in-house microagglutination test (MAT) and indirect immunofluorescence assay (IFA) currently used at the French National Reference Center for Francisella. We evaluated 256 consecutive sera from 208 patients, including 51 confirmed and 23 probable tularemia cases, and 134 control patients not infected with F. tularensis. The IFA tests displayed 72.5% sensitivity for IgM (cutoff titer ≥80) and 74.5% for IgG (cutoff titer ≥160), and 99.3% specificity for both IgM and IgG. Using cutoffs advocated by the manufacturer, the Serion ELISAs displayed 88.2% sensitivity for IgM and 86.3% for IgG antibodies; specificity was 94.8% for IgM and 95.5% for IgG. Compared to MAT and IFA tests, the Serion ELISAs allowed earlier detection of specific antibodies (1 to 2 weeks versus 2 to 3 weeks after the onset of symptoms). The ICT sensitivity and specificity were 90% and 83.6%, respectively, when considering the cutoff advocated by the manufacturer. In conclusion, the Serion ELISAs are useful as screening tests for tularemia diagnosis, but additional confirmatory tests (such as MAT and IFA) are needed, especially in areas of low endemicity. PMID:29118164

  9. On lower order strain gradient plasticity theories

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2003-01-01

    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter...... the tangent moduli governing increments of stress and strain. It is shown that the modification is far from benign from a mathematical standpoint, changing the qualitative character of solutions and leading to a new type of localization that is at odds with what is expected from a strain gradient theory....... The findings raise questions about the physical acceptability of this class of strain gradient theories....

  10. Spontaneous abortion and physical strain around implantation

    DEFF Research Database (Denmark)

    Hjøllund, Niels Henrik Ingvar; Jensen, T.K.; Bonde, J.P.

    2000-01-01

    Existing studies of physical strain and spontaneous abortion are mainly retrospective or based only on pregnancies that have survived the first trimester. Furthermore, almost all studies have relied on averaged measures of physical strain, which tend to blur an effect if peak values during short...... pregnancy the women recorded physical strain prospectively in a structured diary. Physical strain around the time of implantation was associated with later spontaneous abortion. The adjusted risk ratio for women who reported physical strain higher than average at day 6 to 9 after the estimated date...

  11. Local strains in waste tank deflagration analysis

    International Nuclear Information System (INIS)

    Bryan, B.J.; Flanders, H.E. Jr.

    1993-01-01

    In recent years extensive effort has been expended to qualify buried nuclear waste storage tanks under accident conditions. One of these conditions is deflagration of the combustible gases which may build up over time. While much work has been done to calculate the general strain state, less effort has been made to address the local strains at structural discontinuities. An analytical method is presented for calculating these local strains and combining them with the general strain state. A closed form solution of the local strains is compared to a finite element solution

  12. Sensibility of different wheat varieties (strains) to Ar+ implantation

    International Nuclear Information System (INIS)

    Cui Huanhu; Jing Hua; Ma Aiping; Kang Xiuli; Yang Liping; Huang Mingjing; Ma Buzhou; Shanxi Academy of Agricultural Sciences, Taiyuan

    2005-01-01

    The sensibility of different wheat varieties (strains) to Ar + implantation was studied. The results showed that the survival rate of 21 wheat varieties (strains) at the dose of 6 x 10 16 Ar + /cm 2 could be divided into five groups: surplus sensitive varieties (strains), sensitive varieties (strains), transitional varieties (strains), obtuse varieties (strains) and surplus obtuse varieties (strains). The sensibility of wheat varieties (strains) to Ar + injection is high-moisture-fertility wheat varieties (strains) > medium-moisture-fertility wheat varieties (strains) > dry land wheat varieties (strains). The study has provided theoretical basis in induced mutation medial lethal dose of different wheat varieties (strains) to Ar + implantation. (authors)

  13. Stress-strain properties of railway steel at strain rates of upto 105 per second

    International Nuclear Information System (INIS)

    Hashmi, M.S.J.; Islam, M.N.

    1985-01-01

    This paper presents the stress-strain characteristics of railway steel at strain rates of up to 10 5 /s at room temperature determined by a new technique. In determining the results, account has been taken of the strain-rate variation, the total strain and the strain rate history. The effect of friction, material inertia and temperature rise is also assessed and an empirical constitutive equation describing the strain-rate and strain sensitive flow stress for this type of steel is proposed. (orig.)

  14. Comparison of experimental respiratory tularemia in three nonhuman primate species.

    Science.gov (United States)

    Glynn, Audrey R; Alves, Derron A; Frick, Ondraya; Erwin-Cohen, Rebecca; Porter, Aimee; Norris, Sarah; Waag, David; Nalca, Aysegul

    2015-04-01

    Tularemia is a zoonotic disease caused by Francisella tularensis, which is transmitted to humans most commonly by contact with infected animals, tick bites, or inhalation of aerosolized bacteria. F. tularensis is highly infectious via the aerosol route; inhalation of as few as 10-50 organisms can cause pneumonic tularemia. Left untreated, the pneumonic form has more than >30% case-fatality rate but with early antibiotic intervention can be reduced to 3%. This study compared tularemia disease progression across three species of nonhuman primates [African green monkey (AGM), cynomolgus macaque (CM), and rhesus macaque (RM)] following aerosolized F. tularensis Schu S4 exposure. Groups of the animals exposed to various challenge doses were observed for clinical signs of infection and blood samples were analyzed to characterize the disease pathogenesis. Whereas the AGMs and CMs succumbed to disease following challenge doses of 40 and 32 colony forming units (CFU), respectively, the RM lethal dose was 276,667 CFU. Following all challenge doses that caused disease, the NHPs experienced weight loss, bacteremia, fever as early as 4 days post exposure, and tissue burden. Necrotizing-to-pyogranulomatous lesions were observed most commonly in the lung, lymph nodes, spleen, and bone marrow. Overall, the CM model consistently manifested pathological responses similar to those resulting from inhalation of F. tularensis in humans and thereby most closely emulates human tularemia disease. The RM model displayed a higher tolerance to infection and survived exposures of up to 15,593 CFU of aerosolized F. tularensis. Published by Elsevier Ltd.

  15. Strain quantification in epitaxial thin films

    International Nuclear Information System (INIS)

    Cushley, M

    2008-01-01

    Strain arising in epitaxial thin films can be beneficial in some cases but devastating in others. By altering the lattice parameters, strain may give a thin film properties hitherto unseen in the bulk material. On the other hand, heavily strained systems are prone to develop lattice defects in order to relieve the strain, which can cause device failure or, at least, a decrease in functionality. Using convergent beam electron diffraction (CBED) and high-resolution transmission electron microscopy (HRTEM), it is possible to determine local strains within a material. By comparing the results from CBED and HRTEM experiments, it is possible to gain a complete view of a material, including the strain and any lattice defects present. As well as looking at how the two experimental techniques differ from each other, I will also look at how results from different image analysis algorithms compare. Strain in Si/SiGe samples and BST/SRO/MgO capacitor structures will be discussed.

  16. Studies on Drosophila radiosensitivity strains

    International Nuclear Information System (INIS)

    Varentsova, E.R.; Sharygin, V.I.; Khromykh, Yu.U.

    1985-01-01

    Fertility of radiosensitive mutant drosophila female strain rad (2) 201 61 after irradiation and frequency of dominant lethal mutations (DLM), induced by γ-radiation for 0-5 h and 5-7 days, are investigated. It is shown, that oocytes of the mutant strain are more radiosensitive as compared with cells of mongrel flies as to criterion of DLM appearance over the period of maturing. Early oocytes of stages 2-7 are the most sensitive, i.e. at the stages, corresponding to the manifestation of previously established recombination-defective properties of mutations rad (2) 201 61 . It is also sown, that doses of γ-rays, exceeding 10 Gy produce a strong sterilizing effect on mutant females due to destruction and resorption of egg chambers, irradiated at the stages of previtellogenetic growth of oocytes. In females, carrying mutation of radiosensitivity there is no direct correlation betwen sensitivity of oocytes proper to DLM induction and sensitivity of egg folleicles to resorbing effect of γ-rays. The ways of possible involvement of mutant locus studied into genetic processes in various specialized cells of drosophila

  17. Noninvasive characterization of carotid plaque strain.

    Science.gov (United States)

    Khan, Amir A; Sikdar, Siddhartha; Hatsukami, Thomas; Cebral, Juan; Jones, Michael; Huston, John; Howard, George; Lal, Brajesh K

    2017-06-01

    Current risk stratification of internal carotid artery plaques based on diameter-reducing percentage stenosis may be unreliable because ischemic stroke results from plaque disruption with atheroembolization. Biomechanical forces acting on the plaque may render it vulnerable to rupture. The feasibility of ultrasound-based quantification of plaque displacement and strain induced by hemodynamic forces and their relationship to high-risk plaques have not been determined. We studied the feasibility and reliability of carotid plaque strain measurement from clinical B-mode ultrasound images and the relationship of strain to high-risk plaque morphology. We analyzed carotid ultrasound B-mode cine loops obtained in patients with asymptomatic ≥50% stenosis during routine clinical scanning. Optical flow methods were used to quantify plaque motion and shear strain during the cardiac cycle. The magnitude (maximum absolute shear strain rate [MASSR]) and variability (entropy of shear strain rate [ESSR] and variance of shear strain rate [VSSR]) of strain were combined into a composite shear strain index (SSI), which was assessed for interscan repeatability and correlated with plaque echolucency. Nineteen patients (mean age, 70 years) constituting 36 plaques underwent imaging; 37% of patients (n = 7) showed high strain (SSI ≥0.5; MASSR, 2.2; ESSR, 39.7; VSSR, 0.03) in their plaques; the remaining clustered into a low-strain group (SSI routine B-mode imaging using clinical ultrasound machines. High plaque strain correlates with known high-risk echolucent morphology. Strain measurement can complement identification of patients at high risk for plaque disruption and stroke. Copyright © 2017 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

  18. Computational Strain Gradient Crystal Plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2011-01-01

    A model for strain gradient crystal visco-plasticity is formulated along the lines proposed by Fleck andWillis (2009) for isotropic plasticity. Size-effects are included in the model due to the addition of gradient terms in both the free energy as well as through a dissipation potential. A finite...... element solution method is presented, which delivers the slip-rate field and the velocity-field based on two minimum principles. Some plane deformation problems relevant for certain specific orientations of a face centered cubic crystal under plane loading conditions are studied, and effective in......-plane parameters are developed based on the crystallographic properties of the material. The problem of cyclic shear of a single crystal between rigid platens is studied as well as void growth of a cylindrical void....

  19. Thermoresistance in radioresistant strains of 'Drosophila nebulosa'

    International Nuclear Information System (INIS)

    Kratz, F.L.

    1977-01-01

    The detection of thermoresistance in radioresistant strains of 'D. nebulosa' is described, as well as some conclusions on the genetic nature of these differences are presented. The strains used in this experiment were MF 204, from 'Morro de Ferro', in Pocos de Caldas (MG) (one of the biggest radioactive anomalies in the world) whose radioresistance is due to its additive genetic components (Kratz, 1973 and 1975); 85(87) R, an induced radioresistant strain; and MF K a control 'pooled' strain obtained near 'Morro do Ferro'. Survival tests, 72 hours after temperature shocks, performed in the interval of 36 0 C to 39 0 C showed a decreasing gradient of thermoresistance with the following regression coefficients: MF 204 b= - 5,4; 85(87)R b= - 7,2 and MF K b= - 7,9. Bifactorial analysis (strains and sexes) performed at 38 0 C and 39 0 C confirmed differences among strains (P [pt

  20. The many shades of prion strain adaptation.

    Science.gov (United States)

    Baskakov, Ilia V

    2014-01-01

    In several recent studies transmissible prion disease was induced in animals by inoculation with recombinant prion protein amyloid fibrils produced in vitro. Serial transmission of amyloid fibrils gave rise to a new class of prion strains of synthetic origin. Gradual transformation of disease phenotypes and PrP(Sc) properties was observed during serial transmission of synthetic prions, a process that resembled the phenomenon of prion strain adaptation. The current article discusses the remarkable parallels between phenomena of prion strain adaptation that accompanies cross-species transmission and the evolution of synthetic prions occurring within the same host. Two alternative mechanisms underlying prion strain adaptation and synthetic strain evolution are discussed. The current article highlights the complexity of the prion transmission barrier and strain adaptation and proposes that the phenomenon of prion adaptation is more common than previously thought.

  1. Effect of strain rate and temperature at high strains on fatigue behavior of SAP alloys

    DEFF Research Database (Denmark)

    Blucher, J.T.; Knudsen, Per; Grant, N.J.

    1968-01-01

    Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased with decre......Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased...

  2. Surface instabilities during straining of anisotropic materials

    DEFF Research Database (Denmark)

    Legarth, Brian Nyvang; Richelsen, Ann Bettina

    2006-01-01

    The development of instabilities in traction-free surfaces is investigated numerically using a unit cell model. Full finite strain analyses are conducted using isotropic as well as anisotropic yield criteria and both plane strain tension and compression are considered. In the load range of tensio...... of principal overall strain. For other orientations surface instabilities are seen when non-associated plastic flow is taken into account. Compared to tension, smaller compressive deformations are needed in order to initiate a surface instability....

  3. Strain comparisons in aquaculture species: a manual

    OpenAIRE

    Ponzoni, R.W.; James, J.W.; Nguyen, N.H.; Mekkawy, W.; Khaw, H.L.

    2013-01-01

    When different strains or breeds of a particular species are available, the best choice is seldom immediately obvious for producers. Scientists are also interested in the relative performance of different strains because it provides a basis for recommendations to producers and it often stimulates the conduct of work aimed at unraveling the underlying biological mechanisms involved in the expression of such differences. Hence, strain or breed comparisons of some sort are frequently conducted. ...

  4. [Characteristics of Lactobacillus strains contained in pharmaceuticals].

    Science.gov (United States)

    Banach, W; Bucholc, B; Wójcik, B

    2001-01-01

    The aim of the study was to characterize lactic acid bacteria (LAB) which are components of drugs administered orally in cases of intestinal disturbances, or antibiotic--related diarrhea. Biochemical properties, growth behavior, bile tolerance, and survival at low pH of six LAB strains (four strains L. rhamnosus and two L. acidophilus) were studied. The survival at low pH was determined in MRS broth (Difco) acidified to pH 1; 2; 3; and 4. Bile tolerance was tested on MRS broth with 0.3% oxgall (Difco). Between tested strains differences in ability to grow at low pH and survival in bile were observed. Only 0.01% inoculum of all examined strains survived at pH 1. Differences between strains in survival at low pH (pH 2 and pH 3) and tolerance of bile were observed. However, after 2 h incubation at pH 4, 100% of strains stayed alive. Examined strains demonstrated good 3% bile tolerance. All strains met the criteria for probiotic strains: ability to survive at pH 3 and in the presence of bile.

  5. Properties of strain gages at cryogenic temperature

    International Nuclear Information System (INIS)

    Shibata, Nobuo; Fujiyoshi, Toshimitsu.

    1978-01-01

    At the time of developing superconduction generators, the stress measurement for rotor parts is required to grasp the safety and performance of the rotor at cryogenic temperature, which is cooled with liquid helium. In case of carrying out the stress measurement with strain gages, the problems are as follows. The strain gages and lead wires are exposed to cryogenic temperature from 4 to 10 K and strong magnetic field of about 3T, and subjected to high centrifugal acceleration of about 500G. In order to establish the techniques of the stress measurement under such conditions, the adhesives and damp-proof coatings for strain gages and strain gages themselves in Japan and foreign countries were examined on the properties at cryogenic temperature. As for the properties of strain gages, mainly the apparent strain owing to temperature change was investigated, and the change of the gage factors was studies only at liquid nitrogen temperature. The stress measurement with strain gages at low temperature had been studied in detail down to liquid nitrogen temperature concerning LNG tanks. The experimental apparatus, the samples, the testing methods and the test results of cooling tests on adhesives and damp-proof coatings, and the temperature characteristics of strain gages are reported. The usable adhesives and coatings were found, and correction by accurate temperature measurement is required for apparent strain. (Kako, I.)

  6. Comparison of Thermal Creep Strain Calculation Results Using Time Hardening and Strain Hardening Rules

    International Nuclear Information System (INIS)

    Kim, Junehyung; Cheon, Jinsik; Lee, Byoungoon; Lee, Chanbock

    2014-01-01

    One of the design criteria for the fuel rod in PGSFR is the thermal creep strain of the cladding, because the cladding is exposed to a high temperature for a long time during reactor operation period. In general, there are two kind of calculation scheme for thermal creep strain: time hardening and strain hardening rules. In this work, thermal creep strain calculation results for HT9 cladding by using time hardening and strain hardening rules are compared by employing KAERI's current metallic fuel performance analysis code, MACSIS. Also, thermal creep strain calculation results by using ANL's metallic fuel performance analysis code, LIFE-METAL which adopts strain hardening rule are compared with those by using MACSIS. Thermal creep strain calculation results for HT9 cladding by using time hardening and strain hardening rules were compared by employing KAERI's current metallic fuel performance analysis code, MACSIS. Also, thermal creep strain calculation results by using ANL's metallic fuel performance analysis code, LIFE-METAL which adopts strain hardening rule were compared with those by using MACSIS. Tertiary creep started earlier in time hardening rule than in strain hardening rule. Also, calculation results by MACSIS with strain hardening and those obtained by using LIFE-METAL were almost identical to each other

  7. Predicting creep rupture from early strain data

    International Nuclear Information System (INIS)

    Holmstroem, Stefan; Auerkari, Pertti

    2009-01-01

    To extend creep life modelling from classical rupture modelling, a robust and effective parametric strain model has been developed. The model can reproduce with good accuracy all parts of the creep curve, economically utilising the available rupture models. The resulting combined model can also be used to predict rupture from the available strain data, and to further improve the rupture models. The methodology can utilise unfailed specimen data for life assessment at lower stress levels than what is possible from rupture data alone. Master curves for creep strain and rupture have been produced for oxygen-free phosphorus-doped (OFP) copper with a maximum testing time of 51,000 h. Values of time to specific strain at given stress (40-165 MPa) and temperature (125-350 deg. C) were fitted to the models in the strain range of 0.1-38%. With typical inhomogeneous multi-batch creep data, the combined strain and rupture modelling involves the steps of investigation of the data quality, extraction of elastic and creep strain response, rupture modelling, data set balancing and creep strain modelling. Finally, the master curves for strain and rupture are tested and validated for overall fitting efficiency. With the Wilshire equation as the basis for the rupture model, the strain model applies classical parametric principles with an Arrhenius type of thermal activation and a power law type of stress dependence for the strain rate. The strain model also assumes that the processes of primary and secondary creep can be reasonably correlated. The rupture model represents a clear improvement over previous models in the range of the test data. The creep strain information from interrupted and running tests were assessed together with the rupture data investigating the possibility of rupture model improvement towards lower stress levels by inverse utilisation of the combined rupture based strain model. The developed creep strain model together with the improved rupture model is

  8. Conduction band structure and electron mobility in uniaxially strained Si via externally applied strain in nanomembranes

    Energy Technology Data Exchange (ETDEWEB)

    Chen Feng [Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Euaruksakul, Chanan; Himpsel, F J; Lagally, Max G [University of Wisconsin-Madison, Madison, WI 53706 (United States); Liu Zheng; Liu Feng, E-mail: lagally@engr.wisc.edu [University of Utah, Salt Lake City, UT 84112 (United States)

    2011-08-17

    Strain changes the band structure of semiconductors. We use x-ray absorption spectroscopy to study the change in the density of conduction band (CB) states when silicon is uniaxially strained along the [1 0 0] and [1 1 0] directions. High stress can be applied to silicon nanomembranes, because their thinness allows high levels of strain without fracture. Strain-induced changes in both the sixfold degenerate {Delta} valleys and the eightfold degenerate L valleys are determined quantitatively. The uniaxial deformation potentials of both {Delta} and L valleys are directly extracted using a strain tensor appropriate to the boundary conditions, i.e., confinement in the plane in the direction orthogonal to the straining direction, which correspond to those of strained CMOS in commercial applications. The experimentally determined deformation potentials match the theoretical predictions well. We predict electron mobility enhancement created by strain-induced CB modifications.

  9. Nanocomposite Strain Gauges Having Small TCRs

    Science.gov (United States)

    Gregory, Otto; Chen, Ximing

    2009-01-01

    Ceramic strain gauges in which the strain-sensitive electrically conductive strips made from nanocomposites of noble metal and indium tin oxide (ITO) are being developed for use in gas turbine engines and other power-generation systems in which gas temperatures can exceed 1,500 F (about 816 C). In general, strain gauges exhibit spurious thermally induced components of response denoted apparent strain. When temperature varies, a strain-gauge material that has a nonzero temperature coefficient of resistance (TCR) exhibits an undesired change in electrical resistance that can be mistaken for the change in resistance caused by a change in strain. It would be desirable to formulate straingauge materials having TCRs as small as possible so as to minimize apparent strain. Most metals exhibit positive TCRs, while most semiconductors, including ITO, exhibit negative TCRs. The present development is based on the idea of using the negative TCR of ITO to counter the positive TCRs of noble metals and of obtaining the benefit of the ability of both ITO and noble metals to endure high temperatures. The noble metal used in this development thus far has been platinum. Combinatorial libraries of many ceramic strain gauges containing nanocomposites of various proportions of ITO and platinum were fabricated by reactive co-sputtering from ITO and platinum targets onto alumina- and zirconia-based substrates mounted at various positions between the targets.

  10. Strain differentiation of polioviruses with monoclonal antibodies.

    NARCIS (Netherlands)

    A.D.M.E. Osterhaus (Albert); A.L. van Wezel; A.J.H. Stegmann; J.A.A.M. van Asten (Jack)

    1984-01-01

    textabstractPanels of monoclonal antibodies raised against different poliovirus type 1, 2 and 3 strains, were tested in a micro-neutralization test and in a micro-enzyme linked immunosorbent assay against a large number of poliovirus strains. The results were compared with those obtained with the

  11. Organic metabolites produced by Vibrio parahaemolyticus strain ...

    African Journals Online (AJOL)

    Identification and action of several antibacterial metabolites produced by a fish pathogen Vibrio parahaemolyticus strain An3 from marine ecosystem of Goa has been demonstrated. Antibacterial activity of the crude cell extract of the test bacterium has been evaluated against indicator pathogenic bacterial strains such as ...

  12. On lower order strain gradient plasticity theories

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2002-01-01

    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter...

  13. Job strain and time to pregnancy

    DEFF Research Database (Denmark)

    Hjollund, N H; Kold Jensen, T; Bonde, Jens Peter

    1998-01-01

    The association between fertility and job strain defined as high job demands and low job control has not previously been studied. A follow-up study was conducted with prospective collection of information on job strain among women, achievement of pregnancy, and potential confounding variables....

  14. Medically Complex Home Care and Caregiver Strain

    Science.gov (United States)

    Moorman, Sara M.; Macdonald, Cameron

    2013-01-01

    Purpose of the study: To examine (a) whether the content of caregiving tasks (i.e., nursing vs. personal care) contributes to variation in caregivers' strain and (b) whether the level of complexity of nursing tasks contributes to variation in strain among caregivers providing help with such tasks. Design and methods: The data came from the Cash…

  15. Five challenges in modelling interacting strain dynamics

    DEFF Research Database (Denmark)

    Wikramaratna, Paul S; Kurcharski, Adam; Gupta, Sunetra

    2015-01-01

    population models. Next we consider the nature of so-called “strain space”. We describe two key types of host heterogeneities, and explain how models could help generate a better understanding of their effects. Finally, for diseases with many strains, we consider the challenge of modelling how immunity...

  16. Multiple Genome Sequences of Lactobacillus plantarum Strains

    OpenAIRE

    Kafka, Thomas A.; Geissler, Andreas J.; Vogel, Rudi F.

    2017-01-01

    ABSTRACT We report here the genome sequences of four Lactobacillus plantarum strains which vary in surface hydrophobicity. Bioinformatic analysis, using additional genomes of Lactobacillus plantarum strains, revealed a possible correlation between the cell wall teichoic acid-type and cell surface hydrophobicity and provide the basis for consecutive analyses.

  17. Preliminary characterization of slow growing rhizobial strains ...

    African Journals Online (AJOL)

    In this paper, we did some preliminary characterization of six slow growing rhizobial strains, isolated from Retama monosperma (L.) Boiss. root nodules sampled from 3 sites along the coast of Oran (CapeFalcon, Bousfer and MersElHadjadj) in Northwestern Algeria. Results of this study showed that all strains had a very ...

  18. Typing of lymphogranuloma venereum Chlamydia trachomatis strains

    NARCIS (Netherlands)

    Christerson, Linus; de Vries, Henry J. C.; de Barbeyrac, Bertille; Gaydos, Charlotte A.; Henrich, Birgit; Hoffmann, Steen; Schachter, Julius; Thorvaldsen, Johannes; Vall-Mayans, Martí; Klint, Markus; Herrmann, Björn; Morré, Servaas A.

    2010-01-01

    We analyzed by multilocus sequence typing 77 lymphogranuloma venereum Chlamydia trachomatis strains from men who have sex with men in Europe and the United States. Specimens from an outbreak in 2003 in Europe were monoclonal. In contrast, several strains were in the United States in the 1980s,

  19. Typing of Lymphogranuloma Venereum Chlamydia trachomatis Strains

    Science.gov (United States)

    Christerson, Linus; de Vries, Henry J.C.; de Barbeyrac, Bertille; Gaydos, Charlotte A.; Henrich, Birgit; Hoffmann, Steen; Schachter, Julius; Thorvaldsen, Johannes; Vall-Mayans, Martí; Klint, Markus; Morré, Servaas A.

    2010-01-01

    We analyzed by multilocus sequence typing 77 lymphogranuloma venereum Chlamydia trachomatis strains from men who have sex with men in Europe and the United States. Specimens from an outbreak in 2003 in Europe were monoclonal. In contrast, several strains were in the United States in the 1980s, including a variant from Europe. PMID:21029543

  20. MARSI: metabolite analogues for rational strain improvement

    DEFF Research Database (Denmark)

    Cardoso, João G. R.; Zeidan, Ahmad A; Jensen, Kristian

    2018-01-01

    reactions in an organism can be used to predict effects of MAs on cellular phenotypes. Here, we present the Metabolite Analogues for Rational Strain Improvement (MARSI) framework. MARSI provides a rational approach to strain improvement by searching for metabolites as targets instead of genes or reactions...

  1. General Strain Theory and Delinquency: Focusing on the Influences of Key Strain Characteristics on Delinquency

    Science.gov (United States)

    Moon, Byongook; Blurton, David; McCluskey, John D.

    2008-01-01

    The study examines the effects of recent, older, and chronic strains and of perceived injustice of strain on delinquency, sampling 777 Korean youth. Seven key strains most likely leading to delinquency, some of which were often overlooked in previous research, were included, and these are family conflict, parental punishment, teachers' punishment,…

  2. Strain localization band width evolution by electronic speckle pattern interferometry strain rate measurement

    Energy Technology Data Exchange (ETDEWEB)

    Guelorget, Bruno [Institut Charles Delaunay-LASMIS, Universite de technologie de Troyes, FRE CNRS 2848, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)], E-mail: bruno.guelorget@utt.fr; Francois, Manuel; Montay, Guillaume [Institut Charles Delaunay-LASMIS, Universite de technologie de Troyes, FRE CNRS 2848, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)

    2009-04-15

    In this paper, electronic speckle pattern interferometry strain rate measurements are used to quantify the width of the strain localization band, which occurs when a sheet specimen is submitted to tension. It is shown that the width of this band decreases with increasing strain. Just before fracture, this measured width is about five times wider than the shear band and the initial sheet thickness.

  3. Limitations of Hollomon and Ludwigson stress-strain relations in assessing the strain hardening parameters

    International Nuclear Information System (INIS)

    Samuel, K G

    2006-01-01

    It is shown that the deviation from the ideal Hollomon relation in describing the stress-strain behaviour is characteristic of all materials at low strains. The Ludwigson relation describing the deviation from the Hollomon relation at low strains is critically analysed and it is shown that the deviation at low strains is a consequence of some unknown 'plastic strain equivalent' present in the material. Stress strain curves obeying an ideal Hollomon relation as well as that of a structurally modified (prior cold worked) material were simulated and compared. The results show that the yield strength and the flow strength of a material at constant strain rate and temperature are dictated by the magnitude of the 'plastic strain equivalent' term. It is shown that this component need not necessarily mean a prior plastic strain present in the material due to prior cold work alone and that prior cold work strain will add to this. If this component is identified, the stress-strain behaviour can be adequately described by the Swift relation. It is shown that in both formalisms, the strain hardening index is a function of the yield strength of the material

  4. Atlas of stress-strain curves

    CERN Document Server

    2002-01-01

    The Atlas of Stress-Strain Curves, Second Edition is substantially bigger in page dimensions, number of pages, and total number of curves than the previous edition. It contains over 1,400 curves, almost three times as many as in the 1987 edition. The curves are normalized in appearance to aid making comparisons among materials. All diagrams include metric (SI) units, and many also include U.S. customary units. All curves are captioned in a consistent format with valuable information including (as available) standard designation, the primary source of the curve, mechanical properties (including hardening exponent and strength coefficient), condition of sample, strain rate, test temperature, and alloy composition. Curve types include monotonic and cyclic stress-strain, isochronous stress-strain, and tangent modulus. Curves are logically arranged and indexed for fast retrieval of information. The book also includes an introduction that provides background information on methods of stress-strain determination, on...

  5. [New antibiotics produced by Bacillus subtilis strains].

    Science.gov (United States)

    Malanicheva, I A; Kozlov, D G; Efimenko, T A; Zenkova, V A; Kastrukha, G S; Reznikova, M I; Korolev, A M; Borshchevskaia, L N; Tarasova, O D; Sineokiĭ, S P; Efremenkova, O V

    2014-01-01

    Two Bacillus subtilis strains isolated from the fruiting body of a basidiomycete fungus Pholiota squarrosa exhibited a broad range of antibacterial activity, including those against methicillin-resistant Staphylococcus aureus INA 00761 (MRSA) and Leuconostoc mes6nteroides VKPM B-4177 resistant to glycopep-> tide antibiotics, as well as antifungal activity. The strains were identified as belonging to the "B. subtilis" com- plex based on their morphological and physiological characteristics, as well as by sequencing of the 16S rRNA gene fragments. Both strains (INA 01085 and INA 01086) produced insignificant amounts of polyene antibiotics (hexaen and pentaen, respectively). Strain INA 01086 produced also a cyclic polypeptide antibiotic containing Asp, Gly, Leu, Pro, Tyr, Thr, Trp, and Phe, while the antibiotic of strain INA 01085 contained, apart from these, two unidentified nonproteinaceous amino acids. Both polypeptide antibiotics were new compounds efficient against gram-positive bacteria and able to override the natural bacterial antibiotic resistance.

  6. On fracture in finite strain gradient plasticity

    DEFF Research Database (Denmark)

    Martínez Pañeda, Emilio; Niordson, Christian Frithiof

    2016-01-01

    In this work a general framework for damage and fracture assessment including the effect of strain gradients is provided. Both mechanism-based and phenomenological strain gradient plasticity (SGP) theories are implemented numerically using finite deformation theory and crack tip fields are invest......In this work a general framework for damage and fracture assessment including the effect of strain gradients is provided. Both mechanism-based and phenomenological strain gradient plasticity (SGP) theories are implemented numerically using finite deformation theory and crack tip fields...... are investigated. Differences and similarities between the two approaches within continuum SGP modeling are highlighted and discussed. Local strain hardening promoted by geometrically necessary dislocations (GNDs) in the vicinity of the crack leads to much higher stresses, relative to classical plasticity...... in the multiple parameter version of the phenomenological SGP theory. Since this also dominates the mechanics of indentation testing, results suggest that length parameters characteristic of mode I fracture should be inferred from nanoindentation....

  7. Dark field electron holography for strain measurement

    Energy Technology Data Exchange (ETDEWEB)

    Beche, A., E-mail: armand.beche@fei.com [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Rouviere, J.L. [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Barnes, J.P.; Cooper, D. [CEA-LETI, Minatec Campus, F-38054 Grenoble (France)

    2011-02-15

    Dark field electron holography is a new TEM-based technique for measuring strain with nanometer scale resolution. Here we present the procedure to align a transmission electron microscope and obtain dark field holograms as well as the theoretical background necessary to reconstruct strain maps from holograms. A series of experimental parameters such as biprism voltage, sample thickness, exposure time, tilt angle and choice of diffracted beam are then investigated on a silicon-germanium layer epitaxially embedded in a silicon matrix in order to obtain optimal dark field holograms over a large field of view with good spatial resolution and strain sensitivity. -- Research Highlights: {yields} Step by step explanation of the dark field electron holography technique. {yields} Presentation of the theoretical equations to obtain quantitative strain map. {yields} Description of experimental parameters influencing dark field holography results. {yields} Quantitative strain measurement on a SiGe layer embedded in a silicon matrix.

  8. Pseudomagnetic fields and triaxial strain in graphene

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Power, Stephen; Jauho, Antti-Pekka

    2016-01-01

    Pseudomagnetic fields, which can result from nonuniform strain distributions, have received much attention in graphene systems due to the possibility of mimicking real magnetic fields with magnitudes of greater than 100 T. We examine systems with such strains confined to finite regions ("pseudoma......Pseudomagnetic fields, which can result from nonuniform strain distributions, have received much attention in graphene systems due to the possibility of mimicking real magnetic fields with magnitudes of greater than 100 T. We examine systems with such strains confined to finite regions......-binding calculations of single pseudomagnetic dots in extended graphene sheets confirm these predictions, and are also used to study the effect of rotating the strain direction with respect to the underlying graphene lattice, and varying the size of the pseudomagnetic dot....

  9. MODERNIZATION OF GENEOTIPING OF STRAINS B. PERTUSSIS

    Directory of Open Access Journals (Sweden)

    G. A. Ivashinnikova

    2013-01-01

    Full Text Available The new rapid molecular genotyping method was developed for studying the structure of ptxP promoter of pertussis toxin. Method is based on PCR-RFLP analysis, which allows studying the specific restriction profiles of the B. pertussis strains and allows differentiation of the strains with the ptxP structural particularities. The developed method for genotyping of strains of B. pertussis can be hhelpful when monitoring strains of the causative agent of whooping cough in system of an epidemiological surveillance over pertussis infections, allowing observation over circulating population of B.pertussis, revealing strains of the causative agent of whooping cough with high production of pertussis toxin and to watch their distribution.

  10. Strain rate effects in stress corrosion cracking

    Energy Technology Data Exchange (ETDEWEB)

    Parkins, R.N. (Newcastle upon Tyne Univ. (UK). Dept. of Metallurgy and Engineering Materials)

    1990-03-01

    Slow strain rate testing (SSRT) was initially developed as a rapid, ad hoc laboratory method for assessing the propensity for metals an environments to promote stress corrosion cracking. It is now clear, however, that there are good theoretical reasons why strain rate, as opposed to stress per se, will often be the controlling parameter in determining whether or not cracks are nucleated and, if so, are propagated. The synergistic effects of the time dependence of corrosion-related reactions and microplastic strain provide the basis for mechanistic understanding of stress corrosion cracking in high-pressure pipelines and other structures. However, while this may be readily comprehended in the context of laboratory slow strain tests, its extension to service situations may be less apparent. Laboratory work involving realistic stressing conditions, including low-frequency cyclic loading, shows that strain or creep rates give good correlation with thresholds for cracking and with crack growth kinetics.

  11. Strain-controlled nonvolatile magnetization switching

    Science.gov (United States)

    Geprägs, S.; Brandlmaier, A.; Brandt, M. S.; Gross, R.; Goennenwein, S. T. B.

    2014-11-01

    We investigate different approaches towards a nonvolatile switching of the remanent magnetization in single-crystalline ferromagnets at room temperature via elastic strain using ferromagnetic thin film/piezoelectric actuator hybrids. The piezoelectric actuator induces a voltage-controllable strain along different crystalline directions of the ferromagnetic thin film, resulting in modifications of its magnetization by converse magnetoelastic effects. We quantify the magnetization changes in the hybrids via ferromagnetic resonance spectroscopy and superconducting quantum interference device magnetometry. These measurements demonstrate a significant strain-induced change of the magnetization, limited by an inefficient strain transfer and domain formation in the particular system studied. To overcome these obstacles, we address practicable engineering concepts and use a model to demonstrate that a strain-controlled, nonvolatile magnetization switching should be possible in appropriately engineered ferromagnetic/piezoelectric actuator hybrids.

  12. Amerindian Helicobacter pylori strains go extinct, as european strains expand their host range.

    Directory of Open Access Journals (Sweden)

    Maria G Domínguez-Bello

    Full Text Available We studied the diversity of bacteria and host in the H. pylori-human model. The human indigenous bacterium H. pylori diverged along with humans, into African, European, Asian and Amerindian groups. Of these, Amerindians have the least genetic diversity. Since niche diversity widens the sets of resources for colonizing species, we predicted that the Amerindian H. pylori strains would be the least diverse. We analyzed the multilocus sequence (7 housekeeping genes of 131 strains: 19 cultured from Africans, 36 from Spanish, 11 from Koreans, 43 from Amerindians and 22 from South American Mestizos. We found that all strains that had been cultured from Africans were African strains (hpAfrica1, all from Spanish were European (hpEurope and all from Koreans were hspEAsia but that Amerindians and Mestizos carried mixed strains: hspAmerind and hpEurope strains had been cultured from Amerindians and hpEurope and hpAfrica1 were cultured from Mestizos. The least genetically diverse H. pylori strains were hspAmerind. Strains hpEurope were the most diverse and showed remarkable multilocus sequence mosaicism (indicating recombination. The lower genetic structure in hpEurope strains is consistent with colonization of a diversity of hosts. If diversity is important for the success of H. pylori, then the low diversity of Amerindian strains might be linked to their apparent tendency to disappear. This suggests that Amerindian strains may lack the needed diversity to survive the diversity brought by non-Amerindian hosts.

  13. Strain hardening rate sensitivity and strain rate sensitivity in TWIP steels

    Energy Technology Data Exchange (ETDEWEB)

    Bintu, Alexandra [TEMA, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Vincze, Gabriela, E-mail: gvincze@ua.pt [TEMA, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Picu, Catalin R. [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Lopes, Augusto B. [CICECO, Department of Materials and Ceramic Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Grácio, Jose J. [TEMA, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Barlat, Frederic [Materials Mechanics Laboratory, Graduate Institute of Ferrous Technology, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2015-04-01

    TWIP steels are materials with very high strength and exceptional strain hardening capability, parameters leading to large energy absorption before failure. However, TWIP steels also exhibit reduced (often negative) strain rate sensitivity (SRS) which limits the post-necking deformation. In this study we demonstrate for an austenitic TWIP steel with 18% Mn a strong dependence of the twinning rate on the strain rate, which results in negative strain hardening rate sensitivity (SHRS). The instantaneous component of SHRS is large and negative, while its transient is close to zero. The SRS is observed to decrease with strain, becoming negative for larger strains. Direct observations of the strain rate dependence of the twinning rate are made using electron microscopy and electron backscatter diffraction, which substantiate the proposed mechanism for the observed negative SHRS.

  14. Strain hardening rate sensitivity and strain rate sensitivity in TWIP steels

    International Nuclear Information System (INIS)

    Bintu, Alexandra; Vincze, Gabriela; Picu, Catalin R.; Lopes, Augusto B.; Grácio, Jose J.; Barlat, Frederic

    2015-01-01

    TWIP steels are materials with very high strength and exceptional strain hardening capability, parameters leading to large energy absorption before failure. However, TWIP steels also exhibit reduced (often negative) strain rate sensitivity (SRS) which limits the post-necking deformation. In this study we demonstrate for an austenitic TWIP steel with 18% Mn a strong dependence of the twinning rate on the strain rate, which results in negative strain hardening rate sensitivity (SHRS). The instantaneous component of SHRS is large and negative, while its transient is close to zero. The SRS is observed to decrease with strain, becoming negative for larger strains. Direct observations of the strain rate dependence of the twinning rate are made using electron microscopy and electron backscatter diffraction, which substantiate the proposed mechanism for the observed negative SHRS

  15. Measurement of Strain and Strain Rate during the Impact of Tennis Ball Cores

    Directory of Open Access Journals (Sweden)

    Ben Lane

    2018-03-01

    Full Text Available The aim of this investigation was to establish the strains and strain rates experienced by tennis ball cores during impact to inform material characterisation testing and finite element modelling. Three-dimensional surface strains and strain rates were measured using two high-speed video cameras and corresponding digital image correlation software (GOM Correlate Professional. The results suggest that material characterisation testing to a maximum strain of 0.4 and a maximum rate of 500 s−1 in tension and to a maximum strain of −0.4 and a maximum rate of −800 s−1 in compression would encapsulate the demands placed on the material during impact and, in turn, define the range of properties required to encapsulate the behavior of the material during impact, enabling testing to be application-specific and strain-rate-dependent properties to be established and incorporated in finite element models.

  16. Factors affecting finite strain estimation in low-grade, low-strain clastic rocks

    Science.gov (United States)

    Pastor-Galán, Daniel; Gutiérrez-Alonso, Gabriel; Meere, Patrick A.; Mulchrone, Kieran F.

    2009-12-01

    The computer strain analysis methods SAPE, MRL and DTNNM have permitted the characterization of finite strain in two different regions with contrasting geodynamic scenarios; (1) the Talas Ala Tau (Tien Shan, Kyrgyzs Republic) and (2) the Somiedo Nappe and Narcea Antiform (Cantabrian to West Asturian-Leonese Zone boundary, Variscan Belt, NW of Iberia). The performed analyses have revealed low-strain values and the regional strain trend in both studied areas. This study also investigates the relationship between lithology (grain size and percentage of matrix) and strain estimates the two methodologies used. The results show that these methods are comparable and the absence of significant finite strain lithological control in rocks deformed under low metamorphic and low-strain conditions.

  17. Chemical Profile of Monascus ruber Strains

    Directory of Open Access Journals (Sweden)

    Ahamed M. Moharram

    2012-01-01

    Full Text Available Chemical profile of Monascus ruber strains has been studied using gas chromatography-mass spectrometry (GC/MS analysis. The colour intensity of the red pigment and secondary metabolic products of two M. ruber strains (AUMC 4066 and AUMC 5705 cultivated on ten different media were also studied. Metabolic products can be classified into four categories: anticholesterol, anticancer, food colouring, and essential fatty acids necessary for human health. Using GC/MS, the following 88 metabolic products were detected: butyric acid and its derivatives (25 products, other fatty acids and their derivatives (19 products, pyran and its derivatives (22 products and other metabolites (22 products. Among these, 32 metabolites were specific for AUMC 4066 strain and 34 for AUMC 5705 strain, whereas 22 metabolites were produced by both strains on different tested substrates. Production of some metabolites depended on the substrate used. High number of metabolites was recorded in the red pigment extract obtained by both strains grown on malt broth and malt agar. Also, 42 aroma compounds were recorded (4 alcohols, 2 benzaldehydes, 27 esters, 3 lactones, 1 phenol, 1 terpenoid, 3 thiol compounds and acetate-3-mercapto butyric acid. Thin layer chromatography and GC/MS analyses revealed no mycotoxin citrinin in any media used for the growth of the two M. ruber strains.

  18. Resolution of axial shear strain elastography

    International Nuclear Information System (INIS)

    Thitaikumar, Arun; Righetti, Raffaella; Krouskop, Thomas A; Ophir, Jonathan

    2006-01-01

    The technique of mapping the local axial component of the shear strain due to quasi-static axial compression is defined as axial shear strain elastography. In this paper, the spatial resolution of axial shear strain elastography is investigated through simulations, using an elastically stiff cylindrical lesion embedded in a homogeneously softer background. Resolution was defined as the smallest size of the inclusion for which the strain value at the inclusion/background interface was greater than the average of the axial shear strain values at the interface and inside the inclusion. The resolution was measured from the axial shear strain profile oriented at 45 0 to the axis of beam propagation, due to the absence of axial shear strain along the normal directions. The effects of the ultrasound system parameters such as bandwidth, beamwidth and transducer element pitch along with signal processing parameters such as correlation window length (W) and axial shift (ΔW) on the estimated resolution were investigated. The results show that the resolution (at 45 0 orientation) is determined by the bandwidth and the beamwidth. However, the upper bound on the resolution is limited by the larger of the beamwidth and the window length, which is scaled inversely to the bandwidth. The results also show that the resolution is proportional to the pitch and not significantly affected by the axial window shift

  19. Development of intra-strain self-cloning procedure for breeding baker's yeast strains.

    Science.gov (United States)

    Nakagawa, Youji; Ogihara, Hiroyuki; Mochizuki, Chisato; Yamamura, Hideki; Iimura, Yuzuru; Hayakawa, Masayuki

    2017-03-01

    Previously reported self-cloning procedures for breeding of industrial yeast strains require DNA from other strains, plasmid DNA, or mutagenesis. Therefore, we aimed to construct a self-cloning baker's yeast strain that exhibits freeze tolerance via an improved self-cloning procedure. We first disrupted the URA3 gene of a prototrophic baker's yeast strain without the use of any marker gene, resulting in a Δura3 homozygous disruptant. Then, the URA3 gene of the parental baker's yeast strain was used as a selection marker to introduce the constitutive TDH3 promoter upstream of the PDE2 gene encoding high-affinity cyclic AMP phosphodiesterase. This self-cloning procedure was performed without using DNA from other Saccharomyces cerevisiae strains, plasmid DNA, or mutagenesis and was therefore designated an intra-strain self-cloning procedure. Using this self-cloning procedure, we succeeded in producing self-cloning baker's yeast strains that harbor the TDH3p-PDE2 gene heterozygously and homozygously, designated TDH3p-PDE2 hetero and TDH3p-PDE2 homo strains, respectively. These self-cloning strains expressed much higher levels of PDE2 mRNA than the parental strain and exhibited higher viability after freeze stress, as well as higher fermentation ability in frozen dough, when compared with the parental strain. The TDH3p-PDE2 homo strain was genetically more stable than the TDH3p-PDE2 hetero strain. These results indicate that both heterozygous and homozygous strains of self-cloning PDE2-overexpressing freeze-tolerant strains of industrial baker's yeast can be prepared using the intra-strain self-cloning procedure, and, from a practical viewpoint, the TDH3p-PDE2 homo strain constructed in this study is preferable to the TDH3p-PDE2 hetero strain for frozen dough baking. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  20. [Screening and optimization of cholesterol conversion strain].

    Science.gov (United States)

    Fan, Dan; Xiong, Bingjian; Pang, Cuiping; Zhu, Xiangdong

    2014-10-04

    Bacterial strain SE-1 capable of transforming cholesterol was isolated from soil and characterized. The transformation products were identified. Fermentation conditions were optimized for conversion. Cholesterol was used as sole carbon source to isolate strain SE-1. Morphology, physiological and biochemical characteristics of strain SE-1 were studied. 16S rRNA gene was sequenced and subjected to phylogenetic analysis. Fermentation supernatants were extracted with chloroform, the transformation products were analyzed by silica gel thin layer chromatography and Sephadex LH20. Their structures were identified by 1H-NMR and 13C-NMR. Fermentation medium including carbon and nitrogen, methods of adding substrates and fermentation conditions for Strain SE-1 were optimized. Strain SE-1 was a Gram-negative bacterium, exhibiting the highest homologs to Burkholderia cepacia based on the physiological analysis. The sequence analysis of 16S rRNA gene of SE-1 strain and comparison with related Burkholderia show that SE-1 strain was very close to B. cepacia (Genbank No. U96927). The similarity was 99%. The result of silica gel thin layer chromatography shows that strain SE-1 transformed cholesterol to two products, 7beta-hydroxycholesterol and the minor product was 7-oxocholesterol. The optimum culture conditions were: molasses 5%, (NH4 )2SO4 0.3%, 4% of inoculation, pH 7.5 and 36 degrees C. Under the optimum culture condition, the conversion rate reached 34.4% when concentration of cholesterol-Tween 80 was 1 g/L. Cholesterol 7beta-hydroxylation conversion rate under optimal conditions was improved by 20.8%. Strain SE-1 isolated from soil is capable of converting cholesterol at lab-scale.

  1. Ductile Damage Evolution and Strain Path Dependency

    International Nuclear Information System (INIS)

    Tasan, C. C.; Hoefnagels, J. M. P.; Peerlings, R. H. J.; Geers, M. G. D.; ten Horn, C. H. L. J.; Vegter, H.

    2007-01-01

    Forming limit diagrams are commonly used in sheet metal industry to define the safe forming regions. These diagrams are built to define the necking strains of sheet metals. However, with the rise in the popularity of advance high strength steels, ductile fracture through damage evolution has also emerged as an important parameter in the determination of limit strains. In this work, damage evolution in two different steels used in the automotive industry is examined to observe the relationship between damage evolution and the strain path that is followed during the forming operation

  2. Strain-energy effects on dynamic fragmentation

    International Nuclear Information System (INIS)

    Glenn, L.A.; Chudnovsky, A.

    1986-01-01

    Grady's model of the dynamic fragmentation process, in which the average fragment size is determined by balancing the local kinetic energy and the surface energy, is modified to include the stored elastic (strain) energy. The revised model predicts that the strain energy should dominate for brittle materials, with low fracture toughness and high fracture-initiation stress. This conclusion is not borne out, however, by limited experimental data on brittle steels, even when the kinetic-energy density is small compared with the strain-energy density

  3. Stability of germanene under tensile strain

    KAUST Repository

    Kaloni, Thaneshwor P.

    2013-09-01

    The stability of germanene under biaxial tensile strain and the accompanying modifications of the electronic properties are studied by density functional theory. The phonon spectrum shows that up to 16% strain the germanene lattice is stable, where the Dirac cone shifts towards higher energy and hole-doped Dirac states are achieved. The latter is due to weakening of the Ge-Ge bonds and reduction of the s-p hybridization. Our calculated Grüneisen parameter shows a similar dependence on the strain as reported for silicene (which is different from that of graphene). © 2013 Elsevier B.V. All rights reserved.

  4. Stability of germanene under tensile strain

    KAUST Repository

    Kaloni, Thaneshwor P.; Schwingenschlö gl, Udo

    2013-01-01

    The stability of germanene under biaxial tensile strain and the accompanying modifications of the electronic properties are studied by density functional theory. The phonon spectrum shows that up to 16% strain the germanene lattice is stable, where the Dirac cone shifts towards higher energy and hole-doped Dirac states are achieved. The latter is due to weakening of the Ge-Ge bonds and reduction of the s-p hybridization. Our calculated Grüneisen parameter shows a similar dependence on the strain as reported for silicene (which is different from that of graphene). © 2013 Elsevier B.V. All rights reserved.

  5. Rat Strain Ontology: structured controlled vocabulary designed to facilitate access to strain data at RGD.

    Science.gov (United States)

    Nigam, Rajni; Munzenmaier, Diane H; Worthey, Elizabeth A; Dwinell, Melinda R; Shimoyama, Mary; Jacob, Howard J

    2013-11-22

    The Rat Genome Database (RGD) ( http://rgd.mcw.edu/) is the premier site for comprehensive data on the different strains of the laboratory rat (Rattus norvegicus). The strain data are collected from various publications, direct submissions from individual researchers, and rat providers worldwide. Rat strain, substrain designation and nomenclature follow the Guidelines for Nomenclature of Mouse and Rat Strains, instituted by the International Committee on Standardized Genetic Nomenclature for Mice. While symbols and names aid in identifying strains correctly, the flat nature of this information prohibits easy search and retrieval, as well as other data mining functions. In order to improve these functionalities, particularly in ontology-based tools, the Rat Strain Ontology (RS) was developed. The Rat Strain Ontology (RS) reflects the breeding history, parental background, and genetic manipulation of rat strains. This controlled vocabulary organizes strains by type: inbred, outbred, chromosome altered, congenic, mutant and so on. In addition, under the chromosome altered category, strains are organized by chromosome, and further by type of manipulations, such as mutant or congenic. This allows users to easily retrieve strains of interest with modifications in specific genomic regions. The ontology was developed using the Open Biological and Biomedical Ontology (OBO) file format, and is organized on the Directed Acyclic Graph (DAG) structure. Rat Strain Ontology IDs are included as part of the strain report (RS: ######). As rat researchers are often unaware of the number of substrains or altered strains within a breeding line, this vocabulary now provides an easy way to retrieve all substrains and accompanying information. Its usefulness is particularly evident in tools such as the PhenoMiner at RGD, where users can now easily retrieve phenotype measurement data for related strains, strains with similar backgrounds or those with similar introgressed regions. This

  6. Biological assay of attenuated strain NADL-2 and virulent strain NADL-8 of porcine parvovirus.

    Science.gov (United States)

    Mengeling, W L; Pejsak, Z; Paul, P S

    1984-11-01

    Attenuated strain NADL-2 and virulent strain NADL-8 of porcine parvovirus (PPV) were titrated in vivo and in vitro under similar conditions to provide a better understanding of some of the factors involved in virulence of PPV in causing maternal reproductive failure of swine. Both strains cause fetal death when they are injected directly into fetal fluids, but only strain NADL-8 does so when administered to pregnant swine. The strains were tested for their hemagglutinating activity (HA), median cell culture infective dose (CCID50), median fetal infective dose (FID50), and median fetal lethal dose (FLD50). The FID50 and FLD50 were determined by injecting virus directly into the amniotic fluid of fetuses in utero at 44 +/- 2 days of gestation and collecting the fetuses 15 +/- 1 days later. Both strains had an HA titer of 64, suggesting that there is a similar number of virions in stock preparations. However, other measurements differed markedly. The CCID50, FID50, and FLD50 were 10(5.5), 10(3.5), and 10(0.5), respectively, for strain NADL-2, and 10(4.5), 10(7.7), and 10(6.3), respectively, for strain NADL-8. Collectively, the values indicate that more than 10,000 times as much strain NADL-2 would need to reach the conceptus transplacentally to establish infection. These observations may help to explain the different consequences of oronasal exposure of pregnant swine to these strains of PPV.

  7. Solitary waves in morphogenesis: Determination fronts as strain-cued strain transformations among automatous cells

    Science.gov (United States)

    Cox, Brian N.; Landis, Chad M.

    2018-02-01

    We present a simple theory of a strain pulse propagating as a solitary wave through a continuous two-dimensional population of cells. A critical strain is assumed to trigger a strain transformation, while, simultaneously, cells move as automata to tend to restore a preferred cell density. We consider systems in which the strain transformation is a shape change, a burst of proliferation, or the commencement of growth (which changes the shape of the population sheet), and demonstrate isomorphism among these cases. Numerical and analytical solutions describe a strain pulse whose height does not depend on how the strain disturbance was first launched, or the rate at which the strain transformation is achieved, or the rate constant in the rule for the restorative cell motion. The strain pulse is therefore very stable, surviving the imposition of strong perturbations: it would serve well as a timing signal in development. The automatous wave formulation is simple, with few model parameters. A strong case exists for the presence of a strain pulse during amelogenesis. Quantitative analysis reveals a simple relationship between the velocity of the leading edge of the pulse in amelogenesis and the known speed of migration of ameloblast cells. This result and energy arguments support the depiction of wave motion as an automatous cell response to strain, rather than as a response to an elastic energy gradient. The theory may also contribute to understanding the determination front in somitogenesis, moving fronts of convergent-extension transformation, and mitotic wavefronts in the syncytial drosophila embryo.

  8. Five challenges in modelling interacting strain dynamics

    Directory of Open Access Journals (Sweden)

    Paul S. Wikramaratna

    2015-03-01

    Full Text Available Population epidemiological models where hosts can be infected sequentially by different strains have the potential to help us understand many important diseases. Researchers have in recent years started to develop and use such models, but the extra layer of complexity from multiple strains brings with it many technical challenges. It is therefore hard to build models which have realistic assumptions yet are tractable. Here we outline some of the main challenges in this area. First we begin with the fundamental question of how to translate from complex small-scale dynamics within a host to useful population models. Next we consider the nature of so-called “strain space”. We describe two key types of host heterogeneities, and explain how models could help generate a better understanding of their effects. Finally, for diseases with many strains, we consider the challenge of modelling how immunity accumulates over multiple exposures.

  9. (HN1) strain of Aspergillus niger

    African Journals Online (AJOL)

    login123

    2016-09-26

    Sep 26, 2016 ... olive oil) increased the production of lipase up to 20% in case of both the strains. The production of ... insoluble triacylglycerols to generate free fatty acids, mono and ... Two fermentation processes, including solid state.

  10. Mumps vaccine virus strains and aseptic meningitis.

    Science.gov (United States)

    Bonnet, Marie-Claude; Dutta, Anil; Weinberger, Clement; Plotkin, Stanley A

    2006-11-30

    Mumps immunization can easily be included in national schedules, particularly if combined with measles or measles and rubella vaccines, but debate continues concerning the relative safety of various licensed mumps vaccine strains. The opportunities for control of mumps are also being affected by differences in the cost of the vaccines prepared with different strains of mumps virus. The present report evaluates available data on the association of the Urabe and other strains of mumps vaccine with the occurrence of aseptic meningitis. We also review the comparative immunogenicity and efficacies of the most widely used mumps vaccines in controlled clinical trials and field evaluations, and briefly examine relative cost as it relates to the implementation of national immunization programs. We conclude that extensive experience with the most widely used mumps vaccine strains in many countries has shown that the risk-benefit ratio of live mumps vaccines is highly favourable for vaccination, despite the occasional occurence of aseptic meningitis.

  11. Characterization of 3 Strains of Yersinia Pestis

    National Research Council Canada - National Science Library

    Kournikakis, B

    2000-01-01

    .... Antibiotic sensitivities showed that the 3 strains were sensitive to aminoglycosides, the cephalosporins/ cephams, most of the beta lactams/penicillins (e.g. ampicillin) and quinolones (e.g. ciprofloxacin...

  12. Flexoelectricity: strain gradient effects in ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Ma Wenhui [Department of Physics, Shantou Unversity, Shantou, Guangdong 515063 (China)

    2007-12-15

    Mechanical strain gradient induced polarization effect or flexoelectricity in perovskite-type ferroelectric and relaxor ferroelectric ceramics was investigated. The flexoelectric coefficients measured at room temperature ranged from about 1 {mu} C m{sup -1} for lead zirconate titanate to 100 {mu} C m{sup -1} for barium strontium titanate. Flexoelectric effects were discovered to be sensitive to chemical makeup, phase symmetry, and domain structures. Based on phenomenological discussion and experimental data on flexoelectricity, the present study proposed that mechanical strain gradient field could influence polarization responses in a way analogous to electric field. Flexoelectric coefficients were found to be nonlinearly enhanced by dielectric permittivity and strain gradient. Interfacial mismatch in epitaxial thin films can give rise to high strain gradients, enabling flexoelectric effects to make a significant impact in properly engineered ferroelectric heterostructure systems.

  13. Review of strain buckling: analysis methods

    International Nuclear Information System (INIS)

    Moulin, D.

    1987-01-01

    This report represents an attempt to review the mechanical analysis methods reported in the literature to account for the specific behaviour that we call buckling under strain. In this report, this expression covers all buckling mechanisms in which the strains imposed play a role, whether they act alone (as in simple buckling under controlled strain), or whether they act with other loadings (primary loading, such as pressure, for example). Attention is focused on the practical problems relevant to LMFBR reactors. The components concerned are distinguished by their high slenderness ratios and by rather high thermal levels, both constant and variable with time. Conventional static buckling analysis methods are not always appropriate for the consideration of buckling under strain. New methods must therefore be developed in certain cases. It is also hoped that this review will facilitate the coding of these analytical methods to aid the constructor in his design task and to identify the areas which merit further investigation

  14. Systems strategies for developing industrial microbial strains

    DEFF Research Database (Denmark)

    Lee, Sang Yup; Kim, Hyun Uk

    2015-01-01

    Industrial strain development requires system-wide engineering and optimization of cellular metabolism while considering industrially relevant fermentation and recovery processes. It can be conceptualized as several strategies, which may be implemented in an iterative fashion and in different...

  15. Characterization of 21 Strains of Bacillus Anthracis

    National Research Council Canada - National Science Library

    Kournikakis, B

    2000-01-01

    Twenty-one strains of Bacillus anthracis currently held in the culture collection at DRES were characterized by colonial morphology, antibiotic sensitivity and BiologTM metabolic identification profiles...

  16. Phenotypic variability among strains of Pasteurella multocida ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-05-02

    May 2, 2008 ... Available online at http://www.academicjournals.org/AJB. ISSN 1684–5315 ... extended phenotypic characterization methods supported by DNA ... septicaemia African (Obudu) strain (E:2) which are currently employed as ...

  17. Job strain and the risk of stroke

    DEFF Research Database (Denmark)

    Fransson, Eleonor I; Nyberg, Solja T; Heikkilä, Katriina

    2015-01-01

    BACKGROUND AND PURPOSE: Psychosocial stress at work has been proposed to be a risk factor for cardiovascular disease. However, its role as a risk factor for stroke is uncertain. METHODS: We conducted an individual-participant-data meta-analysis of 196 380 males and females from 14 European cohort...... studies to investigate the association between job strain, a measure of work-related stress, and incident stroke. RESULTS: In 1.8 million person-years at risk (mean follow-up 9.2 years), 2023 first-time stroke events were recorded. The age- and sex-adjusted hazard ratio for job strain relative to no job....... CONCLUSION: Job strain may be associated with an increased risk of ischemic stroke, but further research is needed to determine whether interventions targeting job strain would reduce stroke risk beyond existing preventive strategies....

  18. The radiographic observation of the cervical strain

    International Nuclear Information System (INIS)

    Rhee, Chung Sik

    1972-01-01

    A total of 100 cases of cervical disorders were analysed of clinical signs and symptoms. The cervical strain is proved by the loss of normal lordotic curvature of the cervical spinal column on the lateral x-ray film in Ewha University Hospital from January, 1970 to december 1971 with the following results. 1. The 53 cervical strain was diagnosed in radiographic study for its abnormal locations. The hyperextension with abnormal curve is twice more after than hyperflection type. 2. The most frequent location of the cervical strain is demonstrated in the 4-6 th cervical spinal bodies (80%). 3. Most pronounced symptoms of cervical strain are local tenderness (40%), limitation of motion (17%) and radiating pain (15%). 4. The ratio of the sex incidence of male female was 3:2

  19. The radiographic observation of the cervical strain

    Energy Technology Data Exchange (ETDEWEB)

    Rhee, Chung Sik [Ewha Womans University College of Medicine, Seoul (Korea, Republic of)

    1972-12-15

    A total of 100 cases of cervical disorders were analysed of clinical signs and symptoms. The cervical strain is proved by the loss of normal lordotic curvature of the cervical spinal column on the lateral x-ray film in Ewha University Hospital from January, 1970 to december 1971 with the following results. 1. The 53 cervical strain was diagnosed in radiographic study for its abnormal locations. The hyperextension with abnormal curve is twice more after than hyperflection type. 2. The most frequent location of the cervical strain is demonstrated in the 4-6 th cervical spinal bodies (80%). 3. Most pronounced symptoms of cervical strain are local tenderness (40%), limitation of motion (17%) and radiating pain (15%). 4. The ratio of the sex incidence of male female was 3:2.

  20. A strain gradient plasticity theory with application to wire torsion

    KAUST Repository

    Liu, J. X.; El Sayed, Tamer S.

    2014-01-01

    Based on the framework of the existing strain gradient plasticity theories, we have examined three kinds of relations for the plastic strain dependence of the material intrinsic length scale, and thus developed updated strain gradient plasticity

  1. MM98.57 Quantification of Combined Strain Paths

    DEFF Research Database (Denmark)

    Nielsen, Morten Sturgård; Wanheim, Tarras

    1998-01-01

    this curve into useful scalar relations from experimental data.The strain history for plane strain when assuming volume constancy may be plotted in a shear strain, normal strain diagram, which has the property of showing both the rotation of principal deformation axes during the deformation and the amount...... is to describe the total strain history as a curve in the 6-dimensional shear strain, normal strain space. In order to be able to use these experimental data for calculation, the development of this strain curve must be transformed into a set of scalar relations that may be used for predicting the yield surface...... at a given point in a new strain history. A simple example of this concept is to take the length of the strain curve as describing scalar relation: E.g. to use the equivalent strain as parameter for describing the yield stress. This paper focuses on the strain curve concept and the possibilities to convert...

  2. On generalization uniaxial stress-strain relation

    International Nuclear Information System (INIS)

    Sahay, C.; Dubey, R.N.

    1980-01-01

    Different forms of constitutive relations have been advanced for elastic, plastic and elastic-plastic behaviour of materials. It is shown that the various forms of the stress-strain relationship are specialized forms of generalization of a single stress-strain relation. For example, it is shown how the laws of elastic deformation, and the incremental and total deformation relationship for plastic behaviour are derivable from the Ramberg-Osgood relation. (orig.)

  3. Survival and activity of individual bioaugmentation strains

    DEFF Research Database (Denmark)

    Dueholm, Morten Simonsen; G. Marquesa, Irina; Karst, Søren Michael

    2015-01-01

    Successful application of bioaugmentation for enhanced degradation of environmental pollutants is often limited by the lack of methods to monitor the survival and activity of individual bioaugmentation strains. However, recent advancements in sequencing technologies and molecular techniques now...... allow us to address these limitations. Here a complementing set of general applicable molecular methods are presented that provides detailed information on the performance of individual bioaugmentation strains under in situ conditions. The approach involves genome sequencing to establish highly specific...

  4. Strain limit criteria to predict failure

    International Nuclear Information System (INIS)

    Flanders, H.E.

    1995-01-01

    In recent years extensive effort has been expended to qualify existing structures for conditions that are beyond the original design basis. Determination of the component failure load is useful for this type of evaluation. This paper presents criteria based upon strain limits to predict the load at failure. The failure modes addressed are excessive plastic deformations, localized plastic strains, and structural instability. The effects of analytical method sophistication, as built configurations, material properties degradation, and stress state are addressed by the criteria

  5. Deformation strain inhomogeneity in columnar grain nickel

    DEFF Research Database (Denmark)

    Wu, G.L.; Godfrey, A.; Juul Jensen, D.

    2005-01-01

    A method is presented for determination of the local deformation strain of individual grains in the bulk of a columnar grain sample. The method, based on measurement of the change in grain area of each grain, is applied to 12% cold rolled nickel. Large variations are observed in the local strain...... associated with each grain. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved....

  6. Antimicrobial properties of indigenous Lactobacillus sakei strain

    OpenAIRE

    Vesković-Moračanin Slavica; Obradović D.; Velebit B.; Borović Branka; Škrinjar Marija; Turubatović L.

    2010-01-01

    The strain I 154 of Lactobacillus sakei has been isolated from traditionally fermented sausages in the course of the realization of the international project (INCO PROJECT No ICA4-CT-2002-10037). This strain exhibited the ability for bacteriocin production. Antimicrobial properties of the isolated bacteriocin (sakacine), its sensibility towards proteolytic enzymes, as well as the effect of increased to high temperatures on its stability have been examined in this work. Semi purified bacterioc...

  7. A closer look at prion strains

    Science.gov (United States)

    Solforosi, Laura; Milani, Michela; Mancini, Nicasio; Clementi, Massimo; Burioni, Roberto

    2013-01-01

    Prions are infectious proteins that are responsible for transmissible spongiform encephalopathies (TSEs) and consist primarily of scrapie prion protein (PrPSc), a pathogenic isoform of the host-encoded cellular prion protein (PrPC). The absence of nucleic acids as essential components of the infectious prions is the most striking feature associated to these diseases. Additionally, different prion strains have been isolated from animal diseases despite the lack of DNA or RNA molecules. Mounting evidence suggests that prion-strain-specific features segregate with different PrPSc conformational and aggregation states. Strains are of practical relevance in prion diseases as they can drastically differ in many aspects, such as incubation period, PrPSc biochemical profile (e.g., electrophoretic mobility and glycoform ratio) and distribution of brain lesions. Importantly, such different features are maintained after inoculation of a prion strain into genetically identical hosts and are relatively stable across serial passages. This review focuses on the characterization of prion strains and on the wide range of important implications that the study of prion strains involves. PMID:23357828

  8. Instrument for measuring fuel cladding strain

    International Nuclear Information System (INIS)

    Billeter, T.R.

    1976-01-01

    Development work to provide instrumentation for the continuous measurement of strain of material specimens such as nuclear fuel cladding has shown that a microwave sensor and associated instrumentation hold promise. The cylindrical sensor body enclosing the specimen results in a coaxial resonator absorbing microwave energy at frequencies dependent upon the diameter of the specimen. Diametral changes of a microinch can be resolved with use of the instrumentation. Very reasonable values of elastic strain were measured at 75 0 F and 1000 0 F for an internally pressurized 20 percent C.W. 316 stainless steel specimen simulating nuclear fuel cladding. The instrument also indicated the creep strain of the same specimen pressurized at 6500 psi and at a temperature of 1000 0 F for a period of 700 hours. Although the indicated strain appears greater than actual, the sensor/specimen unit experienced considerable oxidation even though an inert gas purge persisted throughout the test duration. By monitoring at least two modes of resonance, the measured strain was shown to be nearly independent of sensor temperature. To prevent oxidation, a second test was performed in which the specimen/sensor units were contained in an evacuated enclosure. The strain of the two prepressurized specimens as indicated by the microwave instrumentation agreed very closely with pre- and post-test measurements obtained with use of a laser interferometer

  9. Strain-controlled electrocatalysis on multimetallic nanomaterials

    Science.gov (United States)

    Luo, Mingchuan; Guo, Shaojun

    2017-11-01

    Electrocatalysis is crucial for the development of clean and renewable energy technologies, which may reduce our reliance on fossil fuels. Multimetallic nanomaterials serve as state-of-the-art electrocatalysts as a consequence of their unique physico-chemical properties. One method of enhancing the electrocatalytic performance of multimetallic nanomaterials is to tune or control the surface strain of the nanomaterials, and tremendous progress has been made in this area in the past decade. In this Review, we summarize advances in the introduction, tuning and quantification of strain in multimetallic nanocrystals to achieve more efficient energy conversion by electrocatalysis. First, we introduce the concept of strain and its correlation with other key physico-chemical properties. Then, using the electrocatalytic reduction of oxygen as a model reaction, we discuss the underlying mechanisms behind the strain-adsorption-reactivity relationship based on combined classical theories and models. We describe how this knowledge can be harnessed to design multimetallic nanocrystals with optimized strain to increase the efficiency of oxygen reduction. In particular, we highlight the unexpectedly beneficial (and previously overlooked) role of tensile strain from multimetallic nanocrystals in improving electrocatalysis. We conclude by outlining the challenges and offering our perspectives on the research directions in this burgeoning field.

  10. Strain rate measurement by Electronic Speckle Pattern Interferometry: A new look at the strain localization onset

    International Nuclear Information System (INIS)

    Guelorget, Bruno; Francois, Manuel; Vial-Edwards, Cristian; Montay, Guillaume; Daniel, Laurent; Lu, Jian

    2006-01-01

    In-plane Electronic Speckle Pattern Interferometry has been successfully used during tensile testing of semi-hard copper sheets in order to measure the strain rate. On one hand, heterogeneity in strain rate field has been found before the maximum of the tensile force (ε t ≅ 19.4 and 25.4%, respectively). Thus, a localization phenomenon occurs before the classic Considere's criterion (dF = 0) for the diffuse neck initiation. On the other hand, strain rate measurement before fracture shows the moment where one of the two slip band systems becomes predominant, then strain concentrates in a small area, the shear band. Uncertainty evaluation has been carried out, which shows a very good accuracy of the total strain and the strain rate measurements

  11. Strain rate measurement by Electronic Speckle Pattern Interferometry: A new look at the strain localization onset

    Energy Technology Data Exchange (ETDEWEB)

    Guelorget, Bruno [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)]. E-mail: bruno.guelorget@utt.fr; Francois, Manuel [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Vial-Edwards, Cristian [Departemento de Ingenieria Mecanica y Metalurgica, Pontificia Universidad Catolica de Chile, Vicuna Mackenna 4860, 6904411 Santiago (Chile); Montay, Guillaume [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Daniel, Laurent [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Lu, Jian [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)

    2006-01-15

    In-plane Electronic Speckle Pattern Interferometry has been successfully used during tensile testing of semi-hard copper sheets in order to measure the strain rate. On one hand, heterogeneity in strain rate field has been found before the maximum of the tensile force ({epsilon} {sup t} {approx_equal} 19.4 and 25.4%, respectively). Thus, a localization phenomenon occurs before the classic Considere's criterion (dF = 0) for the diffuse neck initiation. On the other hand, strain rate measurement before fracture shows the moment where one of the two slip band systems becomes predominant, then strain concentrates in a small area, the shear band. Uncertainty evaluation has been carried out, which shows a very good accuracy of the total strain and the strain rate measurements.

  12. Molecular typing of Brucella melitensis endemic strains and differentiation from the vaccine strain Rev-1.

    Science.gov (United States)

    Noutsios, Georgios T; Papi, Rigini M; Ekateriniadou, Loukia V; Minas, Anastasios; Kyriakidis, Dimitrios A

    2012-03-01

    In the present study forty-four Greek endemic strains of Br. melitensis and three reference strains were genotyped by Multi locus Variable Number Tandem Repeat (ML-VNTR) analysis based on an eight-base pair tandem repeat sequence that was revealed in eight loci of Br. melitensis genome. The forty-four strains were discriminated from the vaccine strain Rev-1 by Restriction Fragment Length Polymorphism (RFLP) and Denaturant Gradient Gel Electrophoresis (DGGE). The ML-VNTR analysis revealed that endemic, reference and vaccine strains are genetically closely related, while most of the loci tested (1, 2, 4, 5 and 7) are highly polymorphic with Hunter-Gaston Genetic Diversity Index (HGDI) values in the range of 0.939 to 0.775. Analysis of ML-VNTRs loci stability through in vitro passages proved that loci 1 and 5 are non stable. Therefore, vaccine strain can be discriminated from endemic strains by allele's clusters of loci 2, 4, 6 and 7. RFLP and DGGE were also employed to analyse omp2 gene and reveled different patterns among Rev-1 and endemic strains. In RFLP, Rev-1 revealed three fragments (282, 238 and 44 bp), while endemic strains two fragments (238 and 44 bp). As for DGGE, the electrophoretic mobility of Rev-1 is different from the endemic strains due to heterologous binding of DNA chains of omp2a and omp2b gene. Overall, our data show clearly that it is feasible to genotype endemic strains of Br. melitensis and differentiate them from vaccine strain Rev-1 with ML-VNTR, RFLP and DGGE techniques. These tools can be used for conventional investigations in brucellosis outbreaks.

  13. Strain-dependent diffusion behavior of H within tungsten

    International Nuclear Information System (INIS)

    Ding, Wenyi; He, Haiyan; Liu, Changsong; Ding, Rui; Chen, Junling; Pan, Bicai

    2014-01-01

    The diffusion behaviors of H in tungsten, a promising material serving as the first wall facing the plasma in nuclear reactors, under either biaxial strain or isotropic strain are theoretically studied. We find that under the isotropic strain, an individual H atom may diffuse along all pathways, and under the biaxial strain, it preferably migrates along the direction perpendicular to the loaded strain. Moreover, in the case of either the isotropic or the biaxial strain, the loaded compressive strain weakens the diffusion of H, while the loaded tensile strain enhances the diffusion of H in bulk W.

  14. Strain-dependent diffusion behavior of H within tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Wenyi; He, Haiyan [Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Liu, Changsong [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P.O. Box 1129, Hefei 230031 (China); Ding, Rui; Chen, Junling [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Pan, Bicai, E-mail: bcpan@ustc.edu.cn [Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Hefei National Laboratory for Physical Science at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2014-06-15

    The diffusion behaviors of H in tungsten, a promising material serving as the first wall facing the plasma in nuclear reactors, under either biaxial strain or isotropic strain are theoretically studied. We find that under the isotropic strain, an individual H atom may diffuse along all pathways, and under the biaxial strain, it preferably migrates along the direction perpendicular to the loaded strain. Moreover, in the case of either the isotropic or the biaxial strain, the loaded compressive strain weakens the diffusion of H, while the loaded tensile strain enhances the diffusion of H in bulk W.

  15. Information about the Current Strain of Clostridium difficile

    Science.gov (United States)

    ... fluoroquinolones may provide the new strain with an advantage over susceptible strains to spread within healthcare facilities where these antibiotics are commonly used. Top of page What should ...

  16. Effects of strain on the Schwinger pair creation in graphene

    International Nuclear Information System (INIS)

    Fanbanrai, P.; Hutem, A.; Boonchui, S.

    2015-01-01

    The effects of strain on mechanically deformed graphene are determined by looking at how the strain affects the amplitude of the Schwinger two particle pair state. The influences of the lattice distortions, such as isotropic tensile strain ϵ is , shear strain ϵ ss , uniaxial armchair strain ϵ as , and zigzag strain ϵ zs , on the photon emission spectrum have been analyzed. We find that the intensities of the emission increases or decreases when compared to those of the unstrained graphene, depending on the type of strain applied. Thus the structure of energy band, the frequencies of the photons and the emission spectrum can be controlled by use of the different strains

  17. Intramyocardial strain estimation from cardiac cine MRI.

    Science.gov (United States)

    Elnakib, Ahmed; Beache, Garth M; Gimel'farb, Georgy; El-Baz, Ayman

    2015-08-01

    Functional strain is one of the important clinical indicators for the quantification of heart performance and the early detection of cardiovascular diseases, and functional strain parameters are used to aid therapeutic decisions and follow-up evaluations after cardiac surgery. A comprehensive framework for deriving functional strain parameters at the endocardium, epicardium, and mid-wall of the left ventricle (LV) from conventional cine MRI data was developed and tested. Cine data were collected using short TR-/TE-balanced steady-state free precession acquisitions on a 1.5T Siemens Espree scanner. The LV wall borders are segmented using a level set-based deformable model guided by a stochastic force derived from a second-order Markov-Gibbs random field model that accounts for the object shape and appearance features. Then, the mid-wall of the segmented LV is determined based on estimating the centerline between the endocardium and epicardium of the LV. Finally, a geometrical Laplace-based method is proposed to track corresponding points on successive myocardial contours throughout the cardiac cycle in order to characterize the strain evolutions. The method was tested using simulated phantom images with predefined point locations of the LV wall throughout the cardiac cycle. The method was tested on 30 in vivo datasets to evaluate the feasibility of the proposed framework to index functional strain parameters. The cine MRI-based model agreed with the ground truth for functional metrics to within 0.30 % for indexing the peak systolic strain change and 0.29 % (per unit time) for indexing systolic and diastolic strain rates. The method was feasible for in vivo extraction of functional strain parameters. Strain indexes of the endocardium, mid-wall, and epicardium can be derived from routine cine images using automated techniques, thereby improving the utility of cine MRI data for characterization of myocardial function. Unlike traditional texture-based tracking, the

  18. Effects of the Strain Rate Sensitivity and Strain Hardening on the Saturated Impulse of Plates

    Directory of Open Access Journals (Sweden)

    Ling Zhu

    Full Text Available Abstract This paper studies the stiffening effects of the material strain rate sensitivity and strain hardening on the saturated impulse of elastic, perfectly plastic plates. Finite element (FE code ABAQUS is employed to simulate the elastoplastic response of square plates under rectangular pressure pulse. Rigid-plastic analyses for saturated impulse, which consider strain rate sensitivity and strain hardening, are conducted. Satisfactory agreement between the finite element models (FEM and predictions of the rigid-plastic analysis is obtained, which verifies that the proposed rigid-plastic methods are effective to solve the problem including strain rate sensitivity and strain hardening. The quantitative results for the scale effect of the strain rate sensitivity are given. The results for the stiffening effects suggest that two general stiffening factors n 1 and n 2, which characterizes the strain rate sensitivity and strain hardening effect, respectively can be defined. The saturated displacement is inversely proportional to the stiffening factors (i.e. n 1 and n 2 and saturated impulse is inversely proportional to the square roots of the stiffening factors (i.e. n 1 and n 2. Formulae for displacement and saturated impulse are proposed based on the empirical analysis.

  19. Genome-Wide Transcription Study of Cryptococcus neoformans H99 Clinical Strain versus Environmental Strains.

    Directory of Open Access Journals (Sweden)

    Elaheh Movahed

    Full Text Available The infection of Cryptococcus neoformans is acquired through the inhalation of desiccated yeast cells and basidiospores originated from the environment, particularly from bird's droppings and decaying wood. Three environmental strains of C. neoformans originated from bird droppings (H4, S48B and S68B and C. neoformans reference clinical strain (H99 were used for intranasal infection in C57BL/6 mice. We showed that the H99 strain demonstrated higher virulence compared to H4, S48B and S68B strains. To examine if gene expression contributed to the different degree of virulence among these strains, a genome-wide microarray study was performed to inspect the transcriptomic profiles of all four strains. Our results revealed that out of 7,419 genes (22,257 probes examined, 65 genes were significantly up-or down-regulated in H99 versus H4, S48B and S68B strains. The up-regulated genes in H99 strain include Hydroxymethylglutaryl-CoA synthase (MVA1, Mitochondrial matrix factor 1 (MMF1, Bud-site-selection protein 8 (BUD8, High affinity glucose transporter 3 (SNF3 and Rho GTPase-activating protein 2 (RGA2. Pathway annotation using DAVID bioinformatics resource showed that metal ion binding and sugar transmembrane transporter activity pathways were highly expressed in the H99 strain. We suggest that the genes and pathways identified may possibly play crucial roles in the fungal pathogenesis.

  20. Variation in the strain anisotropy of Zircaloy with temperature and strain

    International Nuclear Information System (INIS)

    Hindle, E.D.; Worswick, D.

    1984-04-01

    Strain anisotropy was investigated at temperatures in the range 293 to 1117K in circular tensile specimens prepared from rolled Zircaloy-2 plate so that their tensile axes were parallel to and transverse to the rolling direction. The strain anisotropy factor for both types of specimen increased markedly in the high alpha phase region above 923K reaching a maximum at circa 1070K. Above this temperature in the alpha-plus-beta phase region the strain anisotropy decreased rapidly as the proportion of beta phase increased and was almost non-existent at 1173K. The strain anisotropy was markedly strain dependent, particularly in the high alpha phase region. The study was extended to Zircaloy-4 pressurized water reactor (PWR) 17 x 17 type fuel rod tubing specimens which were strained under biaxial conditions using cooling conditions which promoted uniform diametral strain over most of their lengths (circa 250 mm). In these circumstances the strain anisotropy is manifest by a reduction in length. Measurement of this change along with that in diameter and wall thickness produced data from which the strain anisotropy factor was calculated. The results, although influenced by additional factors discussed in the paper, were similar to those observed in the uniaxial Zircaloy-2 tensile tests. (author)

  1. An ultrasensitive strain sensor with a wide strain range based on graphene armour scales.

    Science.gov (United States)

    Yang, Yi-Fan; Tao, Lu-Qi; Pang, Yu; Tian, He; Ju, Zhen-Yi; Wu, Xiao-Ming; Yang, Yi; Ren, Tian-Ling

    2018-06-12

    An ultrasensitive strain sensor with a wide strain range based on graphene armour scales is demonstrated in this paper. The sensor shows an ultra-high gauge factor (GF, up to 1054) and a wide strain range (ε = 26%), both of which present an advantage compared to most other flexible sensors. Moreover, the sensor is developed by a simple fabrication process. Due to the excellent performance, this strain sensor can meet the demands of subtle, large and complex human motion monitoring, which indicates its tremendous application potential in health monitoring, mechanical control, real-time motion monitoring and so on.

  2. Dynamic strains for earthquake source characterization

    Science.gov (United States)

    Barbour, Andrew J.; Crowell, Brendan W

    2017-01-01

    Strainmeters measure elastodynamic deformation associated with earthquakes over a broad frequency band, with detection characteristics that complement traditional instrumentation, but they are commonly used to study slow transient deformation along active faults and at subduction zones, for example. Here, we analyze dynamic strains at Plate Boundary Observatory (PBO) borehole strainmeters (BSM) associated with 146 local and regional earthquakes from 2004–2014, with magnitudes from M 4.5 to 7.2. We find that peak values in seismic strain can be predicted from a general regression against distance and magnitude, with improvements in accuracy gained by accounting for biases associated with site–station effects and source–path effects, the latter exhibiting the strongest influence on the regression coefficients. To account for the influence of these biases in a general way, we include crustal‐type classifications from the CRUST1.0 global velocity model, which demonstrates that high‐frequency strain data from the PBO BSM network carry information on crustal structure and fault mechanics: earthquakes nucleating offshore on the Blanco fracture zone, for example, generate consistently lower dynamic strains than earthquakes around the Sierra Nevada microplate and in the Salton trough. Finally, we test our dynamic strain prediction equations on the 2011 M 9 Tohoku‐Oki earthquake, specifically continuous strain records derived from triangulation of 137 high‐rate Global Navigation Satellite System Earth Observation Network stations in Japan. Moment magnitudes inferred from these data and the strain model are in agreement when Global Positioning System subnetworks are unaffected by spatial aliasing.

  3. Strain preservation of experimental animals: vitrification of two-cell stage embryos for multiple mouse strains.

    Science.gov (United States)

    Eto, Tomoo; Takahashi, Riichi; Kamisako, Tsutomu

    2015-04-01

    Strain preservation of experimental animals is crucial for experimental reproducibility. Maintaining complete animal strains, however, is costly and there is a risk for genetic mutations as well as complete loss due to disasters or illness. Therefore, the development of effective vitrification techniques for cryopreservation of multiple experimental animal strains is important. We examined whether a vitrification method using cryoprotectant solutions, P10 and PEPeS, is suitable for preservation of multiple inbred and outbred mouse strains. First, we investigated whether our vitrification method using cryoprotectant solutions was suitable for two-cell stage mouse embryos. In vitro development of embryos exposed to the cryoprotectant solutions was similar to that of fresh controls. Further, the survival rate of the vitrified embryos was extremely high (98.1%). Next, we collected and vitrified two-cell stage embryos of 14 mouse strains. The average number of embryos obtained from one female was 7.3-33.3. The survival rate of vitrified embryos ranged from 92.8% to 99.1%, with no significant differences among mouse strains. In vivo development did not differ significantly between fresh controls and vitrified embryos of each strain. For strain preservation using cryopreserved embryos, two offspring for inbred lines and one offspring for outbred lines must be produced from two-cell stage embryos collected from one female. The expected number of surviving fetuses obtained from embryos collected from one female of either the inbred or outbred strains ranged from 2.9 to 19.5. The findings of the present study indicated that this vitrification method is suitable for strain preservation of multiple mouse strains. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  4. Mycobacterium tuberculosis strains exhibit differential and strain-specific molecular signatures in pulmonary epithelial cells.

    Science.gov (United States)

    Mvubu, Nontobeko Eunice; Pillay, Balakrishna; Gamieldien, Junaid; Bishai, William; Pillay, Manormoney

    2016-12-01

    Although pulmonary epithelial cells are integral to innate and adaptive immune responses during Mycobacterium tuberculosis infection, global transcriptomic changes in these cells remain largely unknown. Changes in gene expression induced in pulmonary epithelial cells infected with M. tuberculosis F15/LAM4/KZN, F11, F28, Beijing and Unique genotypes were investigated by RNA sequencing (RNA-Seq). The Illumina HiSeq 2000 platform generated 50 bp reads that were mapped to the human genome (Hg19) using Tophat (2.0.10). Differential gene expression induced by the different strains in infected relative to the uninfected cells was quantified and compared using Cufflinks (2.1.0) and MeV (4.0.9), respectively. Gene expression varied among the strains with the total number of genes as follows: F15/LAM4/KZN (1187), Beijing (1252), F11 (1639), F28 (870), Unique (886) and H37Rv (1179). A subset of 292 genes was commonly induced by all strains, where 52 genes were down-regulated while 240 genes were up-regulated. Differentially expressed genes were compared among the strains and the number of induced strain-specific gene signatures were as follows: F15/LAM4/KZN (138), Beijing (52), F11 (255), F28 (55), Unique (186) and H37Rv (125). Strain-specific molecular gene signatures associated with functional pathways were observed only for the Unique and H37Rv strains while certain biological functions may be associated with other strain signatures. This study demonstrated that strains of M. tuberculosis induce differential gene expression and strain-specific molecular signatures in pulmonary epithelial cells. Specific signatures induced by clinical strains of M. tuberculosis can be further explored for novel host-associated biomarkers and adjunctive immunotherapies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. [Evaluation of modern epizootic activity of natural tularemia foci in Voronezh region using immune-serological and molecular-genetic study of main carriers of the disease].

    Science.gov (United States)

    Meshcheriakova, I S; Trankvilevskiĭ, D V; Kvasov, D A; Mikhaĭlova, T V; Kormilitsina, M I; Demidova, T N; Stepkin, Iu I; Zhukov, V I

    2015-01-01

    Improvement of monitoring and prognosis of epidemic manifestations of natural foci of tularemia on the territory of Voronezh region using immune-serological and molecular-genetic study of main carriers of the disease. 539 small mammals captured during summer period of 2011 in 4 districts of North-Eastern part of Voronezh region were studied. Animal organs were studied by serologic (search for Francisella tularensis antigens) and molecular-biologic (detection of F. tularensis DNA) methods. Tularemia antigen was detected using passive hemagglutination reaction (PHAR) with erythrocytic tularemia immunoglobulin diagnosticum. Real-time polymerase chain reaction (RT-PCR) was applied for detection of tularemia causative agent DNA. Complex study revealed epizootic activity of natural foci of tularemia in the examined territory. F. tularensis antigen and/or DNA were detected in 82 objects (15.2%). Use of RT-PCR allowed to additionally detect samples with relatively low content of F. tularensis DNA substrate, when antigen was not detected in samples. High sensitivity and specificity of the RT-PCR was ensured by inclusion of specific probes (tu14-PR2 and ISFTu2P). The results obtained give evidence on functioning and epizootic activity of natural foci of tularemia in Voronezh region that requires constant monitoring of the territory and prophylaxis measures, first of all vaccination of risk groups by live tularemia vaccine.

  6. Anisotropic nature of radially strained metal tubes

    Science.gov (United States)

    Strickland, Julie N.

    Metal pipes are sometimes swaged by a metal cone to enlarge them, which increases the strain in the material. The amount of strain is important because it affects the burst and collapse strength. Burst strength is the amount of internal pressure that a pipe can withstand before failure, while collapse strength is the amount of external pressure that a pipe can withstand before failure. If the burst or collapse strengths are exceeded, the pipe may fracture, causing critical failure. Such an event could cost the owners and their customers millions of dollars in clean up, repair, and lost time, in addition to the potential environmental damage. Therefore, a reliable way of estimating the burst and collapse strength of strained pipe is desired and valuable. The sponsor currently rates strained pipes using the properties of raw steel, because those properties are easily measured (for example, yield strength). In the past, the engineers assumed that the metal would be work-hardened when swaged, so that yield strength would increase. However, swaging introduces anisotropic strain, which may decrease the yield strength. This study measured the yield strength of strained material in the transverse and axial direction and compared them to raw material, to determine the amount of anisotropy. This information will be used to more accurately determine burst and collapse ratings for strained pipes. More accurate ratings mean safer products, which will minimize risk for the sponsor's customers. Since the strained metal has a higher yield strength than the raw material, using the raw yield strength to calculate burst and collapse ratings is a conservative method. The metal has even higher yield strength after strain aging, which indicates that the stresses are relieved. Even with the 12% anisotropy in the strained and 9% anisotropy in the strain aged specimens, the raw yield strengths are lower and therefore more conservative. I recommend that the sponsor continue using the raw

  7. [A prophylactic program for strain urinary incontinence].

    Science.gov (United States)

    Stadnicka, Grazyna; Iwanowicz-Palus, Grazyna J; Bień, Agnieszka M

    2002-01-01

    The aim of the study was to work out a prophylactic program for strain urinary incontinence. Analysis of literature on the subject and results of own investigations presented in the first part of the paper indicate that the program of prophylaxis of strain urinary incontinence should primarily include: (1) Preparation of the medical staff (nurses, midwives) for propagating health education among women on prevention of strain urinary incontinence. (2) Preparation of adequate educational materials in the form of brochures, leaflets, information posters about symptoms, causes and prophylaxis of urinary incontinence indicating health care institutions available to all women when the disease is suspected or already present. (3) Propagation of problems connected with strain urinary incontinence in the mass media providing information to a wide audience in order to make people realize the significance of this social problem and break stereotypes associated with this disease of "shame". (4) Preparation of sets of exercises for the muscles of the base of the pelvis to be performed during pregnancy, confinement and menopause to maintain their proper function. (5) Indicating factors predisposing to strain urinary incontinence with focus on possibilities of their reduction or elimination.

  8. Probiotic features of Lactobacillus plantarum mutant strains.

    Science.gov (United States)

    Bove, Pasquale; Gallone, Anna; Russo, Pasquale; Capozzi, Vittorio; Albenzio, Marzia; Spano, Giuseppe; Fiocco, Daniela

    2012-10-01

    In this study, the probiotic potential of Lactobacillus plantarum wild-type and derivative mutant strains was investigated. Bacterial survival was evaluated in an in vitro system, simulating the transit along the human oro-gastro-intestinal tract. Interaction with human gut epithelial cells was studied by assessing bacterial adhesive ability to Caco-2 cells and induction of genes involved in innate immunity. L. plantarum strains were resistant to the combined stress at the various steps of the simulated gastrointestinal tract. Major decreases in the viability of L. plantarum cells were observed mainly under drastic acidic conditions (pH ≤ 2.0) of the gastric compartment. Abiotic stresses associated to small intestine poorly affected bacterial viability. All the bacterial strains significantly adhered to Caco-2 cells, with the ΔctsR mutant strain exhibiting the highest adhesion. Induction of immune-related genes resulted higher upon incubation with heat-inactivated bacteria rather than with live ones. For specific genes, a differential transcriptional pattern was observed upon stimulation with different L. plantarum strains, evidencing a possible role of the knocked out bacterial genes in the modulation of host cell response. In particular, cells from Δhsp18.55 and ΔftsH mutants strongly triggered immune defence genes. Our study highlights the relevance of microbial genetic background in host-probiotic interaction and might contribute to identify candidate bacterial genes and molecules involved in probiosis.

  9. Brittle superconducting magnets: an equivilent strain model

    International Nuclear Information System (INIS)

    Barzi, E.; Danuso, M.

    2010-01-01

    To exceed fields of 10 T in accelerator magnets, brittle superconductors like A15 Nb 3 Sn and Nb 3 Al or ceramic High Temperature Superconductors have to be used. For such brittle superconductors it is not their maximum tensile yield stress that limits their structural resistance as much as strain values that provoke deformations in their delicate lattice, which in turn affect their superconducting properties. Work on the sensitivity of Nb 3 Sn cables to strain has been conducted in a number of stress states, including uniaxial and multi-axial, producing usually different results. This has made the need of a constituent design criterion imperative for magnet builders. In conventional structural problems an equivalent stress model is typically used to verify mechanical soundness. In the superconducting community a simple scalar equivalent strain to be used in place of an equivalent stress would be an extremely useful tool. As is well known in fundamental mechanics, there is not one single way to reduce a multiaxial strain state as represented by a 2nd order tensor to a scalar. The conceptual experiment proposed here will help determine the best scalar representation to use in the identification of an equivalent strain model.

  10. Novel distributed strain sensing in polymeric materials

    International Nuclear Information System (INIS)

    Abot, Jandro L; Song, Yi; Medikonda, Sandeep; Rooy, Nathan; Schulz, Mark J

    2010-01-01

    Monitoring the state of strain throughout an entire structure is essential to determine its state of stress, detect potential residual stresses after fabrication, and also to help to establish its integrity. Several sensing technologies are presently available to determine the strain in the surface or inside a structure. Large sensor dimensions, complex signal conditioning equipment, and difficulty in achieving a widely distributed system have however hindered their development into robust structural health monitoring techniques. Recently, carbon nanotube forests were spun into a microscale thread that is electrically conductive, tough, and easily tailorable. The thread was integrated into polymeric materials and used for the first time as a piezoresistive sensor to monitor strain and also to detect damage in the material. It is revealed that the created self-sensing polymeric materials are sensitive to normal strains above 0.07% and that the sensor thread exhibits a perfectly linear delta resistance–strain response above 0.3%. The longitudinal gauge factors were determined to be in the 2–5 range. This low cost and simple built-in sensor thread may provide a new integrated and distributed sensor technology that enables robust real-time health monitoring of structures

  11. Crack initiation under generalized plane strain conditions

    International Nuclear Information System (INIS)

    Shum, D.K.M.; Merkle, J.G.

    1991-01-01

    A method for estimating the decrease in crack-initiation toughness, from a reference plane strain value, due to positive straining along the crack front of a circumferential flaw in a reactor pressure vessel is presented in this study. This method relates crack initiation under generalized plane strain conditions with material failure at points within a distance of a few crack-tip-opening displacements ahead of a crack front, and involves the formulation of a micromechanical crack-initiation model. While this study is intended to address concerns regarding the effects of positive out-of- plane straining on ductile crack initiation, the approach adopted in this work can be extended in a straightforward fashion to examine conditions of macroscopic cleavage crack initiation. Provided single- parameter dominance of near-tip fields exists in the flawed structure, results from this study could be used to examine the appropriateness of applying plane strain fracture toughness to the evaluation of circumferential flaws, in particular to those in ring-forged vessels which have no longitudinal welds. In addition, results from this study could also be applied toward the analysis of the effects of thermal streaming on the fracture resistance of circumferentially oriented flaws in a pressure vessel. 37 refs., 8 figs., 1 tab

  12. Influence of anthropogenic transformation of Danube–Dniester interfluve on natural foci of tularaemia

    Directory of Open Access Journals (Sweden)

    I. T. Rusev

    2011-04-01

    Full Text Available The paper is devoted to the problem of occurrence of bacteria Francisella tularensis in steppe coastal zone of the Black Sea west part in the second half of XX century. The key factor decreasing the activity of tularaemia natural foci is anthropogenic influence. Resumed activity of natural foci appeared after implementation of big irrigation and drainage construction in former USSR – building of the Danube-Dniester-Dnepr irrigation system resulted in forming new environmental conditions as well as corridors for tularaemia distribution. The practical recommendation is to implement the eco-epizootological monitoring and to collect data for developing practical management of the natural foci of disease.

  13. [Natural focus of tularemia on the Kerchen peninsula (Crimea)].

    Science.gov (United States)

    Golkovskiĭ, G M; Mitsevich, G F; Khaĭtovich, A B; Alekseev, E V; Korchevskiĭ, P G

    1981-10-01

    The study confirming the existence of the steppe-type natural focus of tularemia on the Kerch peninsula has been carried out. For the first time the cultures of Francisella tularensis have been isolated. Voles and house mice play the main role in the circulation of the infection. The parasitic system comprises ticks (Ixodidae and Nyalomma), as well as some species of fleas. In carrying out erizootological studies for detecting tularemia in the Crimea the use of low temperature (0 degrees C) for the preservation of specimens and preparations in recommended.

  14. A more flexible lipoprotein sorting pathway.

    Science.gov (United States)

    Chahales, Peter; Thanassi, David G

    2015-05-01

    Lipoprotein biogenesis in Gram-negative bacteria occurs by a conserved pathway, each step of which is considered essential. In contrast to this model, LoVullo and colleagues demonstrate that the N-acyl transferase Lnt is not required in Francisella tularensis or Neisseria gonorrhoeae. This suggests the existence of a more flexible lipoprotein pathway, likely due to a modified Lol transporter complex, and raises the possibility that pathogens may regulate lipoprotein processing to modulate interactions with the host. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  15. Changes in the repertoire of natural antibodies caused by immunization with bacterial antigens

    DEFF Research Database (Denmark)

    Shilova, N V; Navakouski, M J; Huflejt, M

    2011-01-01

    The repertoire of natural anti-glycan antibodies in naïve chickens and in chickens immunized with bacteria Burkholderia mallei, Burkholderia pseudomallei, and Francisella tularensis as well as with peptides from an outer membrane protein of B. pseudomallei was studied. A relatively restricted pat...... pattern of natural antibodies (first of all IgY against bacterial cell wall peptidoglycan fragments, L-Rha, and core N-acetyllactosamine) shrank and, moreover, the level of detectable antibodies decreased as a result of immunization....

  16. Methodology to measure strains at high temperatures using electrical strain gages with free filaments

    International Nuclear Information System (INIS)

    Atanazio Filho, Nelson N.; Gomes, Paulo T. Vida; Scaldaferri, Denis H.B.; Silva, Luiz L. da; Rabello, Emerson G.; Mansur, Tanius R.

    2013-01-01

    An experimental methodology used for strains measuring at high temperatures is show in this work. In order to do the measurements, it was used electric strain gages with loose filaments attached to a stainless steel 304 beam with specific cements. The beam has triangular shape and a constant thickness, so the strain is the same along its length. Unless the beam surface be carefully prepared, the strain gage attachment is not efficient. The showed results are for temperatures ranging from 20 deg C to 300 deg C, but the experimental methodology could be used to measure strains at a temperature up to 900 deg C. Analytical calculations based on solid mechanics were used to verify the strain gage electrical installation and the measured strains. At a first moment, beam deformations as a temperature function were plotted. After that, beam deformations with different weighs were plotted as a temperature function. The results shown allowed concluding that the experimental methodology is trustable to measure strains at temperatures up to 300 deg C. (author)

  17. Thermal strain measurement of EAST W/Cu divertor structure using electric resistance strain gauges

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xingli [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Science Island Branch of Graduate School, University of Science & Technology of China, Hefei, 230031 (China); Wang, Wanjing, E-mail: wjwang@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Wang, Jichao [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Wei, Ran; Sun, Zhaoxuan [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Science Island Branch of Graduate School, University of Science & Technology of China, Hefei, 230031 (China); Li, Qiang; Xie, Chunyi [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Chen, Hong-En; Wang, Kaiqiang; Wu, Lei; Chen, Zhenmao [State Key Lab for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University (China); Luo, Guang-Nan [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Science Island Branch of Graduate School, University of Science & Technology of China, Hefei, 230031 (China); Hefei Center for Physical Science and Technology, Hefei, 230022 (China); Hefei Science Center of Chinese Academy of Sciences, Hefei, 230027 (China)

    2016-12-15

    Highlights: • To understand the service behavior of W/Cu divertor, an electrical resistance strain gauge system had been introduced in a thermal strain measurement experiment. • The measurement system successfully finished the experiment and obtained valued thermal strain data. • Two thermomechanical analyses had also been carried out and compared with the measurement results. • Experiment results corresponded well to simulations and threw a light upon the failure of W/Cu divertor in the previous baking tests. - Abstract: W/Cu divertor has complex structure and faces extreme work environment in EAST Tokamak device. To measure its thermal strain shall be a valued way to understand its service behavior and then optimize its design and manufacturing process. This work presents a preliminary study on measuring thermal strain of EAST W/Cu divertor structure using electric resistance strain gauges. Eight gauges had been used in the experiment and the heating temperature had been set to 230 °C with respect to the work temperature. To realize the measuring experiment, an appropriate fixing method of gauges in divertor narrow spaces had been taken and tested, which could not only withstand high temperature but also had no damage to the divertor sample. The measurement results were that three gauges showed positive strain while other three showed negative strain after having been compensated, which corresponded to tensile stress and compressed stress respectively. Two thermomechanical simulations had also been carried out and used for comparing with the experiment.

  18. Strain histograms are equal to strain ratios in predicting malignancy in breast tumours

    DEFF Research Database (Denmark)

    Carlsen, Jonathan Frederik; Ewertsen, Caroline; Sletting, Susanne

    2017-01-01

    Objectives: To assess whether strain histograms are equal to strain ratios in predicting breast tumour malignancy and to see if either could be used to upgrade Breast Imaging Reporting and Data System (BI-RADS) 3 tumours for immediate biopsy. Methods: Ninety-nine breast tumours were examined using...

  19. Validation of perceptual strain index to evaluate the thermal strain in experimental hot conditions

    Directory of Open Access Journals (Sweden)

    Habibollah Dehghan

    2015-01-01

    Conclusions: The research findings showed when there is no access to other forms of methods to evaluate the heat stress, it can be used the PeSI in evaluating the strain because of its favorable correlation with the thermal strain.

  20. Mechanical properties of biaxially strained poly(L-lactide) tubes: Strain rate and temperature dependence

    DEFF Research Database (Denmark)

    Løvdal, Alexandra Liv Vest; Andreasen, Jens Wenzel; Mikkelsen, Lars Pilgaard

    2017-01-01

    Poly(l-lactide) (PLLA) is a bioabsorbable polymer with high stiffness and strength compared to the other commercially available bioabsorbable polymers. The properties of PLLA can be improved by straining, causing deformation-mediated molecular orientation. PLLA tubes were biaxially strained above...

  1. Residual strains in girth-welded linepipe

    International Nuclear Information System (INIS)

    MacEwen, S.R.; Holden, T.M.; Powell, B.M.; Lazor, R.B.

    1987-07-01

    High resolution neutron diffraction has been used to measure the axial residual strains in and adjacent to a multipass girth weld in a complete section of 914 mm (36 inches) diameter, 16 mm (5/8 inch) wall, linepipe. The experiments were carried out at the NRU reactor, Chalk River using the L3 triple-axis spectrometer. The through-wall distribution of axial residual strain was measured at 0, 4, 8, 20 and 50 mm from the weld centerline; the axial variation was determined 1, 5, 8, and 13 mm from the inside surface of the pipe wall. The results have been compared with strain gauge measurements on the weld surface and with through-wall residual stress distributions determined using the block-layering and removal technique

  2. High Strain Rate Characterisation of Composite Materials

    DEFF Research Database (Denmark)

    Eriksen, Rasmus Normann Wilken

    -reinforced polymers, were considered, and it was first shown that the loading history controls equilibrium process. Then the High-speed servo-hydraulic test machine was analysed in terms its ability to create a state of constant strain rate in the specimen. The invertible inertial forces in the load train prevented...... from designing and constructing a high-speed servo-hydraulic test machine and by performing a comprehensive test series. The difficulties encountered in the test work could be addressed with the developed analysis. The conclusion was that the High-speed servo-hydraulic test machine is less suited...... for testing fibre-reinforced polymers due to their elastic behaviour and low strain to failure. This is problematic as the High-speed servo-hydraulic test machine closes the gap between quasi-static tests rates and lower strain rates, which are achievable with the Split Hopkinson Pressure Bar. The Split...

  3. Developments of borehole strain observation outside China

    Institute of Scientific and Technical Information of China (English)

    邱泽华; 石耀霖

    2004-01-01

    Borehole strain observation is playing an increasingly important role in the study on the crustal movements. It hasbeen used by many countries such as China, USA, Japan, Peru, Australia, South Africa, Iceland and Italy, in research fields of plate tectonics, earthquake, volcanic eruption, dam safety, oil field subsidence, mining collapse andso on. Borehole strainmeter has been improved rapidly and tends to get more and more components included inone probe. Based on observations by this kind of instruments, studies on seismic strain step, slow earthquake,earthquake precursor and volcanic eruption forecasting have made remarkable achievements. In the coming years,borehole strain observation is going to become one major geodetic means, together with GPS and InSAR.

  4. The asymptomatic bacteriuria Escherichia coli strain 83972 outcompetes uropathogenic E. coli strains in human urine

    DEFF Research Database (Denmark)

    Hancock, Viktoria; Ulett, G.C.; Schembri, M.A.

    2006-01-01

    Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU). In contrast to uropathogenic E. coli (UPEC), which causes symptomatic urinary tract infections (UTI), very little is known about the mechanisms by which these strains colonize the human urinary tract....... The prototype ABU E. coli strain 83972 was originally isolated from a girl who had carried it asymptomatically for 3 years. Deliberate colonization of UTI-susceptible individuals with E. coli 83972 has been used successfully as an alternative approach for the treatment of patients who are refractory...... to conventional therapy. Colonization with strain 83972 appears to prevent infection with UPEC strains in such patients despite the fact that this strain is unable to express the primary adhesins involved in UTI, viz. P and type 1 fimbriae. Here we investigated the growth characteristics of E. coli 83972 in human...

  5. Evaluating location specific strain rates, temperatures, and accumulated strains in friction welds through microstructure modeling

    Directory of Open Access Journals (Sweden)

    Javed Akram

    2018-04-01

    Full Text Available A microstructural simulation method is adopted to predict the location specific strain rates, temperatures, grain evolution, and accumulated strains in the Inconel 718 friction welds. Cellular automata based 2D microstructure model was developed for Inconel 718 alloy using theoretical aspects of dynamic recrystallization. Flow curves were simulated and compared with experimental results using hot deformation parameter obtained from literature work. Using validated model, simulations were performed for friction welds of Inconel 718 alloy generated at three rotational speed i.e., 1200, 1500, and 1500 RPM. Results showed the increase in strain rates with increasing rotational speed. These simulated strain rates were found to match with the analytical results. Temperature difference of 150 K was noticed from center to edge of the weld. At all the rotational speeds, the temperature was identical implying steady state temperature (0.89Tm attainment. Keywords: Microstructure modeling, Dynamic recrystallization, Friction welding, Inconel 718, EBSD, Hot deformation, Strain map

  6. A new strain gage method for measuring the contractile strain ratio of Zircaloy tubing

    International Nuclear Information System (INIS)

    Hwang, S.K.; Sabol, G.P.

    1988-01-01

    An improved strain gage method for determining the contractile strain ratio (CSR) of Zircaloy tubing was developed. The new method consists of a number of load-unload cyclings at approximately 0.2% plastic strain interval. With this method the CSR of Zircaloy-4 tubing could be determined accurately because it was possible to separate the plastic strains from the elastic strain involvement. The CSR values determined by use of the new method were in good agreement with those calculated from conventional post-test manual measurements. The CSR of the tubing was found to decrease with the amount of deformation during testing because of uneven plastic flow in the gage section. A new technique of inscribing gage marks by use of a YAG laser is discussed. (orig.)

  7. Segregation of genes from donor strain during the production of recombinant congenic strains.

    Science.gov (United States)

    van Zutphen, L F; Den Bieman, M; Lankhorst, A; Demant, P

    1991-07-01

    Recombinant congenic strains (RCS) constitute a set of inbred strains which are designed to dissect the genetic control of multigenic traits, such as tumour susceptibility or disease resistance. Each RCS contains a small fraction of the genome of a common donor strain, while the majority of genes stem from a common background strain. We tested at two stages of the inbreeding process in 20 RCS, derived from BALB/cHeA and STS/A, to see whether alleles from the STS/A donor strain are distributed over the RCS in a ratio as would theoretically be expected. Four marker genes (Pep-3; Pgm-1; Gpi-1 and Es-3) located at 4 different chromosomes were selected and the allelic distribution was tested after 3-4 and after 12 generations of inbreeding. The data obtained do not significantly deviate from the expected pattern, thus supporting the validity of the concept of RCS.

  8. Pheromonal divergence between two strains of Spodoptera frugiperda

    NARCIS (Netherlands)

    Unbehend, M.; Hänniger, S.; Meagher, R.L.; Heckel, D.G.; Groot, A.T.

    2013-01-01

    Spodoptera frugiperda consists of two genetically and behaviorally different strains, the corn- and the rice-strain, which seem to be in the process of sympatric speciation. We investigated the role of strain-specific sexual communication as a prezygotic mating barrier between both strains by

  9. Comparative developmental trajectory of four strains of chicken ...

    African Journals Online (AJOL)

    This study evaluated egg traits, embryonic growth, and early growth rate in four strains of chicken. A total of 1200 hatching eggs, 300 each from four strains of chicken were used for this study. The strains included Nigerian indigenous chicken (NIC), Arbor acre, Hubbard, and Marshall broiler strains. Embryonic weights, yolk ...

  10. ANISOTROPIC STRAIN-HARDENING IN POLYCRYSTALLINE COPPER AND ALUMINUM

    NARCIS (Netherlands)

    HESS, F

    1993-01-01

    A new viscoplastic model for the plastic stress-strain behaviour of f.c.c. metals is presented. In this model the strain hardening results from increasing dislocation densities. The observed stagnation of strain hardening after strain reversals is explained by a lowering of the increase in

  11. Nucleation versus instability race in strained films

    Science.gov (United States)

    Liu, Kailang; Berbezier, Isabelle; David, Thomas; Favre, Luc; Ronda, Antoine; Abbarchi, Marco; Voorhees, Peter; Aqua, Jean-Noël

    2017-10-01

    Under the generic term "Stranski-Krastanov" are grouped two different growth mechanisms of SiGe quantum dots. They result from the self-organized Asaro-Tiller-Grinfel'd (ATG) instability at low strain, while at high strain, from a stochastic nucleation. While these regimes are well known, we elucidate here the origin of the transition between these two pathways thanks to a joint theoretical and experimental work. Nucleation is described within the master equation framework. By comparing the time scales for ATG instability development and three-dimensional (3D) nucleation onset, we demonstrate that the transition between these two regimes is simply explained by the crossover between their divergent evolutions. Nucleation exhibits a strong exponential deviation at low strain while ATG behaves only algebraically. The associated time scale varies with exp(1 /x4) for nucleation, while it only behaves as 1 /x8 for the ATG instability. Consequently, at high (low) strain, nucleation (instability) occurs faster and inhibits the alternate evolution. It is then this different kinetic evolution which explains the transition from one regime to the other. Such a kinetic view of the transition between these two 3D growth regimes was not provided before. The crossover between nucleation and ATG instability is found to occur both experimentally and theoretically at a Ge composition around 50% in the experimental conditions used here. Varying the experimental conditions and/or the system parameters does not allow us to suppress the transition. This means that the SiGe quantum dots always grow via ATG instability at low strain and nucleation at high strain. This result is important for the self-organization of quantum dots.

  12. Tensile strain mapping in flat germanium membranes

    International Nuclear Information System (INIS)

    Rhead, S. D.; Halpin, J. E.; Myronov, M.; Patchett, D. H.; Allred, P. S.; Wilson, N. R.; Leadley, D. R.; Shah, V. A.; Kachkanov, V.; Dolbnya, I. P.; Reparaz, J. S.; Sotomayor Torres, C. M.

    2014-01-01

    Scanning X-ray micro-diffraction has been used as a non-destructive probe of the local crystalline quality of a thin suspended germanium (Ge) membrane. A series of reciprocal space maps were obtained with ∼4 μm spatial resolution, from which detailed information on the strain distribution, thickness, and crystalline tilt of the membrane was obtained. We are able to detect a systematic strain variation across the membranes, but show that this is negligible in the context of using the membranes as platforms for further growth. In addition, we show evidence that the interface and surface quality is improved by suspending the Ge

  13. Tensile strain mapping in flat germanium membranes

    Energy Technology Data Exchange (ETDEWEB)

    Rhead, S. D., E-mail: S.Rhead@warwick.ac.uk; Halpin, J. E.; Myronov, M.; Patchett, D. H.; Allred, P. S.; Wilson, N. R.; Leadley, D. R. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Shah, V. A. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Department of Engineering, University of Warwick, Coventry, CV4 7AL (United Kingdom); Kachkanov, V.; Dolbnya, I. P. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE (United Kingdom); Reparaz, J. S. [ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain); Sotomayor Torres, C. M. [ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain)

    2014-04-28

    Scanning X-ray micro-diffraction has been used as a non-destructive probe of the local crystalline quality of a thin suspended germanium (Ge) membrane. A series of reciprocal space maps were obtained with ∼4 μm spatial resolution, from which detailed information on the strain distribution, thickness, and crystalline tilt of the membrane was obtained. We are able to detect a systematic strain variation across the membranes, but show that this is negligible in the context of using the membranes as platforms for further growth. In addition, we show evidence that the interface and surface quality is improved by suspending the Ge.

  14. Cells as strain-cued automata

    Science.gov (United States)

    Cox, Brian N.; Snead, Malcolm L.

    2016-02-01

    We argue in favor of representing living cells as automata and review demonstrations that autonomous cells can form patterns by responding to local variations in the strain fields that arise from their individual or collective motions. An autonomous cell's response to strain stimuli is assumed to be effected by internally-generated, internally-powered forces, which generally move the cell in directions other than those implied by external energy gradients. Evidence of cells acting as strain-cued automata have been inferred from patterns observed in nature and from experiments conducted in vitro. Simulations that mimic particular cases of pattern forming share the idealization that cells are assumed to pass information among themselves solely via mechanical boundary conditions, i.e., the tractions and displacements present at their membranes. This assumption opens three mechanisms for pattern formation in large cell populations: wavelike behavior, kinematic feedback in cell motility that can lead to sliding and rotational patterns, and directed migration during invasions. Wavelike behavior among ameloblast cells during amelogenesis (the formation of dental enamel) has been inferred from enamel microstructure, while strain waves in populations of epithelial cells have been observed in vitro. One hypothesized kinematic feedback mechanism, "enhanced shear motility", accounts successfully for the spontaneous formation of layered patterns during amelogenesis in the mouse incisor. Directed migration is exemplified by a theory of invader cells that sense and respond to the strains they themselves create in the host population as they invade it: analysis shows that the strain fields contain positional information that could aid the formation of cell network structures, stabilizing the slender geometry of branches and helping govern the frequency of branch bifurcation and branch coalescence (the formation of closed networks). In simulations of pattern formation in

  15. Haemophilus ducreyi Cutaneous Ulcer Strains Diverged from Both Class I and Class II Genital Ulcer Strains: Implications for Epidemiological Studies.

    Directory of Open Access Journals (Sweden)

    Dharanesh Gangaiah

    2016-12-01

    Full Text Available Haemophilus ducreyi has emerged as a major cause of cutaneous ulcers (CU in yaws-endemic regions of the tropics in the South Pacific, South East Asia and Africa. H. ducreyi was once thought only to cause the genital ulcer (GU disease chancroid; GU strains belong to 2 distinct classes, class I and class II. Using whole-genome sequencing of 4 CU strains from Samoa, 1 from Vanuatu and 1 from Papua New Guinea, we showed that CU strains diverged from the class I strain 35000HP and that one CU strain expressed β-lactamase. Recently, the Center for Disease Control and Prevention released the genomes of 11 additional CU strains from Vanuatu and Ghana; however, the evolutionary relationship of these CU strains to previously-characterized CU and GU strains is unknown.We performed phylogenetic analysis of 17 CU and 10 GU strains. Class I and class II GU strains formed two distinct clades. The class I strains formed two subclades, one containing 35000HP and HD183 and the other containing the remainder of the class I strains. Twelve of the CU strains formed a subclone under the class I 35000HP subclade, while 2 CU strains formed a subclone under the other class I subclade. Unexpectedly, 3 of the CU strains formed a subclone under the class II clade. Phylogenetic analysis of dsrA-hgbA-ncaA sequences yielded a tree similar to that of whole-genome phylogenetic tree.CU strains diverged from multiple lineages within both class I and class II GU strains. Multilocus sequence typing of dsrA-hgbA-ncaA could be reliably used for epidemiological investigation of CU and GU strains. As class II strains grow relatively poorly and are relatively more susceptible to vancomycin than class I strains, these findings have implications for methods to recover CU strains. Comparison of contemporary CU and GU isolates would help clarify the relationship between these entities.

  16. Haemophilus ducreyi Cutaneous Ulcer Strains Diverged from Both Class I and Class II Genital Ulcer Strains: Implications for Epidemiological Studies.

    Science.gov (United States)

    Gangaiah, Dharanesh; Spinola, Stanley M

    2016-12-01

    Haemophilus ducreyi has emerged as a major cause of cutaneous ulcers (CU) in yaws-endemic regions of the tropics in the South Pacific, South East Asia and Africa. H. ducreyi was once thought only to cause the genital ulcer (GU) disease chancroid; GU strains belong to 2 distinct classes, class I and class II. Using whole-genome sequencing of 4 CU strains from Samoa, 1 from Vanuatu and 1 from Papua New Guinea, we showed that CU strains diverged from the class I strain 35000HP and that one CU strain expressed β-lactamase. Recently, the Center for Disease Control and Prevention released the genomes of 11 additional CU strains from Vanuatu and Ghana; however, the evolutionary relationship of these CU strains to previously-characterized CU and GU strains is unknown. We performed phylogenetic analysis of 17 CU and 10 GU strains. Class I and class II GU strains formed two distinct clades. The class I strains formed two subclades, one containing 35000HP and HD183 and the other containing the remainder of the class I strains. Twelve of the CU strains formed a subclone under the class I 35000HP subclade, while 2 CU strains formed a subclone under the other class I subclade. Unexpectedly, 3 of the CU strains formed a subclone under the class II clade. Phylogenetic analysis of dsrA-hgbA-ncaA sequences yielded a tree similar to that of whole-genome phylogenetic tree. CU strains diverged from multiple lineages within both class I and class II GU strains. Multilocus sequence typing of dsrA-hgbA-ncaA could be reliably used for epidemiological investigation of CU and GU strains. As class II strains grow relatively poorly and are relatively more susceptible to vancomycin than class I strains, these findings have implications for methods to recover CU strains. Comparison of contemporary CU and GU isolates would help clarify the relationship between these entities.

  17. Failure strains and proposed limit strains for an reactor pressure vessel under severe accident conditions

    International Nuclear Information System (INIS)

    Krieg, R.

    2005-01-01

    The local failure strains of essential design elements of a reactor vessel are investigated. The size influence of the structure is of special interest. Typical severe accident conditions including elevated temperatures and dynamic loads are considered. The main part of work consists of test families with specimens under uniaxial and biaxial load. Within one test family the specimen geometry and the load conditions are similar, but the size is varied up to reactor dimensions. Special attention is given to geometries with a hole or a notch causing non-uniform stress and strain distributions typical for the reactor vessel. A key problem is to determine the local failure strain. Here suitable methods had to be developed including the so-called 'vanishing gap method', and the 'forging die method'. They are based on post-test geometrical measurements of the fracture surfaces and reconstructions of the related strain fields using finite element models. The results indicate that stresses versus dimensionless deformations are approximately size independent up to failure for specimens of similar geometry under similar load conditions. Local failure strains could be determined. The values are rather high and size dependent. Statistical evaluation allow the proposal of limit strains which are also size dependent. If these limit strains are not exceeded, the structures will not fracture

  18. Mechanical strength model for plastic bonded granular materials at high strain rates and large strains

    International Nuclear Information System (INIS)

    Browning, R.V.; Scammon, R.J.

    1998-01-01

    Modeling impact events on systems containing plastic bonded explosive materials requires accurate models for stress evolution at high strain rates out to large strains. For example, in the Steven test geometry reactions occur after strains of 0.5 or more are reached for PBX-9501. The morphology of this class of materials and properties of the constituents are briefly described. We then review the viscoelastic behavior observed at small strains for this class of material, and evaluate large strain models used for granular materials such as cap models. Dilatation under shearing deformations of the PBX is experimentally observed and is one of the key features modeled in cap style plasticity theories, together with bulk plastic flow at high pressures. We propose a model that combines viscoelastic behavior at small strains but adds intergranular stresses at larger strains. A procedure using numerical simulations and comparisons with results from flyer plate tests and low rate uniaxial stress tests is used to develop a rough set of constants for PBX-9501. Comparisons with the high rate flyer plate tests demonstrate that the observed characteristic behavior is captured by this viscoelastic based model. copyright 1998 American Institute of Physics

  19. Life Stress, Strain, and Deviance Across Schools: Testing the Contextual Version of General Strain Theory in China.

    Science.gov (United States)

    Zhang, Jinwu; Liu, Jianhong; Wang, Xin; Zou, Anquan

    2017-08-01

    General Strain Theory delineates different types of strain and intervening processes from strain to deviance and crime. In addition to explaining individual strain-crime relationship, a contextualized version of general strain theory, which is called the Macro General Strain Theory, has been used to analyze how aggregate variables influence aggregate and individual deviance and crime. Using a sample of 1,852 students (Level 1) nested in 52 schools (Level 2), the current study tests the Macro General Strain Theory using Chinese data. The results revealed that aggregate life stress and strain have influences on aggregate and individual deviance, and reinforce the individual stress-deviance association. The current study contributes by providing the first Macro General Strain Theory test based on Chinese data and offering empirical evidence for the multilevel intervening processes from strain to deviance. Limitations and future research directions are discussed.

  20. High strain rate behaviour of polypropylene microfoams

    Directory of Open Access Journals (Sweden)

    Martínez A.B.

    2012-08-01

    Full Text Available Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc. or personal safety (helmets, knee-pads, etc.. In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s−1 in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB. Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

  1. Nature of interstitially induced lattice strains

    International Nuclear Information System (INIS)

    Emin, D.

    1978-01-01

    The addition of interstitial atoms to a metal lattice has been likened to the addition of extra billiard balls to an array of tangentially touching billiard balls. In such a picture the increased clustering of interstitials can lead to the buildup of larger and larger strain fields which ultimately are associated with the production of broken bonds. Simple models of the strain fields associated with the addition of particles to a lattice in which the force exerted between the added atoms and host atoms is finite have been studied. From these studies one can define situations in which the billiard-ball approach has qualitative validity and those in which it is inappropriate. Basically, those situations in which the displacements of the host atoms can be represented as involving acoustic phonons yield long-range strain fields analogous to those of the billiard-ball model with the radius of the extra billiard ball being determined by the stiffness of the host lattice and the forces between the added atom and the surrounding host atoms. If the displacements produced by the added atoms are represented as involving primarily optical phonons the displacement pattern is short-ranged and not described by the usual elasticity theory. For example, Vegard's law does not apply in these instances. Such concerns arise in considering the strains induced by interstitial helium in tritides

  2. Preliminary characterization of slow growing rhizobial strains ...

    African Journals Online (AJOL)

    COMPAQ

    2016-05-18

    May 18, 2016 ... number of nodules was equal to 5.6 nodules per plant for the strain RMB1 from Bousfer site. The intrinsic .... The salt tolerance of rhizobia was tested on YMA plates containing ..... through deep explorations searching for an.

  3. Ductile damage evolution and strain path dependency

    NARCIS (Netherlands)

    Tasan, C.C.; Hoefnagels, J.P.M.; Peerlings, R.H.J.; Geers, M.G.D.; Horn, ten C.H.L.J.; Vegter, H.; Cueto, E.; Chinesta, F.

    2007-01-01

    Forming limit diagrams are commonly used in sheet metal industry to define the safe forming regions. These diagrams are built to define the necking strains of sheet metals. However, with the rise in the popularity of advance high strength steels, ductile fracture through damage evolution has also

  4. Strain engineering of Dirac cones in graphyne

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Gaoxue; Kumar, Ashok; Pandey, Ravindra, E-mail: pandey@mtu.edu [Department of Physics, Michigan Technological University, Houghton, Michigan 49931 (United States); Si, Mingsu [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2014-05-26

    6,6,12-graphyne, one of the two-dimensional carbon allotropes with the rectangular lattice structure, has two kinds of non-equivalent anisotropic Dirac cones in the first Brillouin zone. We show that Dirac cones can be tuned independently by the uniaxial compressive strain applied to graphyne, which induces n-type and p-type self-doping effect, by shifting the energy of the Dirac cones in the opposite directions. On the other hand, application of the tensile strain results into a transition from gapless to finite gap system for the monolayer. For the AB-stacked bilayer, the results predict tunability of Dirac-cones by in-plane strains as well as the strain applied perpendicular to the plane. The group velocities of the Dirac cones show enhancement in the resistance anisotropy for bilayer relative to the case of monolayer. Such tunable and direction-dependent electronic properties predicted for 6,6,12-graphyne make it to be competitive for the next-generation electronic devices at nanoscale.

  5. Strains and Sprains Are a Pain

    Science.gov (United States)

    ... lot of pressure on a muscle or you push it too far, such as when lifting a heavy object. Strains can be more likely to happen if you haven't warmed up first to get blood circulating to the muscles. They're also common for someone returning to a sport after the off-season. That first time playing ...

  6. Photoacclimation of cultured strains of the cyanobacterium

    NARCIS (Netherlands)

    Bañares-España, E.; Kromkamp, J.C.; López-Rodas, V.; Costas, E.; Flores-Moya, A.

    2013-01-01

    The cyanobacterium Microcystis aeruginosa forms blooms that can consist of colonies. We have investigated how M.aeruginosa acclimatizes to changing light conditions such as can occur during blooms. Three different strains were exposed to two irradiance levels: lower (LL) and higher (HL) than the

  7. Strain rate behavior of magnetorheological materials

    International Nuclear Information System (INIS)

    Seminuk, Kenneth; Joshi, Vasant; Gump, Jared; Stoltz, Chad; Forbes, Jerry

    2014-01-01

    Strain rate response of two Hydroxyl-terminated Polybutadiene/ Iron (HTPB/Fe) compositions under electromagnetic fields has been investigated using a Split Hopkinson Pressure bar arrangement equipped with aluminum bars. Two HTPB/Fe compositions were developed, the first without plasticizer and the second containing plasticizer. Samples were tested with and without the application of a 0.01 Tesla magnetic field. Strain gauge data taken from the Split Hopkinson Pressure Bar has been used to determine the extent of change in mechanical properties by inducing a mild electromagnetic field onto each sample. Raw data from strain gages was processed using commercial software (Signo) and Excel spreadsheet. It is of particular interest to determine whether the mechanical properties of binder systems can be manipulated by adding ferrous or Magnetostrictive particulates. Data collected from the Split Hopkinson Pressure bar indicate changes in the Mechanical Stress-Strain curves and suggest that the impedance of a binder system can be altered by means of a magnetic field.

  8. Role Strain in University Research Centers

    Science.gov (United States)

    Boardman, Craig; Bozeman, Barry

    2007-01-01

    One way in which university faculty members' professional lives have become more complex with the advent of contemporary university research centers is that many faculty have taken on additional roles. The authors' concern in this article is to determine the extent to which role strain is experienced by university faculty members who are…

  9. Evolution and Strain Variation in BCG

    KAUST Repository

    Abdallah, Abdallah

    2017-11-07

    BCG vaccines were derived by in vitro passage, during the years 1908–1921, at the Pasteur Institute of Lille. Following the distribution of stocks of BCG to vaccine production laboratories around the world, it was only a few decades before different BCG producers recognized that there were variants of BCG, likely due to different passaging conditions in the different laboratories. This ultimately led to the lyophilization of stable BCG products in the 1950s and 1960s, but not before considerable evolution of the different BCG strains had taken place. The application of contemporary research methodologies has now revealed genomic, transcriptomic and proteomic differences between BCG strains. These molecular differences in part account for phenotypic differences in vitro between BCG strains, such as their variable secretion of antigenic proteins. Yet, the relevance of BCG variability for immunization policy remains elusive. In this chapter we present an overview of what is known about BCG evolution and its resulting strain variability, and provide some speculation as to the potential relevance for a vaccine given to over 100 million newborns each year.

  10. Strain Imaging Using Terahertz Waves and Metamaterials

    Science.gov (United States)

    2016-11-01

    predictions. 14. SUBJECT TERMS Birefringence, Terahertz Waves, Metamaterials 15. NUMBER OF PAGES 16 16. PRICE CODE 17. SECURITY...opaque objects by using the principles of strain-induced birefringence. 4 III. CONCEPT To overcome the inability of visual light to penetrate ...opaque objects, terahertz radiation was investigated. Longer wavelength EM waves, such as radio waves, have excellent penetration ability but low image

  11. Effective stress coefficient for uniaxial strain condition

    DEFF Research Database (Denmark)

    Alam, M.M.; Fabricius, I.L.

    2012-01-01

    one dimensional rock mechanical deformation. We further investigated the effect of boundary condition on the stress dependency of effective stress coefficient and discussed its application in reservoir study. As stress field in the reservoirs are most unlikely to be hydrostatic, effective stress...... determined under uniaxial strain condition will be more relevant in reservoir studies. Copyright 2012 ARMA, American Rock Mechanics Association....

  12. Fibre optic strain sensor: examples of applications

    Science.gov (United States)

    Kruszewski, J.; Beblowska, M.; Wrzosek, P.

    2006-03-01

    Construction of strain sensor for application in safety systems has been presented. The device consists of sensor's head and source and detector units. The head is made of polymer fiber bends. Designed sensor could be mounted in monitoring place (e.g. under a floor) and controlled by PC unit or could be used as a portable device for a valuable object protection.

  13. Falling balls and simple shearing strain

    International Nuclear Information System (INIS)

    Brun, J L; Pacheco, A F

    2006-01-01

    The problem of particles falling under gravity allows us to relate Hamiltonian mechanics to such different subjects as elasticity and fluid mechanics. It is with this in mind that mechanics gives us the opportunity of introducing, in a rather simple and unusual form, some concepts such as vorticity, the incompressibility condition or simple shear strain to physics students at the undergraduate level

  14. What is behind the plastic strain rate?

    NARCIS (Netherlands)

    Hütter, M.; Grmela, M.; Öttinger, H.C.

    2009-01-01

    The plastic strain rate plays a central role in macroscopic models on elasto-viscoplasticity. In order to discuss the concept behind this quantity, we propose, first, a kinetic toy model to describe the dynamics of sliding layers representative of plastic deformation of single crystalline metals.

  15. Preliminary characterization of Rhizobium strains isolated from ...

    African Journals Online (AJOL)

    SERVER

    2008-03-18

    Mar 18, 2008 ... residues for animal feed and helps to maintain soil fertility through .... A loopful of agar slopes of the strains assayed for vitamin production was ... B12 Assay Medium, amended with 2 mmol l-1 Ca-pantothenate, biotin and ...

  16. Strain absorbent modules for cavity filling

    Energy Technology Data Exchange (ETDEWEB)

    1981-04-01

    Strain absorbent modules made from weldmesh panels and helical steel binders can be used, together with timber packing, to support the roof and sides of cavities instead of softwood and hardwood nogs. A description of these modules and a series of load tests and underground trials carried out on the modules is given.

  17. Fano Factor in Strained Graphene Nanoribbon Nanodevices

    Institute of Scientific and Technical Information of China (English)

    Walid Soliman; Mina D.Asham; Adel H.Phillips

    2017-01-01

    We investigate the Fano factor in a strained armchair and zigzag graphene nanoribbon nanodevice under the effect of ac field in a wide range of frequencies at different temperatures (10 K T0 K).This nanodevice is modeled as follows:a graphene nanoribbon is connected to two metallic leads.These two metallic leads operate as a source and a drain.The conducting substance is the gate electrode in this three-terminal nanodevice.Another metallic gate is used to govern the electrostatics and the switching of the graphene nanoribbon channel The substances at the graphene nanoribbon/metal contact are controlled by the back gate.The photon-assisted tunneling probability is deduced by solving the Dirac eigenvalue differential equation in which the Fano factor is expressed in terms of this tunneling probability.The results show that for the investigated nanodevice,the Fano factor decreases as the frequency of the induced ac field increases,while it increases as the temperature increases.In general,the Fano factors for both strained armchair and zigzag graphene nanoribbons are different.This is due to the effect of the uniaxial strain.It is shown that the band structure parameters of graphene nanoribbons at the energy gap,the C-C bond length,the hopping integral,the Fermi energy and the width are modulated by uniaxial strain.This research gives us a promise of the present nanodevice being used for digital nanoelectronics and sensors.

  18. Highly Stretchable, Strain Sensing Hydrogel Optical Fibers.

    Science.gov (United States)

    Guo, Jingjing; Liu, Xinyue; Jiang, Nan; Yetisen, Ali K; Yuk, Hyunwoo; Yang, Changxi; Khademhosseini, Ali; Zhao, Xuanhe; Yun, Seok-Hyun

    2016-12-01

    A core-clad fiber made of elastic, tough hydrogels is highly stretchable while guiding light. Fluorescent dyes are easily doped into the hydrogel fiber by diffusion. When stretched, the transmission spectrum of the fiber is altered, enabling the strain to be measured and also its location. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Strained Si engineering for nanoscale MOSFETs

    International Nuclear Information System (INIS)

    Park, Jea-Gun; Lee, Gon-Sub; Kim, Tae-Hyun; Hong, Seuck-Hoon; Kim, Seong-Je; Song, Jin-Hwan; Shim, Tae-Hun

    2006-01-01

    We have revealed a strain relaxation mechanism for strained Si grown on a relaxed SiGe-on-insulator structure fabricated by the bonding, dislocation sink, or condensation method. Strain relaxation for both the bonding and dislocation sink methods was achieved by grading the Ge concentration; in contrast, the relaxation for the condensation method was achieved through Ge atom condensation during oxidation. In addition, we estimated the surface roughness and threading-dislocation pit density for relaxed SiGe layer fabricated by the bonding, dislocation sink, or condensation method. The surface roughness and threading-dislocation pit density for the bonding, dislocation sink, and condensation methods were 2.45, 0.46, and 0.40 nm and 5.0 x 10 3 , 9 x 10 3 , and 0, respectively. In terms of quality and cost-effectiveness, the condensation method was superior to the bonding and dislocation sink methods for forming strained Si on a relaxed SiGe-on-insulator structure

  20. Simple Numerical Simulation of Strain Measurement

    Science.gov (United States)

    Tai, H.

    2002-01-01

    By adopting the basic principle of the reflection (and transmission) of a plane polarized electromagnetic wave incident normal to a stack of films of alternating refractive index, a simple numerical code was written to simulate the maximum reflectivity (transmittivity) of a fiber optic Bragg grating corresponding to various non-uniform strain conditions including photo-elastic effect in certain cases.

  1. High strain rate studies in rock

    International Nuclear Information System (INIS)

    Grady, D.

    1977-01-01

    Dynamic compression studies using high velocity impact are usually considered to involve a catastrophic process of indeterminate loading rate by which a material is brough to a shock compressed state. Although this is frequently the case, methods are also available to control the rate of strain during the shock compression process. One of the most accurate of these methods makes use of the anomalous nonlinear elastic property of glass to transform an initial shock or step wave input into a ramp wave of known amplitude and duration. Fused silica is the most carefully calibrated material for this purpose and, when placed between the test specimen and the impact projectile, can provide loading strain rates in the range of 10 4 /s to 10 6 /s for final stress states of approximately 3.9 GPa or less.Ramp wave compression experiments have been conducted on dolomite at strain rates of 3 x 10 4 /s. Both initial yielding and subsequent deformation at this strain rate agrees well with previous shock wave studies (epsilon-dotapprox.10 6 /s) and differs substantially from quasi-static measurements (epsilon-dotapprox.10 -4 /s). The ramp wave studies have also uncovered a pressure-induced phase transition in dolomite initiating at 4.0 GPa

  2. Characterizing large strain crush response of redwood

    International Nuclear Information System (INIS)

    Cramer, S.M.; Hermanson, J.C.

    1996-12-01

    Containers for the transportation of hazardous and radioactive materials incorporate redwood in impact limiters. Redwood is an excellent energy absorber, but only the most rudimentary information exists on its crush properties. The objectives of the study were to fill the information gap by collecting triaxial load-deformation data for redwood; to use these data to characterize redwood crush, assess current wood failure theories, provide developments toward a complete stress-strain theory for redwood; and to review the literature on strain-rate effects on redwood crush performance. The load-deformation responses of redwood at temperature conditions corresponding to ambient (70 degrees F), 150 degrees F, and -20 degrees F conditions were measured in approximately 100 confined compression tests for crush levels leading to material densification. Data analysis provided a more complete description of redwood crush performance and a basis for assessing proposed general orthotropic stress-strain relationships for redwood. A review of existing literature indicated that strain-rate effects cause at most a 20 percent increase in crush stress parallel to grain

  3. Characterization and monitoring of selected rhizobial strains ...

    African Journals Online (AJOL)

    SERVER

    2007-06-18

    Jun 18, 2007 ... Fax: +66-44-216345. fixing symbiosis with bacteria known as rhizobia. ... Rhizobial strains were cultured on Yeast-Malt extract agar contain- ing bromthymol blue ... Colony form-ing was observed every day as well as the ...

  4. Preliminary characterization of slow growing rhizobial strains ...

    African Journals Online (AJOL)

    COMPAQ

    2016-05-18

    May 18, 2016 ... strains had a very slow growth rate in yeast malt (YM) agar medium, forming colonies less than 1 mm in ... dominant genus of symbiotic nitrogen-fixing bacteria ... Single colonies were picked up and checked for purity by.

  5. High strain rate behaviour of polypropylene microfoams

    Science.gov (United States)

    Gómez-del Río, T.; Garrido, M. A.; Rodríguez, J.; Arencón, D.; Martínez, A. B.

    2012-08-01

    Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc.) or personal safety (helmets, knee-pads, etc.). In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry) is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s-1) in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB). Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

  6. How strained are carbomeric-cycloalkanes?

    Science.gov (United States)

    Wodrich, Matthew D; Gonthier, Jérôme F; Steinmann, Stephan N; Corminboeuf, Clémence

    2010-06-24

    The ring strain energies of carbomeric-cycloalkanes (molecules with one or more acetylene spacer units placed into carbon single bonds) are assessed using a series of isodesmic, homodesmotic, and hyperhomodesmotic chemical equations. Isodesmic bond separation reactions and other equations derived from the explicitly defined hierarchy of homodesmotic equations are insufficient for accurately determining these values, since not all perturbing effects (i.e., conjugation and hyperconjugation) are fully balanced. A set of homodesmotic reactions is proposed, which succeeds in balancing all stereoelectronic effects present within the carbomeric rings, allowing for a direct assessment of the strain energies. Values calculated from chemical equations are validated using an increment/additivity approach. The ring strain energy decreases as acetylene units are added, manifesting from the net stabilization gained by opening the C-CH(2)-C angle around the methylene groups and the destabilization arising from bending the C-C identical withC angles of the spacer groups. This destabilization vanishes with increasing parent ring size (i.e., the angle distortion is less in the carbomeric-cyclobutanes than in the carbomeric-cyclopropanes), leading to strain energies near zero for carbo(n)-cyclopentanes and carbo(n)-cyclohexanes.

  7. Unsteady Aerodynamic Force Sensing from Measured Strain

    Science.gov (United States)

    Pak, Chan-Gi

    2016-01-01

    A simple approach for computing unsteady aerodynamic forces from simulated measured strain data is proposed in this study. First, the deflection and slope of the structure are computed from the unsteady strain using the two-step approach. Velocities and accelerations of the structure are computed using the autoregressive moving average model, on-line parameter estimator, low-pass filter, and a least-squares curve fitting method together with analytical derivatives with respect to time. Finally, aerodynamic forces over the wing are computed using modal aerodynamic influence coefficient matrices, a rational function approximation, and a time-marching algorithm. A cantilevered rectangular wing built and tested at the NASA Langley Research Center (Hampton, Virginia, USA) in 1959 is used to validate the simple approach. Unsteady aerodynamic forces as well as wing deflections, velocities, accelerations, and strains are computed using the CFL3D computational fluid dynamics (CFD) code and an MSC/NASTRAN code (MSC Software Corporation, Newport Beach, California, USA), and these CFL3D-based results are assumed as measured quantities. Based on the measured strains, wing deflections, velocities, accelerations, and aerodynamic forces are computed using the proposed approach. These computed deflections, velocities, accelerations, and unsteady aerodynamic forces are compared with the CFL3D/NASTRAN-based results. In general, computed aerodynamic forces based on the lifting surface theory in subsonic speeds are in good agreement with the target aerodynamic forces generated using CFL3D code with the Euler equation. Excellent aeroelastic responses are obtained even with unsteady strain data under the signal to noise ratio of -9.8dB. The deflections, velocities, and accelerations at each sensor location are independent of structural and aerodynamic models. Therefore, the distributed strain data together with the current proposed approaches can be used as distributed deflection

  8. On strain and stress in living cells

    Science.gov (United States)

    Cox, Brian N.; Smith, David W.

    2014-11-01

    Recent theoretical simulations of amelogenesis and network formation and new, simple analyses of the basic multicellular unit (BMU) allow estimation of the order of magnitude of the strain energy density in populations of living cells in their natural environment. A similar simple calculation translates recent measurements of the force-displacement relation for contacting cells (cell-cell adhesion energy) into equivalent volume energy densities, which are formed by averaging the changes in contact energy caused by a cell's migration over the cell's volume. The rates of change of these mechanical energy densities (energy density rates) are then compared to the order of magnitude of the metabolic activity of a cell, expressed as a rate of production of metabolic energy per unit volume. The mechanical energy density rates are 4-5 orders of magnitude smaller than the metabolic energy density rate in amelogenesis or bone remodeling in the BMU, which involve modest cell migration velocities, and 2-3 orders of magnitude smaller for innervation of the gut or angiogenesis, where migration rates are among the highest for all cell types. For representative cell-cell adhesion gradients, the mechanical energy density rate is 6 orders of magnitude smaller than the metabolic energy density rate. The results call into question the validity of using simple constitutive laws to represent living cells. They also imply that cells need not migrate as inanimate objects of gradients in an energy field, but are better regarded as self-powered automata that may elect to be guided by such gradients or move otherwise. Thus Ġel=d/dt 1/2 >[(C11+C12)ɛ02+2μγ02]=(C11+C12)ɛ0ɛ˙0+2μγ0γ˙0 or Ġel=ηEɛ0ɛ˙0+η‧Eγ0γ˙0 with 1.4≤η≤3.4 and 0.7≤η‧≤0.8 for Poisson's ratio in the range 0.2≤ν≤0.4 and η=1.95 and η‧=0.75 for ν=0.3. The spatial distribution of shear strains arising within an individual cell as cells slide past one another during amelogenesis is not known

  9. Recent advances in echocardiography: strain and strain rate imaging [version 1; referees: 3 approved

    Directory of Open Access Journals (Sweden)

    Oana Mirea

    2016-04-01

    Full Text Available Deformation imaging by echocardiography is a well-established research tool which has been gaining interest from clinical cardiologists since the introduction of speckle tracking. Post-processing of echo images to analyze deformation has become readily available at the fingertips of the user. New parameters such as global longitudinal strain have been shown to provide added diagnostic value, and ongoing efforts of the imaging societies and industry aimed at harmonizing methods will improve the technique further. This review focuses on recent advances in the field of echocardiographic strain and strain rate imaging, and provides an overview on its current and potential future clinical applications.

  10. Enzyme markers in inbred rat strains: genetics of new markers and strain profiles.

    Science.gov (United States)

    Adams, M; Baverstock, P R; Watts, C H; Gutman, G A

    1984-08-01

    Twenty-six inbred strains of the laboratory rat (Rattus norvegicus) were examined for electrophoretic variation at an estimated 97 genetic loci. In addition to previously documented markers, variation was observed for the enzymes aconitase, aldehyde dehydrogenase, and alkaline phosphatase. The genetic basis of these markers (Acon-1, Ahd-2, and Akp-1) was confirmed. Linkage analysis between 35 pairwise comparisons revealed that the markers Fh-1 and Pep-3 are linked. The strain profiles of the 25 inbred strains at 11 electrophoretic markers are given.

  11. Informal eldercare and work-related strain.

    Science.gov (United States)

    Trukeschitz, Birgit; Schneider, Ulrike; Mühlmann, Richard; Ponocny, Ivo

    2013-03-01

    In light of an aging workforce, reconciling informal eldercare and paid work becomes increasingly pertinent. This article investigates the association between informal eldercare and work-related strain and tests for both the "competing demands" and "expansion" hypotheses. The sample of 938 Austrian employees consisted of employees caring for older relatives and a control group of employees without eldercare obligations. We ran a Tobit regression model on work-related strain with different measures of informal eldercare as explanatory variables and controls for both personal and workplace characteristics. Accounting for different characteristics of eldercare within one estimation model revealed that informal eldercare was associated with work-related strain in 2 ways, that is, it increased with both care hours and subjective care burden. However, after controlling for these burdensome attributes of eldercare, the carer status as such was found to be negatively associated with work-related strain. In addition and independently of care commitments, work-related factors, such as advanced skills and job motivation, reduced work-related strain. This article lends support to both the "competing demands" and the "expansion" hypotheses. Commitment to eldercare can enhance work-related outcomes but entails work-related problems if care burden and time demands of eldercare are substantial. Thus, workers with eldercare responsibilities cannot be considered less productive from the outset. An individual assessment of their situation, considering the care and work setting, is required. Findings from this study support the design of workplace initiatives to uphold workers' productivity in general and bring specific attention to policies alleviating workers' eldercare burden.

  12. Strain rate effects for spallation of concrete

    Science.gov (United States)

    Häussler-Combe, Ulrich; Panteki, Evmorfia; Kühn, Tino

    2015-09-01

    Appropriate triaxial constitutive laws are the key for a realistic simulation of high speed dynamics of concrete. The strain rate effect is still an open issue within this context. In particular the question whether it is a material property - which can be covered by rate dependent stress strain relations - or mainly an effect of inertia is still under discussion. Experimental and theoretical investigations of spallation of concrete specimen in a Hopkinson Bar setup may bring some evidence into this question. For this purpose the paper describes the VERD model, a newly developed constitutive law for concrete based on a damage approach with included strain rate effects [1]. In contrast to other approaches the dynamic strength increase is not directly coupled to strain rate values but related to physical mechanisms like the retarded movement of water in capillary systems and delayed microcracking. The constitutive law is fully triaxial and implemented into explicit finite element codes for the investigation of a wide range of concrete structures exposed to impact and explosions. The current setup models spallation experiments with concrete specimen [2]. The results of such experiments are mainly related to the dynamic tensile strength and the crack energy of concrete which may be derived from, e.g., the velocity of spalled concrete fragments. The experimental results are compared to the VERD model and two further constitutive laws implemented in LS-Dyna. The results indicate that both viscosity and retarded damage are required for a realistic description of the material behaviour of concrete exposed to high strain effects [3].

  13. Strain rate effects for spallation of concrete

    Directory of Open Access Journals (Sweden)

    Häussler-Combe Ulrich

    2015-01-01

    Full Text Available Appropriate triaxial constitutive laws are the key for a realistic simulation of high speed dynamics of concrete. The strain rate effect is still an open issue within this context. In particular the question whether it is a material property – which can be covered by rate dependent stress strain relations – or mainly an effect of inertia is still under discussion. Experimental and theoretical investigations of spallation of concrete specimen in a Hopkinson Bar setup may bring some evidence into this question. For this purpose the paper describes the VERD model, a newly developed constitutive law for concrete based on a damage approach with included strain rate effects [1]. In contrast to other approaches the dynamic strength increase is not directly coupled to strain rate values but related to physical mechanisms like the retarded movement of water in capillary systems and delayed microcracking. The constitutive law is fully triaxial and implemented into explicit finite element codes for the investigation of a wide range of concrete structures exposed to impact and explosions. The current setup models spallation experiments with concrete specimen [2]. The results of such experiments are mainly related to the dynamic tensile strength and the crack energy of concrete which may be derived from, e.g., the velocity of spalled concrete fragments. The experimental results are compared to the VERD model and two further constitutive laws implemented in LS-Dyna. The results indicate that both viscosity and retarded damage are required for a realistic description of the material behaviour of concrete exposed to high strain effects [3].

  14. Occupational stress and strain in the Royal Navy 2007.

    Science.gov (United States)

    Bridger, R S; Brasher, K; Dew, A; Kilminster, S

    2008-12-01

    Previous surveys of psychological strain in the Naval Service (NS) have shown higher than expected levels of strain when compared to the general population. To repeat the survey last carried out in 2004 and to obtain further information on the nature of the occupational stressors associated with strain. General Health Questionnaire-12 strain rates and job/life stressors were measured using a Work and Well-Being Questionnaire. Models of strain were developed for male and female personnel in the Royal Navy (RN) and males in the Royal Marines (RM). The response rate was 57%. The psychological strain rate was 31.5% overall. Personnel suffering from strain tended to be 'overcommitted' to work, had low levels of commitment to the NS and had suffered stressful life events (SLEs) in the previous 12 months. Strain rates declined with age and rank in males, but not in females. Strain was significantly positively correlated with levels of overcommitment, effort-reward imbalance (ERI), role conflict, work-family conflict, organizational commitment and exposure to SLEs. Models of strain in the males and females in the RN and in the RM accounted for between 37 and 44% of the variance in strain. The survey provides evidence for both the demand control and ERI models-components of these models contribute independently to strain. High levels of commitment to the organization were associated with lower strain and exposure to SLEs to higher strain.

  15. Spacecraft Dynamic Characterization by Strain Energies Method

    Science.gov (United States)

    Bretagne, J.-M.; Fragnito, M.; Massier, S.

    2002-01-01

    In the last years the significant increase in satellite broadcasting demand, with the wide band communication dawn, has given a great impulse to the telecommunication satellite market. The big demand is translated from operators (such as SES/Astra, Eutelsat, Intelsat, Inmarsat, EuroSkyWay etc.) in an increase of orders of telecom satellite to the world industrials. The largest part of these telecom satellite orders consists of Geostationary platforms which grow more and more in mass (over 5 tons) due to an ever longer demanded lifetime (up to 20 years), and become more complex due to the need of implementing an ever larger number of repeaters, antenna reflectors and feeds, etc... In this frame, the mechanical design and verification of these large spacecraft become difficult and ambitious at the same time, driven by the dry mass limitation objective. By the Finite Element Method (FEM), and on the basis of the telecom satellite heritage of a world leader constructor such as Alcatel Space Industries it is nowadays possible to model these spacecraft in a realistic and confident way in order to identify the main global dynamic aspects such as mode shapes, mass participation and/or dynamic responses. But on the other hand, one of the main aims consists in identifying soon in a program the most critical aspects of the system behavior in the launch dynamic environment, such as possible dynamic coupling between the different subsystems and secondary structures of the spacecraft (large deployable reflectors, thrusters, etc.). To this aim a numerical method has been developed in the frame of the Alcatel SPACEBUS family program, using MSC/Nastran capabilities and it is presented in this paper. The method is based on Spacecraft sub-structuring and strain energy calculation. The method mainly consists of two steps : 1) subsystem modal strain energy ratio (with respect to the global strain energy); 2) subsystem strain energy calculation for each mode according to the base driven

  16. Brucella abortus Strain 2308 Wisconsin Genome: Importance of the Definition of Reference Strains

    Science.gov (United States)

    Suárez-Esquivel, Marcela; Ruiz-Villalobos, Nazareth; Castillo-Zeledón, Amanda; Jiménez-Rojas, César; Roop II, R. Martin; Comerci, Diego J.; Barquero-Calvo, Elías; Chacón-Díaz, Carlos; Caswell, Clayton C.; Baker, Kate S.; Chaves-Olarte, Esteban; Thomson, Nicholas R.; Moreno, Edgardo; Letesson, Jean J.; De Bolle, Xavier; Guzmán-Verri, Caterina

    2016-01-01

    Brucellosis is a bacterial infectious disease affecting a wide range of mammals and a neglected zoonosis caused by species of the genetically homogenous genus Brucella. As in most studies on bacterial diseases, research in brucellosis is carried out by using reference strains as canonical models to understand the mechanisms underlying host pathogen interactions. We performed whole genome sequencing analysis of the reference strain B. abortus 2308 routinely used in our laboratory, including manual curated annotation accessible as an editable version through a link at https://en.wikipedia.org/wiki/Brucella#Genomics. Comparison of this genome with two publically available 2308 genomes showed significant differences, particularly indels related to insertional elements, suggesting variability related to the transposition of these elements within the same strain. Considering the outcome of high resolution genomic techniques in the bacteriology field, the conventional concept of strain definition needs to be revised. PMID:27746773

  17. Brucella abortus strain 2308 Wisconsin genome: importance of the definition of reference strains

    Directory of Open Access Journals (Sweden)

    Marcela Suárez-Esquivel

    2016-09-01

    Full Text Available Brucellosis is a bacterial infectious disease affecting a wide range of mammals and a neglected zoonosis caused by species of the genetically homogenous genus Brucella. As in most studies on bacterial diseases, research in brucellosis is carried out by using reference strains as canonical models to understand the mechanisms underlying host pathogen interactions. We performed whole genome sequencing (WGS analysis of the reference strain Brucella abortus 2308 routinely used in our laboratory, including manual curated annotation accessible as an editable version at www.wikipedia.Comparison of this genome with two publically available 2308 genomes showed significant differences, particularly indels related to insertional elements, suggesting variability related to the transposition of these elements within the same strain. Considering the outcome of high resolution genomic techniques in the bacteriology field, the conventional concept of strain definition needs to be revised.

  18. Strain-dependent induction of cytokine profiles in the gut by orally administered Lactobacillus strains

    NARCIS (Netherlands)

    Maassen, C.B.M.; Holten-Neelen, C. van; Balk, F.; Bak-Glashouwer, M.-J.H. den; Leer, R.J.; Laman, J.D.; Boersma, W.J.A.; Claassen, E.

    2000-01-01

    Different Lactobacillus strains are frequently used in consumer food products. In addition, recombinant lactobacilli which contain novel expression vectors can now be used in immunotherapeutic applications such as oral vaccination strategies and in T cell tolerance induction approaches for

  19. Vaccination evokes gender-dependent protection against tularemia infection in C57BL/6Tac mice.

    Science.gov (United States)

    Sunagar, Raju; Kumar, Sudeep; Franz, Brian J; Gosselin, Edmund J

    2016-06-17

    Francisella tularensis (Ft) is a Category A biothreat agent for which there currently is no FDA-approved vaccine. Thus, there is a substantial effort underway to develop an effective tularemia vaccine. While it is well established that gender can significantly impact susceptibility to primary infection, the impact of gender on vaccine efficacy is not well established. Thus, development of a successful vaccine against tularemia will require an understanding of the impact gender has on vaccine-induced protection against this organism. In this study, a role for gender in vaccine-induced protection following Ft challenge is identified for the first time. In the present study, mucosal vaccination with inactivated Ft (iFt) LVS elicited gender-based protection in C57BL/6Tac mice against respiratory challenge with Ft LVS. Specifically, vaccinated male mice were more susceptible to subsequent Ft LVS challenge. This increased susceptibility in male mice correlated with increased bacterial burden, increased tissue inflammation, and increased proinflammatory cytokine production late in post-challenge infection. In contrast, improved survival of iFt-vaccinated female mice correlated with reduced bacterial burden and enhanced levels of Ft-specific Abs in serum and broncho-alveolar lavage (BAL) fluid post-challenge. Furthermore, vaccination with a live attenuated vaccine consisting of an Ft LVS superoxide dismutase (SodB) mutant, which has proven efficacious against the highly virulent Ft SchuS4 strain, demonstrated similar gender bias in protection post-Ft SchuS4 challenge. Of particular significance is the fact that these are the first studies to demonstrate that gender differences impact disease outcome in the case of lethal respiratory tularemia following mucosal vaccination. In addition, these studies further emphasize the fact that gender differences must be a serious consideration in any future tularemia vaccine development studies. Copyright © 2016 Elsevier Ltd. All

  20. Genome sequence of the endosymbiont Rickettsia peacockii and comparison with virulent Rickettsia rickettsii: identification of virulence factors.

    Directory of Open Access Journals (Sweden)

    Roderick F Felsheim

    2009-12-01

    Full Text Available Rickettsia peacockii, also known as the East Side Agent, is a non-pathogenic obligate intracellular bacterium found as an endosymbiont in Dermacentor andersoni ticks in the western USA and Canada. Its presence in ticks is correlated with reduced prevalence of Rickettsia rickettsii, the agent of Rocky Mountain Spotted Fever. It has been proposed that a virulent SFG rickettsia underwent changes to become the East Side Agent. We determined the genome sequence of R. peacockii and provide a comparison to a closely related virulent R. rickettsii. The presence of 42 chromosomal copies of the ISRpe1 transposon in the genome of R. peacockii is associated with a lack of synteny with the genome of R. rickettsii and numerous deletions via recombination between transposon copies. The plasmid contains a number of genes from distantly related organisms, such as part of the glycosylation island of Pseudomonas aeruginosa. Genes deleted or mutated in R. peacockii which may relate to loss of virulence include those coding for an ankyrin repeat containing protein, DsbA, RickA, protease II, OmpA, ScaI, and a putative phosphoethanolamine transferase. The gene coding for the ankyrin repeat containing protein is especially implicated as it is mutated in R. rickettsii strain Iowa, which has attenuated virulence. Presence of numerous copies of the ISRpe1 transposon, likely acquired by lateral transfer from a Cardinium species, are associated with extensive genomic reorganization and deletions. The deletion and mutation of genes possibly involved in loss of virulence have been identified by this genomic comparison. It also illustrates that the introduction of a transposon into the genome can have varied effects; either correlating with an increase in pathogenicity as in Francisella tularensis or a loss of pathogenicity as in R. peacockii and the recombination enabled by multiple transposon copies can cause significant deletions in some genomes while not in others.

  1. A wide extent of inter-strain diversity in virulent and vaccine strains of alphaherpesviruses.

    Directory of Open Access Journals (Sweden)

    Moriah L Szpara

    2011-10-01

    Full Text Available Alphaherpesviruses are widespread in the human population, and include herpes simplex virus 1 (HSV-1 and 2, and varicella zoster virus (VZV. These viral pathogens cause epithelial lesions, and then infect the nervous system to cause lifelong latency, reactivation, and spread. A related veterinary herpesvirus, pseudorabies (PRV, causes similar disease in livestock that result in significant economic losses. Vaccines developed for VZV and PRV serve as useful models for the development of an HSV-1 vaccine. We present full genome sequence comparisons of the PRV vaccine strain Bartha, and two virulent PRV isolates, Kaplan and Becker. These genome sequences were determined by high-throughput sequencing and assembly, and present new insights into the attenuation of a mammalian alphaherpesvirus vaccine strain. We find many previously unknown coding differences between PRV Bartha and the virulent strains, including changes to the fusion proteins gH and gB, and over forty other viral proteins. Inter-strain variation in PRV protein sequences is much closer to levels previously observed for HSV-1 than for the highly stable VZV proteome. Almost 20% of the PRV genome contains tandem short sequence repeats (SSRs, a class of nucleic acids motifs whose length-variation has been associated with changes in DNA binding site efficiency, transcriptional regulation, and protein interactions. We find SSRs throughout the herpesvirus family, and provide the first global characterization of SSRs in viruses, both within and between strains. We find SSR length variation between different isolates of PRV and HSV-1, which may provide a new mechanism for phenotypic variation between strains. Finally, we detected a small number of polymorphic bases within each plaque-purified PRV strain, and we characterize the effect of passage and plaque-purification on these polymorphisms. These data add to growing evidence that even plaque-purified stocks of stable DNA viruses exhibit

  2. A wide extent of inter-strain diversity in virulent and vaccine strains of alphaherpesviruses.

    Science.gov (United States)

    Szpara, Moriah L; Tafuri, Yolanda R; Parsons, Lance; Shamim, S Rafi; Verstrepen, Kevin J; Legendre, Matthieu; Enquist, L W

    2011-10-01

    Alphaherpesviruses are widespread in the human population, and include herpes simplex virus 1 (HSV-1) and 2, and varicella zoster virus (VZV). These viral pathogens cause epithelial lesions, and then infect the nervous system to cause lifelong latency, reactivation, and spread. A related veterinary herpesvirus, pseudorabies (PRV), causes similar disease in livestock that result in significant economic losses. Vaccines developed for VZV and PRV serve as useful models for the development of an HSV-1 vaccine. We present full genome sequence comparisons of the PRV vaccine strain Bartha, and two virulent PRV isolates, Kaplan and Becker. These genome sequences were determined by high-throughput sequencing and assembly, and present new insights into the attenuation of a mammalian alphaherpesvirus vaccine strain. We find many previously unknown coding differences between PRV Bartha and the virulent strains, including changes to the fusion proteins gH and gB, and over forty other viral proteins. Inter-strain variation in PRV protein sequences is much closer to levels previously observed for HSV-1 than for the highly stable VZV proteome. Almost 20% of the PRV genome contains tandem short sequence repeats (SSRs), a class of nucleic acids motifs whose length-variation has been associated with changes in DNA binding site efficiency, transcriptional regulation, and protein interactions. We find SSRs throughout the herpesvirus family, and provide the first global characterization of SSRs in viruses, both within and between strains. We find SSR length variation between different isolates of PRV and HSV-1, which may provide a new mechanism for phenotypic variation between strains. Finally, we detected a small number of polymorphic bases within each plaque-purified PRV strain, and we characterize the effect of passage and plaque-purification on these polymorphisms. These data add to growing evidence that even plaque-purified stocks of stable DNA viruses exhibit limited sequence

  3. Internal residual strain mapping in carburized chrome molybdenum steel after quenching by neutron strain scanning

    International Nuclear Information System (INIS)

    Sakaida, Yoshihisa; Serizawa, Takanobu; Manzanka, Michiya

    2011-01-01

    A hollow circular cylinder specimen with an annular U-notch of chrome molybdenum steel with 0.20 mass% C (SCM420) was carburized in carrier gas and quenched in oil bath. In order to determine the case depth, the specimen was cut off and carbon content and Vickers hardness gradients were measured experimentally near the carburized surface. The residual strain mapping in the interior of carburized cylinder was conducted nondestructively by neutron strain scanning. In this study, the neutron diffraction from Fe-211 plane was used for strain scanning. The neutron wavelength was tuned to 0.1654nm so that diffraction angle became about 90deg. Radial, hoop and axial residual strains were measured by scanning diffracting volume along the axial direction of cylinder specimen. Each residual strain was calculated from lattice spacing change. Unstressed lattice spacing was determined experimentally using reference coupon specimens that were cut from the interior of same carburized cylinder. As a result, the diffraction peak width at half height, FWHM, near the carburized surface was about 3.7 times wider than that of coupon specimens. On the other hand, the most peak widths in the interior equaled to that of coupon specimens. Peak width broadened slightly as the diffracting volume approached the carburized case layer. From the center to the quarter of cylinder specimen, the hoop and axial strains were tensile, and the radial one was compressive in the interior. From the quarter to the edge of the cylinder specimen, the hoop tensile strain increased, radial and axial strains changed to tensile and compressive, respectively. Therefore, the interior of the cylinder specimen was found to be deformed elastically to balance the existence of compressive residual stresses in the carburized case layer. (author)

  4. Generating strain signals under consideration of road surface profiles

    Science.gov (United States)

    Putra, T. E.; Abdullah, S.; Schramm, D.; Nuawi, M. Z.; Bruckmann, T.

    2015-08-01

    The current study aimed to develop the mechanism for generating strain signal utilising computer-based simulation. The strain data, caused by the acceleration, were undertaken from a fatigue data acquisition involving car movements. Using a mathematical model, the measured strain signals yielded to acceleration data used to describe the bumpiness of road surfaces. The acceleration signals were considered as an external disturbance on generating strain signals. Based on this comparison, both the actual and simulated strain data have similar pattern. The results are expected to provide new knowledge to generate a strain signal via a simulation.

  5. Hole doped Dirac states in silicene by biaxial tensile strain

    KAUST Repository

    Kaloni, Thaneshwor P.; Cheng, Yingchun; Schwingenschlö gl, Udo

    2013-01-01

    The effects of biaxial tensile strain on the structure, electronic states, and mechanical properties of silicene are studied by ab-initio calculations. Our results show that up to 5% strain the Dirac cone remains essentially at the Fermi level, while higher strain induces hole doped Dirac states because of weakened Si–Si bonds. We demonstrate that the silicene lattice is stable up to 17% strain. It is noted that the buckling first decreases with the strain (up to 10%) and then increases again, which is accompanied by a band gap variation. We also calculate the Grüneisen parameter and demonstrate a strain dependence similar to that of graphene.

  6. Hole doped Dirac states in silicene by biaxial tensile strain

    KAUST Repository

    Kaloni, Thaneshwor P.

    2013-03-11

    The effects of biaxial tensile strain on the structure, electronic states, and mechanical properties of silicene are studied by ab-initio calculations. Our results show that up to 5% strain the Dirac cone remains essentially at the Fermi level, while higher strain induces hole doped Dirac states because of weakened Si–Si bonds. We demonstrate that the silicene lattice is stable up to 17% strain. It is noted that the buckling first decreases with the strain (up to 10%) and then increases again, which is accompanied by a band gap variation. We also calculate the Grüneisen parameter and demonstrate a strain dependence similar to that of graphene.

  7. MM98.83 Quantification of Combined Strain Paths

    DEFF Research Database (Denmark)

    Nielsen, Morten Sturgård; Lindegren, Maria; Wanheim, Tarras

    1998-01-01

    When working with processes where large plastic deformation occurs, a way of desribing the deformation process is to view the whole deformation history as a curve in the 6-dimensional shear strain normal strain space, henceforth called a strain history curve (SHC). This paper focuses on the SHC...... 3D-plasticity. Adirect use of the SHC, is to measure the yield surface at different points at a SHC, thus establishing data describing the importance of strain rotations or even strain reversals within a process. Two subcases for displaying SHC will be mentioned:The plane strain case and the single...

  8. Chromosomal duplication strains of Aspergillus nidulans and their instability

    International Nuclear Information System (INIS)

    Azevedo, J.L. de; Almeida Okino, L.M. de

    1981-01-01

    Strains of Aspergillus nidulans with chromosomal duplication were obtained after gamma irradiation followed by crossing of the translocated strains with normal strains. From 20 analysed colonies, 12 have shown translocations induced by irradiation. Segregants from four of these translocation strains crossed to normal strains have shown to be unstable although presenting normal morphology. Two segregants were genetically analysed. The first one has shown a duplication of part of linkage groups VIII and the second one presented a duplication of a segment of linkage group V. These new duplication strains in A. nidulans open new perspectives of a more detailed study of the instability phenomenon in this fungus. (Author) [pt

  9. Printed strain sensors for early damage detection in engineering structures

    Science.gov (United States)

    Zymelka, Daniel; Yamashita, Takahiro; Takamatsu, Seiichi; Itoh, Toshihiro; Kobayashi, Takeshi

    2018-05-01

    In this paper, we demonstrate the analysis of strain measurements recorded using a screen-printed sensors array bonded to a metal plate and subjected to high strains. The analysis was intended to evaluate the capabilities of the printed strain sensors to detect abnormal strain distribution before actual defects (cracks) in the analyzed structures appear. The results demonstrate that the developed device can accurately localize the enhanced strains at the very early stage of crack formation. The promising performance and low fabrication cost confirm the potential suitability of the printed strain sensors for applications within the framework of structural health monitoring (SHM).

  10. Development of piping strain sensor for stress evaluation

    International Nuclear Information System (INIS)

    Takahama, Tsunemichi; Nishimura, Kazuma; Ninomiya, Seiichiro; Matsumoto, Yoshihiro; Harada, Yutaka

    2014-01-01

    In a small diameter piping, stresses are generated due to internal fluid or pump vibrations especially around the welding parts. Authors have successfully developed a pipe strain sensor which is able to measure such stresses. Unlike conventional methods using strain gages and adhesive bond, the sensor can measure the strain without putting adhesive bond on the piping surface. However, the strain sensor can provide measurements with a level of accuracy equivalent to that of conventional method using strain gages and adhesive bond. Accordingly, the strain sensor can significantly reduce the working time without any loss of the measurement accuracy. (author)

  11. Temperature and strain registration by fibre-optic strain sensor in the polymer composite materials manufacturing

    Science.gov (United States)

    Matveenko; Kosheleva; Shardakov; Voronkov

    2018-04-01

    The presence of process-induced strains induced by various manufacturing and operational factors is one of the characteristics of polymer composite materials (PCM). Conventional methods of registration and evaluation of process-induced strains can be laborious, time-consuming and demanding in terms of technical applications. The employment of embedded fibre-optic strain sensors (FOSS) offers a real prospect of measuring residual strains. This paper demonstrates the potential for using embedded FOSS for recording technological strains in a PCM plate. The PCM plate is manufactured from prepreg, using the direct compression-moulding method. In this method, the prepared reinforcing package is placed inside a mould, heated, and then exposed to compaction pressure. The examined technology can be used for positioning FOSS between the layers of the composite material. Fibre-optic sensors, interacting with the material of the examined object, make it possible to register the evolution of the strain process during all stages of polymer-composite formation. FOSS data were recorded with interrogator ASTRO X 327. The obtained data were processed using specially developed algorithms.

  12. Variation in the strain anisotropy of Zircaloy with temperature and strain

    International Nuclear Information System (INIS)

    Hindle, E.D.; Worswick, D.

    1984-01-01

    The strong crystallographic texture which is developed during the fabrication of zirconium-based alloys causes pronounced anisotropy in their mechanical properties, particularly deformation. The tendency for circular-section tension specimens with a high concentration of basal poles in one direction to become elliptical when deformed in tension has been used in this study to provide quantitative data on the effects of both strain and temperature on strain anisotropy. Tension tests were carried out over a temperature range of 293 to 1193 K on specimens machined from Zircaloy-2 plate. The strain anisotropy was found to increase markedly at temperatures over 923 K, reaching a maximum in the region of 1070 K. The strain anisotropy increased with increasing strain in this temperature region. The study was extended to Zircaloy-4 pressurized-water reactor fuel cladding by carrying out tube swelling tests and evaluating the axial deformation produced. Although scatter in the test results was higher than that exhibited in the tension tests, the general trend in the data was similar. The effects of the strain anisotropy observed are discussed in relation to the effects of temperature on the ductility of Zircaloy fuel cladding tubes during postulated largebreak loss-of-coolant accidents

  13. An Embeddable Strain Sensor with 30 Nano-Strain Resolution Based on Optical Interferometry

    Directory of Open Access Journals (Sweden)

    Chen Zhu

    2018-04-01

    Full Text Available A cost-effective, robust and embeddable optical interferometric strain sensor with nanoscale strain resolution is presented in this paper. The sensor consists of an optical fiber, a quartz rod with one end coated with a thin gold layer, and two metal shells employed to transfer the strain and orient and protect the optical fiber and the quartz rod. The optical fiber endface, combining with the gold-coated surface, forms an extrinsic Fabry–Perot interferometer. The sensor was firstly calibrated, and the result showed that our prototype sensor could provide a measurement resolution of 30 nano-strain (nε and a sensitivity of 10.01 µε/µm over a range of 1000 µε. After calibration of the sensor, the shrinkage strain of a cubic brick of mortar in real time during the drying process was monitored. The strain sensor was compared with a commercial linear variable displacement transducer, and the comparison results in four weeks demonstrated that our sensor had much higher measurement resolution and gained more detailed and useful information. Due to the advantages of the extremely simple, robust and cost-effective configuration, it is believed that the sensor is significantly beneficial to practical applications, especially for structural health monitoring.

  14. Strain mapping near a triple junction in strained Ni-based alloy using EBSD and biaxial nanogauges

    Energy Technology Data Exchange (ETDEWEB)

    Clair, A. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France); Foucault, M.; Calonne, O. [Areva ANP, Centre Technique Departement Corrosion-Chimie, 30 Bd de l' industrie, BP 181, 71205 Le Creusot (France); Lacroute, Y.; Markey, L.; Salazar, M.; Vignal, V. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France); Finot, E., E-mail: Eric.Finot@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France)

    2011-05-15

    Research highlights: > Surface strains measured using nanogauge were compared to the texture obtained by EBSD. > Statistics of the principal strain discern the grains according to the Schmid factor. > Strain hotspots were localized near a triple junction of alloy 600 under tensile loading. > Asymetrical profile of the GB strains is a criterion for surface cracking initiation. - Abstract: A key element for analyzing the crack initiation in strained polycrystalline alloys is the local quantification of the surface strain distribution according to the grain texture. Using electron backscattered diffraction, the local microstructure was determined to both localize a triple junction and deduce the local Schmid factors. Kernel average misorientation (KAM) was also used to map the areas of defect concentration. The maximum principal strain and the in-plane shear strain were quantified using the biaxial nanogauge. Distortions of the array of nanodots used as spot markers were analyzed near the triple junction. The crystallographic orientation and the surface strain were then investigated both statistically for each grain and locally at the grain boundaries. The superimposition of microstructure and strain maps allows the high strain gradient (reaching 3-fold the applied strain) to be localized at preferential grain boundaries near the triple junction. The Schmid factors and the KAM were compared to the maximum principal strain and the in-plane shear strain respectively. The polycrystalline deformation was attributable first to the rotation of some grains, followed by the elongation of all grains along their preferential activated slip systems.

  15. Graphene based strain sensor with LCP substrate

    Science.gov (United States)

    Nie, M.; Yang, H. S.; Xia, Y. H.

    2018-02-01

    A flexible strain sensor constructed by an efficient, low-cost fabrication strategy is presented in this paper. It is assembled by adhering grid-like graphene on LCP substrate. Kinds of measurement setup have been designed to verify that the proposed flexible sensor device is suitable to be used in health monitoring system. From the experiment results, it can be proved that the sensor exhibits the following features: ultra-light, relatively good sensitivity, high reversibility, superior physical robustness, easy fabrication. With the great performance of this flexible strain sensor, it is considered to play an important role in body monitoring, structural health monitoring system, fatigue detection and healthcare systems in the near future.

  16. Electronic transport in torsional strained Weyl semimetals

    Science.gov (United States)

    Soto-Garrido, Rodrigo; Muñoz, Enrique

    2018-05-01

    In a recent paper (Muñoz and Soto-Garrido 2017 J. Phys.: Condens. Matter 29 445302) we have studied the effects of mechanical strain and magnetic field on the electronic transport properties in graphene. In this article we extended our work to Weyl semimetals (WSM). We show that although the WSM are 3D materials, most of the analysis done for graphene (2D material) can be carried out. In particular, we studied the electronic transport through a cylindrical region submitted to torsional strain and external magnetic field. We provide exact analytical expressions for the scattering cross section and the transmitted electronic current. In addition, we show the node-polarization effect on the current and propose a recipe to measure the torsion angle from transmission experiments.

  17. Dynamic strain aging in Haynes 282 superalloy

    Directory of Open Access Journals (Sweden)

    Hörnqvist Magnus

    2014-01-01

    Full Text Available Haynes 282 is a newly introduced Ni-based superallony, developed to provide a combination of high-temperature mechanical properties, thermal stability and processability. The present contribution investigates the effect of dynamic strain aging (DSA on the deformation behaviour of Haynes 282 during monotonic and cyclic loading. It is shown that DSA (presumably related to carbon diffusion based on rough estimates of the activation energy completely dominates the development of the stress during cycling at intermediate temperatures, leading to extensive cyclic hardening and serrated yielding. However, no clear effects on the fatigue life or the resulting dislocation structure could be observed. The tensile properties were not severely affected, in spite of the presence of extensive serrated yielding, although a reduction in ductility was observed in the DSA temperature regime. During monotonic loading at lower strain rates indications of an additional DSA mechanism due to substitutional elements were observed.

  18. Transfer induced compressive strain in graphene

    DEFF Research Database (Denmark)

    Larsen, Martin Benjamin Barbour Spanget; Mackenzie, David; Caridad, Jose

    2014-01-01

    We have used spatially resolved micro Raman spectroscopy to map the full width at half maximum (FWHM) of the graphene G-band and the 2D and G peak positions, for as-grown graphene on copper catalyst layers, for transferred CVD graphene and for micromechanically exfoliated graphene, in order...... to characterize the effects of a transfer process on graphene properties. Here we use the FWHM(G) as an indicator of the doping level of graphene, and the ratio of the shifts in the 2D and G bands as an indicator of strain. We find that the transfer process introduces an isotropic, spatially uniform, compressive...... strain in graphene, and increases the carrier concentration....

  19. Gravitational waves from rotating strained neutron stars

    International Nuclear Information System (INIS)

    Jones, D I

    2002-01-01

    In this review we examine the dynamics and gravitational wave detectability of rotating strained neutron stars. The discussion is divided into two halves: triaxial stars and precessing stars. We summarize recent studies on how crustal strains and magnetic fields can sustain triaxiality, and suggest that Magnus forces connected with pinned superfluid vortices might contribute to deformation also. The conclusions that could be drawn following the successful gravitational wave detection of a triaxial star are discussed, and areas requiring further study identified. The latest ideas regarding free precession are then outlined, and the recent suggestion of Middleditch et al (Middleditch et al 2000 New Astronomy 5 243; 2000 Preprint astro-ph/0010044) that the remnant of SN1987A contains a freely precessing star, spinning down by gravitational wave energy loss, is examined critically. We describe what we would learn about neutron stars should the gravitational wave detectors prove this hypothesis to be correct

  20. SNIT: SNP identification for strain typing

    Directory of Open Access Journals (Sweden)

    Reifman Jaques

    2011-09-01

    Full Text Available Abstract With ever-increasing numbers of microbial genomes being sequenced, efficient tools are needed to perform strain-level identification of any newly sequenced genome. Here, we present the SNP identification for strain typing (SNIT pipeline, a fast and accurate software system that compares a newly sequenced bacterial genome with other genomes of the same species to identify single nucleotide polymorphisms (SNPs and small insertions/deletions (indels. Based on this information, the pipeline analyzes the polymorphic loci present in all input genomes to identify the genome that has the fewest differences with the newly sequenced genome. Similarly, for each of the other genomes, SNIT identifies the input genome with the fewest differences. Results from five bacterial species show that the SNIT pipeline identifies the correct closest neighbor with 75% to 100% accuracy. The SNIT pipeline is available for download at http://www.bhsai.org/snit.html