scholarly journals Francisella tularensis Live Vaccine Strain Folate Metabolism and Pseudouridine Synthase Gene Mutants Modulate Macrophage Caspase-1 Activation

2012 ◽  
Vol 81 (1) ◽  
pp. 201-208 ◽  
Author(s):  
Tyler K. Ulland ◽  
Ann M. Janowski ◽  
Blake W. Buchan ◽  
Matthew Faron ◽  
Suzanne L. Cassel ◽  
...  
Keyword(s):  
Francisella Tularensis ◽  
Vaccine Strain ◽  
Live Vaccine ◽  
Live Vaccine Strain ◽  
Wild Type ◽  
Content Type ◽  
Pseudouridine Synthase ◽  
Caspase 1

Francisella tularensisis a Gram-negative bacterium and the causative agent of the disease tularemia. Escape ofF. tularensisfrom the phagosome into the cytosol of the macrophage triggers the activation of the AIM2 inflammasome through a mechanism that is not well understood. Activation of the AIM2 inflammasome results in autocatalytic cleavage of caspase-1, resulting in the processing and secretion of interleukin-1β (IL-1β) and IL-18, which play a crucial role in innate immune responses toF. tularensis. We have identified the5-formyltetrahydrofolate cycloligasegene (FTL_0724) as being important forF. tularensislive vaccine strain (LVS) virulence. Infection of micein vivowith aF. tularensisLVSFTL_0724mutant resulted in diminished mortality compared to infection of mice with wild-type LVS. TheFTL_0724mutant also induced increased inflammasome-dependent IL-1β and IL-18 secretion and cytotoxicity in macrophagesin vitro. In contrast, infection of macrophages with aF. tularensisLVSrluD pseudouridine synthase(FTL_0699) mutant resulted in diminished IL-1β and IL-18 secretion from macrophagesin vitrocompared to infection of macrophages with wild-type LVS. In addition, theFTL_0699mutant was not attenuatedin vivo. These findings further illustrate thatF. tularensisLVS possesses numerous genes that influence its ability to activate the inflammasome, which is a key host strategy to control infection with this pathogenin vivo.

scholarly journals Interleukin-17 Protects against the Francisella tularensis Live Vaccine Strain but Not against a Virulent F. tularensis Type A Strain

2013 ◽  
Vol 81 (9) ◽  
pp. 3099-3105 ◽  
Author(s):  
Jerod A. Skyberg ◽  
MaryClare F. Rollins ◽  
Joshua W. Samuel ◽  
Marjorie D. Sutherland ◽  
John T. Belisle ◽  
...  
Keyword(s):  
Francisella Tularensis ◽  
Vaccine Strain ◽  
Type A ◽  
Live Vaccine ◽  
Interleukin 17 ◽  
Live Vaccine Strain ◽  
Wild Type ◽  
Content Type ◽  
Protein Levels ◽  
Ifn Γ

ABSTRACTFrancisella tularensisis a highly infectious intracellular bacterium that causes the zoonotic infection tularemia. While much literature exists on the host response toF. tularensisinfection, the vast majority of work has been conducted using attenuated strains ofFrancisellathat do not cause disease in humans. However, emerging data indicate that the protective immune response against attenuatedF. tularensisversusF. tularensistype A differs. Several groups have recently reported that interleukin-17 (IL-17) confers protection against the live vaccine strain (LVS) ofFrancisella. While we too have found that IL-17Rα−/−mice are more susceptible toF. tularensisLVS infection, our studies, using a virulent type A strain ofF. tularensis(SchuS4), indicate that IL-17Rα−/−mice display organ burdens and pulmonary gamma interferon (IFN-γ) responses similar to those of wild-type mice following infection. In addition, oral LVS vaccination conferred equivalent protection against pulmonary challenge with SchuS4 in both IL-17Rα−/−and wild-type mice. While IFN-γ was found to be critically important for survival in a convalescent model of SchuS4 infection, IL-17 neutralization from either wild-type or IFN-γ−/−mice had no effect on morbidity or mortality in this model. IL-17 protein levels were also higher in the lungs of mice infected with the LVS rather thanF. tularensistype A, while IL-23p19 mRNA expression was found to be caspase-1 dependent in macrophages infected with LVS but not SchuS4. Collectively, these results demonstrate that IL-17 is dispensable for host immunity to type AF. tularensisinfection, and that induced and protective immunity differs between attenuated and virulent strains ofF. tularensis.

scholarly journals TolC-Dependent Modulation of Host Cell Death by the Francisella tularensis Live Vaccine Strain

2014 ◽  
Vol 82 (5) ◽  
pp. 2068-2078 ◽  
Author(s):  
Christopher R. Doyle ◽  
Ji-An Pan ◽  
Patricio Mena ◽  
Wei-Xing Zong ◽  
David G. Thanassi
Keyword(s):  
Cell Death ◽  
Immune Responses ◽  
Host Cell ◽  
Francisella Tularensis ◽  
Vaccine Strain ◽  
Live Vaccine ◽  
Live Vaccine Strain ◽  
Type I ◽  
Content Type ◽  
Host Cell Death

ABSTRACTFrancisella tularensisis a facultative intracellular, Gram-negative pathogen and the causative agent of tularemia. We previously identified TolC as a virulence factor of theF. tularensislive vaccine strain (LVS) and demonstrated that a ΔtolCmutant exhibits increased cytotoxicity toward host cells and elicits increased proinflammatory responses compared to those of the wild-type (WT) strain. TolC is the outer membrane channel component used by the type I secretion pathway to export toxins and other bacterial virulence factors. Here, we show that the LVS delays activation of the intrinsic apoptotic pathway in a TolC-dependent manner, both during infection of primary macrophages and during organ colonization in mice. The TolC-dependent delay in host cell death is required forF. tularensisto preserve its intracellular replicative niche. We demonstrate that TolC-mediated inhibition of apoptosis is an active process and not due to defects in the structural integrity of the ΔtolCmutant. These findings support a model wherein the immunomodulatory capacity ofF. tularensisrelies, at least in part, on TolC-secreted effectors. Finally, mice vaccinated with the ΔtolCLVS are protected from lethal challenge and clear challenge doses faster than WT-vaccinated mice, demonstrating that the altered host responses to primary infection with the ΔtolCmutant led to altered adaptive immune responses. Taken together, our data demonstrate that TolC is required for temporal modulation of host cell death during infection byF. tularensisand highlight how shifts in the magnitude and timing of host innate immune responses may lead to dramatic changes in the outcome of infection.

scholarly journals Intranasal Interleukin-12 Treatment for Protection against Respiratory Infection with the Francisella tularensis Live Vaccine Strain

2005 ◽  
Vol 73 (4) ◽  
pp. 2306-2311 ◽  
Author(s):  
Nathalie S. Duckett ◽  
Sofia Olmos ◽  
Douglas M. Durrant ◽  
Dennis W. Metzger
Keyword(s):  
Respiratory Infection ◽  
Francisella Tularensis ◽  
Vaccine Strain ◽  
Live Vaccine ◽  
Interleukin 12 ◽  
Live Vaccine Strain ◽  
Wild Type ◽  
Intranasal Infection ◽  
Ifn Γ

ABSTRACT Francisella tularensis is a gram-negative intracellular bacterium that can induce lethal respiratory infection in humans and rodents. However, little is known about the role of innate or adaptive immunity in protection from respiratory tularemia. In the present study, the role of interleukin-12 (IL-12) in inducing protective immunity in the lungs against intranasal infection of mice with the live vaccine strain (LVS) of F. tularensis was investigated. It was found that gamma interferon (IFN-γ) and IL-12 were strictly required for protection, since mice deficient in IFN-γ, IL-12 p35, or IL-12 p40 all succumbed to LVS doses that were sublethal for wild-type mice. Furthermore, exogenous IL-12 treatment 24 h before intranasal infection with a lethal dose of LVS (10,000 CFU) significantly decreased bacterial loads in the lungs, livers, and spleens of wild-type BALB/c and C57BL/6 mice and allowed the animals to survive infection; such protection was not observed in IFN-γ-deficient mice. The resistance induced by IL-12 to LVS infection was still observed in NK cell-deficient beige mice but not in CD8−/− mice. These results demonstrate that exogenous IL-12 delivered intranasally can prevent respiratory tularemia through a mechanism that is at least partially dependent upon the expression of IFN-γ and CD8 T cells.

scholarly journals A Francisella tularensis Locus Required for Spermine Responsiveness Is Necessary for Virulence

2011 ◽  
Vol 79 (9) ◽  
pp. 3665-3676 ◽  
Author(s):  
Brian C. Russo ◽  
Joseph Horzempa ◽  
Dawn M. O'Dee ◽  
Deanna M. Schmitt ◽  
Matthew J. Brown ◽  
...  
Keyword(s):  
Francisella Tularensis ◽  
Febrile Illness ◽  
Host Cells ◽  
High Morbidity ◽  
Wild Type ◽  
Content Type ◽  
Infectious Dose ◽  
Schu S4

ABSTRACTTularemia is a debilitating febrile illness caused by the category A biodefense agentFrancisella tularensis. This pathogen infects over 250 different hosts, has a low infectious dose, and causes high morbidity and mortality. Our understanding of the mechanisms by whichF. tularensissenses and adapts to host environments is incomplete. Polyamines, including spermine, regulate the interactions ofF. tularensiswith host cells. However, it is not known whether responsiveness to polyamines is necessary for the virulence of the organism. Through transposon mutagenesis ofF. tularensissubsp.holarcticalive vaccine strain (LVS), we identified FTL_0883 as a gene important for spermine responsiveness. In-frame deletion mutants of FTL_0883 and FTT_0615c, the homologue of FTL_0883 inF. tularensissubsp.tularensisSchu S4 (Schu S4), elicited higher levels of cytokines from human and murine macrophages compared to wild-type strains. Although deletion of FTL_0883 attenuated LVS replication within macrophagesin vitro, the Schu S4 mutant with a deletion in FTT_0615c replicated similarly to wild-type Schu S4. Nevertheless, both the LVS and the Schu S4 mutants were significantly attenuatedin vivo. Growth and dissemination of the Schu S4 mutant was severely reduced in the murine model of pneumonic tularemia. This attenuation depended on host responses to elevated levels of proinflammatory cytokines. These data associate responsiveness to polyamines with tularemia pathogenesis and define FTL_0883/FTT_0615c as anF. tularensisgene important for virulence and evasion of the host immune response.

scholarly journals T-bet Regulates Immunity to Francisella tularensis Live Vaccine Strain Infection, Particularly in Lungs

2014 ◽  
Vol 82 (4) ◽  
pp. 1477-1490 ◽  
Author(s):  
Amanda A. Melillo ◽  
Oded Foreman ◽  
Catharine M. Bosio ◽  
Karen L. Elkins
Keyword(s):  
Francisella Tularensis ◽  
Vaccine Strain ◽  
Live Vaccine ◽  
Interleukin 17 ◽  
Live Vaccine Strain ◽  
Respiratory Protection ◽  
Necrosis Factor Alpha ◽  
Secondary Challenge ◽  
Ifn Γ

ABSTRACTUpregulation of the transcription factor T-bet is correlated with the strength of protection against secondary challenge with the live vaccine strain (LVS) ofFrancisella tularensis. Thus, to determine if this mediator had direct consequences in immunity to LVS, we examined its role in infection. Despite substantialin vivogamma interferon (IFN-γ) levels, T-bet-knockout (KO) mice infected intradermally (i.d.) or intranasally (i.n.) with LVS succumbed to infection with doses 2 log units less than those required for their wild-type (WT) counterparts, and exhibited significantly increased bacterial burdens in the lung and spleen. Lungs of LVS-infected T-bet-KO mice contained fewer lymphocytes and more neutrophils and interleukin-17 than WT mice. LVS-vaccinated T-bet-KO mice survived lethal LVS intraperitoneal secondary challenge but not high doses of LVS i.n. challenge, independently of the route of vaccination. Immune T lymphocytes from the spleens of i.d. LVS-vaccinated WT or KO mice controlled intracellular bacterial replication in anin vitrococulture system, but cultures with T-bet-KO splenocyte supernatants contained less IFN-γ and increased amounts of tumor necrosis factor alpha. In contrast, immune T-bet-KO lung lymphocytes were greatly impaired in controlling intramacrophage growth of LVS; this functional defect is the likely mechanism underpinning the lack of respiratory protection. Taken together, T-bet is important in host resistance to primary LVS infection and i.n. secondary challenge. Thus, T-bet represents a true, useful correlate for immunity to LVS.

scholarly journals In vitro and in vivo characterization of chimeric duck Tembusu virus based on Japanese encephalitis live vaccine strain SA14-14-2

2016 ◽  
Vol 97 (7) ◽  
pp. 1551-1556 ◽  
Author(s):  
Hong-Jiang Wang ◽  
Long Liu ◽  
Xiao-Feng Li ◽  
Qing Ye ◽  
Yong-Qiang Deng ◽  
...  
Keyword(s):  
Vaccine Strain ◽  
Japanese Encephalitis ◽  
Live Vaccine ◽  
Live Vaccine Strain ◽  
Duck Tembusu Virus ◽  
Tembusu Virus ◽  
In Vivo Characterization

scholarly journals Differing Effects of Interleukin-10 on Cutaneous and Pulmonary Francisella tularensis Live Vaccine Strain Infection

2013 ◽  
Vol 81 (6) ◽  
pp. 2022-2027 ◽  
Author(s):  
Dennis W. Metzger ◽  
Sharon L. Salmon ◽  
Girish Kirimanjeswara
Keyword(s):  
Francisella Tularensis ◽  
Vaccine Strain ◽  
Pulmonary Infection ◽  
Interleukin 10 ◽  
Live Vaccine ◽  
Live Vaccine Strain ◽  
Content Type ◽  
Infectious Dose ◽  
Therapeutic Benefits

ABSTRACTWe investigated the role of interleukin-10 (IL-10) in cutaneous and pulmonary infection withFrancisella tularensis. We found that after intradermal challenge of mice with the live vaccine strain (LVS) ofF. tularensis, splenic IL-10 levels increased rapidly and reached a peak 5 days after infection. However, IL-10 expression after infection was detrimental, since IL-10−/−mice showed increased bacterial clearance and were resistant to an infectious dose (>106CFU/mouse) that was uniformly lethal for IL-10+/+mice. Furthermore, IL-10+/+mice treated with neutralizing anti-IL-10R monoclonal antibody were able to survive lethal cutaneous LVS challenge. The presence of IL-10 appeared to restrain the expression of IL-17, since high levels of splenic IL-17 were observed after intradermal LVS infection only in IL-10−/−mice. Furthermore, treatment with neutralizing anti-IL-17R antibody ablated the enhanced survival observed in IL-10−/−mice. However, neutralization of IL-10 activity in IL-17R−/−mice failed to provide protection. Thus, IL-10 suppresses a protective IL-17 response that is necessary for resistance to cutaneous LVS infection. Surprisingly, however, IL-10−/−mice were significantly more susceptible to pulmonary infection with LVS. Finally, although IL-10 is a critical and novel regulator of immunity toF. tularensisLVS infection, its effects were masked during infection with the highly virulent SchuS4 strain. Taken together, these findings suggest that differentially regulating expression of the IL-10 pathway in various tissues could ultimately have prophylactic and therapeutic benefits for protection against tularemia.

scholarly journals Protective Role for Macrophages in Respiratory Francisella tularensis Infection

2017 ◽  
Vol 85 (6) ◽  
Author(s):  
Donald J. Steiner ◽  
Yoichi Furuya ◽  
Michael B. Jordan ◽  
Dennis W. Metzger
Keyword(s):  
Francisella Tularensis ◽  
Protective Role ◽  
Interleukin 12 ◽  
Wild Type ◽  
Content Type ◽  
Highly Sensitive ◽  
Neutrophil Depletion ◽  
Ifn Γ

ABSTRACT Francisella tularensis causes lethal pneumonia following infection of the lungs by targeting macrophages for intracellular replication; however, macrophages stimulated with interferon gamma (IFN-γ) can resist infection in vitro. We therefore hypothesized that the protective effect of IFN-γ against F. tularensis in vivo requires macrophages receptive to stimulation. We found that the lethality of pulmonary F. tularensis LVS infection was exacerbated under conditions of alveolar macrophage depletion and in mice with a macrophage-specific defect in IFN-γ signaling (termed mice with macrophages insensitive to IFN-γ [MIIG mice]). We previously found that treatment with exogenous interleukin 12 (IL-12) protects against F. tularensis infection; this protection was lost in MIIG mice. MIIG mice also exhibited reduced neutrophil recruitment to the lungs following infection. Systemic neutrophil depletion was found to render wild-type mice highly sensitive to respiratory F. tularensis infection, and depletion beginning at 3 days postinfection led to more pronounced sensitivity than depletion beginning prior to infection. Furthermore, IL-12-mediated protection required NADPH oxidase activity. These results indicate that lung macrophages serve a critical protective role in respiratory F. tularensis LVS infection. Macrophages require IFN-γ signaling to mediate protection, which ultimately results in recruitment of neutrophils to further aid in survival from infection.

scholarly journals Susceptibility to Secondary Francisella tularensis Live Vaccine Strain Infection in B-Cell-Deficient Mice Is Associated with Neutrophilia but Not with Defects in Specific T-Cell-Mediated Immunity

2001 ◽  
Vol 69 (1) ◽  
pp. 194-203 ◽  
Author(s):  
Catharine M. Bosio ◽  
Karen L. Elkins
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Francisella Tularensis ◽  
Vaccine Strain ◽  
Culture System ◽  
Live Vaccine ◽  
Cell Mediated Immunity ◽  
Live Vaccine Strain ◽  
Wild Type

ABSTRACT Previous studies have demonstrated a role for B cells, not associated with antibody production, in protection against lethal secondary infection of mice with Francisella tularensislive vaccine strain (LVS). However, the mechanism by which B cells contribute to this protection is not known. To study the specific role of B cells during secondary LVS infection, we developed an in vitro culture system that mimics many of the same characteristics of in vivo infection. Using this culture system, we showed that B cells do not directly control LVS infection but that control of LVS growth is mediated primarily by LVS-primed T cells. Importantly, B cells were not required for the generation of effective memory T cells since LVS-primed, B-cell-deficient (BKO) mice generated CD4+ and CD8+ T cells that controlled LVS infection similarly to LVS-primed CD4+ and CD8+ T cells from wild-type mice. The control of LVS growth appeared to depend primarily on gamma interferon and nitric oxide and was similar in wild-type and BKO mice. Rather, the inability of BKO mice to survive secondary LVS infection was associated with marked neutrophil influx into the spleen very early after challenge. The neutrophilia was directly associated with B cells, since BKO mice reconstituted with naive B cells prior to a secondary challenge with LVS had decreased bacterial loads and neutrophils in the spleen and survived.

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