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1.
Infect Immun ; 89(4)2021 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-33318138

RESUMO

Typhoid and paratyphoid fevers have a high incidence worldwide and coexist in many geographical areas, especially in low-middle-income countries (LMIC) in South and Southeast Asia. There is extensive consensus on the urgent need for better and affordable vaccines against systemic Salmonella infections. Generalized modules for membrane antigens (GMMA), outer membrane exosomes shed by Salmonella bacteria genetically manipulated to increase blebbing, resemble the bacterial surface where protective antigens are displayed in their native environment. Here, we engineered S Paratyphi A using the pDC5-viaB plasmid to generate GMMA displaying the heterologous S Typhi Vi antigen together with the homologous O:2 O antigen. The presence of both Vi and O:2 was confirmed by flow cytometry on bacterial cells, and their amount was quantified on the resulting vesicles through a panel of analytical methods. When tested in mice, such GMMA induced a strong antibody response against both Vi and O:2, and these antibodies were functional in a serum bactericidal assay. Our approach yielded a bivalent vaccine candidate able to induce immune responses against different Salmonella serovars, which could benefit LMIC residents and travelers.


Assuntos
Febre Paratifoide/imunologia , Febre Paratifoide/microbiologia , Polissacarídeos Bacterianos/imunologia , Polissacarídeos Bacterianos/metabolismo , Salmonella paratyphi A/fisiologia , Vesículas Transportadoras/metabolismo , Vacinas Combinadas/imunologia , Animais , Antígenos de Bactérias/imunologia , Modelos Animais de Doenças , Humanos , Imunização , Imunogenicidade da Vacina/imunologia , Camundongos , Antígenos O/imunologia , Febre Paratifoide/prevenção & controle , Vacinas Combinadas/administração & dosagem
2.
J Antimicrob Chemother ; 75(10): 2914-2918, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-32613238

RESUMO

OBJECTIVES: To determine the immune cell populations associated with Salmonella enterica serovar Typhimurium before and after ciprofloxacin treatment using a murine model of systemic infection. The effect of depletion of immune cells associating with Salmonella on treatment outcome was also determined. METHODS: We infected mice with a Salmonella enterica serovar Typhimurium strain expressing GFP and used multicolour flow cytometry to identify splenic immune cell populations associating with GFP-positive Salmonella before and after treatment with ciprofloxacin. This was followed by depletion of different immune cell populations using antibodies and liposomes. RESULTS: Our results identified CD11b+CD11chi/lo (dendritic cells/macrophages) and Ly6G+CD11b+ (neutrophils) leucocytes as the main host cell populations that are associated with Salmonella after ciprofloxacin treatment. We therefore proceeded to test the effects of depletion of such populations during treatment. We show that depletion of Ly6G+CD11b+ populations resulted in an increase in the number of viable bacterial cells in the spleen at the end of ciprofloxacin treatment. Conversely, treatment with clodronate liposomes during antimicrobial treatment, which depleted the CD11b+CD11chi/lo populations, resulted in lower numbers of viable bacteria in the tissues. CONCLUSIONS: Our study identified host cells where Salmonella bacteria persist during ciprofloxacin treatment and revealed a dual and opposing effect of removal of Ly6G+CD11b+ and CD11b+CD11chi/lo host cells on the efficacy of antimicrobial treatment. This suggests a dichotomy in the role of these populations in clearance/persistence of Salmonella during antimicrobial treatment.


Assuntos
Salmonelose Animal , Infecções por Salmonella , Salmonella enterica , Animais , Ciprofloxacina/farmacologia , Camundongos , Neutrófilos , Infecções por Salmonella/tratamento farmacológico , Salmonelose Animal/tratamento farmacológico , Baço
3.
J Theor Biol ; 435: 218-228, 2017 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-28919397

RESUMO

Recent technical developments in microbiology have led to new discoveries on the within-host dynamics of bacterial infections in laboratory animals. In particular, they have highlighted the importance of stochastic bottlenecks at the onset of invasive disease. A number of approaches exist for bottleneck-size estimation with respect to within-host bacterial infections; however, some are more appropriate than others under certain circumstances. A Bayesian comparison of several approaches is made in terms of the availability of isogenic multitype bacteria (e.g., WITS), knowledge of post-bottleneck dynamics, and the suitability of dilution with monotype bacteria. A sampling approach to bottleneck-size estimation is also introduced. The results are summarised by a guiding flowchart, which we hope will promote the use of quantitative models in microbiology to refine the analysis of animal experiment data.


Assuntos
Infecções Bacterianas/microbiologia , Teorema de Bayes , Modelos Biológicos , Animais , Interações Hospedeiro-Patógeno , Microbiota
4.
J Antimicrob Chemother ; 72(12): 3390-3397, 2017 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-28962012

RESUMO

OBJECTIVES: We determined the interactions between efficacy of antibiotic treatment, pathogen growth rates and between-organ spread during systemic Salmonella infections. METHODS: We infected mice with isogenic molecularly tagged subpopulations of either a fast-growing WT or a slow-growing ΔaroC Salmonella strain. We monitored viable bacterial numbers and fluctuations in the proportions of each bacterial subpopulation in spleen, liver, blood and mesenteric lymph nodes (MLNs) before, during and after the cessation of treatment with ampicillin and ciprofloxacin. RESULTS: Both antimicrobials induced a reduction in viable bacterial numbers in the spleen, liver and blood. This reduction was biphasic in infections with fast-growing bacteria, with a rapid initial reduction followed by a phase of lower effect. Conversely, a slow and gradual reduction of the bacterial load was seen in infections with the slow-growing strain, indicating a positive correlation between bacterial net growth rates and the efficacy of ampicillin and ciprofloxacin. The viable numbers of either bacterial strain remained constant in MLNs throughout the treatment with a relapse of the infection with WT bacteria occurring after cessation of the treatment. The frequency of each tagged bacterial subpopulation was similar in the spleen and liver, but different from that of the MLNs before, during and after treatment. CONCLUSIONS: In Salmonella infections, bacterial growth rates correlate with treatment efficacy. MLNs are a site with a bacterial population structure different to those of the spleen and liver and where the total viable bacterial load remains largely unaffected by antimicrobials, but can resume growth after cessation of treatment.


Assuntos
Ampicilina/administração & dosagem , Antibacterianos/administração & dosagem , Carga Bacteriana , Ciprofloxacina/administração & dosagem , Infecções por Salmonella/microbiologia , Salmonella/isolamento & purificação , Sepse/microbiologia , Estruturas Animais/microbiologia , Animais , Sangue/microbiologia , Modelos Animais de Doenças , Feminino , Camundongos Endogâmicos C57BL , Salmonella/efeitos dos fármacos , Infecções por Salmonella/tratamento farmacológico , Sepse/tratamento farmacológico , Análise Espaço-Temporal
5.
Phytomedicine ; 25: 52-60, 2017 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-28190471

RESUMO

BACKGROUND: Plant lectins have long been used in biomedical research as immunomodulators against tumor cells and microbial infections. PURPOSE: To test the ability of plant lectins ConBr (Canavalia brasiliensis) and CFL (Cratylia argentea) to activate antimicrobial and immunomodulatory activities of murine peritoneal macrophages (pMØ) infected with a virulent strain of Salmonella enterica serovar Typhimurium (STm). METHODS: We incubated pMØ with non-toxic amounts of ConBr and CFL either before (preventive schedule) or after (curative schedule) exposure to STm. RESULTS: In uninfected pMØ, ConBr and CFL greatly increased levels of mRNA transcripts for IL-1ß, TNF-α and IL-6 and the inducible nitric oxide synthase (iNOs), but not IL-10 and IL-12. Exposure to naïve splenocytes of culture supernatants of pMØ previously stimulated with CFL resulted in expression of IL-12 and IFN-γ. Both preventive and curative treatment schedules significantly reduced the intracellular load of Salmonella. Experiments in infected macrophages exposed to lectins in the preventive schedule showed that mRNA transcripts for IL-6 and TNF-α were increased by CFL, whereas ConBr enhanced IL-12 (subunit p40). In the curative schedule, CFL induced significant expression of IL-12 (p40) whereas ConBr enhanced expression IL-1ß and TNF-α genes. The lectin treatments did not influence on iNOs expression in pMØ infected with STm C5 regardless of the treatment schedule. Curative treatments with CFL increased approximately 130-fold expression of TLR-4 whist expression of TLR-9 was increased by treatments with ConBr. CONCLUSION: We conclude that lectins ConBr and CFL have immunomodulatory properties that are beneficial on control of cells infected by Salmonella.


Assuntos
Citocinas/metabolismo , Fabaceae/química , Macrófagos Peritoneais/efeitos dos fármacos , Lectinas de Plantas/farmacologia , Salmonella typhimurium/efeitos dos fármacos , Receptores Toll-Like/metabolismo , Animais , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Canavalia/química , Fatores Imunológicos/farmacologia , Fatores Imunológicos/uso terapêutico , Inflamação/metabolismo , Interleucina-12/metabolismo , Interleucina-1beta/metabolismo , Interleucina-6/metabolismo , Macrófagos Peritoneais/metabolismo , Macrófagos Peritoneais/microbiologia , Camundongos , Óxido Nítrico Sintase Tipo II/metabolismo , Fitoterapia , Lectinas de Plantas/uso terapêutico , Infecções por Salmonella/tratamento farmacológico , Infecções por Salmonella/metabolismo , Infecções por Salmonella/microbiologia , Sorogrupo , Transdução de Sinais/efeitos dos fármacos , Fator de Necrose Tumoral alfa
6.
Infect Immun ; 83(3): 996-1007, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25547792

RESUMO

Nontyphoidal salmonellae, particularly Salmonella enterica serovar Typhimurium, are a major cause of invasive disease in Africa, affecting mainly young children and HIV-infected individuals. Glycoconjugate vaccines provide a safe and reliable strategy against invasive polysaccharide-encapsulated pathogens, and lipopolysaccharide (LPS) is a target of protective immune responses. With the aim of designing an effective vaccine against S. Typhimurium, we have synthesized different glycoconjugates, by linking O-antigen and core sugars (OAg) of LPS to the nontoxic mutant of diphtheria toxin (CRM(197)). The OAg-CRM(197) conjugates varied in (i) OAg source, with three S. Typhimurium strains used for OAg extraction, producing OAg with differences in structural specificities, (ii) OAg chain length, and (iii) OAg/CRM(197) ratio. All glycoconjugates were compared for immunogenicity and ability to induce serum bactericidal activity in mice. In vivo enhancement of bacterial clearance was assessed for a selected S. Typhimurium glycoconjugate by challenge with live Salmonella. We found that the largest anti-OAg antibody responses were elicited by (i) vaccines synthesized from OAg with the highest glucosylation levels, (ii) OAg composed of mixed- or medium-molecular-weight populations, and (iii) a lower OAg/CRM(197) ratio. In addition, we found that bactericidal activity can be influenced by S. Typhimurium OAg strain, most likely as a result of differences in OAg O-acetylation and glucosylation. Finally, we confirmed that mice immunized with the selected OAg-conjugate were protected against S. Typhimurium colonization of the spleen and liver. In conclusion, our findings indicate that differences in the design of OAg-based glycoconjugate vaccines against invasive African S. Typhimurium can have profound effects on immunogenicity and therefore optimal vaccine design requires careful consideration.


Assuntos
Anticorpos Antibacterianos/biossíntese , Glicoconjugados/imunologia , Antígenos O/imunologia , Salmonelose Animal/prevenção & controle , Vacinas contra Salmonella/imunologia , Salmonella typhimurium/efeitos dos fármacos , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/imunologia , Toxina Diftérica/genética , Toxina Diftérica/imunologia , Desenho de Fármacos , Feminino , Glicoconjugados/administração & dosagem , Glicoconjugados/química , Glicosilação , Humanos , Fígado/efeitos dos fármacos , Fígado/imunologia , Fígado/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Mutação , Antígenos O/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Salmonelose Animal/imunologia , Salmonelose Animal/microbiologia , Vacinas contra Salmonella/administração & dosagem , Vacinas contra Salmonella/química , Salmonella typhimurium/imunologia , Salmonella typhimurium/patogenicidade , Baço/efeitos dos fármacos , Baço/imunologia , Baço/microbiologia , Relação Estrutura-Atividade , Vacinação
7.
Vaccine ; 28(4): 940-9, 2010 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-19925904

RESUMO

The F(0)F(1) ATPase plays a central role in both the generation of ATP and the utilisation of ATP for cellular processes such as rotation of bacterial flagella. We have deleted the entire operon encoding the F(0)F(1) ATPase, as well as genes encoding individual F(0) or F(1) subunits, in Salmonella enteric serovar Typhimurium. These mutants were attenuated for virulence, as assessed by bacterial counts in the livers and spleens of intravenously infected mice. The attenuated in vivo growth of the entire atp operon mutant was complemented by the insertion of the atp operon into the malXY pseudogene region. Following clearance of the attenuated mutants from the organs, mice were protected against challenge with the virulent wild type parent strain. We have shown that the F(0)F(1) ATPase is important for bacterial growth in vivo and that atp mutants are effective live attenuated vaccines against Salmonella infection.


Assuntos
ATPases Bacterianas Próton-Translocadoras/genética , Deleção de Genes , Vacinas contra Salmonella/genética , Vacinas contra Salmonella/imunologia , Salmonella typhimurium/enzimologia , Salmonella typhimurium/patogenicidade , Animais , Contagem de Colônia Microbiana , Feminino , Genes Bacterianos , Teste de Complementação Genética , Fígado/microbiologia , Camundongos , Camundongos Endogâmicos BALB C , Óperon , Salmonelose Animal/microbiologia , Salmonella typhimurium/genética , Salmonella typhimurium/imunologia , Baço/microbiologia , Vacinas Atenuadas/genética , Vacinas Atenuadas/imunologia , Virulência
8.
Infect Immun ; 78(1): 326-36, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19884329

RESUMO

In Salmonella enterica serovar Typhimurium, trxA encodes thioredoxin 1, a small, soluble protein with disulfide reductase activity, which catalyzes thiol disulfide redox reactions in a variety of substrate proteins. Thioredoxins are involved as antioxidants in defense against oxidative stresses, such as exposure to hydrogen peroxide and hydroxyl radicals. We have made a defined, complete deletion of trxA in the mouse-virulent S. Typhimurium strain SL1344 (SL1344 trxA), replacing the gene with a kanamycin resistance gene cassette. SL1344 trxA was attenuated for virulence in BALB/c mice by the oral and intravenous routes and when used in immunization experiments provided protection against challenge with the virulent parent strain. SL1344 trxA induced less inflammation in murine spleens and livers than SL3261, the aroA mutant, live attenuated vaccine strain. The reduced splenomegaly observed following infection with SL1344 trxA was partially attributed to a reduction in the number of both CD4(+) and CD8(+) T cells and B lymphocytes in the spleen and reduced infiltration by CD11b(+) cells into the spleen compared with spleens from mice infected with SL3261. This less severe pathological response indicates that a trxA mutation might be used to reduce reactogenicity of live attenuated vaccine strains. We tested this by deleting trxA in SL3261. SL3261 trxA was also less inflammatory than SL3261 but was slightly less effective as a vaccine strain than either the SL3261 parent strain or SL1344 trxA.


Assuntos
Proteínas de Bactérias/imunologia , Proteínas de Bactérias/metabolismo , Inflamação/induzido quimicamente , Salmonelose Animal/prevenção & controle , Vacinas contra Salmonella/imunologia , Salmonella typhimurium/metabolismo , Animais , Proteínas de Bactérias/genética , Injeções Intravenosas , Lipopolissacarídeos , Fígado/patologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Mutação , Salmonelose Animal/patologia , Vacinas contra Salmonella/administração & dosagem , Vacinas contra Salmonella/efeitos adversos , Salmonella typhimurium/genética , Salmonella typhimurium/imunologia , Baço/patologia , Fatores de Tempo , Receptor 4 Toll-Like/genética , Virulência
9.
J Bacteriol ; 190(2): 769-71, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18024511

RESUMO

LuxS catalyzes the synthesis of the quorum-sensing signaling molecule autoinducer 2. We show that in Salmonella enterica serovar Typhimurium, deletion of the luxS gene polarizes flagellar phase variation toward the more immunogenic phase 1 flagellin. This phenotype is complementable by luxS in trans but is independent of quorum-sensing signals.


Assuntos
Proteínas de Bactérias/metabolismo , Liases de Carbono-Enxofre/metabolismo , Flagelos/química , Flagelina/metabolismo , Salmonella typhimurium/metabolismo , Proteínas de Bactérias/genética , Liases de Carbono-Enxofre/genética , Flagelos/imunologia , Flagelina/imunologia , Deleção de Genes , Teste de Complementação Genética , Percepção de Quorum
10.
Br Poult Sci ; 46(3): 261-7, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16050178

RESUMO

Phagocytes limit replication or kill ingested organisms by producing toxic reactive oxygen and nitrogen species via NADPH oxidase and inducible nitric oxide synthase (iNOS). The present experiments were to investigate the production and the possible roles of superoxide, hydrogen peroxide (H2O2) and nitric oxide (NO) in the MQ-NCSU chicken macrophage cell line infected with Salmonella in vitro. After infection, intracellular Salmonella viable counts remained constant until 24 h post infection (PI) and started to decline from 48 h PI. Infection of cells with S. Typhimurium, S. Enteritidis and S. Gallinarum, as well as exposure to S. Enteritidis LPS induced low, but significant concentrations of superoxide 1 to 2 h PI, as determined by reduction of ferricytochrome c. There was no difference in superoxide production in infected cells and control cells after 4 h. Increased H2O2 was observed from cells infected with all the different Salmonella species between 2 and 3 h of infection. Nitrite was always greater in infected cells compared to uninfected cells at all times. However, Salmonella was not completely eliminated from the cells though these cells are capable of eliciting a noticeable oxidative burst response and great nitrosative responses, indicating that a strong oxidative burst (and other mechanism/s) is essential for the elimination of intracellular Salmonella.


Assuntos
Galinhas/imunologia , Galinhas/microbiologia , Macrófagos/metabolismo , Óxido Nítrico/metabolismo , Estresse Oxidativo , Salmonella enterica/fisiologia , Animais , Linhagem Celular , Galinhas/metabolismo , Peróxido de Hidrogênio/metabolismo , Macrófagos/microbiologia , Salmonella enterica/imunologia , Superóxidos/metabolismo , Fatores de Tempo
11.
New Microbiol ; 26(4): 399-404, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-14596352

RESUMO

Several cytokines are involved in the host response to Leishmania. However, the role played by cytokines during infection with different species of Leishmania is not univocal. In this work, the production of tumor necrosis factor alpha (TNFalpha) and interleukin 18 (IL-18) during interaction of human phagocytes with Leishmania major or L. donovani was comparatively investigated. Peripheral blood mononuclear cells (PBMC) and monocytes from healthy donors were used. The release of TNFalpha and IL-18 during infection of cells with different species of Leishmania "in vitro" was evaluated. L. donovani induced in both PBMC and monocytes significantly more TNFalpha and IL-18 with respect to L. major. The amounts of TNFalpha released by PBMC were always significantly higher than those released by monocytes of the same donors.


Assuntos
Interleucina-18/metabolismo , Leishmania donovani , Leishmania major , Leishmaniose Cutânea/imunologia , Leishmaniose Visceral/imunologia , Fator de Necrose Tumoral alfa/metabolismo , Animais , Células Cultivadas , Humanos , Leucócitos Mononucleares/citologia , Leucócitos Mononucleares/metabolismo , Leucócitos Mononucleares/microbiologia
12.
New Microbiol ; 26(2): 227-31, 2003 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-12737207

RESUMO

It is well known that inflammation induced by Helicobacter pylori is characterized by the local production of cytokines and chemokines. In the present study, we analyse the kinetics of MCP-1, IL-12 and IL-4 induction during the interaction of peripheral blood mononuclear cells with killed and/or live H. pylori. Our results demonstrate that live H. pylori does not induce IL-4 release whereas it stimulates MCP-1 and IL-12 production. In addition, the neutralization of IL-12 with monoclonal antibodies determines a lower MCP-1 release. These data demonstrate that MCP-1 production is in part supported by IL-12 induced by live H. pylori. On the contrary, killed H. pylori stimulates the IL-4 but not MCP-1 and IL-12 production. The combined treatment with killed and live H. pylori upregulates the IL-4 production and at the same time downregulates IL-12 and MCP-1 production.


Assuntos
Citocinas/biossíntese , Helicobacter pylori/patogenicidade , Leucócitos Mononucleares/imunologia , Quimiocina CCL2/análise , Quimiocina CCL2/biossíntese , Relação Dose-Resposta Imunológica , Helicobacter pylori/química , Humanos , Inflamação/imunologia , Interleucina-12/análise , Interleucina-12/biossíntese , Interleucina-4/análise , Interleucina-4/biossíntese , Cinética
13.
New Microbiol ; 25(3): 335-40, 2002 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12173776

RESUMO

Chemokines represent a large family of proinflammatory proteins that orchestrate leukocyte trafficking to sites of viral infection. Human Herpes virus type 6 (HHV-6) is a typical immunosuppressive agent, as suggested by its tropism. In this study the production of monocyte chemoattractant protein-1 (MCP-1) and interleukin-10 (IL-10) by human peripheral blood monocytes was evaluated during HHV-6 infection. Our results demonstrate that HHV-6 infection triggers monocytes to release MCP-1 and IL-10. The addition of exogenous recombinant MCP-1 upregulates the release of extracellular virus, whereas does not influence the percentage of viral-antigen positive cells. Furthermore, the addition of monoclonal antibodies anti-IL-10 down-regulates MCP-1 release induced by HHV-6. These findings indicate that IL-10 and MCP-1 production was closely related and that the marked amounts of MCP-1 were supported not only by virus but also by virus-induced IL-10.


Assuntos
Quimiocina CCL2/imunologia , Regulação da Expressão Gênica/imunologia , Infecções por Herpesviridae/imunologia , Herpesvirus Humano 6/imunologia , Monócitos/imunologia , Monócitos/virologia , Antígenos Virais/imunologia , Antígenos Virais/metabolismo , Quimiocina CCL2/biossíntese , Quimiocina CCL2/farmacologia , Efeito Citopatogênico Viral/imunologia , Infecções por Herpesviridae/metabolismo , Herpesvirus Humano 6/metabolismo , Humanos , Interleucina-10/imunologia , Interleucina-10/farmacologia , Monócitos/metabolismo
14.
New Microbiol ; 25(2): 247-52, 2002 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-12019734

RESUMO

The mechanisms by which H. pylori colonizes and persists within the gastric mucosa are poorly understood. The induction and maintenance of gastric inflammation appear to depend on the complex interaction between a number of cytokines and chemokines. The gastric immune response observed "in vivo", during H. pylori infection, is characterized by a polarization of Th1 cell type that seems to be responsible for gastric pathology. The purpose of this study was to test the direct effect of H. pylori (live or gentamicin-killed) on human PBMC in order to evaluate the "in vitro" Th1-Th2 balance by monitoring IL-18, IFNgamma and IL-10 production. This study demonstrates for the first time that "in vitro" pretreatment with gentamicin-killed H. pylori of PBMC, followed by infection with live bacteria, downregulates the production of inflammatory cytokines such as IL-18 and IFNgamma Our results provide a possible strategy to restore the immunological disorders determined by H. pylori infection.


Assuntos
Citocinas/biossíntese , Helicobacter pylori/fisiologia , Leucócitos Mononucleares/microbiologia , Antibacterianos/farmacologia , Células Cultivadas , Regulação para Baixo , Gentamicinas/farmacologia , Helicobacter pylori/química , Helicobacter pylori/efeitos dos fármacos , Humanos , Interleucina-1/biossíntese , Interleucina-10/biossíntese , Leucócitos Mononucleares/metabolismo
15.
Vaccine ; 19(31): 4465-72, 2001 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-11483272

RESUMO

Mice immunised with lipopolysaccharide (LPS) from Francisella tularensis were protected against challenge with the live vaccine strain (LVS). However, when similarly immunised mice were challenged using the fully virulent F. tularensis strain Schu4, only an increase in the time to death was observed. Passive transfer of serum from LPS-immunised mice to naive mice afforded protection against F. tularensis LVS. LPS-immunised mice depleted of either CD4+ or CD8+ T-cells survived a F. tularensis LVS challenge although the rate of clearance of bacteria from the spleen was significantly reduced in the CD8+ depleted group. LPS-immunised mice boosted with F. tularensis LVS were re-challenged with F. tularensis Schu4. This cohort was significantly protected (LD(50) increased from <1 to >1000 CFU). However, passive transfer of serum did not confer protection and mice depleted of CD4+ or CD8+ T-cells did not survive.


Assuntos
Anticorpos Antibacterianos/fisiologia , Francisella tularensis/imunologia , Francisella tularensis/patogenicidade , Lipopolissacarídeos/imunologia , Tularemia/prevenção & controle , Animais , Vacinas Bacterianas/uso terapêutico , Linfócitos T CD8-Positivos/imunologia , Feminino , Imunização Passiva , Camundongos , Camundongos Endogâmicos BALB C , Subpopulações de Linfócitos T/imunologia , Vacinas Atenuadas/uso terapêutico , Virulência/imunologia
16.
Intervirology ; 44(4): 250-4, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11509888

RESUMO

OBJECTIVE: Interleukin 18 (IL-18) production represents a critical step in the polarization of the Th1 immune response. Human herpes virus type 6 (HHV-6) possesses a peculiar tropism for immunocompetent cells. To understand the relationships among immunocompetent cells, HHV-6 and cytokines, the role of IL-18 during infection of peripheral blood mononuclear cells (PBMC) with HHV-6 was evaluated. METHODS: PBMC were obtained from healthy HHV-6-seronegative donors, after centrifugation of heparinized venous blood over a Ficoll-Hypaque gradient. Supernatants from PBMC were analyzed for the presence of cytokines. To study the effects of exogenous recombinant human (rh) IL-18 on HHV-6 replication, the number of cells expressing viral antigens and the amount of extracellular virus were analysed. RESULTS: No basal production of IL-18 was found in supernatants of unstimulated PBMC. Appreciable amounts of the cytokine were produced by lipopolysaccharide (LPS)-stimulated PBMC. HHV-6 infection of LPS-treated PBMC downregulated IL-18 production. It was found that the addition of rhIL-18 to HHV-6-infected PBMC downregulated the percentage of antigen-positive cells and the release of extracellular virus. CONCLUSION: Impairment of IL-18 release, which is involved in the induction of antiviral cytokines, such as interferon-gamma, could represent a strategy of the virus to evade the immune response of the host.


Assuntos
Herpesvirus Humano 6/fisiologia , Interleucina-18/imunologia , Leucócitos Mononucleares/imunologia , Células Cultivadas , Humanos , Interferon gama/imunologia , Interleucina-18/biossíntese , Interleucina-18/farmacologia , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/virologia , Lipopolissacarídeos/farmacologia , Proteínas Recombinantes/farmacologia , Regulação para Cima , Replicação Viral
17.
Vet J ; 161(2): 132-64, 2001 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11243685

RESUMO

Salmonella infections are a serious medical and veterinary problem world-wide and cause concern in the food industry. Vaccination is an effective tool for the prevention of Salmonella infections. Host resistance to Salmonella relies initially on the production of inflammatory cytokines leading to the infiltration of activated inflammatory cells in the tissues. Thereafter T- and B-cell dependent specific immunity develops allowing the clearance of Salmonella microorganisms from the tissues and the establishment of long-lasting acquired immunity to re-infection. The increased resistance that develops after primary infection/ vaccination requires T-cells cytokines such as IFNgamma TNFalpha and IL12 in addition to opsonising antibody. However for reasons that are not fully understood seroconversion and/or the presence of detectable T-cell memory do not always correlate with the development of acquired resistance to infection.Whole-cell killed vaccines and subunit vaccines are used in the prevention of Salmonella infection in animals and in humans with variable results. A number of early live Salmonella vaccines derived empirically by chemical or u.v. mutagenesis proved to be immunogenic and protective and are still in use despite the need for repeated parenteral administration. Recent progress in the knowledge of the genetics of Salmonella virulence and modern recombinant DNA technology offers the possibility to introduce multiple defined attenuating and irreversible mutations into the bacterial genome. This has recently allowed the development of Salmonella strains devoid of significant side effects but still capable of inducing solid immunity after single oral administration. Live attenuated Salmonella vaccines have been used for the expression of heterologous antigens/proteins that can be successfully delivered to the immune system. Furthermore Salmonella can transfer plasmids encoding foreign antigens under the control of eukaryotic promoters (DNA vaccines) to antigen-presenting cells resulting in targeted delivery of DNA vaccines to these cells. Despite the great recent advances in the development of Salmonella vaccines a large proportion of the work has been conducted in laboratory rodents and more research in other animal species is required.


Assuntos
Vacinas Bacterianas , Salmonelose Animal/prevenção & controle , Salmonella/imunologia , Vacinação/veterinária , Animais , Anticorpos Antibacterianos/biossíntese , Proteínas de Bactérias/genética , Vacinas Bacterianas/imunologia , Citocinas/imunologia , Microbiologia de Alimentos , Imunidade Ativa , Salmonella/genética , Salmonelose Animal/imunologia , Vacinas Atenuadas/imunologia
18.
Microb Pathog ; 30(1): 29-38, 2001 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11162183

RESUMO

Salmonella typhimurium causes an invasive disease in mice that has similarities to human typhoid, with key roles for cytokines and possibly also inducible nitric oxide synthase (iNOS), in mediating host responses to infection. In this paper we demonstrate that iNOS mRNA, protein and enzyme activity is induced within spleens and livers of infected mice as early as 5 h post-infection. Immunohistochemistry and in situ hybridization indicated that iNOS expression occurs predominantly in macrophages in localized, discrete foci in the infected organs. iNOS activity in spleen and liver was not detectable in uninfected control mice. The presence of mRNA encoding pro-inflammatory cytokines (TNFalpha, IL-1beta and IFNgamma) in infected organs was measured using RT-PCR, all three being present from 2 h post-infection onwards, but not before. These data show that there is a very early host response to S. typhimurium infection in mice, limited to foci within the infected organs.


Assuntos
Fígado/enzimologia , Óxido Nítrico Sintase/metabolismo , Salmonelose Animal/imunologia , Salmonella typhimurium/imunologia , Baço/enzimologia , Animais , Citocinas/biossíntese , Modelos Animais de Doenças , Imuno-Histoquímica , Hibridização In Situ/métodos , Fígado/microbiologia , Macrófagos/enzimologia , Camundongos , Camundongos Endogâmicos BALB C , Óxido Nítrico/biossíntese , Óxido Nítrico Sintase Tipo II , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Salmonelose Animal/enzimologia , Salmonelose Animal/microbiologia , Baço/microbiologia
19.
J Exp Med ; 192(2): 227-36, 2000 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-10899909

RESUMO

The contribution of the NADPH phagocyte oxidase (phox) and inducible nitric oxide (NO) synthase (iNOS) to the antimicrobial activity of macrophages for Salmonella typhimurium was studied by using peritoneal phagocytes from C57BL/6, congenic gp91phox(-/)-, iNOS(-/)-, and doubly immunodeficient phox(-/)-iNOS(-/)- mice. The respiratory burst and NO radical (NO.) made distinct contributions to the anti-Salmonella activity of macrophages. NADPH oxidase-dependent killing is confined to the first few hours after phagocytosis, whereas iNOS contributes to both early and late phases of antibacterial activity. NO-derived species initially synergize with oxyradicals to kill S. typhimurium, and subsequently exert prolonged oxidase-independent bacteriostatic effects. Biochemical analyses show that early killing of Salmonella by macrophages coincides with an oxidative chemistry characterized by superoxide anion (O(2).(-)), hydrogen peroxide (H(2)O(2)), and peroxynitrite (ONOO(-)) production. However, immunofluorescence microscopy and killing assays using the scavenger uric acid suggest that peroxynitrite is not responsible for macrophage killing of wild-type S. typhimurium. Rapid oxidative bacterial killing is followed by a sustained period of nitrosative chemistry that limits bacterial growth. Interferon gamma appears to augment antibacterial activity predominantly by enhancing NO. production, although a small iNOS-independent effect was also observed. These findings demonstrate that macrophages kill Salmonella in a dynamic process that changes over time and requires the generation of both reactive oxidative and nitrosative species.


Assuntos
Macrófagos Peritoneais/imunologia , Glicoproteínas de Membrana/fisiologia , NADPH Oxidases/fisiologia , Óxido Nítrico Sintase/fisiologia , Fagocitose , Salmonella typhimurium/imunologia , Animais , Ativação de Macrófagos , Macrófagos Peritoneais/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , NADPH Oxidase 2 , Óxido Nítrico Sintase Tipo II , Espécies Reativas de Oxigênio , Superóxidos/metabolismo , Tirosina/análogos & derivados , Tirosina/metabolismo
20.
J Exp Med ; 192(2): 237-48, 2000 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-10899910

RESUMO

The roles of the NADPH phagocyte oxidase (phox) and inducible nitric oxide synthase (iNOS) in host resistance to virulent Salmonella typhimurium were investigated in gp91phox(-/)-, iNOS(-/)-, and congenic wild-type mice. Although both gp91phox(-/)- and iNOS(-/)- mice demonstrated increased susceptibility to infection with S. typhimurium compared with wild-type mice, the kinetics of bacterial replication were dramatically different in the gp91phox(-/)- and iNOS(-/)- mouse strains. Greater bacterial numbers were present in the spleens and livers of gp91phox(-/)- mice compared with C57BL/6 controls as early as day 1 of infection, and all of the gp91phox(-/)- mice succumbed to infection within 5 d. In contrast, an increased bacterial burden was detected within reticuloendothelial organs of iNOS(-/)- mice only beyond the first week of infection. Influx of inflammatory CD11b(+) cells, granuloma formation, and serum interferon gamma levels were unimpaired in iNOS(-/)- mice, but the iNOS-deficient granulomas were unable to limit bacterial replication. The NADPH phagocye oxidase and iNOS are both required for host resistance to wild-type Salmonella, but appear to operate principally at different stages of infection.


Assuntos
Glicoproteínas de Membrana/fisiologia , NADPH Oxidases/fisiologia , Óxido Nítrico Sintase/fisiologia , Salmonelose Animal/imunologia , Salmonella typhimurium/fisiologia , Animais , Citometria de Fluxo , Interferon gama/sangue , Camundongos , Camundongos Endogâmicos C57BL , NADPH Oxidase 2 , Óxido Nítrico Sintase Tipo II , Salmonelose Animal/mortalidade , Salmonelose Animal/patologia
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