RESUMEN
Salmonella and avian influenza virus are important pathogens affecting the poultry industry and human health worldwide. In this experimental study, we evaluated the consequences of co-infection of Salmonella enteritidis (SE) with H9N2 avian influenza virus (H9N2-AIV) in chickens. Four groups were included: control group, H9N2-AIV group, H9N2-AIV + SE group, and SE group. Infected chickens were intranasally inoculated with H9N2-AIV at 21 days of age and then orally administered SE on the same day. The birds were monitored for clinical signs, mortality rates, and alterations in body weight. Sera, intestinal fluids, oropharyngeal, and cloacal swabs, and tissue samples were collected at 2, 6, 10, and 14 days post-infection (dpi). Significant increases in clinical signs and mortality rates were observed in the H9N2-AIV + SE group. Moreover, chickens with co-infection showed a significant change in body weight. SE faecal shedding and organ colonization were significantly higher in the H9N2-AIV + SE group than in the SE group. H9N2-AIV infection compromised the systemic and mucosal immunity against SE, as evidenced by a significant decrease in lymphoid organ indices as well as systemic antibody and intestinal immunoglobulin A (IgA) responses to SE and a significant increase in splenic and bursal lesion scores. Moreover, SE infection significantly increased shedding titres and duration of H9N2-AIV. In conclusion, this is the first report of co-infection of SE with H9N2-AIV in chickens, which leads to increased pathogenicity, SE faecal shedding and organ colonization, and H9N2-AIV shedding titre and duration, resulting in substantial economic losses and environmental contamination, ultimately leading to increased zoonoses.
Asunto(s)
Pollos/microbiología , Subtipo H9N2 del Virus de la Influenza A/fisiología , Gripe Aviar/virología , Enfermedades de las Aves de Corral/virología , Salmonelosis Animal/microbiología , Salmonella enteritidis/fisiología , Animales , Coinfección/veterinaria , Heces/microbiología , Inmunoglobulina A/inmunología , Gripe Aviar/mortalidad , Intestinos/microbiología , Enfermedades de las Aves de Corral/mortalidad , Distribución Aleatoria , Salmonelosis Animal/mortalidad , Esparcimiento de VirusRESUMEN
BACKGROUND: Salmonella infection is a serious concern in poultry farming because of its impact on both economic loss and human health. Chicks aged 20 days or less are extremely vulnerable to Salmonella pullorum (SP), which causes high mortality. Furthermore, an outbreak of SP infection can result in a considerable number of carriers that become potential transmitters, thus, threatening fellow chickens and offspring. In this study, we conducted a genome-wide association study (GWAS) to detect potential genomic loci and candidate genes associated with two disease-related traits: death and carrier state. METHODS: In total, 818 birds were phenotyped for death and carrier state traits through a SP challenge experiment, and genotyped by using a 600 K high-density single nucleotide polymorphism (SNP) array. A GWAS using a single-marker linear mixed model was performed with the GEMMA software. RNA-sequencing on spleen samples was carried out for further identification of candidate genes. RESULTS: We detected a region that was located between 33.48 and 34.03 Mb on chicken chromosome 4 and was significantly associated with death, with the most significant SNP (rs314483802) accounting for 11.73% of the phenotypic variation. Two candidate genes, FBXW7 and LRBA, were identified as the most promising genes involved in resistance to SP. The expression levels of FBXW7 and LRBA were significantly downregulated after SP infection, which suggests that they may have a role in controlling SP infections. Two other significant loci and related genes (TRAF3 and gga-mir-489) were associated with carrier state, which indicates a different polygenic determinism compared with that of death. In addition, genomic inbreeding coefficients showed no correlation with resistance to SP within each breed in our study. CONCLUSIONS: The results of this GWAS with a carefully organized Salmonella challenge experiment represent an important milestone in understanding the genetics of infectious disease resistance, offer a theoretical basis for breeding SP-resistant chicken lines using marker-assisted selection, and provide new information for salmonellosis research in humans and other animals.
Asunto(s)
Pollos/genética , Resistencia a la Enfermedad/genética , Enfermedades de las Aves de Corral/genética , Salmonelosis Animal/genética , Animales , Mapeo Cromosómico/veterinaria , Femenino , Marcadores Genéticos , Estudio de Asociación del Genoma Completo/veterinaria , Técnicas de Genotipaje/veterinaria , Homocigoto , Masculino , Fenotipo , Polimorfismo de Nucleótido Simple , Salmonelosis Animal/mortalidadRESUMEN
Salmonella enterica serotype Dublin is a cattle-adapted bacterium that typically causes bloodstream infections in humans. To summarize demographic, clinical, and antimicrobial drug resistance characteristics of human infections with this organism in the United States, we analyzed data for 1968-2013 from 5 US surveillance systems. During this period, the incidence rate for infection with Salmonella Dublin increased more than that for infection with other Salmonella. Data from 1 system (FoodNet) showed that a higher percentage of persons with Salmonella Dublin infection were hospitalized and died during 2005-2013 (78% hospitalized, 4.2% died) than during 1996-2004 (68% hospitalized, 2.7% died). Susceptibility data showed that a higher percentage of isolates were resistant to >7 classes of antimicrobial drugs during 2005-2013 (50.8%) than during 1996-2004 (2.4%).
Asunto(s)
Enfermedades de los Bovinos/epidemiología , Farmacorresistencia Bacteriana Múltiple , Hospitalización/estadística & datos numéricos , Salmonelosis Animal/epidemiología , Infecciones por Salmonella/epidemiología , Salmonella enterica/patogenicidad , Adolescente , Adulto , Anciano , Animales , Antibacterianos/uso terapéutico , Bovinos , Enfermedades de los Bovinos/microbiología , Enfermedades de los Bovinos/patología , Niño , Preescolar , Monitoreo Epidemiológico , Femenino , Humanos , Incidencia , Lactante , Recién Nacido , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Infecciones por Salmonella/microbiología , Infecciones por Salmonella/mortalidad , Infecciones por Salmonella/transmisión , Salmonelosis Animal/microbiología , Salmonelosis Animal/mortalidad , Salmonelosis Animal/transmisión , Salmonella enterica/aislamiento & purificación , Salmonella enterica/fisiología , Serogrupo , Índice de Severidad de la Enfermedad , Análisis de Supervivencia , Estados Unidos/epidemiologíaRESUMEN
Orally administrated iron is suspected to increase susceptibility to enteric infections among children in infection endemic regions. Here we investigated the effect of dietary iron on the pathology and local immune responses in intestinal infection models. Mice were held on iron-deficient, normal iron, or high iron diets and after 2 weeks they were orally challenged with the pathogen Citrobacter rodentium. Microbiome analysis by pyrosequencing revealed profound iron- and infection-induced shifts in microbiota composition. Fecal levels of the innate defensive molecules and markers of inflammation lipocalin-2 and calprotectin were not influenced by dietary iron intervention alone, but were markedly lower in mice on the iron-deficient diet after infection. Next, mice on the iron-deficient diet tended to gain more weight and to have a lower grade of colon pathology. Furthermore, survival of the nematode Caenorhabditis elegans infected with Salmonella enterica serovar Typhimurium was prolonged after iron deprivation. Together, these data show that iron limitation restricts disease pathology upon bacterial infection. However, our data also showed decreased intestinal inflammatory responses of mice fed on high iron diets. Thus additionally, our study indicates that the effects of iron on processes at the intestinal host-pathogen interface may highly depend on host iron status, immune status, and gut microbiota composition.
Asunto(s)
Caenorhabditis elegans/efectos de los fármacos , Infecciones por Enterobacteriaceae/patología , Mucosa Intestinal/patología , Intestinos/patología , Hierro de la Dieta/administración & dosificación , Salmonelosis Animal/metabolismo , Proteínas de Fase Aguda/biosíntesis , Proteínas de Fase Aguda/inmunología , Animales , Peso Corporal/inmunología , Caenorhabditis elegans/inmunología , Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/microbiología , Citrobacter rodentium/inmunología , Dieta/métodos , Infecciones por Enterobacteriaceae/inmunología , Infecciones por Enterobacteriaceae/metabolismo , Infecciones por Enterobacteriaceae/microbiología , Heces/microbiología , Femenino , Inmunidad Innata , Mucosa Intestinal/inmunología , Mucosa Intestinal/metabolismo , Mucosa Intestinal/microbiología , Intestinos/inmunología , Intestinos/microbiología , Hierro de la Dieta/efectos adversos , Complejo de Antígeno L1 de Leucocito/biosíntesis , Complejo de Antígeno L1 de Leucocito/inmunología , Lipocalina 2 , Lipocalinas/biosíntesis , Lipocalinas/inmunología , Ratones , Ratones Endogámicos C57BL , Proteínas Oncogénicas/biosíntesis , Proteínas Oncogénicas/inmunología , Salmonelosis Animal/inmunología , Salmonelosis Animal/microbiología , Salmonelosis Animal/mortalidad , Salmonella typhimurium/inmunología , Análisis de SupervivenciaRESUMEN
Salmonella enterica is a ubiquitous Gram-negative intracellular bacterium that continues to pose a global challenge to human health. The etiology of Salmonella pathogenesis is complex and controlled by pathogen, environmental, and host genetic factors. In fact, patients immunodeficient in genes in the IL-12, IL-23/IFN-γ pathway are predisposed to invasive nontyphoidal Salmonella infection. Using a forward genomics approach by N-ethyl-N-nitrosourea (ENU) germline mutagenesis in mice, we identified the Ity14 (Immunity to Typhimurium locus 14) pedigree exhibiting increased susceptibility following in vivo Salmonella challenge. A DNA-binding domain mutation (p.G418_E445) in Stat4 (Signal Transducer and Activator of Transcription Factor 4) was the causative mutation. STAT4 signals downstream of IL-12 to mediate transcriptional regulation of inflammatory immune responses. In mutant Ity14 mice, the increased splenic and hepatic bacterial load resulted from an intrinsic defect in innate cell function, IFN-γ-mediated immunity, and disorganized granuloma formation. We further show that NK and NKT cells play an important role in mediating control of Salmonella in Stat4(Ity14/Ity14) mice. Stat4(Ity14/Ity14) mice had increased expression of genes involved in cell-cell interactions and communication, as well as increased CD11b expression on a subset of splenic myeloid dendritic cells, resulting in compromised recruitment of inflammatory cells to the spleen during Salmonella infection. Stat4(Ity14/Ity14) presented upregulated compensatory mechanisms, although inefficient and ultimately Stat4(Ity14/Ity14) mice develop fatal bacteremia. The following study further elucidates the pathophysiological impact of STAT4 during Salmonella infection.
Asunto(s)
Regulación de la Expresión Génica , Predisposición Genética a la Enfermedad , Interferón gamma/inmunología , Mutación , Factor de Transcripción STAT4/genética , Salmonelosis Animal/genética , Salmonelosis Animal/inmunología , Transcripción Genética , Animales , Carga Bacteriana , Antígeno CD11b/genética , Antígeno CD11b/metabolismo , Proteínas de Transporte de Catión/genética , Análisis por Conglomerados , Análisis Mutacional de ADN , Células Dendríticas/inmunología , Células Dendríticas/metabolismo , Sitios Genéticos , Inmunidad Innata/genética , Interferón gamma/metabolismo , Células Asesinas Naturales/inmunología , Células Asesinas Naturales/metabolismo , Hígado/inmunología , Hígado/metabolismo , Hígado/microbiología , Ratones , Mutación/efectos de los fármacos , Células T Asesinas Naturales/inmunología , Células T Asesinas Naturales/metabolismo , Compuestos de Nitrosourea/toxicidad , Linaje , Salmonelosis Animal/microbiología , Salmonelosis Animal/mortalidad , Salmonella typhimurium/inmunología , Bazo/inmunología , Bazo/metabolismo , Bazo/microbiología , TranscriptomaRESUMEN
Invasive nontyphoidal Salmonella (NTS) infections constitute a major health problem among infants and toddlers in sub-Saharan Africa; these infections also occur in infants and the elderly in developed countries. We genetically engineered a Salmonella enterica serovar Typhimurium strain of multilocus sequence type 313, the predominant genotype circulating in sub-Saharan Africa. We evaluated the capacities of S. Typhimurium and Salmonella enterica serovar Enteritidis ΔguaBA ΔclpX live oral vaccines to protect mice against a highly lethal challenge dose of the homologous serovar and determined protection against other group B and D serovars circulating in sub-Saharan Africa. The vaccines S. Typhimurium CVD 1931 and S. Enteritidis CVD 1944 were immunogenic and protected BALB/c mice against 10,000 50% lethal doses (LD50) of S. Typhimurium or S. Enteritidis, respectively. S. Typhimurium CVD 1931 protected mice against the group B serovar Salmonella enterica serovar Stanleyville (91% vaccine efficacy), and S. Enteritidis CVD 1944 protected mice against the group D serovar Salmonella enterica serovar Dublin (85% vaccine efficacy). High rates of survival were observed when mice were infected 12 weeks postimmunization, indicating that the vaccines elicited long-lived protective immunity. Whereas CVD 1931 did not protect against S. Enteritidis R11, CVD 1944 did mediate protection against S. Typhimurium D65 (81% efficacy). These findings suggest that a bivalent (S. Typhimurium and S. Enteritidis) vaccine would provide broad protection against the majority of invasive NTS infections in sub-Saharan Africa.
Asunto(s)
Anticuerpos Antibacterianos/biosíntesis , Antígenos Bacterianos/inmunología , Salmonelosis Animal/prevención & control , Vacunas contra la Salmonella/inmunología , Salmonella enteritidis/inmunología , Salmonella typhimurium/inmunología , Administración Oral , África del Sur del Sahara , Animales , Antígenos Bacterianos/administración & dosificación , Protección Cruzada , Femenino , Genotipo , Humanos , Dosificación Letal Mediana , Ratones , Ratones Endogámicos BALB C , Salmonelosis Animal/inmunología , Salmonelosis Animal/microbiología , Salmonelosis Animal/mortalidad , Vacunas contra la Salmonella/administración & dosificación , Salmonella enteritidis/efectos de los fármacos , Salmonella enteritidis/genética , Salmonella typhimurium/efectos de los fármacos , Salmonella typhimurium/genética , Serotipificación , Análisis de Supervivencia , Vacunación , Vacunas AtenuadasRESUMEN
Mortality of 20% of a flock of 1000 chukar partridge chicks occurred over a 6-week period in Northern California from August to September 2012. Affected birds were 2 to 42 days old and died without premonitory clinical signs or after showing ruffled feathers and anorexia for 24 to 72 hours. Three carcasses were submitted for necropsy, 2 birds had hemorrhagic tracheitis grossly, and all 3 had lymphoplasmacytic and histiocytic myocarditis with myocardial necrosis microscopically. The differential diagnoses and the diagnostic workup to achieve a final diagnosis are discussed. The detection of 2 zoonotic agents in these birds makes this an interesting case from a public health perspective.
Asunto(s)
Enfermedades de las Aves/patología , Salmonelosis Animal/patología , Salmonella typhimurium/aislamiento & purificación , Fiebre del Nilo Occidental/veterinaria , Virus del Nilo Occidental/aislamiento & purificación , Animales , Enfermedades de las Aves/mortalidad , California , Diagnóstico Diferencial , Plumas , Femenino , Galliformes , Masculino , Salmonelosis Animal/mortalidad , Fiebre del Nilo Occidental/mortalidad , Fiebre del Nilo Occidental/patologíaRESUMEN
AIM: Study biological properties of salmonella, isolated from clinical materials and water of Don river. MATERIALS AND METHODS: Salmonella strains of various serovars were used in the study. Biochemical characteristics were studied by generally accepted methods, antigenic properties were evaluated in agglutination reactions, virulence was determined by Dlm for laboratory animals, antibiotics sensitivity was verified by disc-diffusion method. RESULTS: The presence of pathogenicity factors in isolated strains was shown: hemolytic activity--in 64 and 36.8% of cases, DNAse activity--in 28 and 26%, respectively in clinical and wild strains. Microorganism dose, resulting in death of all the animals (LD100) did not depend on serovar of salmonella and varied from 10(3) to 10(10) PFU/ml. CONCLUSION: Clinical strains were established to possess higher virulence and resistance to antibiotics compared with strains isolated from the aquatic envionment.
Asunto(s)
Desoxirribonucleasas/genética , Salmonelosis Animal/microbiología , Infecciones por Salmonella/epidemiología , Salmonella/patogenicidad , Factores de Virulencia/genética , Factores de Virulencia/metabolismo , Animales , Antibacterianos/farmacología , Desoxirribonucleasas/metabolismo , Pruebas Antimicrobianas de Difusión por Disco , Farmacorresistencia Bacteriana , Monitoreo Epidemiológico , Expresión Génica , Hemólisis , Humanos , Ratones , Ríos/microbiología , Federación de Rusia/epidemiología , Salmonella/efectos de los fármacos , Salmonella/crecimiento & desarrollo , Salmonella/aislamiento & purificación , Infecciones por Salmonella/microbiología , Infecciones por Salmonella/patología , Salmonelosis Animal/mortalidad , Salmonelosis Animal/patología , Análisis de Supervivencia , VirulenciaRESUMEN
Some species of garden birds are considered to be sensitive to Salmonella (S.) spp. infections. The aim of this study was to determine the cause of mortality of six free-living birds in one private property in suburban area of Wroclaw (Poland). In 2013 Poland experienced prolonged winter, with low temperatures and snow precipitations. During March and April, two dead individuals of the Eurasian siskin (Carduelis spinus) and four dead individuals of the Greenfinch (Carduelis chloris) were found in proximity of the bird feeder. At the time of ringing procedure in the same area, faecal samples of all individuals belonging to these two species of birds were collected, regardless clinical symptoms. In total, twenty two faecal samples of birds belonging to both bird species were collected in the same property. All of them were Salmonella enterica subsp. enterica serovar Typhimurium positive. The visible illness among European siskins and Greenfinches, caused by S. Typhimurium, sug- gests that both Eurasian siskin and Greenfinch may be potential reservoirs of Salmonella spp. Therefore they might play a role in transmission of zoonotic pathogens to other garden bird species or to people.
Asunto(s)
Enfermedades de las Aves/microbiología , Salmonelosis Animal/patología , Salmonella/aislamiento & purificación , Pájaros Cantores , Animales , Enfermedades de las Aves/epidemiología , Enfermedades de las Aves/mortalidad , Heces/microbiología , Masculino , Polonia/epidemiología , Salmonella/clasificación , Salmonelosis Animal/epidemiología , Salmonelosis Animal/mortalidadRESUMEN
Thymic atrophy is known to occur during infections; however, there is limited understanding of its causes and of the cross-talk between different pathways. This study investigates mechanisms involved in thymic atrophy during a model of oral infection by Salmonella enterica serovar Typhimurium (S. typhimurium). Significant death of CD4(+) CD8(+) thymocytes, but not of single-positive thymocytes or peripheral lymphocytes, is observed at later stages during infection with live, but not heat-killed, bacteria. The death of CD4(+) CD8(+) thymocytes is Fas-independent as shown by infection studies with lpr mice. However, apoptosis occurs with lowering of mitochondrial potential and higher caspase-3 activity. The amounts of cortisol, a glucocorticoid, and interferon-γ (IFN-γ), an inflammatory cytokine, increase upon infection. To investigate the functional roles of these molecules, studies were performed using Ifnγ(-/-) mice together with RU486, a glucocorticoid receptor antagonist. Treatment of C57BL/6 mice with RU486 does not affect colony-forming units (CFU), amounts of IFN-γ and mouse survival; however, there is partial rescue in thymocyte death. Upon infection, Ifnγ(-/-) mice display higher CFU and lower survival but more surviving thymocytes are recovered. However, there is no difference in cortisol amounts in C57BL/6 and Ifnγ(-/-) mice. Importantly, the number of CD4(+) CD8(+) thymocytes is significantly higher in Ifnγ(-/-) mice treated with RU486 along with lower caspase-3 activity and mitochondrial damage. Hence, endogenous glucocorticoid and IFN-γ-mediated pathways are parallel but synergize in an additive manner to induce death of CD4(+) CD8(+) thymocytes during S. typhimurium infection. The implications of this study for host responses during infection are discussed.
Asunto(s)
Hidrocortisona/inmunología , Interferón gamma/inmunología , Salmonelosis Animal/inmunología , Salmonella typhimurium/inmunología , Timocitos/inmunología , Timo/inmunología , Animales , Antígenos CD4/genética , Antígenos CD4/inmunología , Antígenos CD8/genética , Antígenos CD8/inmunología , Caspasa 3/genética , Caspasa 3/inmunología , Recuento de Células , Muerte Celular/efectos de los fármacos , Muerte Celular/inmunología , Regulación de la Expresión Génica/efectos de los fármacos , Antagonistas de Hormonas/farmacología , Hidrocortisona/biosíntesis , Interferón gamma/biosíntesis , Interferón gamma/genética , Ratones , Ratones Noqueados , Mifepristona/farmacología , Receptores de Glucocorticoides/antagonistas & inhibidores , Salmonelosis Animal/microbiología , Salmonelosis Animal/mortalidad , Transducción de Señal/efectos de los fármacos , Células Madre , Tasa de Supervivencia , Timocitos/microbiología , Timocitos/patología , Timo/microbiología , Timo/patologíaRESUMEN
A die-off of passerine birds, mostly Eurasian siskins (Carduelis spinus), occurred in multiple areas of Switzerland between February and March 2010. Several of the dead birds were submitted for full necropsy. Bacteriological examination was carried out on multiple tissues of each bird. At gross examination, common findings were light-tan nodules, 1 to 4 mm in diameter, scattered through the esophagus/crop. Histologically, a necroulcerative transmural esophagitis/ingluvitis was observed. Bacterial cultures yielded Salmonella enterica subsp. enterica serovar Typhimurium. At the same time, 2 pet clinics reported an unusual increase of domestic cats presented with fever, anorexia, occasionally dolent abdomen, and history of presumed consumption of passerine birds. Analysis of rectal swabs revealed the presence of S. Typhimurium in all tested cats. PFGE (pulsed field electrophoresis) analysis was performed to characterize and compare the bacterial isolates, and it revealed an indistinguishable pattern between all the avian and all but 1 of the feline isolates. Cloacal swabs collected from clinically healthy migrating Eurasian siskins (during autumn 2010) did not yield S. Typhimurium. The histological and bacteriological findings were consistent with a systemic infection caused by S. Typhimurium. Isolation of the same serovar from the dead birds and ill cats, along with the overlapping results of the PFGE analysis for all the animal species, confirmed a spillover from birds to cats through predation. The sudden increase of the number of siskins over the Swiss territory and their persistency during the whole winter of 2009-2010 is considered the most likely predisposing factor for the onset of the epidemic.
Asunto(s)
Enfermedades de las Aves/epidemiología , Enfermedades de los Gatos/epidemiología , Epidemias/veterinaria , Passeriformes/microbiología , Salmonelosis Animal/epidemiología , Salmonella typhimurium/aislamiento & purificación , Migración Animal , Animales , Enfermedades de las Aves/mortalidad , Enfermedades de las Aves/patología , Enfermedades de las Aves/transmisión , Enfermedades de los Gatos/mortalidad , Enfermedades de los Gatos/patología , Enfermedades de los Gatos/transmisión , Gatos , Electroforesis en Gel de Campo Pulsado/veterinaria , Esófago/patología , Genotipo , Densidad de Población , Salmonelosis Animal/mortalidad , Salmonelosis Animal/patología , Salmonelosis Animal/transmisión , Salmonella typhimurium/clasificación , Salmonella typhimurium/genética , Estaciones del Año , Suiza/epidemiologíaRESUMEN
Infection with Salmonella spp. is a significant source of disease globally. A substantial proportion of these infections are caused by Salmonella enterica serovar Typhimurium. Here, we characterize the role of the enterobacterial common antigen (ECA), a surface glycolipid ubiquitous among enteric bacteria, in S. Typhimurium pathogenesis. Construction of a defined mutation in the UDP-N-acetylglucosamine-1-phosphate transferase gene, wecA, in two clinically relevant strains of S. Typhimurium, TML and SL1344, resulted in strains that were unable to produce ECA. Loss of ECA did not affect the gross cell surface ultrastructure, production of lipopolysaccharide (LPS), flagella, or motility. However, the wecA mutant strains were attenuated in both oral and intraperitoneal mouse models of infection (P<0.001 for both routes of infection; log rank test), and virulence could be restored by complementation of the wecA gene in trans. Despite the avirulence of the ECA-deficient strains, the wecA mutant strains were able to persistently colonize systemic sites (spleen and liver) at moderate levels for up to 70 days postinfection. Moreover, immunization with the wecA mutant strains provided protection against a subsequent lethal oral or intraperitoneal challenge with wild-type S. Typhimurium. Thus, wecA mutant (ECA-negative) strains of Salmonella may be useful as live attenuated vaccine strains or as vehicles for heterologous antigen expression.
Asunto(s)
Antígenos Bacterianos/metabolismo , Eliminación de Gen , Salmonelosis Animal/microbiología , Salmonella typhimurium/patogenicidad , Transferasas (Grupos de Otros Fosfatos Sustitutos)/genética , Factores de Virulencia/metabolismo , Animales , Antígenos Bacterianos/genética , Proteínas Bacterianas/genética , Femenino , Prueba de Complementación Genética , Hígado/microbiología , Ratones , Ratones Endogámicos C57BL , Proteínas Mutantes/genética , Salmonelosis Animal/mortalidad , Salmonelosis Animal/patología , Salmonella typhimurium/genética , Salmonella typhimurium/inmunología , Bazo/microbiología , Análisis de Supervivencia , Factores de Virulencia/genéticaRESUMEN
The bacterial adrenergic sensor kinases QseC and QseE respond to epinephrine and/or norepinephrine to initiate a complex phosphorelay regulatory cascade that modulates virulence gene expression in several pathogens. We have previously shown that QseC activates virulence gene expression in Salmonella enterica serovar Typhimurium. Here we report the role of QseE in S. Typhimurium pathogenesis as well as the interplay between these two histidine sensor kinases in gene regulation. An S. Typhimurium qseE mutant is hampered in the invasion of epithelial cells and intramacrophage replication. The ΔqseC strain is highly attenuated for intramacrophage survival but has only a minor defect in invasion. However, the ΔqseEC strain has only a slight attenuation in invasion, mirroring the ΔqseC strain, and has an intermediary intramacrophage replication defect in comparison to the ΔqseE and ΔqseC strains. The expressions of the sipA and sopB genes, involved in the invasion of epithelial cells, are activated by epinephrine via QseE. The expression levels of these genes are still decreased in the ΔqseEC double mutant, albeit to a lesser extent, congruent with the invasion phenotype of this mutant. The expression level of the sifA gene, important for intramacrophage replication, is decreased in the qseE mutant and the ΔqseEC double mutant grown in vitro. However, as previously reported by us, the epinephrine-dependent activation of this gene occurs via QseC. In the systemic model of S. Typhimurium infection of BALB/c mice, the qseC and qseE mutants are highly attenuated, while the double mutant has an intermediary phenotype. Altogether, these data suggest that both adrenergic sensors play an important role in modulating several aspects of S. Typhimurium pathogenesis.
Asunto(s)
Proteínas Bacterianas/metabolismo , Regulación Bacteriana de la Expresión Génica , Proteínas Quinasas/metabolismo , Salmonella typhimurium/patogenicidad , Animales , Proteínas Bacterianas/genética , Línea Celular , Epinefrina/farmacología , Células Epiteliales/microbiología , Femenino , Células HeLa , Histidina Quinasa , Humanos , Macrófagos/microbiología , Ratones , Ratones Endogámicos BALB C , Mutación , Proteínas Quinasas/genética , Salmonelosis Animal/microbiología , Salmonelosis Animal/mortalidad , Salmonella typhimurium/enzimología , Salmonella typhimurium/genética , VirulenciaRESUMEN
The production of IgA is induced in an antigen-unspecific manner by commensal flora. These secretory antibodies (SAbs) may bind multiple antigens and are thought to eliminate commensal bacteria and self-antigens to avoid systemic recognition. In this study, we addressed the role of "innate" SAbs, i.e., those that are continuously produced in normal individuals, in protection against infection of the gastrointestinal tract. We used polymeric immunoglobulin receptor (pIgR-/-) knock-out mice, which are unable to bind and actively transport dimeric IgA and pentameric IgM to the mucosae, and examined the role of innate SAbs in protection against the invasive pathogen Salmonella typhimurium. In vitro experiments suggested that innate IgA in pIgR-/- serum bound S. typhimurium in a cross-reactive manner which inhibited epithelial cell invasion. Using a "natural" infection model, we demonstrated that pIgR-/- mice are profoundly sensitive to infection with S. typhimurium via the fecal-oral route and, moreover, shed more bacteria that readily infected other animals. These results imply an important evolutionary role for innate SAbs in protecting both the individual and the herd against infections, and suggest that the major role of SAbs may be to prevent the spread of microbial pathogens throughout the population, rather than protection of local mucosal surfaces.
Asunto(s)
Anticuerpos Antibacterianos/inmunología , Receptores de Inmunoglobulina Polimérica/deficiencia , Salmonelosis Animal/inmunología , Salmonella typhimurium/patogenicidad , Animales , Línea Celular , Recuento de Colonia Microbiana , Perros , Heces/microbiología , Inmunidad Innata , Inmunoglobulina A/sangre , Intestino Delgado/inmunología , Intestino Delgado/microbiología , Dosificación Letal Mediana , Ratones , Ratones Endogámicos , Ratones Noqueados , Ganglios Linfáticos Agregados/inmunología , Ganglios Linfáticos Agregados/microbiología , Receptores de Inmunoglobulina Polimérica/sangre , Receptores de Inmunoglobulina Polimérica/genética , Salmonelosis Animal/mortalidad , Salmonelosis Animal/transmisiónAsunto(s)
Farmacorresistencia Bacteriana Múltiple/genética , Ajo/química , Extractos Vegetales/farmacología , Aves de Corral/microbiología , Salmonella/efectos de los fármacos , Salmonella/genética , Salmonella/aislamiento & purificación , Animales , Biopelículas/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Peso Corporal , Genes Bacterianos/genética , Pruebas de Sensibilidad Microbiana , Salmonelosis Animal/microbiología , Salmonelosis Animal/mortalidad , Serotipificación , Virulencia/genéticaRESUMEN
Previously, we demonstrated that cell-cell communications via the CD40-CD154 pathway play a critical role in the induction of type 1 cytokine responses, including IL-12 and IFN-γ, which in turn greatly influence the response to Salmonella infections. Mice genetically deficient in the expression of CD154 exhibited markedly increased susceptibility to infection by an attenuated, double auxotrophic (aroA-aroD-) strain, designated BRD509, of Salmonella enterica Serovar Typhimurium. In the present study, we used a strain of Salmonella engineered to express murine IFN-γ, designated GIDIFN, in order to assess its potential to enhance the host's immune response in CD154-deficient animals. We demonstrate that infection of animals with GIDIFN results in markedly enhanced anti-bacterial response, as evidenced by the significant reduction in bacterial loads in target organs and decreased animal mortality. This was associated with a more robust proinflammatory cytokine response, including IL-6, IL-12, TNF-α and IFN-γ. In protection studies, GIDIFN strain was demonstrably superior than the BRD509 strain in affording protection against virulent Salmonella challenge in naïve CD154-/- mice. Interestingly, however, infection with GIDIFN failed to correct the isotype switching defect in CD154-/- mice, suggesting that the enhanced immunity triggered by GIDIFN strain occurs independently of humoral immune responses. These findings demonstrate that GIDIFN has immunopotentiating effects on the host's immune response and provide direct evidence for the utility of IFN-γ-expressing attenuated Salmonella in enhancement of immune responsiveness in immunodeficient hosts.
Asunto(s)
Ligando de CD40/deficiencia , Expresión Génica , Interferón gamma/biosíntesis , Salmonella typhimurium/inmunología , Estructuras Animales/microbiología , Animales , Carga Bacteriana , Ligando de CD40/inmunología , Citocinas/metabolismo , Modelos Animales de Enfermedad , Huésped Inmunocomprometido , Interferón gamma/genética , Ratones , Ratones Noqueados , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/genética , Salmonelosis Animal/inmunología , Salmonelosis Animal/microbiología , Salmonelosis Animal/mortalidad , Salmonella typhimurium/genética , Salmonella typhimurium/patogenicidad , Análisis de SupervivenciaRESUMEN
Salmonella enterica serovar Enteritidis (S. Enteritidis) is a major cause of food-borne gastroenteritis in humans worldwide. Poultry and poultry products are considered the major vehicles of transmission to humans. Using cell invasiveness as a surrogate marker for pathogenicity, we tested the invasiveness of 53 poultry-associated isolates of S. Enteritidis in a well-differentiated intestinal epithelial cell model (Caco-2). The method allowed classification of the isolates into low (nâ=â7), medium (nâ=â18) and high (nâ=â30) invasiveness categories. Cell invasiveness of the isolates did not correlate with the presence of the virulence-associated gene spvB or the ability of the isolates to form biofilms. Testing of representative isolates with high and low invasiveness in a mouse model revealed that the former were more invasive in vivo and caused more and earlier mortalities, whereas the latter were significantly less invasive in vivo, causing few or no mortalities. Further characterization of representative isolates with low and high invasiveness showed that most of the isolates with low invasiveness had impaired motility and impaired secretion of either flagella-associated proteins (FlgK, FljB and FlgL) or type III secretion system (TTSS)-secreted proteins (SipA and SipD) encoded on Salmonella pathogenicity island-1. In addition, isolates with low invasiveness had impaired ability to invade and/or survive within chicken macrophages. These data suggest that not all isolates of S. Enteritidis recovered from poultry may be equally pathogenic, and that the pathogenicity of S. Enteritidis isolates is associated, in part, with both motility and secretion of TTSS effector proteins.
Asunto(s)
Proteínas Bacterianas/metabolismo , Enfermedades de las Aves de Corral/microbiología , Salmonelosis Animal/microbiología , Infecciones por Salmonella/microbiología , Salmonella enteritidis/fisiología , Salmonella enteritidis/patogenicidad , Animales , Proteínas Bacterianas/genética , Biopelículas , Células CACO-2 , Pollos , Femenino , Contaminación de Alimentos , Islas Genómicas , Humanos , Estimación de Kaplan-Meier , Carne/microbiología , Ratones , Ratones Endogámicos BALB C , Modelos Biológicos , Datos de Secuencia Molecular , Filogenia , Transporte de Proteínas , Infecciones por Salmonella/mortalidad , Salmonelosis Animal/mortalidad , Salmonella enteritidis/clasificación , Salmonella enteritidis/genética , Virulencia , Factores de Virulencia/genética , Factores de Virulencia/metabolismoRESUMEN
We used mast cell-engrafted genetically mast cell-deficient C57BL/6-Kit(W-sh/W-sh) mice to investigate the roles of mast cells and mast cell-derived tumor necrosis factor in two models of severe bacterial infection. In these mice, we confirmed findings derived from studies of mast cell-deficient WBB6F(1)-Kit(W/W-v) mice indicating that mast cells can promote survival in cecal ligation and puncture (CLP) of moderate severity. However, we found that the beneficial role of mast cells in this setting can occur independently of mast cell-derived tumor necrosis factor. By contrast, using mast cell-engrafted C57BL/6-Kit(W-sh/W-sh) mice, we found that mast cell-derived tumor necrosis factor can increase mortality during severe CLP and can also enhance bacterial growth and hasten death after intraperitoneal inoculation of Salmonella typhimurium. In WBB6F(1)-Kit(W-sh/W-sh) mice, mast cells enhanced survival during moderately severe CLP but did not significantly change the survival observed in severe CLP. Our findings in three types of genetically mast cell-deficient mice thus support the hypothesis that, depending on the circumstances (including mouse strain background, the nature of the mutation resulting in a mast cell deficiency, and type and severity of infection), mast cells can have either no detectable effect or opposite effects on survival during bacterial infections, eg, promoting survival during moderately severe CLP associated with low mortality but, in C57BL/6-Kit(W-sh/W-sh) mice, increasing mortality during severe CLP or infection with S. typhimurium.
Asunto(s)
Infecciones Bacterianas/mortalidad , Mastocitos/metabolismo , Proteínas Proto-Oncogénicas c-kit/genética , Factor de Necrosis Tumoral alfa/farmacología , Animales , Infecciones Bacterianas/genética , Infecciones Bacterianas/metabolismo , Infecciones Bacterianas/terapia , Progresión de la Enfermedad , Femenino , Inmunoterapia Adoptiva/métodos , Mastocitos/trasplante , Ratones , Ratones Congénicos , Ratones Endogámicos C3H , Ratones Endogámicos C57BL , Ratones Transgénicos , Proteínas Proto-Oncogénicas c-kit/metabolismo , Salmonelosis Animal/genética , Salmonelosis Animal/metabolismo , Salmonelosis Animal/mortalidad , Salmonelosis Animal/terapia , Salmonella typhimurium/fisiología , Índice de Severidad de la Enfermedad , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
BACKGROUND: Salmonella enterica serovar Typhimurium is an intracellular bacterial pathogen which can colonize a variety of hosts, including human, causing syndromes that vary from gastroenteritis and diarrhea to systemic disease. RESULTS: In this work we present structural information as well as insights into the in vivo function of YqiC, a 99-residue protein of S. Typhimurium, which belongs to the cluster of the orthologous group 2960 (COG2960). We found that YqiC shares biophysical and biochemical properties with Brucella abortus BMFP, the only previously characterized member of this group, such as a high alpha helix content, a coiled-coil domain involved in trimerization and a membrane fusogenic activity in vitro. In addition, we demonstrated that YqiC localizes at cytoplasmic and membrane subcellular fractions, that a S. Typhimurium yqiC deficient strain had a severe attenuation in virulence in the murine model when inoculated both orally and intraperitoneally, and was impaired to replicate at physiological and high temperatures in vitro, although it was still able to invade and replicate inside epithelial and macrophages cell lines. CONCLUSION: This work firstly demonstrates the importance of a COG2960 member for pathogen-host interaction, and suggests a common function conserved among members of this group.
Asunto(s)
Proteínas Bacterianas/metabolismo , Fusión de Membrana , Proteínas de la Membrana/metabolismo , Salmonella typhimurium/patogenicidad , Factores de Virulencia/metabolismo , Animales , Membrana Celular/química , Citoplasma/química , Modelos Animales de Enfermedad , Femenino , Interacciones Huésped-Patógeno , Humanos , Ratones , Ratones Endogámicos BALB C , Enfermedades de los Roedores/microbiología , Enfermedades de los Roedores/mortalidad , Salmonelosis Animal/microbiología , Salmonelosis Animal/mortalidad , Salmonella typhimurium/crecimiento & desarrollo , Homología de Secuencia de Aminoácido , Análisis de Supervivencia , VirulenciaRESUMEN
A Salmonella Gallinarum (SG)-specific bacteriophage isolated from sewage effluent was used to prevent horizontal transmission of SG in commercial layer chickens. Six-week-old chickens, each challenged with 5 x 10(8) colony-forming units of SG, cohabited with contact chickens treated with 10(6) plaque-forming units/kg of bacteriophage, prepared in feed additives, for 7 days before, and 21 days after challenge with SG. Mortality was observed for 3 wk after challenge and SG was periodically reisolated from the liver, spleen, and cecum of chickens. SG re-isolation from organs was decreased and a significant (P < 0.05) reduction in mortality was observed in contact chickens treated with the bacteriophage, as compared to untreated contact chickens, indicating that bacteriophage administration in feed additives significantly prevented the horizontal transmission of SG. These results provide important insights into prevention and control strategies against SG infection and suggest that the use of bacteriophages may be a novel, safe, and effectively plausible alternative to antibiotics for the prevention of SG infection in poultry.