scholarly journals Infection of Mice by Salmonella enterica Serovar Enteritidis Involves Additional Genes That Are Absent in the Genome of Serovar Typhimurium

2011 ◽  
Vol 80 (2) ◽  
pp. 839-849 ◽  
Author(s):  
Cecilia A. Silva ◽  
Carlos J. Blondel ◽  
Carolina P. Quezada ◽  
Steffen Porwollik ◽  
Helene L. Andrews-Polymenis ◽  
...  

ABSTRACTSalmonella entericaserovar Enteritidis causes a systemic, typhoid-like infection in newly hatched poultry and mice. In the present study, a library of 54,000 transposon mutants ofS.Enteritidis phage type 4 (PT4) strain P125109 was screened for mutants deficient in thein vivocolonization of the BALB/c mouse model using a microarray-based negative-selection screening. Mutants in genes known to contribute to systemic infection (e.g.,Salmonellapathogenicity island 2 [SPI-2],aro,rfa,rfb,phoP, andphoQ) and enteric infection (e.g., SPI-1 and SPI-5) in this and otherSalmonellaserovars displayed colonization defects in our assay. In addition, a strong attenuation was observed for mutants in genes and genomic islands that are not present inS.Typhimurium or in most otherSalmonellaserovars. These genes include a type I restriction/modification system (SEN4290toSEN4292), thepegfimbrial operon (SEN2144AtoSEN2145B), a putative pathogenicity island (SEN1970 to SEN1999), and a type VI secretion system remnantSEN1001, encoding a hypothetical protein containing a lysin motif (LysM) domain associated with peptidoglycan binding. Proliferation defects for mutants in these individual genes and in exemplar genes for each of these clusters were confirmed in competitive infections with wild-typeS.Enteritidis. A ΔSEN1001mutant was defective for survival within RAW264.7 murine macrophagesin vitro. Complementation assays directly linked theSEN1001gene to phenotypes observedin vivoandin vitro. The genes identified here may perform novel virulence functions not characterized in previousSalmonellamodels.

2015 ◽  
Vol 81 (23) ◽  
pp. 8192-8201 ◽  
Author(s):  
Bryan Troxell ◽  
Nicholas Petri ◽  
Caitlyn Daron ◽  
Rafaela Pereira ◽  
Mary Mendoza ◽  
...  

ABSTRACTSalmonella entericaserovars Typhimurium (S. Typhimurium) and Enteritidis (S. Enteritidis) are foodborne pathogens, and outbreaks are often associated with poultry products. Chickens are typically asymptomatic when colonized by these serovars; however, the factors contributing to this observation are uncharacterized. Whereas symptomatic mammals have a body temperature between 37°C and 39°C, chickens have a body temperature of 41°C to 42°C. Here,in vivoexperiments using chicks demonstrated that numbers of viableS. Typhimurium orS. Enteritidis bacteria within the liver and spleen organ sites were ≥4 orders of magnitude lower than those within the ceca. When similar doses ofS. Typhimurium orS. Enteritidis were given to C3H/HeN mice, the ratio of the intestinal concentration to the liver/spleen concentration was 1:1. In the avian host, this suggested poor survival within these tissues or a reduced capacity to traverse the host epithelial layer and reach liver/spleen sites or both.Salmonellapathogenicity island 1 (SPI-1) promotes localization to liver/spleen tissues through invasion of the epithelial cell layer. Followingin vitrogrowth at 42°C, SPI-1 genessipC,invF, andhilAand the SPI-1rtsAactivator were downregulated compared to expression at 37°C. Overexpression of thehilAactivatorsfur,fliZ, andhilDwas capable of inducinghilA-lacZat 37°C but not at 42°C despite the presence of similar levels of protein at the two temperatures. In contrast, overexpression of eitherhilCorrtsAwas capable of inducinghilAandsipCat 42°C. These data indicate that physiological parameters of the poultry host, such as body temperature, have a role in modulating expression of virulence.


2014 ◽  
Vol 80 (24) ◽  
pp. 7710-7716 ◽  
Author(s):  
R. Raspoet ◽  
C. Appia-Ayme ◽  
N. Shearer ◽  
A. Martel ◽  
F. Pasmans ◽  
...  

ABSTRACTSalmonella entericaserovar Enteritidis has developed the potential to contaminate table eggs internally, by colonization of the chicken reproductive tract and internalization in the forming egg. The serotype Enteritidis has developed mechanisms to colonize the chicken oviduct more successfully than other serotypes. Until now, the strategies exploited bySalmonellaEnteritidis to do so have remained largely unknown. For that reason, a microarray-based transposon library screen was used to identify genes that are essential for the persistence ofSalmonellaEnteritidis inside primary chicken oviduct gland cellsin vitroand inside the reproductive tractin vivo. A total of 81 genes with a potential role in persistence in both the oviduct cells and the oviduct tissue were identified. Major groups of importance include theSalmonellapathogenicity islands 1 and 2, genes involved in stress responses, cell wall, and lipopolysaccharide structure, and the region-of-difference genomic islands 9, 21, and 40.


2018 ◽  
Vol 86 (9) ◽  
Author(s):  
Vivek Belde ◽  
Matthew P. Cravens ◽  
Dania Gulandijany ◽  
Justin A. Walker ◽  
Isabel Palomo-Caturla ◽  
...  

ABSTRACTB cell antigen receptor (BCR) diversity increases by several orders of magnitude due to the action of terminal deoxynucleotidyl transferase (TdT) during V(D)J recombination. Unlike adults, infants have limited BCR diversity, in part due to reduced expression of TdT. Since human infants and young mice respond poorly to polysaccharide vaccines, such as the pneumococcal polysaccharide vaccine Pneumovax23 and Vi polysaccharide (ViPS) ofSalmonella entericaserovar Typhi, we tested the contribution of TdT-mediated BCR diversity in response to these vaccines. We found that TdT+/−and TdT−/−mice generated comparable antibody responses to Pneumovax23 and survivedStreptococcus pneumoniaechallenge. Moreover, passive immunization of B cell-deficient mice with serum from Pneumovax23-immunized TdT+/−or TdT−/−mice conferred protection. TdT+/−and TdT−/−mice generated comparable levels of anti-ViPS antibodies and antibody-dependent, complement-mediated bactericidal activity againstS. Typhiin vitro. To test the protective immunity conferred by ViPS immunizationin vivo, TdT+/−and TdT−/−mice were challenged with a chimericSalmonella entericaserovar Typhimurium strain expressing ViPS, since mice are nonpermissive hosts forS. Typhi infection. Compared to their unimmunized counterparts, immunized TdT+/−and TdT−/−mice challenged with ViPS-expressingS. Typhimurium exhibited a significant reduction in the bacterial burden and liver pathology. These data suggest that the impaired antibody response to the Pneumovax23 and ViPS vaccines in the young is not due to limited TdT-mediated BCR diversification.


2001 ◽  
Vol 69 (7) ◽  
pp. 4673-4677 ◽  
Author(s):  
Chris A. Allen ◽  
Paula J. Fedorka-Cray ◽  
Andrés Vazquez-Torres ◽  
Mitsu Suyemoto ◽  
Craig Altier ◽  
...  

ABSTRACT Multidrug-resistant Salmonella enterica serovar Typhimurium phage type DT104 has become a widespread cause of human and other animal infection worldwide. The severity of clinical illness inS. enterica serovar Typhimurium DT104 outbreaks has led to the suggestion that this strain possesses enhanced virulence. In the present study, in vitro and in vivo virulence-associated phenotypes of several clinical isolates of S. enterica serovar Typhimurium DT104 were examined and compared to S. entericaserovar Typhimurium ATCC 14028s. The ability of these DT104 isolates to survive within murine peritoneal macrophages, invade cultured epithelial cells, resist antimicrobial actions of reactive oxygen and nitrogen compounds, and cause lethal infection in mice were assessed. Our results failed to demonstrate that S. enterica serovar Typhimurium DT104 isolates are more virulent than S. enterica serovar Typhimurium ATCC 14028s.


2014 ◽  
Vol 58 (6) ◽  
pp. 3312-3326 ◽  
Author(s):  
B. K. Kishore Reddy ◽  
Sudhir Landge ◽  
Sudha Ravishankar ◽  
Vikas Patil ◽  
Vikas Shinde ◽  
...  

ABSTRACTPantothenate kinase (PanK) catalyzes the phosphorylation of pantothenate, the first committed and rate-limiting step toward coenzyme A (CoA) biosynthesis. In our earlier reports, we had established that the type I isoform encoded by thecoaAgene is an essential pantothenate kinase inMycobacterium tuberculosis, and this vital information was then exploited to screen large libraries for identification of mechanistically different classes of PanK inhibitors. The present report summarizes the synthesis and expansion efforts to understand the structure-activity relationships leading to the optimization of enzyme inhibition along with antimycobacterial activity. Additionally, we report the progression of two distinct classes of inhibitors, the triazoles, which are ATP competitors, and the biaryl acetic acids, with a mixed mode of inhibition. Cocrystallization studies provided evidence of these inhibitors binding to the enzyme. This was further substantiated with the biaryl acids having MIC against the wild-typeM. tuberculosisstrain and the subsequent establishment of a target link with an upshift in MIC in a strain overexpressing PanK. On the other hand, the ATP competitors had cellular activity only in aM. tuberculosisknockdown strain with reduced PanK expression levels. Additionally,in vitroandin vivosurvival kinetic studies performed with aM. tuberculosisPanK (MtPanK) knockdown strain indicated that the target levels have to be significantly reduced to bring in growth inhibition. The dual approaches employed here thus established the poor vulnerability of PanK inM. tuberculosis.


2020 ◽  
Vol 64 (3) ◽  
Author(s):  
Jixu Li ◽  
Huanping Guo ◽  
Eloiza May Galon ◽  
Yang Gao ◽  
Seung-Hun Lee ◽  
...  

ABSTRACT Toxoplasma gondii is an obligate intracellular protozoan parasite and a successful parasitic pathogen in diverse organisms and host cell types. Hydroxylamine (HYD) and carboxymethoxylamine (CAR) have been reported as inhibitors of aspartate aminotransferases (AATs) and interfere with the proliferation in Plasmodium falciparum. Therefore, AATs are suggested as drug targets against Plasmodium. The T. gondii genome encodes only one predicted AAT in both T. gondii type I strain RH and type II strain PLK. However, the effects of HYD and CAR, as well as their relationship with AAT, on T. gondii remain unclear. In this study, we found that HYD and CAR impaired the lytic cycle of T. gondii in vitro, including the inhibition of invasion or reinvasion, intracellular replication, and egress. Importantly, HYD and CAR could control acute toxoplasmosis in vivo. Further studies showed that HYD and CAR could inhibit the transamination activity of rTgAAT in vitro. However, our results confirmed that deficiency of AAT in both RH and PLK did not reduce the virulence in mice, although the growth ability of the parasites was affected in vitro. HYD and CAR could still inhibit the growth of AAT-deficient parasites. These findings indicated that HYD and CAR inhibition of T. gondii growth and control of toxoplasmosis can occur in an AAT-independent pathway. Overall, further studies focusing on the elucidation of the mechanism of inhibition are warranted. Our study hints at new substrates of HYD and CAR as potential drug targets to inhibit T. gondii growth.


2013 ◽  
Vol 81 (4) ◽  
pp. 1207-1220 ◽  
Author(s):  
Carlos J. Blondel ◽  
Juan C. Jiménez ◽  
Lorenzo E. Leiva ◽  
Sergio A. Álvarez ◽  
Bernardo I. Pinto ◽  
...  

ABSTRACTSalmonella entericaserotype Gallinarum is the causative agent of fowl typhoid, a disease characterized by high morbidity and mortality that causes major economic losses in poultry production. We have reported thatS. Gallinarum harbors a type VI secretion system (T6SS) encoded inSalmonellapathogenicity island 19 (SPI-19) that is required for efficient colonization of chicks. In the present study, we aimed to characterize the SPI-19 T6SS functionality and to investigate the mechanisms behind the phenotypes previously observedin vivo. Expression analyses revealed that SPI-19 T6SS core components are expressed and produced underin vitrobacterial growth conditions. However, secretion of the structural/secreted components Hcp1, Hcp2, and VgrG to the culture medium could not be determined, suggesting that additional signals are required for T6SS-dependent secretion of these proteins.In vitrobacterial competition assays failed to demonstrate a role for SPI-19 T6SS in interbacterial killing. In contrast, cell culture experiments with murine and avian macrophages (RAW264.7 and HD11, respectively) revealed production of a green fluorescent protein-tagged version of VgrG soon afterSalmonellauptake. Furthermore, infection of RAW264.7 and HD11 macrophages with deletion mutants of SPI-19 or strains with genes encoding specific T6SS core components (clpVandvgrG) revealed that SPI-19 T6SS contributes toS. Gallinarum survival within macrophages at 20 h postuptake. SPI-19 T6SS function was not linked toSalmonella-induced cytotoxicity or cell death of infected macrophages, as has been described for other T6SS. Our data indicate that SPI-19 T6SS corresponds to a novel tool used bySalmonellato survive within host cells.


mSphere ◽  
2017 ◽  
Vol 2 (6) ◽  
Author(s):  
George Sakoulas ◽  
Monika Kumaraswamy ◽  
Armin Kousha ◽  
Victor Nizet

ABSTRACT It is becoming increasingly understood that the current paradigms of in vitro antimicrobial susceptibility testing may have significant shortcomings in predicting activity in vivo. This study evaluated the activity of several antibiotics alone and in combination against clinical isolates of Salmonella enterica serotype Newport (meningitis case) utilizing both conventional and physiological media. In addition, the interactions of these antibiotics with components of the innate immune system were evaluated. Azithromycin, which has performed quite well clinically despite high MICs in conventional media, was shown to be more active in physiological media and to enhance innate immune system killing. Alternatively, chloramphenicol did not show enhanced immune system killing, paralleling its inferior clinical performance to other antibiotics that have been used to treat Salmonella meningitis. These findings are important additions to the building understanding of current in vitro antimicrobial assay limitations that hopefully will amount to future improvements in these assays to better predict clinical efficacy and activity in vivo. This study examines the pharmacodynamics of antimicrobials that are used to treat Salmonella with each other and with key components of the innate immune system. Antimicrobial synergy was assessed using time-kill and checkerboard assays. Antimicrobial interactions with innate immunity were studied by employing cathelicidin LL-37, whole-blood, and neutrophil killing assays. Ceftriaxone and ciprofloxacin were found to be synergistic in vitro against Salmonella enterica serotype Newport. Ceftriaxone, ciprofloxacin, and azithromycin each demonstrated synergy with the human cathelicidin defense peptide LL-37 in killing Salmonella. Exposure of Salmonella to sub-MICs of ceftriaxone resulted in enhanced susceptibility to LL-37, whole blood, and neutrophil killing. The activity of antibiotics in vivo against Salmonella may be underestimated in bacteriologic media lacking components of innate immunity. The pharmacodynamic interactions of antibiotics used to treat Salmonella with each other and with components of innate immunity warrant further study in light of recent findings showing in vivo selection of antimicrobial resistance by single agents in this pathogen. IMPORTANCE It is becoming increasingly understood that the current paradigms of in vitro antimicrobial susceptibility testing may have significant shortcomings in predicting activity in vivo. This study evaluated the activity of several antibiotics alone and in combination against clinical isolates of Salmonella enterica serotype Newport (meningitis case) utilizing both conventional and physiological media. In addition, the interactions of these antibiotics with components of the innate immune system were evaluated. Azithromycin, which has performed quite well clinically despite high MICs in conventional media, was shown to be more active in physiological media and to enhance innate immune system killing. Alternatively, chloramphenicol did not show enhanced immune system killing, paralleling its inferior clinical performance to other antibiotics that have been used to treat Salmonella meningitis. These findings are important additions to the building understanding of current in vitro antimicrobial assay limitations that hopefully will amount to future improvements in these assays to better predict clinical efficacy and activity in vivo.


2018 ◽  
Vol 92 (13) ◽  
Author(s):  
Junjie Feng ◽  
Arthur Wickenhagen ◽  
Matthew L. Turnbull ◽  
Veronica V. Rezelj ◽  
Felix Kreher ◽  
...  

ABSTRACT Bunyaviruses pose a significant threat to human health, prosperity, and food security. In response to viral infections, interferons (IFNs) upregulate the expression of hundreds of interferon-stimulated genes (ISGs), whose cumulative action can potently inhibit the replication of bunyaviruses. We used a flow cytometry-based method to screen the ability of ∼500 unique ISGs from humans and rhesus macaques to inhibit the replication of Bunyamwera orthobunyavirus (BUNV), the prototype of both the Peribunyaviridae family and the Bunyavirales order. Candidates possessing antibunyaviral activity were further examined using a panel of divergent bunyaviruses. Interestingly, one candidate, ISG20, exhibited potent antibunyaviral activity against most viruses examined from the Peribunyaviridae , Hantaviridae , and Nairoviridae families, whereas phleboviruses ( Phenuiviridae ) largely escaped inhibition. Similar to the case against other viruses known to be targeted by ISG20, the antibunyaviral activity of ISG20 is dependent upon its functional RNase activity. Through use of an infectious virus-like particle (VLP) assay (based on the BUNV minigenome system), we confirmed that gene expression from all 3 viral segments is strongly inhibited by ISG20. Using in vitro evolution, we generated a substantially ISG20-resistant BUNV and mapped the determinants of ISG20 sensitivity/resistance. Taking all the data together, we report that ISG20 is a broad and potent antibunyaviral factor but that some bunyaviruses are remarkably ISG20 resistant. Thus, ISG20 sensitivity/resistance may influence the pathogenesis of bunyaviruses, many of which are emerging viruses of clinical or veterinary significance. IMPORTANCE There are hundreds of bunyaviruses, many of which cause life-threatening acute diseases in humans and livestock. The interferon (IFN) system is a key component of innate immunity, and type I IFNs limit bunyaviral propagation both in vitro and in vivo . Type I IFN signaling results in the upregulation of hundreds of IFN-stimulated genes (ISGs), whose concerted action generates an “antiviral state.” Although IFNs are critical in limiting bunyaviral replication and pathogenesis, much is still unknown about which ISGs inhibit bunyaviruses. Using ISG-expression screening, we examined the ability of ∼500 unique ISGs to inhibit Bunyamwera orthobunyavirus (BUNV), the prototypical bunyavirus. Using this approach, we identified ISG20, an interferon-stimulated exonuclease, as a potent inhibitor of BUNV. Interestingly, ISG20 possesses highly selective antibunyaviral activity, with multiple bunyaviruses being potently inhibited while some largely escape inhibition. We speculate that the ability of some bunyaviruses to escape ISG20 may influence their pathogenesis.


2013 ◽  
Vol 82 (1) ◽  
pp. 221-232 ◽  
Author(s):  
Cristina Núñez-Hernández ◽  
Ana Alonso ◽  
M. Graciela Pucciarelli ◽  
Josep Casadesús ◽  
Francisco García-del Portillo

ABSTRACTSalmonella entericauses effector proteins delivered by type III secretion systems (TTSS) to colonize eukaryotic cells. Recentin vivostudies have shown that intracellular bacteria activate the TTSS encoded bySalmonellapathogenicity island-2 (SPI-2) to restrain growth inside phagocytes. Growth attenuation is also observedin vivoin bacteria colonizing nonphagocytic stromal cells of the intestinal lamina propria and in cultured fibroblasts. SPI-2 is required for survival of nongrowing bacteria persisting inside fibroblasts, but its induction mode and the effectors involved remain unknown. Here, we show that nongrowing dormant intracellular bacteria use the two-component system OmpR-EnvZ to induce SPI-2 expression and the PhoP-PhoQ system to regulate the time at which induction takes place, 2 h postentry. Dormant bacteria were shown to discriminate the usage of SPI-2 effectors. Among the effectors tested, SseF, SseG, and SseJ were required for survival, while others, such as SifA and SifB, were not. SifA and SifB dispensability correlated with the inability of intracellular bacteria to secrete these effectors even when overexpressed. Conversely, SseJ overproduction resulted in augmented secretion and exacerbated bacterial growth. Dormant bacteria produced other effectors, such as PipB and PipB2, that, unlike what was reported for epithelial cells, did not to traffic outside the phagosomal compartment. Therefore, permissiveness for secreting only a subset of SPI-2 effectors may be instrumental for dormancy. We propose that theS. entericaserovar Typhimurium nonproliferative intracellular lifestyle is sustained by selection of SPI-2 effectors that are produced in tightly defined amounts and delivered to phagosome-confined locations.


Sign in / Sign up

Export Citation Format

Share Document