scholarly journals Identification ofIn Vivo-Induced Bacterial Proteins during Human Infection with Salmonella enterica Serotype Paratyphi A

2013 ◽  
Vol 20 (5) ◽  
pp. 712-719 ◽  
Author(s):  
Mohammad Murshid Alam ◽  
Lillian L. Tsai ◽  
Sean M. Rollins ◽  
Alaullah Sheikh ◽  
Farhana Khanam ◽  
...  

ABSTRACTSalmonella entericaserotype Paratyphi A is a human-restricted pathogen and the cause of paratyphoid A fever. Using a high-throughput immunoscreening technique,in vivo-induced antigen technology (IVIAT), we identified 20 immunogenic bacterial proteins expressed in humans who were bacteremic withS. Paratyphi A but not those expressed inS. Paratyphi A grown under standard laboratory conditions. The majority of these proteins have known or potential roles in the pathogenesis ofS. enterica. These include proteins implicated in cell adhesion, fimbrial structure, adaptation to atypical conditions, oxidoreductase activity, proteolysis, antimicrobial resistance, and ion transport. Of particular interest among thesein vivo-expressed proteins wereS. Paratyphi A (SPA)2397, SPA2612, and SPA1604. SPA2397 and SPA2612 are prophage related, and SPA1604 is inSalmonellapathogenicity island 11 (SPI-11). Using real-time quantitative PCR (RT-qPCR), we confirmed increased levels of mRNA expressed by genes identified by IVIAT in a comparison of mRNA levels in organisms in the blood of bacteremic patients to those inin vitrocultures. Comparing convalescent- to acute-phase samples, we also detected a significant increase in the reaction of convalescent-phase antibodies with two proteins identified by IVIAT: SPA2397 and SPA0489. SPA2397 is a phage-related lysozyme, Gp19, and SPA0489 encodes a protein containing NlpC/P60 and cysteine, histidine-dependent amidohydrolase/peptidase (CHAP) domains. In a previous study utilizing a different approach, we found that transcripts for 11 and 7 of the genes identified by IVIAT were detectable in organisms in the blood of humans in Bangladesh who were bacteremic withS. Paratyphi A andSalmonella entericaserovar Typhi, respectively.S.Paratyphi A antigens identified by IVIAT warrant further evaluation for their contributions to pathogenesis and might have diagnostic, therapeutic, or preventive relevance.

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.


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.


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.


2019 ◽  
Vol 87 (5) ◽  
Author(s):  
Liliane Mukaremera ◽  
Tami R. McDonald ◽  
Judith N. Nielsen ◽  
Christopher J. Molenaar ◽  
Andrew Akampurira ◽  
...  

ABSTRACTCryptococcal meningitis (CM) causes high rates of HIV-related mortality, yet theCryptococcusfactors influencing patient outcome are not well understood. Pathogen-specific traits, such as the strain genotype and degree of antigen shedding, are associated with the clinical outcome, but the underlying biology remains elusive. In this study, we examined factors determining disease outcome in HIV-infected cryptococcal meningitis patients infected withCryptococcus neoformansstrains with the same multilocus sequence type (MLST). Both patient mortality and survival were observed during infections with the same sequence type. Disease outcome was not associated with the patient CD4 count. Patient mortality was associated with higher cryptococcal antigen levels, the cerebrospinal fluid (CSF) fungal burden by quantitative culture, and low CSF fungal clearance. The virulence of a subset of clinical strains with the same sequence type was analyzed using a mouse inhalation model of cryptococcosis. We showed a strong association between human and mouse mortality rates, demonstrating that the mouse inhalation model recapitulates human infection. Similar to human infection, the ability to multiplyin vivo, demonstrated by a high fungal burden in lung and brain tissues, was associated with mouse mortality. Mouse survival time was not associated with singleC. neoformansvirulence factorsin vitroorin vivo; rather, a trend in survival time correlated with a suite of traits. These observations show that MLST-derived genotype similarities betweenC. neoformansstrains do not necessarily translate into similar virulence either in the mouse model or in human patients. In addition, our results show thatin vitroassays do not fully reproducein vivoconditions that influenceC. neoformansvirulence.


2019 ◽  
Vol 88 (2) ◽  
Author(s):  
Srinjoy Chakraborti ◽  
Sunita Gulati ◽  
Bo Zheng ◽  
Frank J. Beurskens ◽  
Janine Schuurman ◽  
...  

ABSTRACT The sialylatable lacto-N-neotetraose (LNnT; Gal-GlcNAc-Gal-Glc) moiety from heptose I (HepI) of the lipooligosaccharide (LOS) of Neisseria gonorrhoeae undergoes positive selection during human infection. Lactose (Gal-Glc) from HepII, although phase variable, is commonly expressed in humans; loss of HepII lactose compromises gonococcal fitness in mice. Anti-LOS monoclonal antibody (MAb) 2C7, a promising antigonococcal immunotherapeutic that elicits complement-dependent bactericidal activity and attenuates gonococcal colonization in mice, recognizes an epitope comprised of lactoses expressed simultaneously from HepI and HepII. Glycan extensions beyond lactose on HepI modulate binding and function of MAb 2C7 in vitro. Here, four gonococcal LOS mutants, each with lactose from HepII but fixed (unable to phase-vary) LOS HepI glycans extended beyond the lactose substitution of HepI (lactose alone, Gal-lactose, LNnT, or GalNAc-LNnT), were used to define how HepI glycan extensions affect (i) mouse vaginal colonization and (ii) efficacy in vitro and in vivo of a human IgG1 chimeric derivative of MAb 2C7 (2C7-Ximab) with a complement-enhancing E-to-G Fc mutation at position 430 (2C7-Ximab-E430G). About 10-fold lower 2C7-Ximab-E430G concentrations achieved similar complement-dependent killing of three gonococcal mutants with glycan extensions beyond lactose-substituted HepI (lactose alone, LNnT, or GalNAc-LNnT) as 2C7-Ximab (unmodified Fc). The fourth mutant (Gal-lactose) resisted direct complement-dependent killing but was killed approximately 70% by 2C7-Ximab-E430G in the presence of polymorphonuclear leukocytes and complement. Only mutants with (sialylatable) LNnT from HepI colonized mice for >3 days, reiterating the importance of LNnT sialylation for infection. 2C7-Ximab-E430G significantly attenuated colonization caused by the virulent mutants.


2016 ◽  
Vol 84 (11) ◽  
pp. 3243-3251 ◽  
Author(s):  
Haley E. Adcox ◽  
Erin M. Vasicek ◽  
Varun Dwivedi ◽  
Ky V. Hoang ◽  
Joanne Turner ◽  
...  

Salmonella enterica serovar Typhi, the causative agent of typhoid fever in humans, forms biofilms encapsulated by an extracellular matrix (ECM). Biofilms facilitate colonization and persistent infection in gallbladders of humans and mouse models of chronic carriage. Individual roles of matrix components have not been completely elucidated in vitro or in vivo . To examine individual functions, strains of Salmonella enterica serovar Typhimurium, the murine model of S . Typhi, in which various ECM genes were deleted or added, were created to examine biofilm formation, colonization, and persistence in the gallbladder. Studies show that curli contributes most significantly to biofilm formation. Expression of Vi antigen decreased biofilm formation in vitro and virulence and bacterial survival in vivo without altering the examined gallbladder pro- or anti-inflammatory cytokines. Oppositely, loss of all ECM components (Δ wcaM Δ csgA Δ yihO Δ bcsE ) increased virulence and bacterial survival in vivo and reduced gallbladder interleukin-10 (IL-10) levels. Colanic acid and curli mutants had the largest defects in biofilm-forming ability and contributed most significantly to the virulence increase of the Δ wcaM Δ csgA Δ yihO Δ bcsE mutant strain. While the Δ wcaM Δ csgA Δ yihO Δ bcsE mutant was not altered in resistance to complement or growth in macrophages, it attached and invaded macrophages better than the wild-type (WT) strain. These data suggest that ECM components have various levels of importance in biofilm formation and gallbladder colonization and that the ECM diminishes disseminated disease in our model, perhaps by reducing cell attachment/invasion and dampening inflammation by maintaining/inducing IL-10 production. Understanding how ECM components aid acute disease and persistence could lead to improvements in therapeutic treatment of typhoid fever patients.


2016 ◽  
Vol 84 (5) ◽  
pp. 1514-1525 ◽  
Author(s):  
Dharanesh Gangaiah ◽  
Xinjun Zhang ◽  
Beth Baker ◽  
Kate R. Fortney ◽  
Hongyu Gao ◽  
...  

Haemophilus ducreyicauses the sexually transmitted disease chancroid in adults and cutaneous ulcers in children. In humans,H. ducreyiresides in an abscess and must adapt to a variety of stresses. Previous studies (D. Gangaiah, M. Labandeira-Rey, X. Zhang, K. R. Fortney, S. Ellinger, B. Zwickl, B. Baker, Y. Liu, D. M. Janowicz, B. P. Katz, C. A. Brautigam, R. S. Munson, Jr., E. J. Hansen, and S. M. Spinola, mBio 5:e01081-13, 2014,http://dx.doi.org/10.1128/mBio.01081-13) suggested thatH. ducreyiencounters growth conditions in human lesions resembling those found in stationary phase. However, howH. ducreyitranscriptionally responds to stress during human infection is unknown. Here, we determined theH. ducreyitranscriptome in biopsy specimens of human lesions and compared it to the transcriptomes of bacteria grown to mid-log, transition, and stationary phases. Multidimensional scaling showed that thein vivotranscriptome is distinct from those ofin vitrogrowth. Compared to the inoculum (mid-log-phase bacteria),H. ducreyiharvested from pustules differentially expressed ∼93 genes, of which 62 were upregulated. The upregulated genes encode homologs of proteins involved in nutrient transport, alternative carbon pathways (l-ascorbate utilization and metabolism), growth arrest response, heat shock response, DNA recombination, and anaerobiosis.H. ducreyiupregulated few genes (hgbA,flp-tad, andlspB-lspA2) encoding virulence determinants required for human infection. Most genes regulated by CpxRA, RpoE, Hfq, (p)ppGpp, and DksA, which control the expression of virulence determinants and adaptation to a variety of stresses, were not differentially expressedin vivo, suggesting that these systems are cycling on and off during infection. Taken together, these data suggest that thein vivotranscriptome is distinct from those ofin vitrogrowth and that adaptation to nutrient stress and anaerobiosis is crucial forH. ducreyisurvival in humans.


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.


2014 ◽  
Vol 197 (2) ◽  
pp. 314-325 ◽  
Author(s):  
Kristy L. Hentchel ◽  
Jorge C. Escalante-Semerena

Protein and small-molecule acylation reactions are widespread in nature. Many of the enzymes catalyzing acylation reactions belong to theGcn5-relatedN-acetyltransferase (GNAT; PF00583) family, named after the yeast Gcn5 protein. The genome ofSalmonella entericaserovar Typhimurium LT2 encodes 26 GNATs, 11 of which have no known physiological role. Here, we providein vivoandin vitroevidence for the role of the MddA (methioninederivativedetoxifier; formerly YncA) GNAT in the detoxification of oxidized forms of methionine, including methionine sulfoximine (MSX) and methionine sulfone (MSO). MSX and MSO inhibited the growth of anS. entericaΔmddAstrain unless glutamine or methionine was present in the medium. We used anin vitrospectrophotometric assay and mass spectrometry to show that MddA acetylated MSX and MSO. AnmddA+strain displayed biphasic growth kinetics in the presence of MSX and glutamine. Deletion of two amino acid transporters (GlnHPQ and MetNIQ) in a ΔmddAstrain restored growth in the presence of MSX. Notably, MSO was transported by GlnHPQ but not by MetNIQ. In summary, MddA is the mechanism used byS. entericato respond to oxidized forms of methionine, which MddA detoxifies by acetyl coenzyme A-dependent acetylation.


2017 ◽  
Vol 86 (1) ◽  
Author(s):  
Sebastián Sasías ◽  
Adriana Martínez-Sanguiné ◽  
Laura Betancor ◽  
Arací Martínez ◽  
Bruno D'Alessandro ◽  
...  

ABSTRACTSalmonella entericaserovar Dublin is adapted to cattle but is able to infect humans with high invasiveness. An acute inflammatory response at the intestine helps to preventSalmonelladissemination to systemic sites. Flagella contribute to this response by providing motility and FliC-mediated signaling through pattern recognition receptors. In a previous work, we reported a high frequency (11 out of 25) ofS. Dublin isolates lacking flagella in a collection obtained from humans and cattle. The aflagellate strains were impaired in their proinflammatory propertiesin vitroandin vivo. The aim of this work was to elucidate the underlying cause of the absence of flagella inS. Dublin isolates. We report here that class 3 flagellar genes are repressed in the human aflagellate isolates, due to impaired secretion of FliA anti-sigma factor FlgM. This phenotype is due to an in-frame 42-nucleotide deletion in thefliEgene, which codes for a protein located in the flagellar basal body. The deletion is predicted to produce a protein lacking amino acids 18 to 31. The aflagellate phenotype was highly stable; revertants were obtained only whenfliAwas artificially overexpressed combined with several successive passages in motility agar. DNA sequence analysis revealed that motile revertants resulted from duplications of DNA sequences infliEadjacent to the deleted region. These duplications produced a FliE protein of similar length to the wild type and demonstrate that amino acids 18 to 31 of FliE are not essential. The same deletion was detected inS. Dublin isolates obtained from cattle, indicating that this mutation circulates in nature.


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