scholarly journals Terminal Deoxynucleotidyl Transferase Is Not Required for Antibody Response to Polysaccharide Vaccines againstStreptococcus pneumoniaeandSalmonella entericaSerovar Typhi

2018 ◽  
Vol 86 (9) ◽  
Author(s):  
Vivek Belde ◽  
Matthew P. Cravens ◽  
Dania Gulandijany ◽  
Justin A. Walker ◽  
Isabel Palomo-Caturla ◽  
...  
Keyword(s):  
Antibody Response ◽  
B Cell ◽  
Salmonella Enterica ◽  
Passive Immunization ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Human Infants ◽  
Content Type ◽  
Serovar Typhimurium

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.

scholarly journals In Salmonella enterica, the Gcn5-Related Acetyltransferase MddA (Formerly YncA) Acetylates Methionine Sulfoximine and Methionine Sulfone, Blocking Their Toxic Effects

2014 ◽  
Vol 197 (2) ◽  
pp. 314-325 ◽  
Author(s):  
Kristy L. Hentchel ◽  
Jorge C. Escalante-Semerena
Keyword(s):  
Salmonella Enterica ◽  
Physiological Role ◽  
Methionine Sulfoximine ◽  
Amino Acid Transporters ◽  
Content Type ◽  
Methionine Sulfone ◽  
Serovar Typhimurium ◽  
Acylation Reactions

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.

scholarly journals Role of Mouse Peptidoglycan Recognition Protein PGLYRP2 in the Innate Immune Response to Salmonella enterica Serovar Typhimurium InfectionIn Vivo

2012 ◽  
Vol 80 (8) ◽  
pp. 2645-2654 ◽  
Author(s):  
Jooeun Lee ◽  
Kaoru Geddes ◽  
Catherine Streutker ◽  
Dana J. Philpott ◽  
Stephen E. Girardin
Keyword(s):  
Salmonella Enterica ◽  
Fluorescent Protein ◽  
Intraepithelial Lymphocytes ◽  
Innate Immune ◽  
Th17 Response ◽  
Content Type ◽  
Serovar Typhimurium

ABSTRACTPeptidoglycan recognition proteins (PGRPs) are a family of innate pattern recognition molecules that bind bacterial peptidoglycan. While the role of PGRPs inDrosophilainnate immunity has been extensively studied, how the four mammalian PGRP proteins (PGLYRP1 to PGLYRP4) contribute to host defense against bacterial pathogensin vivoremains poorly understood. PGLYRP1, PGLYRP3, and PGLYRP4 are directly bactericidalin vitro, whereas PGLYRP2 is anN-acetylmuramyl-l-alanine amidase that cleaves peptidoglycan between the sugar backbone and the peptide stem. Because PGLYRP2 cleaves muramyl peptides detected by host peptidoglycan sensors Nod1 and Nod2, we speculated that PGLYRP2 may act as a modifier of Nod1/Nod2-dependent innate immune responses. We investigated the role of PGLYRP2 inSalmonella entericaserovar Typhimurium-induced colitis, which is regulated by Nod1/Nod2 through the induction of an early Th17 response. PGLYRP2 did not contribute to expression of Th17-associated cytokines, interleukin-22 (IL-22)-dependent antimicrobial proteins, or inflammatory cytokines. However, we found thatPglyrp2-deficient mice displayed significantly enhanced inflammation in the cecum at 72 h postinfection, reflected by increased polymorphonuclear leukocyte (PMN) infiltration and goblet cell depletion.Pglyrp2expression was also induced in the cecum ofSalmonella-infected mice, and expression of green fluorescent protein under control of thePglyrp2promoter was increased in discrete populations of intraepithelial lymphocytes. Lastly,Nod2−/−Pglyrp2−/−mice displayed increased susceptibility to infection at 24 h postinfection compared toPglyrp2−/−mice, which correlated with increased PMN infiltration and submucosal edema. Thus, PGLYRP2 plays a protective rolein vivoin the control ofS. Typhimurium infection through a Nod1/Nod2-independent mechanism.

scholarly journals Cathelicidin Antimicrobial Peptide Expression Is Not Induced or Required for Bacterial Clearance during Salmonella enterica Infection of Human Monocyte-Derived Macrophages

2012 ◽  
Vol 80 (11) ◽  
pp. 3930-3938 ◽  
Author(s):  
Kristi L. Strandberg ◽  
Susan M. Richards ◽  
John S. Gunn
Keyword(s):  
Antimicrobial Peptide ◽  
Salmonella Enterica ◽  
Active Form ◽  
Human Monocyte ◽  
Content Type ◽  
Mutant Strains ◽  
Serovar Typhimurium ◽  
Proinflammatory Responses

ABSTRACTSalmonella entericaserovar Typhimurium is able to resist antimicrobial peptide killing by induction of the PhoP-PhoQ and PmrA-PmrB two-component systems and the lipopolysaccharide (LPS) modifications they mediate. Murine cathelin-related antimicrobial peptide (CRAMP) has been reported to inhibitS. Typhimurium growthin vitroandin vivo. We hypothesize that infection of human monocyte-derived macrophages (MDMs) withSalmonella entericaserovar Typhi andS. Typhimurium will induce human cathelicidin antimicrobial peptide (CAMP) production, and exposure to LL-37 (processed, active form of CAMP/hCAP18) will lead to upregulation of PmrAB-mediated LPS modifications and increased survivalin vivo. Unlike in mouse macrophages, in which CRAMP is upregulated during infection,campgene expression was not induced in human MDMs infected withS. Typhi orS. Typhimurium. Upon infection, intracellular levels of ΔphoPQ, ΔpmrAB, and PhoPcS. Typhi decreased over time but were not further inhibited by the vitamin D3-induced increase incampexpression. MDMs infected with wild-type (WT)S. Typhi orS. Typhimurium released similar levels of proinflammatory cytokines; however, the LPS modification mutant strains dramatically differed in MDM-elicited cytokine levels. Overall, these findings indicate thatcampis not induced duringSalmonellainfection of MDMs nor is key toSalmonellaintracellular clearance. However, the cytokine responses from MDMs infected with WT or LPS modification mutant strains differ significantly, indicating a role for LPS modifications in altering the host inflammatory response. Our findings also suggest thatS. Typhi andS. Typhimurium elicit different proinflammatory responses from MDMs, despite being capable of adding similar modifications to their LPS structures.

scholarly journals The Homolog of the Gene bstA of the BTP1 Phage from Salmonella enterica Serovar Typhimurium ST313 Is an Antivirulence Gene in Salmonella enterica Serovar Dublin

2017 ◽  
Vol 86 (1) ◽  
Author(s):  
Ana Herrero-Fresno ◽  
Irene Cartas Espinel ◽  
Malene Roed Spiegelhauer ◽  
Priscila Regina Guerra ◽  
Karsten Wiber Andersen ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Type Strain ◽  
Wild Type Strain ◽  
Luria Bertani ◽  
Wild Type ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Cattle Blood

ABSTRACTIn a previous study, a novel virulence gene,bstA, identified in aSalmonella entericaserovar Typhimurium sequence type 313 (ST313) strain was found to be conserved in all publishedSalmonella entericaserovar Dublin genomes. In order to analyze the role of this gene in the host-pathogen interaction inS. Dublin, a mutant where this gene was deleted (S. Dublin ΔbstA) and a mutant which was further genetically complemented withbstA(S. Dublin 3246-C) were constructed and tested in models ofin vitroandin vivoinfection as well as during growth competition assays in M9 medium, Luria-Bertani broth, and cattle blood. In contrast to the results obtained for a strain ofS. Typhimurium ST313, the lack ofbstAwas found to be associated with increased virulence inS. Dublin. Thus,S. Dublin ΔbstAshowed higher levels of uptake than the wild-type strain during infection of mouse and cattle macrophages and higher net replication within human THP-1 cells. Furthermore, during mouse infections,S. Dublin ΔbstAwas more virulent than the wild type following a single intraperitoneal infection and showed an increased competitive index during competitive infection assays. Deletion ofbstAdid not affect either the amount of cytokines released by THP-1 macrophages or the cytotoxicity toward these cells. The histology of the livers and spleens of mice infected with the wild-type strain and theS. Dublin ΔbstAmutant revealed similar levels of inflammation between the two groups. The gene was not important for adherence to or invasion of human epithelial cells and did not influence bacterial growth in rich medium, minimal medium, or cattle blood. In conclusion, a lack ofbstAaffects the pathogenicity ofS. Dublin by decreasing its virulence. Therefore, it might be regarded as an antivirulence gene in this serovar.

scholarly journals TheIn VitroRedundant Enzymes PurN and PurT Are Both Essential for Systemic Infection of Mice in Salmonella enterica Serovar Typhimurium

2016 ◽  
Vol 84 (7) ◽  
pp. 2076-2085 ◽  
Author(s):  
Lotte Jelsbak ◽  
Mie I. B. Mortensen ◽  
Mogens Kilstrup ◽  
John E. Olsen
Keyword(s):  
Salmonella Enterica ◽  
Single Gene ◽  
Systemic Infection ◽  
Gene Deletions ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Genes Encoding ◽  
Glycine Cleavage

Metabolic enzymes show a high degree of redundancy, and for that reason they are generally ignored in searches for novel targets for anti-infective substances. The enzymes PurN and PurT are redundantin vitroinSalmonella entericaserovar Typhimurium, in which they perform the third step of purine synthesis. Surprisingly, the results of the current study demonstrated that single-gene deletions of each of the genes encoding these enzymes caused attenuation (competitive infection indexes [CI] of <0.03) in mouse infections. While the ΔpurTmutant multiplied as fast as the wild-type strain in cultured J774A.1 macrophages, net multiplication of the ΔpurNmutant was reduced approximately 50% in 20 h. The attenuation of the ΔpurTmutant was abolished by simultaneous removal of the enzyme PurU, responsible for the formation of formate, indicating that the attenuation was related to formate accumulation or wasteful consumption of formyl tetrahydrofolate by PurU. In the process of further characterization, we disclosed that the glycine cleavage system (GCV) was the most important for formation of C1unitsin vivo(CI = 0.03 ± 0.03). In contrast, GlyA was the only important enzyme for the formation of C1unitsin vitro. The results with the ΔgcvTmutant further revealed that formation of serine by SerA and further conversion of serine into C1units and glycine by GlyA were not sufficient to ensure C1formation inS. Typhimuriumin vivo. The results of the present study call for reinvestigations of the concept of metabolic redundancy inS. Typhimuriumin vivo.

scholarly journals SadA, a Trimeric Autotransporter from Salmonella enterica Serovar Typhimurium, Can Promote Biofilm Formation and Provides Limited Protection against Infection

2011 ◽  
Vol 79 (11) ◽  
pp. 4342-4352 ◽  
Author(s):  
Dhaarini Raghunathan ◽  
Timothy J. Wells ◽  
Faye C. Morris ◽  
Robert K. Shaw ◽  
Saeeda Bobat ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Biofilm Formation ◽  
Protective Antigen ◽  
Outer Membrane Proteins ◽  
Cell Aggregation ◽  
Sub Saharan Africa ◽  
Content Type ◽  
Serovar Typhimurium

ABSTRACTSalmonella entericais a major cause of morbidity worldwide and mortality in children and immunocompromised individuals in sub-Saharan Africa. Outer membrane proteins ofSalmonellaare of significance because they are at the interface between the pathogen and the host, they can contribute to adherence, colonization, and virulence, and they are frequently targets of antibody-mediated immunity. In this study, the properties of SadA, a purported trimeric autotransporter adhesin ofSalmonella entericaserovar Typhimurium, were examined. We demonstrated that SadA is exposed on theSalmonellacell surfacein vitroandin vivoduring infection of mice. Expression of SadA resulted in cell aggregation, biofilm formation, and increased adhesion to human intestinal Caco-2 epithelial cells. Immunization of mice with folded, full-length, purified SadA elicited an IgG response which provided limited protection against bacterial challenge. When anti-SadA IgG titers were enhanced by administering alum-precipitated protein, a modest additional protection was afforded. Therefore, despite SadA having pleiotropic functions, it is not a dominant, protective antigen for antibody-mediated protection againstSalmonella.

scholarly journals Effect of Deletion of Genes Involved in Lipopolysaccharide Core and O-Antigen Synthesis on Virulence and Immunogenicity of Salmonella enterica Serovar Typhimurium

2011 ◽  
Vol 79 (10) ◽  
pp. 4227-4239 ◽  
Author(s):  
Qingke Kong ◽  
Jiseon Yang ◽  
Qing Liu ◽  
Praveen Alamuri ◽  
Kenneth L. Roland ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Lipid A ◽  
Outer Core ◽  
Wild Type ◽  
Core Oligosaccharide ◽  
Content Type ◽  
O Antigen ◽  
Serovar Typhimurium

ABSTRACTLipopolysaccharide (LPS) is a major virulence factor ofSalmonella entericaserovar Typhimurium and is composed of lipid A, core oligosaccharide (C-OS), and O-antigen polysaccharide (O-PS). While the functions of the gene products involved in synthesis of core and O-antigen have been elucidated, the effect of removing O-antigen and core sugars on the virulence and immunogenicity ofSalmonella entericaserovar Typhimurium has not been systematically studied. We introduced nonpolar, defined deletion mutations inwaaG(rfaG),waaI(rfaI),rfaH,waaJ(rfaJ),wbaP(rfbP),waaL(rfaL), orwzy(rfc) into wild-typeS.Typhimurium. The LPS structure was confirmed, and a number ofin vitroandin vivoproperties of each mutant were analyzed. All mutants were significantly attenuated compared to the wild-type parent when administered orally to BALB/c mice and were less invasive in host tissues. Strains with ΔwaaGand ΔwaaImutations, in particular, were deficient in colonization of Peyer's patches and liver. This deficiency could be partially overcome in the ΔwaaImutant when it was administered intranasally. In the context of an attenuated vaccine strain delivering the pneumococcal antigen PspA, all of the mutations tested resulted in reduced immune responses against PspA andSalmonellaantigens. Our results indicate that nonreversible truncation of the outer core is not a viable option for developing a live oralSalmonellavaccine, while awzymutant that retains one O-antigen unit is adequate for stimulating the optimal protective immunity to homologous or heterologous antigens by oral, intranasal, or intraperitoneal routes of administration.

scholarly journals Toll-Like Receptor 2 (TLR2) and TLR9 Play Opposing Roles in Host Innate Immunity against Salmonella enterica Serovar Typhimurium Infection

2015 ◽  
Vol 83 (4) ◽  
pp. 1641-1649 ◽  
Author(s):  
Renhui Zhan ◽  
Qiuju Han ◽  
Cai Zhang ◽  
Zhigang Tian ◽  
Jian Zhang
Keyword(s):  
Innate Immunity ◽  
Host Defense ◽  
Salmonella Enterica ◽  
Nk Cell ◽  
Bacterial Load ◽  
Content Type ◽  
Serovar Typhimurium ◽  
High Bacterial Load

Toll-like receptors (TLRs) are evolutionarily conserved host proteins that are essential for effective host defense against pathogens. However, recent studies suggest that some TLRs can negatively regulate immune responses. We observed here that TLR2 and TLR9 played opposite roles in regulating innate immunity against oral infection ofSalmonella entericaserovar Typhimurium in mice. WhileTLR9−/−mice exhibited shortened survival, an increased cytokine storm, and more severeSalmonellahepatitis than wild-type (WT) mice,TLR2−/−mice exhibited the opposite phenomenon. Further studies demonstrated that TLR2 deficiency and TLR9 deficiency in macrophages both disrupted NK cell cytotoxicity againstS. Typhimurium-infected macrophages by downregulating NK cell degranulation and gamma interferon (IFN-γ) production through decreased macrophage expression of the RAE-1 NKG2D ligand. But more importantly, we found thatS. Typhimurium-infectedTLR2−/−macrophages upregulated inducible nitric oxide synthase (iNOS) expression, resulting in a lower bacterial load than that in WT macrophagesin vitroand liversin vivoas well as low proinflammatory cytokine levels. In contrast,TLR9−/−macrophages showed decreased reactive oxygen species (ROS) expression concomitant with a high bacterial load in the macrophages and in livers ofTLR9−/−mice.TLR9−/−macrophages were also more susceptible than WT macrophages toS. Typhimurium-induced necroptosisin vitro, likely contributing to bacterial spread and transmissionin vivo. Collectively, these findings indicate that TLR2 negatively regulates anti-S. Typhimurium immunity, whereas TLR9 is vital to host defense and survival againstS. Typhimurium invasion. TLR2 antagonists or TLR9 agonists may thus serve as potential anti-S. Typhimurium therapeutic agents.

scholarly journals Salmonella enterica Serovar Typhimurium Colonizing the Lumen of the Chicken Intestine Grows Slowly and Upregulates a Unique Set of Virulence and Metabolism Genes

2011 ◽  
Vol 79 (10) ◽  
pp. 4105-4121 ◽  
Author(s):  
P. C. Harvey ◽  
M. Watson ◽  
S. Hulme ◽  
M. A. Jones ◽  
M. Lovell ◽  
...  
Keyword(s):  
Cell Division ◽  
Salmonella Enterica ◽  
Carbon Sources ◽  
Global Gene Expression ◽  
Intestinal Lumen ◽  
Broth Culture ◽  
Content Type ◽  
Serovar Typhimurium

ABSTRACTThe pattern of global gene expression inSalmonella entericaserovar Typhimurium bacteria harvested from the chicken intestinal lumen (cecum) was compared with that of a late-log-phase LB broth culture using a whole-genome microarray. Levels of transcription, translation, and cell divisionin vivowere lower than thosein vitro.S.Typhimurium appeared to be using carbon sources, such as propionate, 1,2-propanediol, and ethanolamine, in addition to melibiose and ascorbate, the latter possibly transformed tod-xylulose. Amino acid starvation appeared to be a factor during colonization. Bacteria in the lumen were non- or weakly motile and nonchemotactic but showed upregulation of a number of fimbrial andSalmonellapathogenicity island 3 (SPI-3) and 5 genes, suggesting a close physical association with the host during colonization.S.Typhimurium bacteria harvested from the cecal mucosa showed an expression profile similar to that of bacteria from the intestinal lumen, except that levels of transcription, translation, and cell division were higher and glucose may also have been used as a carbon source.

scholarly journals Needle-Free Delivery of Acetalated Dextran-Encapsulated AR-12 Protects Mice from Francisella tularensis Lethal Challenge

2016 ◽  
Vol 60 (4) ◽  
pp. 2052-2062 ◽  
Author(s):  
Ky V. Hoang ◽  
Heather Curry ◽  
Michael A. Collier ◽  
Hassan Borteh ◽  
Eric M. Bachelder ◽  
...  
Keyword(s):  
Francisella Tularensis ◽  
Lethal Challenge ◽  
Content Type ◽  
Human Macrophages ◽  
Gentamicin Treatment ◽  
Significant Toxicity ◽  
Serovar Typhimurium ◽  
Spectrum Activity

ABSTRACTFrancisella tularensiscauses tularemia and is a potential biothreat. Given the limited antibiotics for treating tularemia and the possible use of antibiotic-resistant strains as a biowarfare agent, new antibacterial agents are needed. AR-12 is an FDA-approved investigational new drug (IND) compound that induces autophagy and has shown host-directed, broad-spectrum activityin vitroagainstSalmonella entericaserovar Typhimurium andF. tularensis. We have shown that AR-12 encapsulated within acetalated dextran (Ace-DEX) microparticles (AR-12/MPs) significantly reduces host cell cytotoxicity compared to that with free AR-12, while retaining the ability to controlS.Typhimurium within infected human macrophages. In the present study, the toxicity and efficacy of AR-12/MPs in controlling virulent type AF. tularensisSchuS4 infection were examinedin vitroandin vivo. No significant toxicity of blank MPs or AR-12/MPs was observed in lung histology sections when the formulations were given intranasally to uninfected mice. In histology sections from the lungs of intranasally infected mice treated with the formulations, increased macrophage infiltration was observed for AR-12/MPs, with or without suboptimal gentamicin treatment, but not for blank MPs, soluble AR-12, or suboptimal gentamicin alone. AR-12/MPs dramatically reduced the burden ofF. tularensisin infected human macrophages, in a manner similar to that of free AR-12. However,in vivo, AR-12/MPs significantly enhanced the survival ofF. tularensisSchuS4-infected mice compared to that seen with free AR-12. In combination with suboptimal gentamicin treatment, AR-12/MPs further improved the survival ofF. tularensisSchuS4-infected mice. These studies provide support for Ace-DEX-encapsulated AR-12 as a promising new therapeutic agent for tularemia.

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