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1.
Front Cell Infect Microbiol ; 14: 1347813, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38487353

RESUMO

Introduction: Different serovars of Salmonella enterica cause systemic diseases in humans including enteric fever, caused by S. Typhi and S. Paratyphi A, and invasive nontyphoidal salmonellosis (iNTS), caused mainly by S. Typhimurium and S. Enteritidis. No vaccines are yet available against paratyphoid fever and iNTS but different strategies, based on the immunodominant O-Antigen component of the lipopolysaccharide, are currently being tested. The O-Antigens of S. enterica serovars share structural features including the backbone comprising mannose, rhamnose and galactose as well as further modifications such as O-acetylation and glucosylation. The importance of these O-Antigen decorations for the induced immunogenicity and cross-reactivity has been poorly characterized. Methods: These immunological aspects were investigated in this study using Generalized Modules for Membrane Antigens (GMMA) as delivery systems for the different O-Antigen variants. This platform allowed the rapid generation and in vivo testing of defined and controlled polysaccharide structures through genetic manipulation of the O-Antigen biosynthetic genes. Results: Results from mice and rabbit immunization experiments highlighted the important role played by secondary O-Antigen decorations in the induced immunogenicity. Moreover, molecular modeling of O-Antigen conformations corroborated the likelihood of cross-protection between S. enterica serovars. Discussion: Such results, if confirmed in humans, could have a great impact on the design of a simplified vaccine composition able to maximize functional immune responses against clinically relevant Salmonella enterica serovars.


Assuntos
Infecções por Salmonella , Vacinas contra Salmonella , Salmonella enterica , Humanos , Animais , Camundongos , Coelhos , Antígenos O/genética , Salmonella enterica/genética , Salmonella typhimurium/genética , Sorogrupo , Imunidade , Modelos Animais , Vacinas contra Salmonella/genética
2.
Vet Microbiol ; 291: 110030, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38428226

RESUMO

We have analyzed the capsule (CPS) and the lipopolysaccharide O-Antigen (O-Ag) biosynthesis loci of twelve Spanish field isolates of Actinobacillus pleuropneumoniae biovar 2, eleven of them previously typed serologically as serovar 4 and one non-typable (NT) (Maldonado et al., 2009, 2011). These isolates have the common core genes of the type I CPS locus, sharing >98% identity with those of serovar 2. However, the former possesses the O-Ag locus as serovar 4, and the latter possesses the O-Ag locus as serovar 7. The main difference found between the CPS loci of the 11 isolates and that of serovar 2 reference strain S1536 are two deletions, one of an 8 bp sequence upstream of the coding sequence and one of 111 bp sequence at the 5' end of the cps2G gene. The deletion mutations mentioned lead to a defect in the production of CPS in these isolates, which contributed to their previous mis-identification. In order to complement the serotyping of A. pleuropneumoniae in diagnostics and epidemiology, we have developed a multiplex PCR for the comprehensive O-Ag typing of all A. pleuropneumoniae isolates.


Assuntos
Infecções por Actinobacillus , Actinobacillus pleuropneumoniae , Doenças dos Suínos , Animais , Suínos , Sorogrupo , Reação em Cadeia da Polimerase Multiplex/veterinária , Antígenos O/genética , Infecções por Actinobacillus/veterinária , Sorotipagem/veterinária
3.
mBio ; 15(3): e0301323, 2024 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-38349180

RESUMO

A fundamental feature of Gram-negative bacteria is their outer membrane that protects the cell against environmental stressors. This defense is predominantly due to its asymmetry, with glycerophospholipids located in the inner leaflet and lipopolysaccharide (LPS) or lipooligosaccharide (LOS) confined to the outer leaflet. LPS consists of a lipid A anchor, a core oligosaccharide, and a distal O-antigen while LOS lacks O-antigen. While LPS/LOS is typically essential for growth, this is not the case for Acinetobacter baumannii. Despite this unique property, the synthesis of the core oligosaccharide of A. baumannii LOS is not well-described. Here, we characterized the LOS chemotypes of A. baumannii strains with mutations in a predicted core oligosaccharide locus via tandem mass spectrometry. This allowed for an extensive identification of genes required for core assembly that can be exploited to generate precise structural LOS modifications in many A. baumannii strains. We further investigated two chemotypically identical yet phenotypically distinct mutants, ∆2903 and ∆lpsB, that exposed a possible link between LOS and the peptidoglycan cell wall-two cell envelope components whose coordination has not yet been described in A. baumannii. Selective reconstruction of the core oligosaccharide via expression of 2903 and LpsB revealed that these proteins rely on each other for the unusual tandem transfer of two residues, KdoIII and N-acetylglucosaminuronic acid. The data presented not only allow for better usage of A. baumannii as a tool to study outer membrane integrity but also provide further evidence for a novel mechanism of core oligosaccharide assembly. IMPORTANCE: Acinetobacter baumannii is a multidrug-resistant pathogen that produces lipooligosaccharide (LOS), a glycolipid that confers protective asymmetry to the bacterial outer membrane. The core oligosaccharide is a ubiquitous component of LOS that typically follows a well-established model of synthesis. In addition to providing an extensive analysis of the genes involved in the synthesis of the core region, we demonstrate that this organism has evidently diverged from the long-held archetype of core synthesis. Moreover, our data suggest that A. baumannii LOS assembly is important for cell division and likely intersects with the synthesis of the peptidoglycan cell wall, another essential component of the Gram-negative cell envelope. This connection between LOS and cell wall synthesis provides an intriguing foundation for a unique method of outer membrane biogenesis and cell envelope coordination.


Assuntos
Acinetobacter baumannii , Lipopolissacarídeos , Lipopolissacarídeos/metabolismo , Acinetobacter baumannii/genética , Antígenos O/metabolismo , Peptidoglicano/metabolismo
4.
Int J Mol Sci ; 25(4)2024 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-38396650

RESUMO

Lipopolysaccharides (LPSs) are major components of the outer membranes of Gram-negative bacteria. In this work, the structure of the O-polysaccharide of Ochrobactrum quorumnocens T1Kr02 was identified by nuclear magnetic resonance (NMR), and the physical-chemical properties and biological activity of LPS were also investigated. The NMR analysis showed that the O-polysaccharide has the following structure: →2)-ß-d-Fucf-(1→3)-ß-d-Fucp-(1→. The structure of the periplasmic glucan coextracted with LPS was established by NMR spectroscopy and chemical methods: →2)-ß-d-Glcp-(1→. Non-stoichiometric modifications were identified in both polysaccharides: 50% of d-fucofuranose residues at position 3 were O-acetylated, and 15% of d-Glcp residues at position 6 were linked with succinate. This is the first report of a polysaccharide containing both d-fucopyranose and d-fucofuranose residues. The fatty acid analysis of the LPS showed the prevalence of 3-hydroxytetradecanoic, hexadecenoic, octadecenoic, lactobacillic, and 27-hydroxyoctacosanoic acids. The dynamic light scattering demonstrated that LPS (in an aqueous solution) formed supramolecular particles with a size of 72.2 nm and a zeta-potential of -21.5 mV. The LPS solution (10 mkg/mL) promoted the growth of potato microplants under in vitro conditions. Thus, LPS of O. quorumnocens T1Kr02 can be recommended as a promoter for plants and as a source of biotechnological production of d-fucose.


Assuntos
Lipopolissacarídeos , Ochrobactrum , Lipopolissacarídeos/química , Fucose/química , Antígenos O/química , Bactérias
5.
Microbiology (Reading) ; 170(2)2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38421161

RESUMO

Two clinically important subspecies, Francisella tularensis subsp. tularensis (type A) and F. tularensis subsp. holarctica (type B) are responsible for most tularaemia cases, but these isolates typically form a weak biofilm under in vitro conditions. Phase variation of the F. tularensis lipopolysaccharide (LPS) has been reported in these subspecies, but the role of variation is unclear as LPS is crucial for virulence. We previously demonstrated that a subpopulation of LPS variants can constitutively form a robust biofilm in vitro, but it is unclear whether virulence was affected. In this study, we show that biofilm-forming variants of both fully virulent F. tularensis subspecies were highly attenuated in the murine tularaemia model by multiple challenge routes. Genomic sequencing was performed on these strains, which revealed that all biofilm-forming variants contained a lesion within the wbtJ gene, a formyltransferase involved in O-antigen synthesis. A ΔwbtJ deletion mutant recapitulated the biofilm, O-antigen and virulence phenotypes observed in natural variants and could be rescued through complementation with a functional wbtJ gene. Since the spontaneously derived biofilm-forming isolates in this study were a subpopulation of natural variants, reversion events to the wbtJ gene were detected that eliminated the phenotypes associated with biofilm variants and restored virulence. These results demonstrate a role for WbtJ in biofilm formation, LPS variation and virulence of F. tularensis.


Assuntos
Francisella tularensis , Francisella , Hidroximetil e Formil Transferases , Tularemia , Animais , Camundongos , Francisella tularensis/genética , Antígenos O/genética , Lipopolissacarídeos , Hidroximetil e Formil Transferases/genética , Variação de Fase , Mutação
6.
Org Biomol Chem ; 22(12): 2414-2422, 2024 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-38414386

RESUMO

Chemical synthesis of the tetrasaccharide repeating unit of the O-specific polysaccharide from Enterobacter cloacae G3422 is reported. The synthesis of the target tetrasaccharide is achieved through a convergent [2 + 2]-block strategy. The conjugation ready target oligosaccharide is attractive for further glycoconjugate formation with a suitable aglycon. Synthesis of the challenging 6-deoxy-L-talose moiety is reported using two different approaches and the obvious difficulties are discussed.


Assuntos
Glicosídeos , Lactonas , Antígenos O , Enterobacter cloacae , Oligossacarídeos
7.
Int J Med Microbiol ; 314: 151610, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38310676

RESUMO

Shiga toxin-producing E. coli (STEC), including the subgroup of enterohemorrhagic E. coli (EHEC), are important bacterial pathogens which cause diarrhea and the severe clinical manifestation hemolytic uremic syndrome (HUS). Genomic surveillance of STEC/EHEC is a state-of-the-art tool to identify infection clusters and to extract markers of circulating clinical strains, such as their virulence and resistance profile for risk assessment and implementation of infection prevention measures. The aim of the study was characterization of the clinical STEC population in Germany for establishment of a reference data set. To that end, from 2020 to 2022 1257 STEC isolates, including 39 of known HUS association, were analyzed and lead to a classification of 30.4 % into 129 infection clusters. Major serogroups in all clinical STEC analyzed were O26, O146, O91, O157, O103, and O145; and in HUS-associated strains were O26, O145, O157, O111, and O80. stx1 was less frequently and stx2 or a combination of stx, eaeA and ehxA were more frequently found in HUS-associated strains. Predominant stx gene subtypes in all STEC strains were stx1a (24 %) and stx2a (21 %) and in HUS-associated strains were mainly stx2a (69 %) and the combination of stx1a and stx2a (12.8 %). Furthermore, two novel O-antigen gene clusters (RKI6 and RKI7) and strains of serovars O45:H2 and O80:H2 showing multidrug resistance were detected. In conclusion, the implemented surveillance tools now allow to comprehensively define the population of clinical STEC strains including those associated with the severe disease manifestation HUS reaching a new surveillance level in Germany.


Assuntos
Escherichia coli Êntero-Hemorrágica , Infecções por Escherichia coli , Proteínas de Escherichia coli , Síndrome Hemolítico-Urêmica , Escherichia coli Shiga Toxigênica , Humanos , Virulência/genética , Antígenos O/genética , Proteínas de Escherichia coli/genética , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/microbiologia , Genômica , Alemanha/epidemiologia , Síndrome Hemolítico-Urêmica/epidemiologia , Síndrome Hemolítico-Urêmica/microbiologia , Família Multigênica
8.
Elife ; 122024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-38358918

RESUMO

Bacterial cell surface glycoconjugates are critical for cell survival and for interactions between bacteria and their hosts. Consequently, the pathways responsible for their biosynthesis have untapped potential as therapeutic targets. The localization of many glycoconjugate biosynthesis enzymes to the membrane represents a significant challenge for expressing, purifying, and characterizing these enzymes. Here, we leverage cutting-edge detergent-free methods to stabilize, purify, and structurally characterize WbaP, a phosphoglycosyl transferase (PGT) from the Salmonella enterica (LT2) O-antigen biosynthesis. From a functional perspective, these studies establish WbaP as a homodimer, reveal the structural elements responsible for dimerization, shed light on the regulatory role of a domain of unknown function embedded within WbaP, and identify conserved structural motifs between PGTs and functionally unrelated UDP-sugar dehydratases. From a technological perspective, the strategy developed here is generalizable and provides a toolkit for studying other classes of small membrane proteins embedded in liponanoparticles beyond PGTs.


Assuntos
Salmonella enterica , Transferases , Transferases/genética , Transferases/química , Antígenos O , Metabolismo dos Carboidratos , Membrana Celular , Salmonella enterica/genética
9.
Curr Opin Chem Biol ; 78: 102424, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38168589

RESUMO

O-Antigens and core oligosaccharides from bacterial lipopolysaccharides (LPS) are often structurally unique and immunologically active, have become attractive targets in the development of antibacterial vaccines. Structurally well-defined and pure oligosaccharides can be used in identifying protective epitopes of the carbohydrate antigens, which is important for the design of an effective vaccine. Here, the recent progress on chemical synthesis and immunological evaluation of glycans related to O-antigens and core oligosaccharides from bacterial LPS are summarized.


Assuntos
Lipopolissacarídeos , Antígenos O , Oligossacarídeos , Epitopos , Antibacterianos
10.
ACS Infect Dis ; 10(2): 377-383, 2024 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-38252850

RESUMO

Shigellosis poses an ongoing global public health threat. The presence and length of the O-antigen in lipopolysaccharide play critical roles in Shigella pathogenesis. The plasmid-mediated opt gene encodes a phosphoethanolamine (PEtN) transferase that catalyzes the addition of PEtN to the O-antigen of Shigella flexneri serotype X and Y strains, converting them into serotype Xv and Yv strains, respectively. Since 2002, these modified strains have become prevalent in China. Here we demonstrate that PEtN-mediated O-antigen modification in S. flexneri increase the severity of corneal infection in guinea pigs without any adaptive cost. This heightened virulence is associated with epithelial cell adhesion and invasion, as well as an enhanced inflammatory response of macrophage. Notably, PEtN addition allow S. flexneri to attenuate the binding of complement C3 and better resist phagocytosis, potentially contributing to the retention of S. flexneri in the host environment.


Assuntos
Etanolaminas , Antígenos O , Shigella flexneri , Animais , Cobaias , Antígenos O/genética , Antígenos O/metabolismo , Sorotipagem , Plasmídeos , Shigella flexneri/genética , Shigella flexneri/metabolismo
11.
Org Lett ; 26(3): 745-750, 2024 01 26.
Artigo em Inglês | MEDLINE | ID: mdl-38198674

RESUMO

Herein, we report the first total synthesis of the tetrasaccharide repeating unit of Vibrio cholerae O:3 O-antigen polysaccharide. The highly complex tetrasaccharide contains rare amino sugars such as d-bacillosamine and l-fucosamine, highly labile sugar ascarylose, and higher carbon sugar d-d-heptose. Stereoselective glycosylation of the notoriously reactive ascarylose with d-d-heptose, poor nucleophilicity of the axial C4-OH of l-fucosamine, and amide coupling are the key challenges encountered in the total synthesis, which was completed via a longest linear sequence of 23 steps in 4.2% overall yield.


Assuntos
Antígenos O , Vibrio cholerae , Sequência de Carboidratos , Oligossacarídeos , Heptoses
12.
Carbohydr Res ; 536: 109019, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38211449

RESUMO

Lipopolysaccharide was obtained from the aerobic moderately halophilic bacterium Halomonas fontilapidosi KR26. The O-polysaccharide was isolated by mild acid degradation of the lipopolysaccharide and was examined by chemical methods and by 1H and 13C NMR spectroscopy, including 1H,1H COSY, TOCSY, ROESY, and 1H,13C HSQC, and HMBC experiments. The following structure of the linear tetrasaccharide repeating unit was deduced. →2)-α-l-Rhap-(1→2)-α-l-Rhap-(1→3)-α-l-Rhap-(1→3)-ß-d-Galp-(1→.


Assuntos
Halomonas , Lipopolissacarídeos , Polissacarídeos/química , Espectroscopia de Ressonância Magnética , Antígenos O/química
13.
Int J Biol Macromol ; 261(Pt 1): 129516, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38278393

RESUMO

The lipopolysaccharides of Herbaspirillum lusitanum P6-12T (HlP6-12T) and H. frisingense GSF30T (HfGSF30T) was isolated by phenol-water extraction from bacterial cells and was characterized using chemical analysis and SDS-PAGE. It was shown that these bacteria produce LPSs that differ in their physicochemical properties and macromolecular organization. In this paper, the lipid A structure of the HlP6-12T LPS, was characterized through chemical analyses and matrix-assisted laser desorption ionization (MALDI) mass spectrometry. To prove the effect of the size of micelles on their bioavailability, we examined the activity of both LPSs toward the morphology of wheat seedlings. Analysis of the HlP6-12T and HfGSF30T genomes showed no significant differences between the operons that encode proteins involved in the biosynthesis of the lipids A and core oligosaccharides. The difference may be due to the composition of the O-antigen operon. HfGSF30T has two copies of the rfb operon, with the main one divided into two fragments. In contrast, the HlP6-12T genome contains only a single rfb-containing operon, and the other O-antigen operons are not comparable at all. The integrity of O-antigen-related genes may also affect LPS variability of. Specifically, we have observed a hairpin structure in the middle of the O-antigen glycosyltransferase gene, which led to the division of the gene into two fragments, resulting in incorrect protein synthesis and potential abnormalities in O-antigen production.


Assuntos
Herbaspirillum , Lipopolissacarídeos , Lipopolissacarídeos/química , Antígenos O/metabolismo , Interações entre Hospedeiro e Microrganismos , Herbaspirillum/genética , Cromatografia Gasosa-Espectrometria de Massas , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
14.
Microbiol Spectr ; 12(1): e0235523, 2024 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-38092668

RESUMO

IMPORTANCE: Hemolytic uremic syndrome (HUS) is a life-threatening disease caused by Shiga toxin-producing Escherichia coli (STEC) infection. The treatment approaches for STEC-mediated typical HUS and atypical HUS differ, underscoring the importance of rapid and accurate diagnosis. However, specific detection methods for STECs other than major serogroups, such as O157, O26, and O111, are limited. This study focuses on the utility of PCR-based O-serotyping, serum agglutination tests utilizing antibodies against the identified Og type, and isolation techniques employing antibody-conjugated immunomagnetic beads for STEC isolation. By employing these methods, we successfully isolated a STEC strain of a minor serotype, O76:H7, from a HUS patient.


Assuntos
Infecções por Escherichia coli , Síndrome Hemolítico-Urêmica , Escherichia coli Shiga Toxigênica , Humanos , Toxina Shiga/genética , Antígenos O/genética , Sorotipagem/métodos , Síndrome Hemolítico-Urêmica/diagnóstico , Infecções por Escherichia coli/diagnóstico , Genômica , Testes Sorológicos
15.
Int J Biol Macromol ; 258(Pt 2): 128922, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38141699

RESUMO

Burkholderia pseudomallei, an intracellular pathogen, is responsible for melioidosis, a zoonotic disease. Its pathogenesis involves several virulence factors, among which lipopolysaccharide (LPS) plays a crucial role. Our research reveals that the O antigen present within the LPS significantly regulates the host immune response. In a previous study, we obtained a B. pseudomallei mutant strain ΔwbiI. Here, the purification of LPS from ΔwbiI and a gas chromatography-mass spectrometry (GC-MS) analysis were conducted. The results confirmed the absence of specific sugar 6-deoxy-Talp, which is a typical component of the O antigen in the wild type B. pseudomallei. Our findings underscore the potent impact the O antigen exerts on the virulence of B. pseudomallei. The ΔwbiI strain displayed significantly increased invasiveness and cytotoxicity in vitro. This enhanced cytotoxicity seems to be related to the exposure of lipid A and an increased cell membrane hydrophobicity resulting from the deletion of the O antigen. Additionally, in mouse models, the ΔwbiI strain resulted in a heightened host lethality and an excessive inflammatory response in mice. These findings indicate that the O-antigenic polysaccharide moiety of B. pseudomallei plays a role in its pathogenicity in vitro and in vivo.


Assuntos
Burkholderia pseudomallei , Camundongos , Animais , Antígenos O/genética , Lipopolissacarídeos , Virulência , Mutação
16.
Org Lett ; 26(1): 321-326, 2024 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-38147353

RESUMO

Herein, the trisaccharide repeating unit of Fusobacterium nucleatum ssp. animalis ATCC 51191, which is used to develop oncomicrobial vaccines, was efficiently synthesized for the first time. The synthetic approach featured the following: (i) construction of the 1,2-cis-glycosidic linkage using the large steric hindrance of a phthalimide group at C4 of fucosamine; (ii) synthesis of the trisaccharide via a linear [2 + 1] glycosylation strategy; and (iii) installation of l-alanine using hexafluorophosphate azabenzotriazole tetramethyl uronium as a promoter.


Assuntos
Fusobacterium nucleatum , Trissacarídeos , Fusobacterium , Antígenos O , Alanina/química , Hidrocarbonetos Fluorados
17.
Carbohydr Polym ; 326: 121581, 2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-38142087

RESUMO

Klebsiella pneumoniae is one of the priority objects for the development of new therapies against infections. The species has been perceived as of limited variety of O antigens (11 O serotypes identified to date). That trait makes lipopolysaccharide an attractive target for protective antibodies. Nowadays, K. pneumoniae O antigens encoding genes are often analysed by bioinformatic tools, such as Kaptive, indicating higher actual diversity of the O antigen loci. One of the novel K. pneumoniae O loci for which the antigen structure has not been elucidated so far is OL101. In this study, four clinical isolates predicted as OL101 were characterized and found to have the O antigen structure composed of ß-Kdop-[→3)-α-l-Rhap-(1→4)-α-d-Glcp-(1→]n, representing a novel serotype O13. Identification of the ß-Kdop terminus was based on the analysis of the complete LPS molecule by the HR-MAS NMR spectroscopy. The bioinformatic analysis of 71,377 K. pneumoniae genomes from public databases (July 2023) revealed a notable OL101 prevalence of 6.55 %.


Assuntos
Infecções por Klebsiella , Antígenos O , Humanos , Antígenos O/genética , Antígenos O/química , Klebsiella pneumoniae/genética , Sorogrupo , Lipopolissacarídeos/química
18.
Poult Sci ; 103(2): 103354, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38154449

RESUMO

In this study, we incorporated deletion of the O-antigen ligase gene to an attenuated Salmonella Enteritidis (SE) strain, JOL919 (SE PS; Δlon ΔcpxR), using the Lambda-Red recombination method and evaluated the safety and immunological aspects of the novel genotype, JOL2381 (SE VS: Δlon, ΔcpxR, ΔrfaL). Assessment of fecal shedding and organ persistence following administration via oral and IM routes revealed that the SE VS was safer than its parent strain, SE PS. Immunological assays confirmed that immunization via the oral route with SE PS was superior to the SE VS. However, chickens immunized with SE PS and SE VS strains via the IM route showed higher humoral and cell-mediated immune responses. Compared to PBS control, the IM route of immunization with SE VS resulted in a higher IgY antibody titer and expansion of CD4+ and CD8+ T-cell populations, which resulted in the clearance of Salmonella from the liver and splenic tissues. Furthermore, deletion of the O-antigen ligase gene caused lower production of LPS-specific antibodies in the host, promoting DIVA functionality and making it a plausible candidate for field utilization. Due to significant protection, high attenuation, and environmental safety concerns, the present SE VS strain is an ideal choice to prevent chicken salmonellosis and ensure public health.


Assuntos
Doenças das Aves Domésticas , Intoxicação Alimentar por Salmonella , Salmonelose Animal , Vacinas contra Salmonella , Animais , Salmonella enteritidis , Galinhas , Antígenos O , Salmonelose Animal/prevenção & controle , Intoxicação Alimentar por Salmonella/veterinária , Ligases , Doenças das Aves Domésticas/prevenção & controle
19.
Int J Mol Sci ; 24(24)2023 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-38139217

RESUMO

In most Gram-negative bacteria, outer membrane (OM) lipopolysaccharide (LPS) molecules carry long polysaccharide chains known as the O antigens or O polysaccharides (OPS). The OPS structure varies highly from strain to strain, with more than 188 O serotypes described in E. coli. Although many bacteriophages recognize OPS as their primary receptors, these molecules can also screen OM proteins and other OM surface receptors from direct interaction with phage receptor-binding proteins (RBP). In this review, I analyze the body of evidence indicating that most of the E. coli OPS types robustly shield cells completely, preventing phage access to the OM surface. This shield not only blocks virulent phages but also restricts the acquisition of prophages. The available data suggest that OPS-mediated OM shielding is not merely one of many mechanisms of bacterial resistance to phages. Rather, it is an omnipresent factor significantly affecting the ecology, phage-host co-evolution and other related processes in E. coli and probably in many other species of Gram-negative bacteria. The phages, in turn, evolved multiple mechanisms to break through the OPS layer. These mechanisms rely on the phage RBPs recognizing the OPS or on using alternative receptors exposed above the OPS layer. The data allow one to forward the interpretation that, regardless of the type of receptors used, primary receptor recognition is always followed by the generation of a mechanical force driving the phage tail through the OPS layer. This force may be created by molecular motors of enzymatically active tail spikes or by virion structural re-arrangements at the moment of infection.


Assuntos
Bacteriófagos , Antígenos O , Antígenos O/metabolismo , Escherichia coli/metabolismo , Bacteriófagos/metabolismo , Colífagos/metabolismo , Lipopolissacarídeos/metabolismo
20.
Carbohydr Res ; 534: 108977, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37949033

RESUMO

Herein, we report the total synthesis of the trisaccharide repeating unit of the O-antigen of Actinobacillus actinomycetemcomitans serotype f. The trisaccharide comprising of α-(1-2) and α-(1-3)-linked L-rhamnopyranosides backbone with the latter rhamnose containing a branching N-acetyl-d-galactosaminopyranoside at the C2-O via a ß-glycosidic bond was synthesized by two methods. Initially, the protected trisaccharide has been synthesized by step-wise assembly of the monosaccharide building blocks and subsequently the former was synthesized by the one-pot assembly of the latter components. The synthesized trisaccharide contains an aminoethyl linker appended as an O-glycoside at the reducing end, thereby providing scope for further conjugation for different applications.


Assuntos
Aggregatibacter actinomycetemcomitans , Antígenos O , Antígenos O/química , Aggregatibacter actinomycetemcomitans/química , Sorogrupo , Monossacarídeos , Glicosídeos , Trissacarídeos
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