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Carbohydrate Research Aug 2018Streptococcus suis serotype 3 is counted among the S. suis serotypes causing clinical disease in pigs. Yet, limited information is available on this serotype. Here we...
Streptococcus suis serotype 3 is counted among the S. suis serotypes causing clinical disease in pigs. Yet, limited information is available on this serotype. Here we determined for the first time the chemical composition and structure of serotype 3 capsular polysaccharide (CPS), a major bacterial virulence factor and the antigen at the origin of S. suis classification into serotypes. Chemical and spectroscopic data gave the repeating unit sequence for serotype 3: [4)D-GlcA (β1-3)d-QuiNAc4NAc(β1-]. To the best of our knowledge, this is the first report of di-N-acetyl-d-bacillosamine (QuiNAc4NAc) containing polysaccharides in Streptococci and the second time this rare diamino sugar has been observed in a Gram-positive bacterial species since its initial report. This led to the identification of homologues of UDP-QuiNAc4NAc synthesis genes in S. suis serotype 18. Thus, the repeating unit sequence for serotype 18 is: [3)d-GalNAc(α1-3)[d-Glc (β1-2)]d-GalA4OAc(β1-3)d-GalNAc(α1-3)d-QuiNAc4NAc(α1-]. A correlation between S. suis serotypes 3 and 18 CPS sequences and genes of these serotypes' cps loci encoding putative glycosyltransferases and polymerase responsible for the biosynthesis of the repeating unit was tentatively established. Knowledge of CPS structure and composition will contribute to better dissect the role of this bacterial component in the pathogenesis of S. suis serotypes 3 and 18.
Topics: Hexosamines; Polysaccharides; Streptococcus suis
PubMed: 30014879
DOI: 10.1016/j.carres.2018.07.003 -
International Immunopharmacology Apr 2019Streptococcus suis, a globally distributed bacterial pathogen, is an important zoonotic agent for humans and animals that can lead to multiple deaths and cause major...
Streptococcus suis, a globally distributed bacterial pathogen, is an important zoonotic agent for humans and animals that can lead to multiple deaths and cause major economic losses. Suilysin (SLY), secreted by most pathogenic S. suis strains, is a cytotoxic toxin that belongs to the cholesterol-dependent cytolysin family; this toxin plays a key role in a mouse meningitis model, suggesting that effective interference with the biological activity of SLY may be a potential treatment for S. suis infection. In addition, the inflammatory response induced by S. suis is an important manifestation in infections and is associated with multiple fatal diseases. In this study, we found that the natural compound quercetin can directly inhibit the pore-forming activity of SLY without affecting bacterial growth and SLY secretion at the concentrations tested in our assay. In addition, quercetin treatment significantly alleviated cytotoxicity caused by S. suis infection and effectively reduced the release of the pro-inflammatory cytokines IL-1β, IL-6, and tumor necrosis factor alpha (TNF-α) stimulated by bacteria. Significantly decreased mortality was observed for the S. suis-infected mice that received quercetin. Our results suggested that quercetin may represent a promising therapeutic candidate for S. suis infection by targeting SLY and the subsequent inflammation. The present study provides a new strategy and leading compound for S. suis infection.
Topics: Animals; Anti-Inflammatory Agents; Cell Line; Cytokines; Disease Models, Animal; Female; Hemolysin Proteins; Humans; Inflammation Mediators; Macrophages; Mice; Mice, Inbred C57BL; Quercetin; Streptococcal Infections; Streptococcus suis; Swine; Swine Diseases; Virulence
PubMed: 30682719
DOI: 10.1016/j.intimp.2019.01.017 -
Journal of Applied Microbiology Jun 2020The aim of this study is to investigate Streptococcus suis strains present in Jiangsu province, China.
AIMS
The aim of this study is to investigate Streptococcus suis strains present in Jiangsu province, China.
METHODS AND RESULTS
In all, 1650 nasal and anal swab samples and 100 tonsils were collected from clinically healthy swine. Culture characteristics, colony morphology and PCR-based analysis of the glutamate dehydrogenase (gdh) gene were performed for S. suis identification, and eight isolates were confirmed to be S. suis. The isolates serogroups were identified by agglutinating test, including 4, 7, 3, 5 and 8. Gene profiling by PCR showed that the manN, purD, orf2, gdh genes were conserved among the isolates and that 50% of the isolates carried dltA, pgdA, srtA and sspA. Antimicrobial susceptibility test showed the isolates displayed resistance to clindamycin, erythromycin, tetracycline, penicillin G, vancomycin and linezolid; while none was resistant to chloramphenicol, multi-drug resistance was seen in most of the isolates. Finally, the LD (assessed by zebrafish) of isolates RD105 was 2·6431 × 10 and HA24 was 7·1198 × 10 , which showed RD105 more virulent and was consistent with the results of virulence factor identification.
CONCLUSIONS
There is a very low proportion of S. suis in the healthy pigs. The virulence factors were related to pathogenicity. Bacteria in Nantong possess greater virulence potential than those in Huaian.
SIGNIFICANCE AND IMPACT OF THE STUDY
Systematic investigation of S. suis provided the most basic theoretical support for the prevention and control of swine streptococcosis.
Topics: Animals; Anti-Bacterial Agents; Bacterial Proteins; China; Drug Resistance, Bacterial; Microbial Sensitivity Tests; Serogroup; Streptococcal Infections; Streptococcus suis; Swine; Swine Diseases; Virulence; Virulence Factors
PubMed: 31981255
DOI: 10.1111/jam.14591 -
BMC Research Notes Dec 2019Streptococcus suis (S. suis) is a causative agent for various syndromes in pigs. It can be transmitted to humans with typical symptoms of meningitis and death. Although...
OBJECTIVE
Streptococcus suis (S. suis) is a causative agent for various syndromes in pigs. It can be transmitted to humans with typical symptoms of meningitis and death. Although human infections have been confirmed at Bali Referral Hospital, Indonesia, since 2014, the bacteria have not been isolated from pigs. Here, we provide confirmation of the presence of the bacteria in sick pigs in the province.
RESULTS
Streptococcus suis was confirmed in 8 of 30 cases. The final confirmation was made using PCR and sequencing of the glutamate dehydrogenase (GDH) and recombination/repair protein (recN) gene fragments. Upon PCR serotyping, two were confirmed to be serotype 2 or 1/2. Prominent histopathological lesions of confirmed cases were meningitis, endocarditis, pericarditis, bronchopneumonia, enteritis and glomerulonephritis. The dominant inflammatory cells were neutrophils and macrophages. Further research is needed to understand the risk factors for human infection. Community awareness on the risk of contracting S. suis and vaccine development are needed to prevent human infections.
Topics: Animals; Glutamate Dehydrogenase; Indonesia; Molecular Typing; Polymerase Chain Reaction; Streptococcal Infections; Streptococcus suis; Swine; Swine Diseases
PubMed: 31806042
DOI: 10.1186/s13104-019-4826-7 -
Journal of Applied Microbiology Aug 2021This study aimed to explore potential drug targets of Streptococcus suis at the system level.
AIMS
This study aimed to explore potential drug targets of Streptococcus suis at the system level.
METHODS AND RESULTS
A homologous protein mapping method was used in the construction of a protein-protein interaction (PPI) network of S. suis, which presented 1147 non-redundant interaction pairs among 286 proteins. The parameters of PPI networks were calculated and showed scale-free network properties. In all, 41 possibly essential proteins identified from 47 highly connected proteins were selected as potential drug target candidates. Of these proteins, 30 were already regarded as drug targets in other bacterial species. Six transporters with high connections to other functional proteins were identified as probably not essential but important functional proteins. Afterward, the subnetwork centred with cell division protein FtsZ was used in confirming the PPI network through bacterial two-hybrid analysis.
CONCLUSIONS
The predicted PPI network covers 13·04% of the proteome in S. suis. The selected 41 potential drug target candidates are conserved between S. suis and several model bacteria.
SIGNIFICANCE AND IMPACT OF THE STUDY
The predictions included proteins known to be drug targets, and a verifying experiment confirmed the reliability of predicted interactions. This work is the first to present systematic computational PPI data for S. suis and provides potential drug targets, which are valuable in exploring novel anti-streptococcus drugs.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Membrane Transport Proteins; Protein Interaction Mapping; Proteome; Streptococcus suis
PubMed: 33249680
DOI: 10.1111/jam.14950 -
Archives of Microbiology Apr 2023Streptococcus suis is a major bacterial pathogen of swine and an emerging zoonotic agent that has to date resulted in substantial economic losses to the swine industry...
Streptococcus suis is a major bacterial pathogen of swine and an emerging zoonotic agent that has to date resulted in substantial economic losses to the swine industry worldwide, and can cause persistent infection by forming biofilms. GrpE and histidine protein kinase ComD are important proteins implicated in the pathogenicity of S. suis, although whether they play roles in adhesion and biofilm formation has yet to be sufficiently clarified. In this study, we constructed grpE and comD deletion strains of S. suis by homologous recombination, and examined their cell adhesion and biofilm formation capacities compared with those of the wild-type strain. The pathogenicity of the grpE and comD deletion strains was evaluated using a mouse infection model, which revealed that compared with the wild-type, these deletion strains induced milder symptoms and lower bacteremia, as well as comparatively minor organ (brain, spleen, liver, and lung) lesions, in the infected mice. Moreover, the deletion of grpE and comD significantly reduced the pro-inflammatory cytokine (IL-6, IL-1β, and TNF-α) induction capacity of S. suis. Collectively, the findings of this study indicate that the GrpE and ComD proteins of Streptococcus suis play key roles in the adherence to PK-15 cells and the formation of biofilms, thereby contributing to the virulence of this pathogen.
Topics: Animals; Swine; Virulence; Streptococcus suis; Biofilms; Cytokines; Brain; Disease Models, Animal; Bacterial Proteins
PubMed: 37005968
DOI: 10.1007/s00203-023-03503-1 -
Microbiology Spectrum Dec 2022Little is known about the damage to the important peripheral immune organ spleen caused by Streptococcus suis infection. In this study, we found that S. suis induced...
Little is known about the damage to the important peripheral immune organ spleen caused by Streptococcus suis infection. In this study, we found that S. suis induced splenomegaly and lymphocyte disruption in spleens of mice. To explore the mechanism of splenic lesions induced by S. suis, we conducted further studies. The results showed that S. suis induced apoptosis in B cells, which is related to the cleavage of caspase-3 and caspase-8, but not the release of apoptosis-inducing factor (AIF). Thus, S. suis induced apoptosis in the spleen through caspase-dependent and AIF-independent pathways. Inflammation lesions induced in the spleen of infected mice were also investigated; we found macrophages increased in histopathological lesions of infected spleens from 12 h postinoculation to 7 days postinoculation (dpi), and the type of increased macrophages was M1 type by confocal microscopy, which can secrete proinflammatory cytokines. Meanwhile, inflammasome NLRP3 and caspase-1 were activated, and gasdermin D (GSDMD) was cleaved, which causes pyroptosis that may result in the release of numerous proinflammatory cytokines. What's more, the increase of p-JNK and p-p38 indicated that the MAPK pathway was also involved in the proinflammatory responses during S. suis infection, whereas anti-inflammatory responses in spleen were suppressed, with regulatory T cells (Tregs) upregulating at 1 dpi. Taken together, proinflammatory immune responses dominate in early infection, which induce splenomegaly and splenocyte apoptosis. This is the first report of mechanisms associated with S. suis-induced splenic lesions. Streptococcus suis serotype 2 is considered an emerging pathogen and represents a threat to humans and animals. The spleen is an important peripheral immune organ, and splenomegaly is a consequence of lesions and an important clinical indicator of S. suis infection. However, knowledge of the mechanisms underlying spleen lesions is still very limited. In the present work, we made the investigation to explain the phenomenon and the related immunomodulation in a mouse infection model. The obtained results show that inflammation contributes to splenomegaly, while apoptosis contributes to lymphocyte disruption in spleens. Related signaling pathways were discovered which have never been associated with S. suis-induced splenic injury. The new knowledge generated will help us better understand the mechanism of S. suis pathogenesis.
Topics: Humans; Animals; Mice; Spleen; Streptococcus suis; Splenomegaly; Serogroup; Cytokines; Apoptosis; Inflammation
PubMed: 36287014
DOI: 10.1128/spectrum.03210-22 -
Virulence 2018Streptococcus suis is a major porcine bacterial pathogen and emerging zoonotic agent. S. suis 5'-nucleotidase is able to convert adenosine monophosphate to adenosine,...
Streptococcus suis is a major porcine bacterial pathogen and emerging zoonotic agent. S. suis 5'-nucleotidase is able to convert adenosine monophosphate to adenosine, resulting in inhibiting neutrophil functions in vitro and it is an important virulence factor. Here, we show that S. suis 5'-nucleotidase not only enables producing 2'-deoxyadenosine from 2'-deoxyadenosine monophosphate by the enzymatic assay and reversed-phase high performance liquid chromatography (RP-HPLC) analysis in vitro, but also synthesizes both 2'-deoxyadenosine and adenosine in mouse blood in vivo by RP-HPLC and liquid chromatography with tandem mass spectrometry analyses. Cellular cytotoxicity assay and Western blot analysis indicated that the production of 2'-deoxyadenosine by 5'-nucleotidase triggered the death of mouse macrophages RAW 264.7 in a caspase-3-dependent way. The in vivo infection experiment showed that 2'-deoxyadenosine synthesized by 5'-nucleotidase caused monocytopenia in mouse blood. The in vivo transcriptome analysis in mouse blood showed the inhibitory effect of 5'-nucleotidase on neutrophil functions and immune responses probably mediated through the generation of adenosine. Taken together, these findings indicate that S. suis synthesizes 2'-deoxyadenosine and adenosine by 5'-nucleotidase to dampen host immune responses, which represents a new mechanism of S. suis pathogenesis.
Topics: 5'-Nucleotidase; Adenosine; Animals; Bacterial Proteins; Deoxyadenosines; Female; Gene Expression Profiling; Host-Pathogen Interactions; Macrophages; Mice; Neutrophils; RAW 264.7 Cells; Streptococcal Infections; Streptococcus suis; Virulence Factors
PubMed: 30221577
DOI: 10.1080/21505594.2018.1520544 -
Talanta Jan 2024Streptococcus suis serotype 2 is an economically important zoonotic pathogen that causes septicemia, arthritis, and meningitis in pigs and humans. S. suis serotype 2 is...
Streptococcus suis serotype 2 is an economically important zoonotic pathogen that causes septicemia, arthritis, and meningitis in pigs and humans. S. suis serotype 2 is responsible for substantial economic losses to the swine industry and poses a serious threat to public health, and accurate and rapid detection is important for the prevention and control of epidemic disease. In this study, we developed a high-fidelity detection and serotyping platform for S. suis serotype 2 based on recombinase polymerase amplification (RPA) and a clustered regularly interspaced short palindromic repeat (CRISPR)-Cas12a system called Cards-SSJ/K. Cards-SSJ had a detection limit of 10 CFU, takes <60 min, and no cross-reaction was found with other S. suis serotypes, closely related Streptococcus spp., or common pig pathogens, and Cards-SSK could differentiate serotype 2 from serotype 1/2. Results from Cards-SSJ and qPCR were equivalent in detecting S. suis serotype 2 in tissue samples. Analysis indicated that despite a relatively high reagent cost compared to PCR and qPCR, Cards-SSJ was less time-consuming and had low requirements for equipment and personnel. Thus, it is an excellent method for point-of-care detection for S. suis serotype 2.
Topics: Humans; Swine; Animals; Serotyping; Serogroup; Streptococcus suis; CRISPR-Cas Systems; Streptococcal Infections
PubMed: 37734291
DOI: 10.1016/j.talanta.2023.125202 -
Future Microbiology Jul 2016Streptococcus suis is an important swine and zoonotic pathogen equipped with several virulence factors. The pore-forming toxins are the most abundant bacterial toxins... (Review)
Review
Streptococcus suis is an important swine and zoonotic pathogen equipped with several virulence factors. The pore-forming toxins are the most abundant bacterial toxins and classified as critical virulence (associated) factors of several pathogens. The role of suilysin (SLY), a pore-forming cholesterol-dependent cytolysin of S. suis, as a true virulence factor is under debate. Most of the bacterial toxins have been reported to modulate the host immune system to facilitate invasion and subsequent replication of bacteria within respective host cells. SLY has been demonstrated to play an important role in the pathogenesis of S. suis infection and inflammatory response in vitro and in vivo. This review highlights the contributions of SLY to the pathogenicity of S. suis. It will address its role during the development of S. suis meningitis in pigs, as well as humans, and discuss SLY as a potential vaccine candidate.
Topics: Animals; Cell Line; Hemolysin Proteins; Humans; Meningitis, Bacterial; Serotyping; Streptococcal Infections; Streptococcus suis; Swine; Swine Diseases; Virulence Factors; Zoonoses
PubMed: 27357518
DOI: 10.2217/fmb-2016-0028