Toxin–antitoxin(TA)systems,which are prevalent in bacteria and archaea,play diverse roles in bacterial physiology and have been proposed to be significant in stress adaptation.Despite the extensive characterization o...Toxin–antitoxin(TA)systems,which are prevalent in bacteria and archaea,play diverse roles in bacterial physiology and have been proposed to be significant in stress adaptation.Despite the extensive characterization of numerous TA systems in various bacteria,the investigation of these systems within Streptococcus suis is still limited.Here,we systematically analyzed the type Ⅱ TA systems of 95 S.suis genomes available in the GenBank database using TAfinder.A total of 612 putative type Ⅱ TA systems were retrieved and classified into 10 categories by phylogenetic analysis.Notably,an elevated occurrence of these TA systems was observed among the important prevalent serotypes 2,4,5,9,14,Chz,NCL1,and NCL3 strains.The following study identified the activities of TA systems using 2 strategies and confirmed the regulatory effect of HigBA on the type Ⅶ secretion system in S.suis by measuringβ-galactosidase activity and transcriptional changes.Moreover,we unveiled a hitherto uncharacterized,highly prevalent novel TA system,with the composition of antitoxin–toxin–antitoxin(SS-ATA),which regulates the downstream two-component signaling system.Altogether,this study systematically analyzed the type Ⅱ TA systems within S.suis,highlighting the widespread distribution of Hig BA and SS-ATA as important regulatory elements in S.suis.展开更多
Streptococcus suis serotype 2(SS2)is a zoonotic pathogen that can cause acute infection,such as septicemia in pigs and streptococcal toxic shock-like syndrome(STSLS)in humans,indicating that SS2 can evade innate immun...Streptococcus suis serotype 2(SS2)is a zoonotic pathogen that can cause acute infection,such as septicemia in pigs and streptococcal toxic shock-like syndrome(STSLS)in humans,indicating that SS2 can evade innate immunity.Macrophages perform essential antimicrobial functions in the innate immune system by engulfing and killing pathogens.Previously,a dna K mutant strain that showed impaired phagocytosis resistance ability was screened from the transposon mutant library of SS2,but the specific mechanism is unclear.In this study,we further demonstrated that DnaK was required for SS2 to be antiphagocytosed by macrophages and survive in adverse environments.A mouse challenge experiment indicated that DnaK promoted bacteremia and systemic dissemination of SS2,enhancing bacterial pathogenicity.Western blot and immunofluorescence results indicated that DnaK could be secreted by SS2 and was able to enter RAW264.7 macrophages.Then,the endocytic receptor LRP1 regulated by DnaK was identified through RNA sequencing(RNA-Seq).We found that DnaK decreased both the mRNA and protein levels of LRP1.Knockdown of the LRP1β-chain(LRP1β)significantly decreased the phagocytosis rate of the SS2 strain ZY05719,suggesting that LRP1 is a phagocytic receptor of SS2.Furthermore,inhibitor treatment assays revealed that DnaK decreased LRP1 protein levels through the transcription factor PPARγand the ubiquitin-proteasome system.In summary,DnaK contributes to the phagocytosis resistance of SS2 by decreasing LRP1 protein levels in macrophages,providing new insights into the antiphagocytosis mechanisms of SS2 and helping to understand its pathogenesis.展开更多
Streptococcus suis serotype 2(SS2)is an emerging zoonotic pathogen that causes meningitis in humans and pigs.This pathogen generates substantial economic losses in the swine industry while posing a significant threat ...Streptococcus suis serotype 2(SS2)is an emerging zoonotic pathogen that causes meningitis in humans and pigs.This pathogen generates substantial economic losses in the swine industry while posing a significant threat to public health security.The mechanisms through which SS2 penetrates the brain and induces meningitis remain incompletely understood.This study examines the role and mechanism of SS2 collagenase-like protease(Clp)in facilitating bacterial passage across the blood-brain barrier(BBB).The research demonstrates that SS2 Clp enhanced virulence and tissue colonization while promoting BBB degradation in mice.The Δclp mutant exhibited reduced ability to traverse human brain microvascular endothelial(hCMEC/D3)cell monolayers compared to wild-type SS2,while the addition of recombinant protein rClp increased permeability.Furthermore,rClp significantly enhanced SS2 adhesion to hCMEC/D3,suppressed the expression of intercellular tight junction proteins ZO-1,Occludin,and Claudin-5 independent of its enzyme activity,and triggered hCMEC/D3 apoptosis through cell receptor ligand apoptosis and mitochondrial apoptosis pathways,partially dependent on its enzyme activity,leading to BBB disruption and enhanced permeability.Additionally,Clp enhanced the infiltration of macrophages(F4/80+),monocytes(F4/80-Ly6C+),and neutrophils(Ly6G+)into the brain following SS2 infection.These findings establish that SS2 Clp is essential for bacterial passage across the BBB,offering a theoretical foundation for improved prevention and treatment strategies for SS2-induced meningitis.展开更多
Streptococcus suis(S.suis)is a major disease impacting pig farming globally.It can also be transferred to humans by eating raw pork.A comprehensive study was recently carried out to determine the indices throughmultip...Streptococcus suis(S.suis)is a major disease impacting pig farming globally.It can also be transferred to humans by eating raw pork.A comprehensive study was recently carried out to determine the indices throughmultiple geographic regions in China.Methods:The well-posed theorems were employed to conduct a thorough analysis of the model’s feasible features,including positivity,boundedness equilibria,reproduction number,and parameter sensitivity.Stochastic Euler,Runge Kutta,and EulerMaruyama are some of the numerical techniques used to replicate the behavior of the streptococcus suis infection in the pig population.However,the dynamic qualities of the suggested model cannot be restored using these techniques.Results:For the stochastic delay differential equations of the model,the non-standard finite difference approach in the sense of stochasticity is developed to avoid several problems such as negativity,unboundedness,inconsistency,and instability of the findings.Results from traditional stochastic methods either converge conditionally or diverge over time.The stochastic non-negative step size convergence nonstandard finite difference(NSFD)method unconditionally converges to the model’s true states.Conclusions:This study improves our understanding of the dynamics of streptococcus suis infection using versions of stochastic with delay approaches and opens up new avenues for the study of cognitive processes and neuronal analysis.Theplotted interaction behaviour and new solution comparison profiles.展开更多
[Objective] This study aimed to establish a method for quantitative detection of mRNA transcriptional level of SS2 adhesive related-factors of Streptococcus suis serotype 2 （SS2） by fluorescent quantitative PCR. []V...[Objective] This study aimed to establish a method for quantitative detection of mRNA transcriptional level of SS2 adhesive related-factors of Streptococcus suis serotype 2 （SS2） by fluorescent quantitative PCR. []Vlethod] The gene fragments en- coding SS2 adhesive related-factors MRP, FBPS and CPS2J and a housekeeping gene aroA were amplified by reverse transcription PCR from the total RNA of SS2, cloned, and sequenced. The recombinant plasmids containing the target genes were constructed, and used as templates in Real-time PCR. [Result] Dynamic curves, stan- dard curves and melting curves of the adhesive related-factors and aroA were ob- tained by the optimized Real-time PCR system. The standard curves showed a good linear relationship between template copy number and circulation number, and the correlation coefficients （FF） of the standard curves were over 0.995. Also, these as- says were highly specific a^d there was single specific melting peak for every gene. Moreover, the assays were highly sensitive and had a detection limit of 1.0×102 copies in 1 μl of initial templates. Finally, it was highly repeatable and had a coeffi- cient of variation less than 2% for intra-assay. [Conclusion] This study will provide a way to reveal the adhesion mechanism of SS2 to different host cells at molecular level.展开更多
Respiratory diseases are one of the most important health problems in pig herds. The porcine respiratory disease complex (PRDC) is the term used to describe pneumonic diseases caused by multiple infectious agents that...Respiratory diseases are one of the most important health problems in pig herds. The porcine respiratory disease complex (PRDC) is the term used to describe pneumonic diseases caused by multiple infectious agents that provoke weight loss in animals or death. In the PRDC multiple pathogens (bacteria and/or viruses) work in combination to induce this respiratory disease. Within this complex, Actinobacillus pleuropneumoniae, Streptococcus suis, Pasteurella multocida, Bordetella bronchiseptica, Haemophilus parasuis and Mycoplasma hyopneumoniae are the main bacterial pathogens involved in great economic losses to the swine industry. The aim of this work was to estimate the presence of A. pleuropneumoniae, S. suis, P. multocida, B. bronchiseptica, H. parasuis and M. hyopneumoniae in the upper respiratory tract of pigs in representative swine farms inAguascalientes,Mexico, using PCR technique. The study was performed in 14 swine farms. We obtained a total of 212 nasal swabs. Near 20% of samples were positive for A. pleuropneumoniae (located in the 79% of farms);17% were positive for S. suis (in 86% of farms), of these, 3% were S. suis serovar 2;30% were positive for H. parasuis (93% of farms);23% of the samples to P. multocida (in 79% of farms);and 19% to M. hyopneumoniae (in 64% of farms). B. bronchiseptica was not detected in this study. The results obtained show that bacterial pathogens of PRDC were present in the upper respiratory tract of pigs in all farms studied;therefore, these pathogens are widely disseminated in pig farms of Aguascalientes, Mexico.展开更多
Brucella suis is responsible for swine brucellosis worldwide. Of the five different B. suis biovars （by.）, bv. 2 appears restricted to Europe where it is frequently isolated from wild boar and hares, can infect pigs...Brucella suis is responsible for swine brucellosis worldwide. Of the five different B. suis biovars （by.）, bv. 2 appears restricted to Europe where it is frequently isolated from wild boar and hares, can infect pigs and can cause human brucellosis. In this study, the differ- ential gene expression profile was characterized in spleens of Eurasian wild boar naturally infected with B. suis bv. 2. Of the 20,201 genes analyzed in the microarray, 633 and 1,373 were significantly （fold change 〉 1.8; P 〈 0.01） upregulated and downregulated, respectively, in infected wild boar. The analysis was focused on genes that were over represented after conditional test for biological process gene ontology. Upregulated genes suggested that B. suis bv. 2 infection induced cell maturation, migration and/or proliferation in infected animals. The genes downregulated in infected wild boar impaired the activity of several important cellular metabolic pathways such as metabolism, cytoskeleton organization and biogenesis, immune response and lysosomal function and vesicle-mediated transport. In addition, the response to stress, sperm fertility, muscle development and apoptosis seemed to be also impaired in infected animals. These results suggested that B. suis bv. 2 may use strategies similar to other smooth brucellae to facilitate intracellular multiplication and the development of chronic infections. To our knowledge, this is the first report of the analysis of gene expression profile in hosts infected with B. suis bv. 2, which is important to understand the molecular mechanisms at the host-pathogen interface in the main reservoir species with possible implications in the zoonotic cycle of the pathogen.展开更多
Brucellosis is a bacterial anthropozoonosis usually caused by Brucella abortus, Brucella melitensis, Brucella suis and Brucella canis. Brucella suis, the causative agent of swine brucellosis, is classified into five b...Brucellosis is a bacterial anthropozoonosis usually caused by Brucella abortus, Brucella melitensis, Brucella suis and Brucella canis. Brucella suis, the causative agent of swine brucellosis, is classified into five biovars and preferentially infects different animal hostsIll. In China, brucellosis is a national notifiable communicable disease both in animals and in human. In 2009, 35 816 brucellosis cases were reported. The annual incidence was 2.7 per 100 000 population.展开更多
对四川猪链球菌2型(S.suis 2)强毒株05ZYH33溶血素样蛋白(hemolysin-like protein,HLP)编码基因hlp进行序列信息分析、分子克隆表达及溶血活性检测,深入探讨HLP的致病机制.用Blast和Clustal X程序对HLP进行基因同源性分析,用Signal P 4....对四川猪链球菌2型(S.suis 2)强毒株05ZYH33溶血素样蛋白(hemolysin-like protein,HLP)编码基因hlp进行序列信息分析、分子克隆表达及溶血活性检测,深入探讨HLP的致病机制.用Blast和Clustal X程序对HLP进行基因同源性分析,用Signal P 4.1和TMHMM Server 2.0分析HLP氨基酸序列.设计合成hlp引物进行PCR扩增,先后将hlp克隆入p MD-18T载体和p ET30a表达载体中,构建p ET30a::hly原核表达质粒.将重组质粒转化至E.coli BL21中诱导表达,并对重组HLP蛋白进行纯化和溶血活性检测.同源性分析表明HLP与多种具有溶血活性的蛋白相似性较高.氨基酸序列分析发现HLP具有信号肽和跨膜区,且由DUF21、CBS和Cor CHly C 3部分组成.序列测定显示hly片段全长1 335 bp,编码445个氨基酸.重组质粒经诱导表达和纯化后电泳显示,HLP分子量约为70 k Da,具有溶血活性.结果表明,HLP是一个膜结合蛋白,不同于能够分泌到细胞外的溶血素Suilysin.重组HLP具有一定的溶血效价,此可能与致病相关.展开更多
BACKGROUND Streptococcus suis(S.suis)is an anthropozoonotic pathogen that shows clinical manifestations of meningitis,septicemia,and arthritis in infected humans.Nocardia is another type of anthropozoonotic bacteria,w...BACKGROUND Streptococcus suis(S.suis)is an anthropozoonotic pathogen that shows clinical manifestations of meningitis,septicemia,and arthritis in infected humans.Nocardia is another type of anthropozoonotic bacteria,with clinical manifestations of skin,lung,and brain abscesses in infected humans.Few intracranial infections caused by S.suis or Nocardia have been reported.To the best of our knowledge,no study has reported a patient with simultaneous intracranial infection by S.suis and Nocardia.CASE SUMMARY A 66-year-old male presented at Liaocheng People’s Hospital(Liaocheng,Shandong Province,China)reporting dizziness with nausea and vomiting.Metagenomic next-generation sequencing(m NGS)was performed on cerebrospinal fluid for examination,and the patient was diagnosed with suppurative meningitis caused by S.suis infection.He received anti-infection treatment with penicillin sodium and ceftriaxone.The patient’s condition initially improved but then deteriorated.Further m NGS of cerebrospinal fluid revealed both S.suis and Nocardia.Imaging examination revealed a brain abscess.Furthermore,a mixed infection of S.suis and Nocardia was detected in the patient’s central nervous system.The patient was treated with antibiotics and sulfamethoxazole.He was discharged after his condition improved.CONCLUSION This case shows that the disease can be recurrent in patients with intracranial infection of a rare pathogen.The possibility of mixed infection should also be considered,especially in patients treated with immunosuppressive agents.m NGS of cerebrospinal fluid is a supplement to conventional microbial pathogen identification methods.Patients with unknown pathogen diagnosis,early extensive use of antibiotics and infection with rare pathogens can be diagnosed by the combination of conventional methods and m NGS of cerebrospinal fluid.展开更多
[Objectives]This study aimed to investigate the pathogenicity,growth characteristics and drug resistance of Streptococcus suis type 2.[Methods]Bacterial isolation and identification,biochemical experiments,determinati...[Objectives]This study aimed to investigate the pathogenicity,growth characteristics and drug resistance of Streptococcus suis type 2.[Methods]Bacterial isolation and identification,biochemical experiments,determination of growth curve and correlation curve between OD 600 values and viable counts,drug susceptibility tests,pathogenicity analysis,and histopathological observations were carried out.[Results]The Streptococcus strain isolated from infected pigs was identified as Streptococcus suis type 2,which was named TA01 strain.TA01 strain reached the growth peak at 6-8 h post-incubation,and viable counts gradually declined after 8 h of incubation.The correlation equation between OD 600 values and viable counts is y=24.659 x-1.076 1,R^2=0.996 7.TA01 strain was sensitive to penicillin,erythromycin,florfenicol and oxacillin,and resistant to ciprofloxacin,polymyxin B and clindamycin.According to the results of pathogenicity analysis,all the mice in 3.6×10^9 cfu/mouse group died within 48,and these dead mice exhibited acute pyaemia septica.Based on the Reed-Muench formula,it was calculated that LD 50 of TA01 strain was 1.137×10^8 cfu/mouse.Pathological examination showed obvious blue-stained bacteria clusters,accompanied by neutrophil infiltration.[Conclusions]TA01 strain was a virulent strain of Streptococcus suis type 2.Compared with Streptococcus strains which were isolated and reported in China,TA01 strain exhibited strong virulence and rapid proliferation.展开更多
Streptococcus suis serotype 2(S.suis 2)is a zoonotic pathogen that clinically causes severe swine and human infections(such as meningitis,endocarditis,and septicemia).In order to cause widespread diseases in different...Streptococcus suis serotype 2(S.suis 2)is a zoonotic pathogen that clinically causes severe swine and human infections(such as meningitis,endocarditis,and septicemia).In order to cause widespread diseases in different organs,S.suis 2 must colonize the host,break the blood barrier,and cause exaggerated inflammation.In the last few years,most studies have focused on a single virulence factor and its influences on the host.Membrane vesicles(MVs)can be actively secreted into the extracellular environment contributing to bacteria-host interactions.Gram-negative bacteria-derived outer membrane vesicles(OMVs)were recently shown to activate host Caspase-11-mediated non-canonical inflammasome pathway via deliverance of OMV-bound lipopolysaccharide(LPS),causing host cell pyroptosis.However,little is known about the effect of the MVs from S.suis 2(Gram-positive bacteria without LPS)on cell pyroptosis.Thus,we investigated the molecular mechanism by which S.suis 2 MVs participate in endothelial cell pyroptosis.In this study,we used proteomics,electron scanning microscopy,fluorescence microscope,Western blotting,and bioassays,to investigate the MVs secreted by S.suis 2.First,we demonstrated that S.suis 2 secreted MVs with an average diameter of 72.04 nm,and 200 proteins in MVs were identified.Then,we showed that MVs were transported to cells via mainly dynamin-dependent endocytosis.The S.suis 2 MVs activated NLRP3/Caspase-1/GSDMD canonical inflammasome signaling pathway,resulting in cell pyroptosis,but it did not activate the Caspase-4/-5 pathway.More importantly,endothelial cells produce large amounts of reactive oxygen species(ROS)and lost their mitochondrial membrane potential under induction by S.suis 2 MVs.The results in this study suggest for the first time that MVs from S.suis 2 were internalized by endothelial cells via mainly dynamin-dependent endocytosis and might promote NLRP3/Caspase-1/GSDMD pathway by mitochondrial damage,which produced mtDNA and ROS under induction,leading to the pyroptosis of endothelial cells.展开更多
Streptococcus suis is an important pathogen in pigs. Transmission of this pathogen is generally believed to occur between healthy carrier sows and their offspring, so the carrier status of S. suis in healthy sows is i...Streptococcus suis is an important pathogen in pigs. Transmission of this pathogen is generally believed to occur between healthy carrier sows and their offspring, so the carrier status of S. suis in healthy sows is important for the control of S. suis infections in pigs, especially in suckling and growing pigs. In this study, the prevalence of S. suis isolated from clinically healthy sows in China was studied for the first time. A total of 1 043 tonsil samples were collected from clinically healthy sows from 10 regions in China from 2005 to 2007. Among the 421 S. suis isolates, 31 strains were identified as capsular type 2. The results showed that S. suis was widespread in swine herds in China with the carrier rates in different herds ranging from 19.5 to 93.9%. Overall, 40.4 and 3.0% of clinically healthy sows harbored S. suis and capsular type 2 in their palatine tonsils, respectively. Statistically significant differences of carrier rates of S. suis and capsular type 2 between the different farms were observed, which was independent of herd sizes and geographic distributions of different herds.展开更多
Streptococcus suis(S.suis)is a Gram-positive zoonotic pathogen.S.suis infection in humans commonly causes meningitis,septicemia,arthritis,and streptococcal toxic shock-like syndrome(STSLS).S.suis has 29 serotypes,of w...Streptococcus suis(S.suis)is a Gram-positive zoonotic pathogen.S.suis infection in humans commonly causes meningitis,septicemia,arthritis,and streptococcal toxic shock-like syndrome(STSLS).S.suis has 29 serotypes,of which S.suis serotype 2(SS2)has the highest clinical isolation rate and strongest pathogenicity and causes most S.suis human infections.About 1,000 different sequence types(STs)were identified in S.suis based on multilocus sequence typing(MLST).Among these,STs,ST1,and ST7 belong to serotype 2 and are the major hazards of S.suis.in 1998 and 2005,two cases of SS2 human infection outbreak were reported in Jiangsu and Sichuan,China,causing 14 deaths and 38 deaths,respectively.展开更多
[ Objective] To obtain detection antigen for diagnosis of Streptococcus suis infection. [ Method] The complete ORF of glutamate dehy- drogenase （GDH） gene was amplified from the genomic DNA of Streptococcus suis ser...[ Objective] To obtain detection antigen for diagnosis of Streptococcus suis infection. [ Method] The complete ORF of glutamate dehy- drogenase （GDH） gene was amplified from the genomic DNA of Streptococcus suis serotype 2 strain SC22 isolated in Sichuan Province by poly- merase chain reaction （PCR）. The resulting product was cloned into the prokaryotic expression vector pET-30a, which was then transformed into E. coil BL21 （DE3）. The identified positive transformants were screened for expression induced by IPTG. The expression products were subjected to SDS-PAGE and the recombinant protein was purified by nickel ion-agarose affinity chromatography. New Zealand rabbits were immunized with the purified recombinant GDH protein to prepare polyclonal antibodies. Titers of the anti-serum were determined by indirect ELISA and Western blot assay. [ Result] The recombinant GDH protein was effectively expressed in the host bacteria, and highly pure recombinant protein was obtained by nickel ion-agarose affinity chromatography. High-titer anti-serum against the recombinant protein was obtained. As evidenced by western blot as- say, the sera could react specifically with the lysates of all detected Streptococcus suis strains. In addition, the recombinant GDH protein could re- act specifically with serum samples collected from five pigs experimentally infected by strain SC22. [ Conclusion] The expressed GDH fusion protein has some common epitopes of natural GDH and can be used as detection antigen to develop ELISA and other diagnostic methods.展开更多
Streptococcus suis （S. suis） is a Gram-positive, facultatively anaerobic coccus that has been implicated as the cause of a wide range of clinical disease syndromes in swine and other domestic animals. S. suis has al...Streptococcus suis （S. suis） is a Gram-positive, facultatively anaerobic coccus that has been implicated as the cause of a wide range of clinical disease syndromes in swine and other domestic animals. S. suis has also been implicated in disease in humans, especially anaong abattoir workers, swine and pork handlers. Here we report a case of streptococcal toxic shock syndrome（STSS） caused by S. suis in a 59-year-old man. Despite of intensive treatment, the patient died of shock with multiple organ failure 14 h after admission. One bacterial isolate obtained from blood culture was identified to the species level by biochemical tests and serological tests as S. suis serotype 2. Identification was confirmed by PCR amplification of genes encoding 16sRNA of S. suis and the capsule of S. suis serotype 2（cps 23）. Genes encoding virulence factors were also detected. An investigation to identify the source of S. suis revealed that several days before admission the affected man had been handling sick pigs or their meat. Transmission may occur through breaks in the skin of feet with tinea due to that no measures for personal protection was taken. This case should highten awareness of the potential for occupational exposure and human infection with S. suis.展开更多
Muramidase-released protein(MRP)is now being recognized as a critical indicator of the virulence and pathogenicity of Streptococcus suis(S.suis).However,the identification of viable therapeutics for S.suis infection w...Muramidase-released protein(MRP)is now being recognized as a critical indicator of the virulence and pathogenicity of Streptococcus suis(S.suis).However,the identification of viable therapeutics for S.suis infection was hindered by the absence of an explicit mechanism for MRP-actuated inflammation.Dihydroartemisinin(DhA)is an artemisinin derivative with potential anti-inflammatory activity.The modulatory effect of DhA on the inflammatory response mediated by the virulence factor MRP remains obscure.This research aimed to identify the signaling mechanism by which MRP triggers the innate immune response in mouse spleen and cultured macrophages.With the candidate mechanism in mind,we investigated DhA for its ability to dampen the pro-inflammatory response induced by MRP.The innate immune response in mice was drastically triggered by MRP,manifesting as splenic and systemic inflammation with splenomegaly,immune cell infiltration,and an elevation in pro-inflammatory cytokines.A crucial role for Toll-like receptor 4(TLR4)in coordinating the MRP-mediated inflammatory response via nuclear factor-kappa B(NF-kB)activation was revealed by TLR4 blockade.In addition,NFkB-dependent transducer and activator of transcription 3(STAT3)and mitogen-activated protein kinases(MAPKs)activation was required for the inflammatory signal transduction engendered by MRP.Intriguingly,we observed an alleviation effect of DhA on the MRP-induced immune response,which referred to the suppression of TLR4-mediated actuation of NF-kB-STAT3/MAPK cascades.The inflammatory response elicited by MRP is relevant to TLR4-dependent NF-kB activation,followed by an increase in the activity of STAT3 or MAPKs.DhA mitigates the inflammation process induced by MRP via blocking the TLR4 cascade,highlighting the therapeutic potential of DhA in targeting S.suis infection diseases.展开更多
基金supported by the National Key Research and Development Program of China(2022YFD1800904)the National Natural Science Foundation of China(31972650 and 32102673)+1 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(KYCX22_0780)the China Postdoctoral Science Foundation(2020M682297)。
文摘Toxin–antitoxin(TA)systems,which are prevalent in bacteria and archaea,play diverse roles in bacterial physiology and have been proposed to be significant in stress adaptation.Despite the extensive characterization of numerous TA systems in various bacteria,the investigation of these systems within Streptococcus suis is still limited.Here,we systematically analyzed the type Ⅱ TA systems of 95 S.suis genomes available in the GenBank database using TAfinder.A total of 612 putative type Ⅱ TA systems were retrieved and classified into 10 categories by phylogenetic analysis.Notably,an elevated occurrence of these TA systems was observed among the important prevalent serotypes 2,4,5,9,14,Chz,NCL1,and NCL3 strains.The following study identified the activities of TA systems using 2 strategies and confirmed the regulatory effect of HigBA on the type Ⅶ secretion system in S.suis by measuringβ-galactosidase activity and transcriptional changes.Moreover,we unveiled a hitherto uncharacterized,highly prevalent novel TA system,with the composition of antitoxin–toxin–antitoxin(SS-ATA),which regulates the downstream two-component signaling system.Altogether,this study systematically analyzed the type Ⅱ TA systems within S.suis,highlighting the widespread distribution of Hig BA and SS-ATA as important regulatory elements in S.suis.
基金funded by the National Key Research and Development Program of China(2021YFD1800400)the National Natural Science Foundation of China(32373018)+2 种基金Jiangsu Agriculture Science and Technology Innovation Fund,China(CX(23)1029)the Excellent Research Innovation Team in Universities in Anhui Province,China(2022AH010088)the Shennong Scholar Project of Anhui Agricultural University,China(rc392101)。
文摘Streptococcus suis serotype 2(SS2)is a zoonotic pathogen that can cause acute infection,such as septicemia in pigs and streptococcal toxic shock-like syndrome(STSLS)in humans,indicating that SS2 can evade innate immunity.Macrophages perform essential antimicrobial functions in the innate immune system by engulfing and killing pathogens.Previously,a dna K mutant strain that showed impaired phagocytosis resistance ability was screened from the transposon mutant library of SS2,but the specific mechanism is unclear.In this study,we further demonstrated that DnaK was required for SS2 to be antiphagocytosed by macrophages and survive in adverse environments.A mouse challenge experiment indicated that DnaK promoted bacteremia and systemic dissemination of SS2,enhancing bacterial pathogenicity.Western blot and immunofluorescence results indicated that DnaK could be secreted by SS2 and was able to enter RAW264.7 macrophages.Then,the endocytic receptor LRP1 regulated by DnaK was identified through RNA sequencing(RNA-Seq).We found that DnaK decreased both the mRNA and protein levels of LRP1.Knockdown of the LRP1β-chain(LRP1β)significantly decreased the phagocytosis rate of the SS2 strain ZY05719,suggesting that LRP1 is a phagocytic receptor of SS2.Furthermore,inhibitor treatment assays revealed that DnaK decreased LRP1 protein levels through the transcription factor PPARγand the ubiquitin-proteasome system.In summary,DnaK contributes to the phagocytosis resistance of SS2 by decreasing LRP1 protein levels in macrophages,providing new insights into the antiphagocytosis mechanisms of SS2 and helping to understand its pathogenesis.
基金supported by the National Key Research and Development Program of China(2021FYD1800405)the National Natural Science Foundation of China(32072823).
文摘Streptococcus suis serotype 2(SS2)is an emerging zoonotic pathogen that causes meningitis in humans and pigs.This pathogen generates substantial economic losses in the swine industry while posing a significant threat to public health security.The mechanisms through which SS2 penetrates the brain and induces meningitis remain incompletely understood.This study examines the role and mechanism of SS2 collagenase-like protease(Clp)in facilitating bacterial passage across the blood-brain barrier(BBB).The research demonstrates that SS2 Clp enhanced virulence and tissue colonization while promoting BBB degradation in mice.The Δclp mutant exhibited reduced ability to traverse human brain microvascular endothelial(hCMEC/D3)cell monolayers compared to wild-type SS2,while the addition of recombinant protein rClp increased permeability.Furthermore,rClp significantly enhanced SS2 adhesion to hCMEC/D3,suppressed the expression of intercellular tight junction proteins ZO-1,Occludin,and Claudin-5 independent of its enzyme activity,and triggered hCMEC/D3 apoptosis through cell receptor ligand apoptosis and mitochondrial apoptosis pathways,partially dependent on its enzyme activity,leading to BBB disruption and enhanced permeability.Additionally,Clp enhanced the infiltration of macrophages(F4/80+),monocytes(F4/80-Ly6C+),and neutrophils(Ly6G+)into the brain following SS2 infection.These findings establish that SS2 Clp is essential for bacterial passage across the BBB,offering a theoretical foundation for improved prevention and treatment strategies for SS2-induced meningitis.
基金supported by the Deanship of Scientific Research,Vice Presidency for Graduate Studies and Scientific Research,King Faisal University,Saudi Arabia[KFU250259].
文摘Streptococcus suis(S.suis)is a major disease impacting pig farming globally.It can also be transferred to humans by eating raw pork.A comprehensive study was recently carried out to determine the indices throughmultiple geographic regions in China.Methods:The well-posed theorems were employed to conduct a thorough analysis of the model’s feasible features,including positivity,boundedness equilibria,reproduction number,and parameter sensitivity.Stochastic Euler,Runge Kutta,and EulerMaruyama are some of the numerical techniques used to replicate the behavior of the streptococcus suis infection in the pig population.However,the dynamic qualities of the suggested model cannot be restored using these techniques.Results:For the stochastic delay differential equations of the model,the non-standard finite difference approach in the sense of stochasticity is developed to avoid several problems such as negativity,unboundedness,inconsistency,and instability of the findings.Results from traditional stochastic methods either converge conditionally or diverge over time.The stochastic non-negative step size convergence nonstandard finite difference(NSFD)method unconditionally converges to the model’s true states.Conclusions:This study improves our understanding of the dynamics of streptococcus suis infection using versions of stochastic with delay approaches and opens up new avenues for the study of cognitive processes and neuronal analysis.Theplotted interaction behaviour and new solution comparison profiles.
基金Supported by National Natural Science Foundation of China(31072155)Natural Science Foundation of Jiangsu Province(BK2010068)+1 种基金Fund for Independent Innovation of Agricultural Science in Jiangsu Province[CX(11)2060]Special Fund for Agroscientific Research in the Public Interest(201303041)~~
文摘[Objective] This study aimed to establish a method for quantitative detection of mRNA transcriptional level of SS2 adhesive related-factors of Streptococcus suis serotype 2 （SS2） by fluorescent quantitative PCR. []Vlethod] The gene fragments en- coding SS2 adhesive related-factors MRP, FBPS and CPS2J and a housekeeping gene aroA were amplified by reverse transcription PCR from the total RNA of SS2, cloned, and sequenced. The recombinant plasmids containing the target genes were constructed, and used as templates in Real-time PCR. [Result] Dynamic curves, stan- dard curves and melting curves of the adhesive related-factors and aroA were ob- tained by the optimized Real-time PCR system. The standard curves showed a good linear relationship between template copy number and circulation number, and the correlation coefficients （FF） of the standard curves were over 0.995. Also, these as- says were highly specific a^d there was single specific melting peak for every gene. Moreover, the assays were highly sensitive and had a detection limit of 1.0×102 copies in 1 μl of initial templates. Finally, it was highly repeatable and had a coeffi- cient of variation less than 2% for intra-assay. [Conclusion] This study will provide a way to reveal the adhesion mechanism of SS2 to different host cells at molecular level.
文摘Respiratory diseases are one of the most important health problems in pig herds. The porcine respiratory disease complex (PRDC) is the term used to describe pneumonic diseases caused by multiple infectious agents that provoke weight loss in animals or death. In the PRDC multiple pathogens (bacteria and/or viruses) work in combination to induce this respiratory disease. Within this complex, Actinobacillus pleuropneumoniae, Streptococcus suis, Pasteurella multocida, Bordetella bronchiseptica, Haemophilus parasuis and Mycoplasma hyopneumoniae are the main bacterial pathogens involved in great economic losses to the swine industry. The aim of this work was to estimate the presence of A. pleuropneumoniae, S. suis, P. multocida, B. bronchiseptica, H. parasuis and M. hyopneumoniae in the upper respiratory tract of pigs in representative swine farms inAguascalientes,Mexico, using PCR technique. The study was performed in 14 swine farms. We obtained a total of 212 nasal swabs. Near 20% of samples were positive for A. pleuropneumoniae (located in the 79% of farms);17% were positive for S. suis (in 86% of farms), of these, 3% were S. suis serovar 2;30% were positive for H. parasuis (93% of farms);23% of the samples to P. multocida (in 79% of farms);and 19% to M. hyopneumoniae (in 64% of farms). B. bronchiseptica was not detected in this study. The results obtained show that bacterial pathogens of PRDC were present in the upper respiratory tract of pigs in all farms studied;therefore, these pathogens are widely disseminated in pig farms of Aguascalientes, Mexico.
基金supported by the Grupo Santander and Fundación Marcelino Botín,Spain (Project Control of Tu-berculosis in Wildlife), Ministerio de Educación y Ciencia (MECProject AGL2005-07401)FEDER,Spain. R.C. Galindo was funded by MEC,Spain
文摘Brucella suis is responsible for swine brucellosis worldwide. Of the five different B. suis biovars （by.）, bv. 2 appears restricted to Europe where it is frequently isolated from wild boar and hares, can infect pigs and can cause human brucellosis. In this study, the differ- ential gene expression profile was characterized in spleens of Eurasian wild boar naturally infected with B. suis bv. 2. Of the 20,201 genes analyzed in the microarray, 633 and 1,373 were significantly （fold change 〉 1.8; P 〈 0.01） upregulated and downregulated, respectively, in infected wild boar. The analysis was focused on genes that were over represented after conditional test for biological process gene ontology. Upregulated genes suggested that B. suis bv. 2 infection induced cell maturation, migration and/or proliferation in infected animals. The genes downregulated in infected wild boar impaired the activity of several important cellular metabolic pathways such as metabolism, cytoskeleton organization and biogenesis, immune response and lysosomal function and vesicle-mediated transport. In addition, the response to stress, sperm fertility, muscle development and apoptosis seemed to be also impaired in infected animals. These results suggested that B. suis bv. 2 may use strategies similar to other smooth brucellae to facilitate intracellular multiplication and the development of chronic infections. To our knowledge, this is the first report of the analysis of gene expression profile in hosts infected with B. suis bv. 2, which is important to understand the molecular mechanisms at the host-pathogen interface in the main reservoir species with possible implications in the zoonotic cycle of the pathogen.
文摘Brucellosis is a bacterial anthropozoonosis usually caused by Brucella abortus, Brucella melitensis, Brucella suis and Brucella canis. Brucella suis, the causative agent of swine brucellosis, is classified into five biovars and preferentially infects different animal hostsIll. In China, brucellosis is a national notifiable communicable disease both in animals and in human. In 2009, 35 816 brucellosis cases were reported. The annual incidence was 2.7 per 100 000 population.
文摘对四川猪链球菌2型(S.suis 2)强毒株05ZYH33溶血素样蛋白(hemolysin-like protein,HLP)编码基因hlp进行序列信息分析、分子克隆表达及溶血活性检测,深入探讨HLP的致病机制.用Blast和Clustal X程序对HLP进行基因同源性分析,用Signal P 4.1和TMHMM Server 2.0分析HLP氨基酸序列.设计合成hlp引物进行PCR扩增,先后将hlp克隆入p MD-18T载体和p ET30a表达载体中,构建p ET30a::hly原核表达质粒.将重组质粒转化至E.coli BL21中诱导表达,并对重组HLP蛋白进行纯化和溶血活性检测.同源性分析表明HLP与多种具有溶血活性的蛋白相似性较高.氨基酸序列分析发现HLP具有信号肽和跨膜区,且由DUF21、CBS和Cor CHly C 3部分组成.序列测定显示hly片段全长1 335 bp,编码445个氨基酸.重组质粒经诱导表达和纯化后电泳显示,HLP分子量约为70 k Da,具有溶血活性.结果表明,HLP是一个膜结合蛋白,不同于能够分泌到细胞外的溶血素Suilysin.重组HLP具有一定的溶血效价,此可能与致病相关.
文摘BACKGROUND Streptococcus suis(S.suis)is an anthropozoonotic pathogen that shows clinical manifestations of meningitis,septicemia,and arthritis in infected humans.Nocardia is another type of anthropozoonotic bacteria,with clinical manifestations of skin,lung,and brain abscesses in infected humans.Few intracranial infections caused by S.suis or Nocardia have been reported.To the best of our knowledge,no study has reported a patient with simultaneous intracranial infection by S.suis and Nocardia.CASE SUMMARY A 66-year-old male presented at Liaocheng People’s Hospital(Liaocheng,Shandong Province,China)reporting dizziness with nausea and vomiting.Metagenomic next-generation sequencing(m NGS)was performed on cerebrospinal fluid for examination,and the patient was diagnosed with suppurative meningitis caused by S.suis infection.He received anti-infection treatment with penicillin sodium and ceftriaxone.The patient’s condition initially improved but then deteriorated.Further m NGS of cerebrospinal fluid revealed both S.suis and Nocardia.Imaging examination revealed a brain abscess.Furthermore,a mixed infection of S.suis and Nocardia was detected in the patient’s central nervous system.The patient was treated with antibiotics and sulfamethoxazole.He was discharged after his condition improved.CONCLUSION This case shows that the disease can be recurrent in patients with intracranial infection of a rare pathogen.The possibility of mixed infection should also be considered,especially in patients treated with immunosuppressive agents.m NGS of cerebrospinal fluid is a supplement to conventional microbial pathogen identification methods.Patients with unknown pathogen diagnosis,early extensive use of antibiotics and infection with rare pathogens can be diagnosed by the combination of conventional methods and m NGS of cerebrospinal fluid.
基金Supported by National Key Basic Research Program of China(973 Program)(2017YFD0500605)
文摘[Objectives]This study aimed to investigate the pathogenicity,growth characteristics and drug resistance of Streptococcus suis type 2.[Methods]Bacterial isolation and identification,biochemical experiments,determination of growth curve and correlation curve between OD 600 values and viable counts,drug susceptibility tests,pathogenicity analysis,and histopathological observations were carried out.[Results]The Streptococcus strain isolated from infected pigs was identified as Streptococcus suis type 2,which was named TA01 strain.TA01 strain reached the growth peak at 6-8 h post-incubation,and viable counts gradually declined after 8 h of incubation.The correlation equation between OD 600 values and viable counts is y=24.659 x-1.076 1,R^2=0.996 7.TA01 strain was sensitive to penicillin,erythromycin,florfenicol and oxacillin,and resistant to ciprofloxacin,polymyxin B and clindamycin.According to the results of pathogenicity analysis,all the mice in 3.6×10^9 cfu/mouse group died within 48,and these dead mice exhibited acute pyaemia septica.Based on the Reed-Muench formula,it was calculated that LD 50 of TA01 strain was 1.137×10^8 cfu/mouse.Pathological examination showed obvious blue-stained bacteria clusters,accompanied by neutrophil infiltration.[Conclusions]TA01 strain was a virulent strain of Streptococcus suis type 2.Compared with Streptococcus strains which were isolated and reported in China,TA01 strain exhibited strong virulence and rapid proliferation.
基金supported by the National Natural Science Foundation of China(U22A20520)the Innovation Team Project of Modern Agricultural Industrial Technology System of Guangdong Province,China(2023KJ119)the Natural Science Foundation Program of Guangdong Province,China(2023A1515012206)。
文摘Streptococcus suis serotype 2(S.suis 2)is a zoonotic pathogen that clinically causes severe swine and human infections(such as meningitis,endocarditis,and septicemia).In order to cause widespread diseases in different organs,S.suis 2 must colonize the host,break the blood barrier,and cause exaggerated inflammation.In the last few years,most studies have focused on a single virulence factor and its influences on the host.Membrane vesicles(MVs)can be actively secreted into the extracellular environment contributing to bacteria-host interactions.Gram-negative bacteria-derived outer membrane vesicles(OMVs)were recently shown to activate host Caspase-11-mediated non-canonical inflammasome pathway via deliverance of OMV-bound lipopolysaccharide(LPS),causing host cell pyroptosis.However,little is known about the effect of the MVs from S.suis 2(Gram-positive bacteria without LPS)on cell pyroptosis.Thus,we investigated the molecular mechanism by which S.suis 2 MVs participate in endothelial cell pyroptosis.In this study,we used proteomics,electron scanning microscopy,fluorescence microscope,Western blotting,and bioassays,to investigate the MVs secreted by S.suis 2.First,we demonstrated that S.suis 2 secreted MVs with an average diameter of 72.04 nm,and 200 proteins in MVs were identified.Then,we showed that MVs were transported to cells via mainly dynamin-dependent endocytosis.The S.suis 2 MVs activated NLRP3/Caspase-1/GSDMD canonical inflammasome signaling pathway,resulting in cell pyroptosis,but it did not activate the Caspase-4/-5 pathway.More importantly,endothelial cells produce large amounts of reactive oxygen species(ROS)and lost their mitochondrial membrane potential under induction by S.suis 2 MVs.The results in this study suggest for the first time that MVs from S.suis 2 were internalized by endothelial cells via mainly dynamin-dependent endocytosis and might promote NLRP3/Caspase-1/GSDMD pathway by mitochondrial damage,which produced mtDNA and ROS under induction,leading to the pyroptosis of endothelial cells.
基金supported by the National Key Tech-nologies R&D Program of China (2004BA519A60,2006BAK02A03-1)
文摘Streptococcus suis is an important pathogen in pigs. Transmission of this pathogen is generally believed to occur between healthy carrier sows and their offspring, so the carrier status of S. suis in healthy sows is important for the control of S. suis infections in pigs, especially in suckling and growing pigs. In this study, the prevalence of S. suis isolated from clinically healthy sows in China was studied for the first time. A total of 1 043 tonsil samples were collected from clinically healthy sows from 10 regions in China from 2005 to 2007. Among the 421 S. suis isolates, 31 strains were identified as capsular type 2. The results showed that S. suis was widespread in swine herds in China with the carrier rates in different herds ranging from 19.5 to 93.9%. Overall, 40.4 and 3.0% of clinically healthy sows harbored S. suis and capsular type 2 in their palatine tonsils, respectively. Statistically significant differences of carrier rates of S. suis and capsular type 2 between the different farms were observed, which was independent of herd sizes and geographic distributions of different herds.
基金supported by the National Natural Science Foundation of China[82172332]Gusu health youth talent of Suzhou[GSWS2019039,GSWS2020030]+2 种基金the Science and Technology Program of Suzhou[SKY2021007]Discipline Construction of The Second Affiliated Hospital of Soochow University[XKTJ-TD202001]Postgraduate Research&Practice Innovation Program of Jiangsu Province
文摘Streptococcus suis(S.suis)is a Gram-positive zoonotic pathogen.S.suis infection in humans commonly causes meningitis,septicemia,arthritis,and streptococcal toxic shock-like syndrome(STSLS).S.suis has 29 serotypes,of which S.suis serotype 2(SS2)has the highest clinical isolation rate and strongest pathogenicity and causes most S.suis human infections.About 1,000 different sequence types(STs)were identified in S.suis based on multilocus sequence typing(MLST).Among these,STs,ST1,and ST7 belong to serotype 2 and are the major hazards of S.suis.in 1998 and 2005,two cases of SS2 human infection outbreak were reported in Jiangsu and Sichuan,China,causing 14 deaths and 38 deaths,respectively.
基金supported by the grants of the Independent Innovation Fund of Shandong Binzhou Animal Science & Veterinary Medicine Academy (200802)
文摘[ Objective] To obtain detection antigen for diagnosis of Streptococcus suis infection. [ Method] The complete ORF of glutamate dehy- drogenase （GDH） gene was amplified from the genomic DNA of Streptococcus suis serotype 2 strain SC22 isolated in Sichuan Province by poly- merase chain reaction （PCR）. The resulting product was cloned into the prokaryotic expression vector pET-30a, which was then transformed into E. coil BL21 （DE3）. The identified positive transformants were screened for expression induced by IPTG. The expression products were subjected to SDS-PAGE and the recombinant protein was purified by nickel ion-agarose affinity chromatography. New Zealand rabbits were immunized with the purified recombinant GDH protein to prepare polyclonal antibodies. Titers of the anti-serum were determined by indirect ELISA and Western blot assay. [ Result] The recombinant GDH protein was effectively expressed in the host bacteria, and highly pure recombinant protein was obtained by nickel ion-agarose affinity chromatography. High-titer anti-serum against the recombinant protein was obtained. As evidenced by western blot as- say, the sera could react specifically with the lysates of all detected Streptococcus suis strains. In addition, the recombinant GDH protein could re- act specifically with serum samples collected from five pigs experimentally infected by strain SC22. [ Conclusion] The expressed GDH fusion protein has some common epitopes of natural GDH and can be used as detection antigen to develop ELISA and other diagnostic methods.
文摘Streptococcus suis （S. suis） is a Gram-positive, facultatively anaerobic coccus that has been implicated as the cause of a wide range of clinical disease syndromes in swine and other domestic animals. S. suis has also been implicated in disease in humans, especially anaong abattoir workers, swine and pork handlers. Here we report a case of streptococcal toxic shock syndrome（STSS） caused by S. suis in a 59-year-old man. Despite of intensive treatment, the patient died of shock with multiple organ failure 14 h after admission. One bacterial isolate obtained from blood culture was identified to the species level by biochemical tests and serological tests as S. suis serotype 2. Identification was confirmed by PCR amplification of genes encoding 16sRNA of S. suis and the capsule of S. suis serotype 2（cps 23）. Genes encoding virulence factors were also detected. An investigation to identify the source of S. suis revealed that several days before admission the affected man had been handling sick pigs or their meat. Transmission may occur through breaks in the skin of feet with tinea due to that no measures for personal protection was taken. This case should highten awareness of the potential for occupational exposure and human infection with S. suis.
基金supported by the National Key R&D Program of China(Grant Nos.:2022YFF1100104 and 2022YFF1100102)the National Natural Science Foundation of China(Grant Nos.:31625025,32172749,and 32202701)+1 种基金the 2115 Talent Development Program of China Agricultural University(Grant No.:00109016)the Zhengzhou 1125 Talent Program,China(Grant No.:2016XT016).
文摘Muramidase-released protein(MRP)is now being recognized as a critical indicator of the virulence and pathogenicity of Streptococcus suis(S.suis).However,the identification of viable therapeutics for S.suis infection was hindered by the absence of an explicit mechanism for MRP-actuated inflammation.Dihydroartemisinin(DhA)is an artemisinin derivative with potential anti-inflammatory activity.The modulatory effect of DhA on the inflammatory response mediated by the virulence factor MRP remains obscure.This research aimed to identify the signaling mechanism by which MRP triggers the innate immune response in mouse spleen and cultured macrophages.With the candidate mechanism in mind,we investigated DhA for its ability to dampen the pro-inflammatory response induced by MRP.The innate immune response in mice was drastically triggered by MRP,manifesting as splenic and systemic inflammation with splenomegaly,immune cell infiltration,and an elevation in pro-inflammatory cytokines.A crucial role for Toll-like receptor 4(TLR4)in coordinating the MRP-mediated inflammatory response via nuclear factor-kappa B(NF-kB)activation was revealed by TLR4 blockade.In addition,NFkB-dependent transducer and activator of transcription 3(STAT3)and mitogen-activated protein kinases(MAPKs)activation was required for the inflammatory signal transduction engendered by MRP.Intriguingly,we observed an alleviation effect of DhA on the MRP-induced immune response,which referred to the suppression of TLR4-mediated actuation of NF-kB-STAT3/MAPK cascades.The inflammatory response elicited by MRP is relevant to TLR4-dependent NF-kB activation,followed by an increase in the activity of STAT3 or MAPKs.DhA mitigates the inflammation process induced by MRP via blocking the TLR4 cascade,highlighting the therapeutic potential of DhA in targeting S.suis infection diseases.
