Methicillin-resistant Staphylococcus aureus(MRSA) causes widespread infections and poses serious public health concerns. Its high level of resistance to multiple antibiotics has garnered growing interest in identifyin...Methicillin-resistant Staphylococcus aureus(MRSA) causes widespread infections and poses serious public health concerns. Its high level of resistance to multiple antibiotics has garnered growing interest in identifying and applying novel antibacterial compounds derived from natural sources. In this study, we purified a biosurfactant(BS) from Bacillus rugosus HH2 to develop a natural antibacterial agent. This agent was then reinforced with chitooligosaccharide(COS) and polyvinyl alcohol(PVA) to create a hydrogel that promoted healing in MRSA-infected wounds. The COS/PVA/BS hydrogel was readily fabricated via the freeze-thaw method and demonstrated excellent mechanical strength, biological activity,and biocompatibility. In vitro assays confirmed that the hydrogel significantly enhanced the proliferation, migration, angiogenesis, and extracellular matrix deposition of fibroblasts,keratinocytes, and endothelial cells. Moreover, it exhibited strong bacteriostatic and bactericidal activities against MRSA, along with potent antibiofilm activity and inhibition of virulence factors relevant to MRSA-induced wound infections. Its anti-virulence effects have been linked to the downregulation of quorum sensing and virulence-related genes in MRSA. In an in vivo model of MRSA-induced infection, the COS/PVA/BS hydrogel significantly accelerated wound healing and markedly reduced the MRSA burden. Immunofluorescence staining confirmed enhanced neovascularization and regulated macrophage responses,underscoring the angiogenic and immunomodulatory effects of the hydrogel. Overall,the COS/PVA/BS hydrogel represents a promising therapeutic strategy for addressing antibiotic-resistant bacterial infections and promoting wound repair, supported by the use of common raw materials, a simple fabrication process, and high-yield production of natural antibacterial agents.展开更多
Staphylococcus aureus(S.aureus)is the third most common pathogen causing 10.6%of bacterial foodborne illnesses in China in 2021[1].Heat-stable Staphylococcal Enterotoxins(SEs)produced by S.aureus are the main contribu...Staphylococcus aureus(S.aureus)is the third most common pathogen causing 10.6%of bacterial foodborne illnesses in China in 2021[1].Heat-stable Staphylococcal Enterotoxins(SEs)produced by S.aureus are the main contributors to staphylococcal food poisoning(SFP),causing vomiting,diarrhea,abdominal pain,headache,muscle cramps,and other acute gastroenteritis symptoms.More than 25 SEs and staphylococcal enterotoxin-like toxins(SE/s)have been described and which together comprise a superfamily of pyrogenic toxin superantigens(SAgs)[2].展开更多
Objective Pseudomonas aeruginosa(P.aeruginosa)is a prevalent pathogenic bacterium involved in meningitis;however,the virulence factors contributing to this disease remain poorly understood.Methods The virulence of the...Objective Pseudomonas aeruginosa(P.aeruginosa)is a prevalent pathogenic bacterium involved in meningitis;however,the virulence factors contributing to this disease remain poorly understood.Methods The virulence of the P.aeruginosa A584,isolated from meningitis samples,was evaluated by constructing in vitro blood-brain barrier and in vivo systemic infection models.qPCR,whole-genome sequencing,and drug efflux assays of A584 were performed to analyze the virulence factors.Results Genomic sequencing showed that A584 formed a phylogenetic cluster with the reference strains NY7610,DDRC3,Pa58,and Pa124.Its genome includes abundant virulence factors,such as hemolysin,the Type IV secretion system,and pyoverdine.A584 is a multidrug-resistant strain,and its wide-spectrum resistance is associated with enhanced drug efflux.Moreover,this strain caused significantly more severe damage to the blood-brain barrier than the standard strain,PAO1.qPCR assays further revealed the downregulation of the blood-brain barrier-associated proteins Claudin-5 and Occludin by A584.During systemic infection,A584 exhibited a higher capacity of brain colonization than PAO1(37.1×10^(6) CFU/g brain versus 2.5×10^(6) CFU/g brain),leading to higher levels of the proinflammatory factors IL-1βand TNF-α.Conclusion This study sheds light on the virulence factors of P.aeruginosa involved in meningitis.展开更多
Group A streptococcus （GAS） causes a wide range of diseases in the human population. GAS diseases are more common in children than in adults, with clinical manifestations ranging from pharyngitis and impetigo to inv...Group A streptococcus （GAS） causes a wide range of diseases in the human population. GAS diseases are more common in children than in adults, with clinical manifestations ranging from pharyngitis and impetigo to invasive infections and post streptococcal sequelae, such as acute rheumatic fever and acute post-streptococcal glomerulonephritis[1]. GAS harbors a host of virulence factors that contribute to its complex pathogenicity and differences in the disease severity and frequency. M protein, one of the major virulence factors, is encoded by the emm gene induces a type of specific host immune response and confers antiphagocytic properties.展开更多
Helicobacter pylori(H.pylori)is a Gram-negative bacterium that infects about half of the world's population.H.pylori infection prevails by several mechanisms of adaptation of the bacteria and by its virulence fact...Helicobacter pylori(H.pylori)is a Gram-negative bacterium that infects about half of the world's population.H.pylori infection prevails by several mechanisms of adaptation of the bacteria and by its virulence factors including the cytotoxin associated antigen A(CagA).CagA is an oncoprotein that is the protagonist of gastric carcinogenesis associated with prolonged H.pylori infection.In this sense,small regulatory RNAs(sRNAs)are important macromolecules capable of inhibiting and activating gene expression.This function allows sRNAs to act in adjusting to unstable environmental conditions and in responding to cellular stresses in bacterial infections.Recent discoveries have shown that nickelregulated small RNA(NikS)is a post-transcriptional regulator of virulence properties of H.pylori,including the oncoprotein CagA.Notably,high concentrations of nickel cause the reduction of NikS expression and consequently this increases the levels of CagA.In addition,NikS expression appears to be lower in clinical isolates from patients with gastric cancer when compared to patients without.With that in mind,this minireview approaches,in an accessible way,the most important and current aspects about the role of NikS in the control of virulence factors of H.pylori and the potential clinical repercussions of this modulation.展开更多
Oral diseases related to dental biofilms continue to afflict the majority of the world＇s population. Among them, dental caries continues to be the single most prevalent and costly oral infectious disease （Marsh, 200...Oral diseases related to dental biofilms continue to afflict the majority of the world＇s population. Among them, dental caries continues to be the single most prevalent and costly oral infectious disease （Marsh, 2003; Dye et al., 2007）. Dental caries results from the interaction of specific bacteria with constituents of the diet within a dental biofilm known as plaque （Bowen, 2002）. Sucrose is considered to be the ＂arch criminal＂ from the dietary aspect because it serves as a substrate for synthesis of extracellular （EPS） and intracellular （IPS） polysaccharides in dental biofilm and is also fermentable （Bowen, 2002）.展开更多
BACKGROUND The high prevalence and persistence of Helicobacter pylori(H. pylori) infection, as well as the diversity of pathologies related to it, suggest that the virulence factors used by this microorganism are vari...BACKGROUND The high prevalence and persistence of Helicobacter pylori(H. pylori) infection, as well as the diversity of pathologies related to it, suggest that the virulence factors used by this microorganism are varied. Moreover, as its proteome contains 340hypothetical proteins, it is important to investigate them to completely understand the mechanisms of its virulence and survival. We have previously reported that the hypothetical protein HP0953 is overexpressed during the first hours of adhesion to inert surfaces, under stress conditions, suggesting its role in the environmental survival of this bacterium and perhaps as a virulence factor.AIM To investigate the expression and localization of HP0953 during adhesion to an inert surface and against gastric(AGS) cells.METHODS Expression analysis was performed for HP0953 during H. pylori adhesion. HP0953 expression at 0,3, 12, 24, and 48 h was evaluated and compared using the Kruskal-Wallis equality-of-populations rank test. Recombinant protein was produced and used to obtain polyclonal antibodies for immunolocalization. Immunogold technique was performed on bacterial sections during adherence to inert surfaces and AGS cells, which was analyzed by transmission electron microscopy. HP0953 protein sequence was analyzed to predict the presence of a signal peptide and transmembrane helices, both provided by the ExPASy platform, and using the GLYCOPP platform for glycosylation sites. Different programs, via, I-TASSER, RaptorX, and HHalign-Kbest, were used to perform three-dimensional modeling.RESULTS HP0953 exhibited its maximum expression at 12 h of infection in gastric epithelium cells.Immunogold technique revealed HP0953 localization in the cytoplasm and accumulation in some peripheral areas of the bacterial body, with greater expression when it is close to AGS cells.Bioinformatics analysis revealed the presence of a signal peptide that interacts with the transmembrane region and then allows the release of the protein to the external environment. The programs also showed a similarity with the Tip-alpha protein of H. pylori. Tip-alpha is an exotoxin that penetrates cells and induces tumor necrosis factor alpha production, and HP0953 could have a similar function as posttranslational modification sites were found;modifications in turn require enzymes located in eukaryotic cells. Thus, to be functional, HP0953 may necessarily need to be translocated inside the cell where it can trigger different mechanisms producing cellular damage.CONCLUSION The location of HP0953 around infected cells, the probable posttranslational modifications, and its similarity to an exotoxin suggest that this protein is a virulence factor.展开更多
Objective:To investigate the effect of Corchorus olitorius aqueous fraction(COAF)on quorum sensing(QS)-regulated virulence factors and biofilm formation in Pseudomonas aeruginosa(PAO1).Methods:The preliminary screenin...Objective:To investigate the effect of Corchorus olitorius aqueous fraction(COAF)on quorum sensing(QS)-regulated virulence factors and biofilm formation in Pseudomonas aeruginosa(PAO1).Methods:The preliminary screening of the anti-QS effect of COAF was performed by evaluating the anti-pathogenic activity against Chromobacterium violaceum CV026 biosensor strain.Next,the inhibitory effects of COAF on QS-regulated pyocyanin production,proteolytic and elastolytic activities,swarming motility,and biofilm formation were evaluated in PAO1.Results:The results showed that the treatment of COAF significantly decreased the biofilm biomass,attenuated virulence factors,and inhibited swarming motility of PAO1 without affecting the growth of the bacteria in a dose-dependent manner.COAF at 2000μg/mL significantly decreased Las B elastase activity in PAO1 culture,exopolysaccharide production,swarming motility,pyocyanin level,and biomass of PAO1 by 55%(P<0.05),60%(P<0.01),61%(P<0.01),65%(P<0.01)and 73%(P<0.01),respectively.In addition,the production of violacein was decreased by 62%(P<0.01)with the treatment of a high dose of COAF.Conclusions:These findings indicate that COAF can be a potential source of anti-QS agents.展开更多
This study investigates the biofilm formation, presence and distribution of virulence genes and the capacity to induce an inflammatory response in strains of Staphylococcus aureus isolated from milk samples in Bahia, ...This study investigates the biofilm formation, presence and distribution of virulence genes and the capacity to induce an inflammatory response in strains of Staphylococcus aureus isolated from milk samples in Bahia, Brazil. A total of 132 samples of raw milk were collected from four dairy farms (designated A to D) located in southwestern Bahia, in the municipality of Vitória da Conquista, from October/2009 to September/2010. After processing of the samples, 94 (71.2%) S. aureus isolates were obtained. These strains were subjected to the antibiogram method MIC (Minimum Inhibitory Concentration). As for the pathogenicity, tests were performedin vitrobiofilm formation induced by glucose. Moreover, we performed PCR for their virulence genes: sea (enterotoxin A), seb (B), sec (C), pvl (Panton-Valentine Leukocidin), clfA (Clumping Factor A) and spa (protein A) and analysis of cytokine induction in the inflammatory response of J774 macrophages by exocellular lipoteichoic acid. No isolates were resistant to oxacillin and vancomycin. In biofilm production, 5.31% (5/94) isolates did not produce biofilm, 5.31% (5/94) of the samples were poor producers, 15.96% (15/94) strains were moderate producers, 18.09% (17/94) were producers and 55.32% (55/94) of isolates were strong biofilm producers. One (1.06%) isolate expressed the seb gene, one (1.06%) sec, 18 (19.2%) cflA and 44 (46.8%) had spa. There was no expression of sea and pvl between isolates analyzed. The analysis of cytokine induction in the inflammatory response did not show statistical difference in the levels of IL-6, TNF-α and IL-10 induction. However, there was statistical difference in IL-1 induction between isolates from different farms. Thus, it appears that the results obtained in this study show significant effects for the region studied, since it is an important dairy region, hence the need for further studies, with the intent of attracting funding that contributes to improving prevention and control in both dairy farms and dairy industries, since milk contamination poses a serious potential health risk to consumers.展开更多
Virulence factors(VFs)confer upon pathogens the ability to cause various types of damage or diseases.Wastewater treatment plants(WWTPs)are important point sources for the emission of pathogens and VFs into receiving r...Virulence factors(VFs)confer upon pathogens the ability to cause various types of damage or diseases.Wastewater treatment plants(WWTPs)are important point sources for the emission of pathogens and VFs into receiving rivers.Conventional WWTP upgrades are often implemented to improve the water quality of receiving ecosystems.However,knowledge on the pathogens,VFs,and health risks to receiving aquatic ecosystems after upgrade remains limited.In this study,we investigated detailed pathogenic information,including taxa,pathogenicity,and health risk,in two wastewater-dominant rivers after WWTP upgrade.Using 16S rRNA gene sequencing,we screened 14 potential pathogens in water and epilithic biofilm samples,though they were significantly more enriched in the biofilms.Combining 16S rRNA and metagenomic sequencing data,we identified Pseudomonas and Aeromonas as the dominant pathogenic taxa carrying functional VFs(e.g.,mobility and offensive)in the epilithic biofilm.Moreover,strong pathogen-specific VF-host co-occurrence events were observed in the epilithic biofilm samples,indicating the importance of biofilms as reservoirs and vehicles for VFs.Further,we demonstrated that mobility VF is crucial for biofilm formation and pathogens in biofilm carrying offensive VF may be highly invasive.Quantification and health risk assessment suggested that the skin contact risk of P.aeruginosa carrying VFs was higher than the acceptable probability of 10^(-4)in both water and epilithic biofilm samples,which may threaten ecological and human health.展开更多
BACKGROUND The pathogenicity of Helicobacter pylori is dependent on factors including the environment and the host.Although selenium is closely related to pathogenicity as an environmental factor,the specific correlat...BACKGROUND The pathogenicity of Helicobacter pylori is dependent on factors including the environment and the host.Although selenium is closely related to pathogenicity as an environmental factor,the specific correlation between them remains unclear.AIM To investigate how selenium acts on virulence factors and reduces their toxicity.METHODS H.pylori strains were induced by sodium selenite.The expression of cytotoxin-associated protein A(CagA)and vacuolating cytotoxin gene A(VacA)was determined by quantitative PCR and Western blotting.Transcriptomics was used to analyze CagA,CagM,CagE,Cag1,Cag3,and CagT.C57BL/6A mice were infected with the attenuated strains subjected to sodium selenite induction,and H.pylori colonization,inflammatory reactions,and the cell adhesion ability of H.pylori were assessed.RESULTS CagA and VacA expression was upregulated at first and then downregulated in the H.pylori strains after sodium selenite treatment.Their expression was significantly and steadily downregulated after the 5th cycle(10 d).Transcriptome analysis revealed that sodium selenite altered the levels affect H.pylori virulence factors such as CagA,CagM,CagE,Cag1,Cag3,and CagT.Of these factors,CagM and CagE expression was continuously downregulated and further downregulated after 2 h of induction with sodium selenite.Moreover,CagT expression was upregulated before the 3rd cycle(6 d)and significantly downregulated after the 5th cycle.Cag1 and Cag3 expression was upregulated and downregulated,respectively,but no significant change was observed by the 5th cycle.C57BL/6A mice were infected with the attenuated strains subjected to sodium selenite induction.The extent of H.pylori colonization in the stomach increased;however,sodium selenite also induced a mild inflammatory reaction in the gastric mucosa of H.pylori-infected mice,and the cell adhesion ability of H.pylori was significantly weakened.CONCLUSION These results demonstrate that H.pylori displayed virulence attenuation after the 10th d of sodium selenite treatment.Sodium selenite is a low toxicity compound with strong stability that can reduce the cell adhesion ability of H.pylori,thus mitigating the inflammatory damage to the gastric mucosa.展开更多
Salmonella is a common genus of seriously harmful food-borne zoonotic bacteria. Humans and animals may be infected with Salmonella through ingestion of SalmoneUa-contaminated eggs and poultry meat. Therefore, in order...Salmonella is a common genus of seriously harmful food-borne zoonotic bacteria. Humans and animals may be infected with Salmonella through ingestion of SalmoneUa-contaminated eggs and poultry meat. Therefore, in order to reduce the incidence of Salmonella infections, it is crucial to explore the pathogenic mech- anism of Salmonella. invA and invE are major virulence factor genes that encode invasion proteins of Salmonella. In order to explore the pathogenic mechanism of Salmonella, phylogenetic analysis of major virulence factor genes in 33 Salmonella strains isolated from chicken was analyzed. According to the results, ivnA gene was successfully amplified from 33 Salmonella strains; ivnE gene was successfully amplified from 32 Salmonella strains, ivnA nucleotide sequences shared 72.9% - 97.6% homology among 12 sequenced Salmonella strains and shared 78.9% - 97.2% homology with those in GenBank ; ivnE nucleotide sequences shared over 95.3% homology among 23 sequenced Salmonella strains and shared 89.6% -98.6% homology with those in GenBank, which exhibited no genetic relationship to other organisms. This study provided the basis for rapid molecular detection, epidemiological research and molecular pathogenesis analysis of Salmonella.展开更多
Sugarcane leaf shows the classical arrangement of cells, which defines a C4 species. Vascular bundles consist of xylem, phloem and fibres, surrounded by an outer layer ofsclereids and an inner ring of stone cells asso...Sugarcane leaf shows the classical arrangement of cells, which defines a C4 species. Vascular bundles consist of xylem, phloem and fibres, surrounded by an outer layer ofsclereids and an inner ring of stone cells associated with the phloem. Some sclereids located below and above the vascular bundles act as docking cells and connect the vascular bundle to the internal surfaces of upper and lower layers of the epidermis. A compact mass ofsclereids occupies the total internal volume of the leaf edge. Neither docking cells nor the internal mass of sclereids in the edge were markedly coloured by phloroglucinol, indicating the absence of lignin in their cell walls. However, such staining indicated that fibres of the vascular bundle and the external layer of sclereids were strongly lignified. Incubation of leaf discs with an virulence factors produced by the pathogen Sporisorium scitamineum increased the thickness of the lignified cell walls of sclereids as well as the mid and small xylem vessels, as a possible mechanical defence response to the potential entry of the pathogen. This mechanism was mainly revealed for the resistant cv. Mayari 55-14, whereas lignification decreased for the susceptible cv. B 42231.展开更多
Species of Staphylococcus are common in hospital infection (HI). Methicillin resistant S. aureus (MRSA) has also become a serious problem in Brazilian HI. The aim of this study was to characterize the pathogenicity of...Species of Staphylococcus are common in hospital infection (HI). Methicillin resistant S. aureus (MRSA) has also become a serious problem in Brazilian HI. The aim of this study was to characterize the pathogenicity of methicillin-resistant S. aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) isolated in public hospitals. The clinical isolates were obtained from intensive care unit. The MRSA and MSSA strains were genotyped by PCR for detection genes related to virulence factors. Moreover, the strains were tested for biofilm formation and cytokine induction in macrophages. Three strains of MRSA (9.68%) expressed the Sea gene, one (3.23%) Seb, 17 (54.84%) Spa and seven (22.58%) had PVL. Two MSSA strains (2.98%) expressed the Sea gene, three (4.48%) Seb, 18 (26.87%) Spa and 11 (16.42%) showed positive results for the PVL gene. There was no expression of Sec and CflA between MRSA and MSSA strains. Among MRSA and MSSA isolates, none statistical differences were observed in biofilm production. The analysis of cytokine induction in the inflammatory response of J774 macrophages by MRSA and MSSA isolates did not show statistical difference. Understanding the mechanisms of pathogenesis of S. aureus could provide important clues for both preventing and treating infection caused by these organisms.展开更多
Enteroaggregative (EAEC) and atypical enteropathogenic (EPEC) Escherichia coli are important bacterial etiologic agents causing diarrhea among children. The aim of the present study was to examine the impact of virule...Enteroaggregative (EAEC) and atypical enteropathogenic (EPEC) Escherichia coli are important bacterial etiologic agents causing diarrhea among children. The aim of the present study was to examine the impact of virulence factors predisposes to diarrhea. In this study some virulence properties were examined on 11 EAEC and 8 EPEC strains identified by Polymerase Chain Reaction (PCR), isolated from stool samples of children were analyzed genotypically and phenoltypically for the prevalence of virulence factors. The most frequently detected factor was resistance to serum (94%), followed by curli fimbriae (78%), biofilm production (73%), and gene coding for Extended-Spectrum Beta-Lactamase (ESBL) (68%). EPEC isolates showed at least three of the evaluated properties, while EAEC isolates showed at least two. The prevalence of these virulence factors between the two strains showed no statistical difference. This study showed the heterogeneity of the virulence profile of the isolates of EAEC and atypical EPEC strains and suggests that this diversity may influence in the disease severity.展开更多
Inexpressible Island is a small rocky island in Terra Nova Bay,Victoria Land,Antarctica,which is an area with limited human activities.Understanding the distribution of antibiotic-resistance genes(ARGs)and virulence f...Inexpressible Island is a small rocky island in Terra Nova Bay,Victoria Land,Antarctica,which is an area with limited human activities.Understanding the distribution of antibiotic-resistance genes(ARGs)and virulence factor genes(VFGs)in this environment can provide key information on their potential risks to humans and their roles for microbial survival.In this study,we investigated the ARGs and VFGs in lake sediments from Inexpressible Island using metagenomic sequencing.We identified 11,502,071 open-reading frames(ORFs),with 1,749 classified as ARGs and 6,838 as VFGs.The dominant ARGs were associated with antibiotic target alteration and efflux pump mechanisms,while the VFGs were related to adher-ence and immune modulation functions.While associated within microbial genomes,these ARGs and VFGs were mobile genetic elements like viruses and insertion sequences,distinct from ecosystems with strong human influence.We identified 974 metagenome-assembled genomes(MAGs),with 465 being medium-to-high quality.Of these,325(69.9%)contained ARGs,primarily affiliated with Actinomycetota and Pseudomonadota.Additionally,269 MAGs contained VFGs,with 174 MAGs carrying both ARGs and VFGs,highlighting significant microbial antibiotic resistance and pathogenic potential.Our findings highlight the need for ongoing monitoring of ARGs and VFGs in Antarctica,particularly in light of increasing human activity and climate change.展开更多
Bacteria of the family Weeksellaceae are Gram-negative,and include 17 genera and 185 species.The emerging infectious pathogens of the family include Chryseobacterium indologenes,C.gleum,Elizabethkingia anophelis,E.men...Bacteria of the family Weeksellaceae are Gram-negative,and include 17 genera and 185 species.The emerging infectious pathogens of the family include Chryseobacterium indologenes,C.gleum,Elizabethkingia anophelis,E.meningoseptica,and E.miricola.In this review,we summarize the reported infections and the virulence factors of these pathogens.The main virulence factors of C.indologenes include phosphatases and proteases.The formation of the E.anophelis biofilm is associated with its pathogenicity,and the virulence factors of E.miricola,E.anophelis,and E.meningoseptica have been predicted from the genomic sequences of clinical strains.In this article,we summarize the case reports of infection and the virulence factors of pathogens in the family Weeksellaceae,to provide important data for evaluating the potential pathogenicity of other species within the family.展开更多
Two-component signal transduction systems(TCSTSs),consisting of a histidine kinase and a response regulator,play a critical role in regulating virulence gene expression in Gram-negative phytopathogenic bacteria Xantho...Two-component signal transduction systems(TCSTSs),consisting of a histidine kinase and a response regulator,play a critical role in regulating virulence gene expression in Gram-negative phytopathogenic bacteria Xanthomonas spp..To date,12 TCSTS genes have been identified,accounting for approximately 10%of the TCSTS genes in each genome that have been experimen-tally identified to be related to pathogenesis.These TCSTSs modulate the expression of a number of virulence factors through diverse molecular mechanisms such as interacting with DNA,protein-binding and involvement in second messenger metabolism,which generates a high level of regulatory versatility.Here we summarize the current knowledge in thisfield and discuss the emerging themes and remaining questions that are important in deciphering the signaling network of TCSTSs in Xantho-monas.展开更多
Probiotics are emerging as a promising approach to treating foodborne infections or gastrointestinal diseases.This study aimed to explore the protective effect of Lactiplantibacillus plantarum YZX28(YZX28)on intestina...Probiotics are emerging as a promising approach to treating foodborne infections or gastrointestinal diseases.This study aimed to explore the protective effect of Lactiplantibacillus plantarum YZX28(YZX28)on intestinal barrier dysfunction induced by enterotoxigenic Escherichia coli K80(ETEC K80).Caco-2 cells were used for in vitro co-culture experiments of enterotoxin-producing ETEC K80 and YZX28.The barrier permeability(higher phenol red flux and decreased TEER)and levels of pro-inflammatory cytokines TNF-αand IL-8 increased by ETEC K 80 were attenuated by YZX28,and the mRNA levels of tight junctions,including ZO-1,occludin,claudin-1,and cingulin were significantly increased by YZX28 intervention.The redistribution of ZO-1,claudin-1,and actin fibers in Caco-2 cells induced by ETEC K 80 was restored.Furthermore,YZX28 could effectively reduce the adhesion level of ETEC to Caco-2 cells,alleviate the decrease of cell viability induced by ETEC,and inhibit the expression of ETEC virulence factors,including enterotoxin STa(est-A),STb(est-B),LT(elt)as well as fimbria adhesin FaeG and reduced the corresponding cAMP,cGMP,and CEACAM6 levels.This strain may be a potential therapeutic agent for treating intestinal-related problems caused by the intestinal pathogen ETEC.展开更多
Quorum sensing(Qs)inhibition has emerged as a promising target for directed drug design,providing an appealing strategy for developing antimicrobials,particularly against infections caused by drug-resistant pathogens....Quorum sensing(Qs)inhibition has emerged as a promising target for directed drug design,providing an appealing strategy for developing antimicrobials,particularly against infections caused by drug-resistant pathogens.In this study,we designed and synthesized a total of 33β-nitrostyrene derivatives using 1-nitro-2-phenylethane(NPe)as the lead compound,to target the facultative anaerobic bacterial pathogen Serratia marcescens.The QS-inhibitory effects of these compounds were evaluated using S.marcescens NJ01 and the reporter strain Chromobacterium violaceum CV026.Among the 33 newβ-nitrostyrene derivatives,(E)-1-methyl-4-(2-nitrovinyl)benzene(m-NPe,compound 28)was proven to be a potent inhibitor that reduced biofilm formation of S.marcescens NJ01 by 79%.Scanning electron microscopy(SEM)and confocal laser scanning microscopy(CLSM)results revealed that treatment with m-NPe(50μg/ml)not only enhanced the susceptibility of the formed biofilms but also disrupted the architecture of biofilms by 84%.m-NPe(50μg/ml)decreased virulence factors in S.marcescens NJ01,reducing the activity of protease,prodigiosin,and extracellular polysaccharide(EPs)by 36%,72%,and 52%,respectively.In S.marcescens 4547,the activities of hemolysin and EPs were reduced by 28%and 40%,respectively,outperforming the positive control,vanillic acid(VAN).The study also found that the expression levels of QS-and biofilm-related genes(flhD,fimA,fimC,sodB,bsmB,pigA,pigC,and shlA)were downregulated by 1.21-to 2.32-fold.Molecular dynamics analysis showed that m-NPe could bind stably to SmaR,Rhll,RhiR,LasR,and CviR proteins in a 0.1 M sodium chloride solution.Importantly,a microscale thermophoresis(MST)test revealed that SmaR could be a target protein for the screening of a quorum sensing inhibitor(QSl)against S.marcescens.Overall,this study highlights the efficacy of m-NPe in suppressing the virulence factors of S.marcescens,identifying it as a new potential Qsl and antibiofilm agent capable of restoring or improving antimicrobial drug sensitivity.展开更多
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education (RS-2021-NR060118,RS-2024-00408404, and RS-2025-00555808)supported by the Korea Institute of Marine Science&Technology Promotion (KIMST)funded by the Ministry of Oceans and Fisheries (RS-2024-00404977)。
文摘Methicillin-resistant Staphylococcus aureus(MRSA) causes widespread infections and poses serious public health concerns. Its high level of resistance to multiple antibiotics has garnered growing interest in identifying and applying novel antibacterial compounds derived from natural sources. In this study, we purified a biosurfactant(BS) from Bacillus rugosus HH2 to develop a natural antibacterial agent. This agent was then reinforced with chitooligosaccharide(COS) and polyvinyl alcohol(PVA) to create a hydrogel that promoted healing in MRSA-infected wounds. The COS/PVA/BS hydrogel was readily fabricated via the freeze-thaw method and demonstrated excellent mechanical strength, biological activity,and biocompatibility. In vitro assays confirmed that the hydrogel significantly enhanced the proliferation, migration, angiogenesis, and extracellular matrix deposition of fibroblasts,keratinocytes, and endothelial cells. Moreover, it exhibited strong bacteriostatic and bactericidal activities against MRSA, along with potent antibiofilm activity and inhibition of virulence factors relevant to MRSA-induced wound infections. Its anti-virulence effects have been linked to the downregulation of quorum sensing and virulence-related genes in MRSA. In an in vivo model of MRSA-induced infection, the COS/PVA/BS hydrogel significantly accelerated wound healing and markedly reduced the MRSA burden. Immunofluorescence staining confirmed enhanced neovascularization and regulated macrophage responses,underscoring the angiogenic and immunomodulatory effects of the hydrogel. Overall,the COS/PVA/BS hydrogel represents a promising therapeutic strategy for addressing antibiotic-resistant bacterial infections and promoting wound repair, supported by the use of common raw materials, a simple fabrication process, and high-yield production of natural antibacterial agents.
基金supported by the Ministry of Science and Technology of the People’s Republic of China(2022YFD1800400).
文摘Staphylococcus aureus(S.aureus)is the third most common pathogen causing 10.6%of bacterial foodborne illnesses in China in 2021[1].Heat-stable Staphylococcal Enterotoxins(SEs)produced by S.aureus are the main contributors to staphylococcal food poisoning(SFP),causing vomiting,diarrhea,abdominal pain,headache,muscle cramps,and other acute gastroenteritis symptoms.More than 25 SEs and staphylococcal enterotoxin-like toxins(SE/s)have been described and which together comprise a superfamily of pyrogenic toxin superantigens(SAgs)[2].
基金supported by National Natural Science Foundation of China,China(32170102)Natural Science Foundation of Tianjin(21JCYBJC01420)the Fundamental Research Funds for the Central Universities(63233050)。
文摘Objective Pseudomonas aeruginosa(P.aeruginosa)is a prevalent pathogenic bacterium involved in meningitis;however,the virulence factors contributing to this disease remain poorly understood.Methods The virulence of the P.aeruginosa A584,isolated from meningitis samples,was evaluated by constructing in vitro blood-brain barrier and in vivo systemic infection models.qPCR,whole-genome sequencing,and drug efflux assays of A584 were performed to analyze the virulence factors.Results Genomic sequencing showed that A584 formed a phylogenetic cluster with the reference strains NY7610,DDRC3,Pa58,and Pa124.Its genome includes abundant virulence factors,such as hemolysin,the Type IV secretion system,and pyoverdine.A584 is a multidrug-resistant strain,and its wide-spectrum resistance is associated with enhanced drug efflux.Moreover,this strain caused significantly more severe damage to the blood-brain barrier than the standard strain,PAO1.qPCR assays further revealed the downregulation of the blood-brain barrier-associated proteins Claudin-5 and Occludin by A584.During systemic infection,A584 exhibited a higher capacity of brain colonization than PAO1(37.1×10^(6) CFU/g brain versus 2.5×10^(6) CFU/g brain),leading to higher levels of the proinflammatory factors IL-1βand TNF-α.Conclusion This study sheds light on the virulence factors of P.aeruginosa involved in meningitis.
文摘Group A streptococcus （GAS） causes a wide range of diseases in the human population. GAS diseases are more common in children than in adults, with clinical manifestations ranging from pharyngitis and impetigo to invasive infections and post streptococcal sequelae, such as acute rheumatic fever and acute post-streptococcal glomerulonephritis[1]. GAS harbors a host of virulence factors that contribute to its complex pathogenicity and differences in the disease severity and frequency. M protein, one of the major virulence factors, is encoded by the emm gene induces a type of specific host immune response and confers antiphagocytic properties.
基金Supported by CNPq Brazil (National Council for Scientific and Technological Development)-FFM,No. 317005/2021-09
文摘Helicobacter pylori(H.pylori)is a Gram-negative bacterium that infects about half of the world's population.H.pylori infection prevails by several mechanisms of adaptation of the bacteria and by its virulence factors including the cytotoxin associated antigen A(CagA).CagA is an oncoprotein that is the protagonist of gastric carcinogenesis associated with prolonged H.pylori infection.In this sense,small regulatory RNAs(sRNAs)are important macromolecules capable of inhibiting and activating gene expression.This function allows sRNAs to act in adjusting to unstable environmental conditions and in responding to cellular stresses in bacterial infections.Recent discoveries have shown that nickelregulated small RNA(NikS)is a post-transcriptional regulator of virulence properties of H.pylori,including the oncoprotein CagA.Notably,high concentrations of nickel cause the reduction of NikS expression and consequently this increases the levels of CagA.In addition,NikS expression appears to be lower in clinical isolates from patients with gastric cancer when compared to patients without.With that in mind,this minireview approaches,in an accessible way,the most important and current aspects about the role of NikS in the control of virulence factors of H.pylori and the potential clinical repercussions of this modulation.
文摘Oral diseases related to dental biofilms continue to afflict the majority of the world＇s population. Among them, dental caries continues to be the single most prevalent and costly oral infectious disease （Marsh, 2003; Dye et al., 2007）. Dental caries results from the interaction of specific bacteria with constituents of the diet within a dental biofilm known as plaque （Bowen, 2002）. Sucrose is considered to be the ＂arch criminal＂ from the dietary aspect because it serves as a substrate for synthesis of extracellular （EPS） and intracellular （IPS） polysaccharides in dental biofilm and is also fermentable （Bowen, 2002）.
基金Supported by the Federal Funds,HIM/2009/037.SSA851 and HIM/2014/012.SSA 1098the grant from Secretaría de Investigación y Posgrado,SIP 20161878the Instituto Politécnico Nacional by Consejo Nacional de Ciencia y Tecnología,CB-222180.
文摘BACKGROUND The high prevalence and persistence of Helicobacter pylori(H. pylori) infection, as well as the diversity of pathologies related to it, suggest that the virulence factors used by this microorganism are varied. Moreover, as its proteome contains 340hypothetical proteins, it is important to investigate them to completely understand the mechanisms of its virulence and survival. We have previously reported that the hypothetical protein HP0953 is overexpressed during the first hours of adhesion to inert surfaces, under stress conditions, suggesting its role in the environmental survival of this bacterium and perhaps as a virulence factor.AIM To investigate the expression and localization of HP0953 during adhesion to an inert surface and against gastric(AGS) cells.METHODS Expression analysis was performed for HP0953 during H. pylori adhesion. HP0953 expression at 0,3, 12, 24, and 48 h was evaluated and compared using the Kruskal-Wallis equality-of-populations rank test. Recombinant protein was produced and used to obtain polyclonal antibodies for immunolocalization. Immunogold technique was performed on bacterial sections during adherence to inert surfaces and AGS cells, which was analyzed by transmission electron microscopy. HP0953 protein sequence was analyzed to predict the presence of a signal peptide and transmembrane helices, both provided by the ExPASy platform, and using the GLYCOPP platform for glycosylation sites. Different programs, via, I-TASSER, RaptorX, and HHalign-Kbest, were used to perform three-dimensional modeling.RESULTS HP0953 exhibited its maximum expression at 12 h of infection in gastric epithelium cells.Immunogold technique revealed HP0953 localization in the cytoplasm and accumulation in some peripheral areas of the bacterial body, with greater expression when it is close to AGS cells.Bioinformatics analysis revealed the presence of a signal peptide that interacts with the transmembrane region and then allows the release of the protein to the external environment. The programs also showed a similarity with the Tip-alpha protein of H. pylori. Tip-alpha is an exotoxin that penetrates cells and induces tumor necrosis factor alpha production, and HP0953 could have a similar function as posttranslational modification sites were found;modifications in turn require enzymes located in eukaryotic cells. Thus, to be functional, HP0953 may necessarily need to be translocated inside the cell where it can trigger different mechanisms producing cellular damage.CONCLUSION The location of HP0953 around infected cells, the probable posttranslational modifications, and its similarity to an exotoxin suggest that this protein is a virulence factor.
基金supported by a grant from the“Research Center of the Female Scientific and Medical Colleges”,Deanship of Scientific Research,King Saud University
文摘Objective:To investigate the effect of Corchorus olitorius aqueous fraction(COAF)on quorum sensing(QS)-regulated virulence factors and biofilm formation in Pseudomonas aeruginosa(PAO1).Methods:The preliminary screening of the anti-QS effect of COAF was performed by evaluating the anti-pathogenic activity against Chromobacterium violaceum CV026 biosensor strain.Next,the inhibitory effects of COAF on QS-regulated pyocyanin production,proteolytic and elastolytic activities,swarming motility,and biofilm formation were evaluated in PAO1.Results:The results showed that the treatment of COAF significantly decreased the biofilm biomass,attenuated virulence factors,and inhibited swarming motility of PAO1 without affecting the growth of the bacteria in a dose-dependent manner.COAF at 2000μg/mL significantly decreased Las B elastase activity in PAO1 culture,exopolysaccharide production,swarming motility,pyocyanin level,and biomass of PAO1 by 55%(P<0.05),60%(P<0.01),61%(P<0.01),65%(P<0.01)and 73%(P<0.01),respectively.In addition,the production of violacein was decreased by 62%(P<0.01)with the treatment of a high dose of COAF.Conclusions:These findings indicate that COAF can be a potential source of anti-QS agents.
文摘This study investigates the biofilm formation, presence and distribution of virulence genes and the capacity to induce an inflammatory response in strains of Staphylococcus aureus isolated from milk samples in Bahia, Brazil. A total of 132 samples of raw milk were collected from four dairy farms (designated A to D) located in southwestern Bahia, in the municipality of Vitória da Conquista, from October/2009 to September/2010. After processing of the samples, 94 (71.2%) S. aureus isolates were obtained. These strains were subjected to the antibiogram method MIC (Minimum Inhibitory Concentration). As for the pathogenicity, tests were performedin vitrobiofilm formation induced by glucose. Moreover, we performed PCR for their virulence genes: sea (enterotoxin A), seb (B), sec (C), pvl (Panton-Valentine Leukocidin), clfA (Clumping Factor A) and spa (protein A) and analysis of cytokine induction in the inflammatory response of J774 macrophages by exocellular lipoteichoic acid. No isolates were resistant to oxacillin and vancomycin. In biofilm production, 5.31% (5/94) isolates did not produce biofilm, 5.31% (5/94) of the samples were poor producers, 15.96% (15/94) strains were moderate producers, 18.09% (17/94) were producers and 55.32% (55/94) of isolates were strong biofilm producers. One (1.06%) isolate expressed the seb gene, one (1.06%) sec, 18 (19.2%) cflA and 44 (46.8%) had spa. There was no expression of sea and pvl between isolates analyzed. The analysis of cytokine induction in the inflammatory response did not show statistical difference in the levels of IL-6, TNF-α and IL-10 induction. However, there was statistical difference in IL-1 induction between isolates from different farms. Thus, it appears that the results obtained in this study show significant effects for the region studied, since it is an important dairy region, hence the need for further studies, with the intent of attracting funding that contributes to improving prevention and control in both dairy farms and dairy industries, since milk contamination poses a serious potential health risk to consumers.
基金supported by the National Natural Science Foundation of China(Nos.51778603,51820105011 and 51578537)Chinese Academy of Sciences(No.QYZDY SSW-DQC004)。
文摘Virulence factors(VFs)confer upon pathogens the ability to cause various types of damage or diseases.Wastewater treatment plants(WWTPs)are important point sources for the emission of pathogens and VFs into receiving rivers.Conventional WWTP upgrades are often implemented to improve the water quality of receiving ecosystems.However,knowledge on the pathogens,VFs,and health risks to receiving aquatic ecosystems after upgrade remains limited.In this study,we investigated detailed pathogenic information,including taxa,pathogenicity,and health risk,in two wastewater-dominant rivers after WWTP upgrade.Using 16S rRNA gene sequencing,we screened 14 potential pathogens in water and epilithic biofilm samples,though they were significantly more enriched in the biofilms.Combining 16S rRNA and metagenomic sequencing data,we identified Pseudomonas and Aeromonas as the dominant pathogenic taxa carrying functional VFs(e.g.,mobility and offensive)in the epilithic biofilm.Moreover,strong pathogen-specific VF-host co-occurrence events were observed in the epilithic biofilm samples,indicating the importance of biofilms as reservoirs and vehicles for VFs.Further,we demonstrated that mobility VF is crucial for biofilm formation and pathogens in biofilm carrying offensive VF may be highly invasive.Quantification and health risk assessment suggested that the skin contact risk of P.aeruginosa carrying VFs was higher than the acceptable probability of 10^(-4)in both water and epilithic biofilm samples,which may threaten ecological and human health.
基金National Natural Science Foundation of China,No.32060018 and No.32360035Through Special Fund Projects for Guide Local Science and Technology Development by the China Government,No.GUIKEZY20198004+2 种基金Anhui Provincial Natural Science Foundation,No.2308085QH245the Natural Science Foundation of the Anhui Higher Education Institutions of China,No.2023AH040261Changzhou Science and Technology Project Fund,No.CJ20210012.
文摘BACKGROUND The pathogenicity of Helicobacter pylori is dependent on factors including the environment and the host.Although selenium is closely related to pathogenicity as an environmental factor,the specific correlation between them remains unclear.AIM To investigate how selenium acts on virulence factors and reduces their toxicity.METHODS H.pylori strains were induced by sodium selenite.The expression of cytotoxin-associated protein A(CagA)and vacuolating cytotoxin gene A(VacA)was determined by quantitative PCR and Western blotting.Transcriptomics was used to analyze CagA,CagM,CagE,Cag1,Cag3,and CagT.C57BL/6A mice were infected with the attenuated strains subjected to sodium selenite induction,and H.pylori colonization,inflammatory reactions,and the cell adhesion ability of H.pylori were assessed.RESULTS CagA and VacA expression was upregulated at first and then downregulated in the H.pylori strains after sodium selenite treatment.Their expression was significantly and steadily downregulated after the 5th cycle(10 d).Transcriptome analysis revealed that sodium selenite altered the levels affect H.pylori virulence factors such as CagA,CagM,CagE,Cag1,Cag3,and CagT.Of these factors,CagM and CagE expression was continuously downregulated and further downregulated after 2 h of induction with sodium selenite.Moreover,CagT expression was upregulated before the 3rd cycle(6 d)and significantly downregulated after the 5th cycle.Cag1 and Cag3 expression was upregulated and downregulated,respectively,but no significant change was observed by the 5th cycle.C57BL/6A mice were infected with the attenuated strains subjected to sodium selenite induction.The extent of H.pylori colonization in the stomach increased;however,sodium selenite also induced a mild inflammatory reaction in the gastric mucosa of H.pylori-infected mice,and the cell adhesion ability of H.pylori was significantly weakened.CONCLUSION These results demonstrate that H.pylori displayed virulence attenuation after the 10th d of sodium selenite treatment.Sodium selenite is a low toxicity compound with strong stability that can reduce the cell adhesion ability of H.pylori,thus mitigating the inflammatory damage to the gastric mucosa.
基金Supported by National Natural Science Foundation of China(31270171)Agricultural Science and Technology Achievement Transformation Project of the Ministry of Science and Technology of China(2012GB2A200044)Project of Shijiazhuang Municipal Science and Technology Bureau(11150093A)
文摘Salmonella is a common genus of seriously harmful food-borne zoonotic bacteria. Humans and animals may be infected with Salmonella through ingestion of SalmoneUa-contaminated eggs and poultry meat. Therefore, in order to reduce the incidence of Salmonella infections, it is crucial to explore the pathogenic mech- anism of Salmonella. invA and invE are major virulence factor genes that encode invasion proteins of Salmonella. In order to explore the pathogenic mechanism of Salmonella, phylogenetic analysis of major virulence factor genes in 33 Salmonella strains isolated from chicken was analyzed. According to the results, ivnA gene was successfully amplified from 33 Salmonella strains; ivnE gene was successfully amplified from 32 Salmonella strains, ivnA nucleotide sequences shared 72.9% - 97.6% homology among 12 sequenced Salmonella strains and shared 78.9% - 97.2% homology with those in GenBank ; ivnE nucleotide sequences shared over 95.3% homology among 23 sequenced Salmonella strains and shared 89.6% -98.6% homology with those in GenBank, which exhibited no genetic relationship to other organisms. This study provided the basis for rapid molecular detection, epidemiological research and molecular pathogenesis analysis of Salmonella.
文摘Sugarcane leaf shows the classical arrangement of cells, which defines a C4 species. Vascular bundles consist of xylem, phloem and fibres, surrounded by an outer layer ofsclereids and an inner ring of stone cells associated with the phloem. Some sclereids located below and above the vascular bundles act as docking cells and connect the vascular bundle to the internal surfaces of upper and lower layers of the epidermis. A compact mass ofsclereids occupies the total internal volume of the leaf edge. Neither docking cells nor the internal mass of sclereids in the edge were markedly coloured by phloroglucinol, indicating the absence of lignin in their cell walls. However, such staining indicated that fibres of the vascular bundle and the external layer of sclereids were strongly lignified. Incubation of leaf discs with an virulence factors produced by the pathogen Sporisorium scitamineum increased the thickness of the lignified cell walls of sclereids as well as the mid and small xylem vessels, as a possible mechanical defence response to the potential entry of the pathogen. This mechanism was mainly revealed for the resistant cv. Mayari 55-14, whereas lignification decreased for the susceptible cv. B 42231.
基金supported by FAPESB(N.SUS0012/2009)and PIBIC/CNPq.
文摘Species of Staphylococcus are common in hospital infection (HI). Methicillin resistant S. aureus (MRSA) has also become a serious problem in Brazilian HI. The aim of this study was to characterize the pathogenicity of methicillin-resistant S. aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) isolated in public hospitals. The clinical isolates were obtained from intensive care unit. The MRSA and MSSA strains were genotyped by PCR for detection genes related to virulence factors. Moreover, the strains were tested for biofilm formation and cytokine induction in macrophages. Three strains of MRSA (9.68%) expressed the Sea gene, one (3.23%) Seb, 17 (54.84%) Spa and seven (22.58%) had PVL. Two MSSA strains (2.98%) expressed the Sea gene, three (4.48%) Seb, 18 (26.87%) Spa and 11 (16.42%) showed positive results for the PVL gene. There was no expression of Sec and CflA between MRSA and MSSA strains. Among MRSA and MSSA isolates, none statistical differences were observed in biofilm production. The analysis of cytokine induction in the inflammatory response of J774 macrophages by MRSA and MSSA isolates did not show statistical difference. Understanding the mechanisms of pathogenesis of S. aureus could provide important clues for both preventing and treating infection caused by these organisms.
基金Fundacao de Amparo a Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhao(FAPEMA)(APP-Universal-01176/09 and APP-Universal-011 80/09).
文摘Enteroaggregative (EAEC) and atypical enteropathogenic (EPEC) Escherichia coli are important bacterial etiologic agents causing diarrhea among children. The aim of the present study was to examine the impact of virulence factors predisposes to diarrhea. In this study some virulence properties were examined on 11 EAEC and 8 EPEC strains identified by Polymerase Chain Reaction (PCR), isolated from stool samples of children were analyzed genotypically and phenoltypically for the prevalence of virulence factors. The most frequently detected factor was resistance to serum (94%), followed by curli fimbriae (78%), biofilm production (73%), and gene coding for Extended-Spectrum Beta-Lactamase (ESBL) (68%). EPEC isolates showed at least three of the evaluated properties, while EAEC isolates showed at least two. The prevalence of these virulence factors between the two strains showed no statistical difference. This study showed the heterogeneity of the virulence profile of the isolates of EAEC and atypical EPEC strains and suggests that this diversity may influence in the disease severity.
基金supported by the National Natu-ral Science Foundation of China(42171138 and 32241037)the Ministry of Science and Technology of the People's Republic of China(2021YFC2300904).
文摘Inexpressible Island is a small rocky island in Terra Nova Bay,Victoria Land,Antarctica,which is an area with limited human activities.Understanding the distribution of antibiotic-resistance genes(ARGs)and virulence factor genes(VFGs)in this environment can provide key information on their potential risks to humans and their roles for microbial survival.In this study,we investigated the ARGs and VFGs in lake sediments from Inexpressible Island using metagenomic sequencing.We identified 11,502,071 open-reading frames(ORFs),with 1,749 classified as ARGs and 6,838 as VFGs.The dominant ARGs were associated with antibiotic target alteration and efflux pump mechanisms,while the VFGs were related to adher-ence and immune modulation functions.While associated within microbial genomes,these ARGs and VFGs were mobile genetic elements like viruses and insertion sequences,distinct from ecosystems with strong human influence.We identified 974 metagenome-assembled genomes(MAGs),with 465 being medium-to-high quality.Of these,325(69.9%)contained ARGs,primarily affiliated with Actinomycetota and Pseudomonadota.Additionally,269 MAGs contained VFGs,with 174 MAGs carrying both ARGs and VFGs,highlighting significant microbial antibiotic resistance and pathogenic potential.Our findings highlight the need for ongoing monitoring of ARGs and VFGs in Antarctica,particularly in light of increasing human activity and climate change.
文摘Bacteria of the family Weeksellaceae are Gram-negative,and include 17 genera and 185 species.The emerging infectious pathogens of the family include Chryseobacterium indologenes,C.gleum,Elizabethkingia anophelis,E.meningoseptica,and E.miricola.In this review,we summarize the reported infections and the virulence factors of these pathogens.The main virulence factors of C.indologenes include phosphatases and proteases.The formation of the E.anophelis biofilm is associated with its pathogenicity,and the virulence factors of E.miricola,E.anophelis,and E.meningoseptica have been predicted from the genomic sequences of clinical strains.In this article,we summarize the case reports of infection and the virulence factors of pathogens in the family Weeksellaceae,to provide important data for evaluating the potential pathogenicity of other species within the family.
基金supported by the National Natural Science Foundation of China(Grant No.30771401)The National Basic Research Program(No.2011CB100700)from the Ministry of Science and Technology of China.
文摘Two-component signal transduction systems(TCSTSs),consisting of a histidine kinase and a response regulator,play a critical role in regulating virulence gene expression in Gram-negative phytopathogenic bacteria Xanthomonas spp..To date,12 TCSTS genes have been identified,accounting for approximately 10%of the TCSTS genes in each genome that have been experimen-tally identified to be related to pathogenesis.These TCSTSs modulate the expression of a number of virulence factors through diverse molecular mechanisms such as interacting with DNA,protein-binding and involvement in second messenger metabolism,which generates a high level of regulatory versatility.Here we summarize the current knowledge in thisfield and discuss the emerging themes and remaining questions that are important in deciphering the signaling network of TCSTSs in Xantho-monas.
基金supported by the Project of Taishan Industry Leading Talent of Shandong Province(LJNY202101)the National Natural Science Foundation of China(grant number:31901664).
文摘Probiotics are emerging as a promising approach to treating foodborne infections or gastrointestinal diseases.This study aimed to explore the protective effect of Lactiplantibacillus plantarum YZX28(YZX28)on intestinal barrier dysfunction induced by enterotoxigenic Escherichia coli K80(ETEC K80).Caco-2 cells were used for in vitro co-culture experiments of enterotoxin-producing ETEC K80 and YZX28.The barrier permeability(higher phenol red flux and decreased TEER)and levels of pro-inflammatory cytokines TNF-αand IL-8 increased by ETEC K 80 were attenuated by YZX28,and the mRNA levels of tight junctions,including ZO-1,occludin,claudin-1,and cingulin were significantly increased by YZX28 intervention.The redistribution of ZO-1,claudin-1,and actin fibers in Caco-2 cells induced by ETEC K 80 was restored.Furthermore,YZX28 could effectively reduce the adhesion level of ETEC to Caco-2 cells,alleviate the decrease of cell viability induced by ETEC,and inhibit the expression of ETEC virulence factors,including enterotoxin STa(est-A),STb(est-B),LT(elt)as well as fimbria adhesin FaeG and reduced the corresponding cAMP,cGMP,and CEACAM6 levels.This strain may be a potential therapeutic agent for treating intestinal-related problems caused by the intestinal pathogen ETEC.
基金This work was supported by the National Natural Science Foundation of China(Nos.82160664 and 31760246)the Hainan Province Science and Technology Special Fund(ZDYF2024SHFZ103)+1 种基金the Natural Science Foundation of Hainan Province(222RC557 and 221QN170)Anhui Laboratory of Molecule-Based Materials(fzj21006).
文摘Quorum sensing(Qs)inhibition has emerged as a promising target for directed drug design,providing an appealing strategy for developing antimicrobials,particularly against infections caused by drug-resistant pathogens.In this study,we designed and synthesized a total of 33β-nitrostyrene derivatives using 1-nitro-2-phenylethane(NPe)as the lead compound,to target the facultative anaerobic bacterial pathogen Serratia marcescens.The QS-inhibitory effects of these compounds were evaluated using S.marcescens NJ01 and the reporter strain Chromobacterium violaceum CV026.Among the 33 newβ-nitrostyrene derivatives,(E)-1-methyl-4-(2-nitrovinyl)benzene(m-NPe,compound 28)was proven to be a potent inhibitor that reduced biofilm formation of S.marcescens NJ01 by 79%.Scanning electron microscopy(SEM)and confocal laser scanning microscopy(CLSM)results revealed that treatment with m-NPe(50μg/ml)not only enhanced the susceptibility of the formed biofilms but also disrupted the architecture of biofilms by 84%.m-NPe(50μg/ml)decreased virulence factors in S.marcescens NJ01,reducing the activity of protease,prodigiosin,and extracellular polysaccharide(EPs)by 36%,72%,and 52%,respectively.In S.marcescens 4547,the activities of hemolysin and EPs were reduced by 28%and 40%,respectively,outperforming the positive control,vanillic acid(VAN).The study also found that the expression levels of QS-and biofilm-related genes(flhD,fimA,fimC,sodB,bsmB,pigA,pigC,and shlA)were downregulated by 1.21-to 2.32-fold.Molecular dynamics analysis showed that m-NPe could bind stably to SmaR,Rhll,RhiR,LasR,and CviR proteins in a 0.1 M sodium chloride solution.Importantly,a microscale thermophoresis(MST)test revealed that SmaR could be a target protein for the screening of a quorum sensing inhibitor(QSl)against S.marcescens.Overall,this study highlights the efficacy of m-NPe in suppressing the virulence factors of S.marcescens,identifying it as a new potential Qsl and antibiofilm agent capable of restoring or improving antimicrobial drug sensitivity.
