-
Molecular Therapy. Oncology Mar 2024Cancer immunotherapy based on bioengineering of bacteria can effectively increase anticancer immune responses. However, few studies have investigated the antitumor...
Cancer immunotherapy based on bioengineering of bacteria can effectively increase anticancer immune responses. However, few studies have investigated the antitumor potential of engineering . Here, we genetically engineered to overexpress flagellin B (FlaB) protein in a murine CT26 tumor model. We found that a large number of FlaB-expressing colonized tumor tissues, enhanced T cell infiltration and secretion of cytokines and cytotoxic proteins in tumors, and significantly restrained tumor growth. Our results also showed that programmed death ligand 1 (PD-L1) expression in tumor-infiltrating immune cells was elevated after treatment with FlaB-expressing . In addition, combination therapy with FlaB-expressing and PD-L1 blockade synergistically improved antitumor efficacy by enhancing infiltration of CD8 cells. Furthermore, serum liver biochemical indices of mice increased in the short term in both the and the FlaB-expressing treatment groups but gradually recovered in the later stage of treatment so that FlaB protein expression did not increase the toxicity of . Taken together, our results suggest that could serve as an engineered bacterium for bacterium-based cancer immunotherapy.
PubMed: 38596299
DOI: 10.1016/j.omton.2024.200770 -
CMAJ : Canadian Medical Association... Apr 2024
Topics: Female; Humans; Adult; Fasciitis, Necrotizing; Vibrio vulnificus; Vibrio Infections
PubMed: 38589031
DOI: 10.1503/cmaj.231766 -
Microbiology Spectrum May 2024is a genus of halophilic, gram-negative bacteria found in estuaries around the globe. Integral parts of coastal cultures often involve contact with vectors of...
UNLABELLED
is a genus of halophilic, gram-negative bacteria found in estuaries around the globe. Integral parts of coastal cultures often involve contact with vectors of pathogenic spp. (e.g., consuming raw shellfish). High rates of mortality from certain spp. infections demonstrate the need for an improved understanding of spp. dynamics in estuarine regions. Our study assessed meteorological, hydrographic, and biological correlates of and at 10 sites in the Eastern Mississippi Sound System (EMSS) from April to October 2019. During the sampling period, median abundances of and were 2.31 log MPN/L and 2.90 log MPN/L, respectively. spp. dynamics were largely driven by site-based variation, with sites closest to freshwater inputs having the highest abundances. The E-W wind scalar, which affects Ekman transport, was a novel spp. correlate observed. A potential salinity effect on bacterial-particle associations was identified, where was associated with larger particles in conditions outside of their optimal salinity. Additionally, abundances were correlated to those of harmful algal species that did not dominate community chlorophyll. Correlates from this study may be used to inform the next iteration of regionally predictive models and may lend additional insight to spp. ecology in similar systems.
IMPORTANCE
spp. are bacteria found in estuaries worldwide; some species can cause illness and infections in humans. Relationships between spp. abundance, salinity, and temperature are well documented, but correlations to other environmental parameters are less understood. This study identifies unique correlates (e.g., E-W wind scalar and harmful algal species) that could potentially inform the next iteration of predictive models for the EMSS region. Additionally, these correlates may allow existing environmental monitoring efforts to be leveraged in providing data inputs for future Vibrio risk models. An observed correlation between salinity and /particle-size associations suggests that predicted environmental changes may affect the abundance of spp. in certain reservoirs, which may alter which vectors present the greatest vibrio risk.
Topics: Vibrio parahaemolyticus; Vibrio vulnificus; Estuaries; Alabama; Population Dynamics; Salinity; Vibrio Infections; Seawater; Water Microbiology
PubMed: 38578091
DOI: 10.1128/spectrum.03674-23 -
MBio May 2024Bacterial enhancer-binding proteins (bEBPs) acquire a transcriptionally active state via phosphorylation. However, transcriptional activation by the dephosphorylated...
Bacterial enhancer-binding proteins (bEBPs) acquire a transcriptionally active state via phosphorylation. However, transcriptional activation by the dephosphorylated form of bEBP has been observed in DctD, which belongs to Group I bEBP. The formation of a complex between dephosphorylated DctD (d-DctD) and dephosphorylated IIA (d-IIA) is a prerequisite for the transcriptional activity of d-DctD. In the present study, characteristics of the transcriptionally active complex composed of d-IIA and phosphorylation-deficient DctD (DctD) of were investigated in its multimeric conformation and DNA-binding ability. DctD formed a homodimer that could not bind to the DNA. In contrast, when DctD formed a complex with d-IIA in a 1:1 molar ratio, it produced two conformations: dimer and dodecamer of the complex. Only the dodecameric complex exhibited ATP-hydrolyzing activity and DNA-binding affinity. For successful DNA-binding and transcriptional activation by the dodecameric d-IIA/DctD complex, extended upstream activator sequences were required, which encompass the nucleotide sequences homologous to the known DctD-binding site and additional nucleotides downstream. This is the first report to demonstrate the molecular characteristics of a dephosphorylated bEBP complexed with another protein to form a transcriptionally active dodecameric complex, which has an affinity for a specific DNA-binding sequence.IMPORTANCEResponse regulators belonging to the bacterial two-component regulatory system activate the transcription initiation of their regulons when they are phosphorylated by cognate sensor kinases and oligomerized to the appropriate multimeric states. Recently, it has been shown that a dephosphorylated response regulator, DctD, could activate transcription in a phosphorylation-independent manner in . The dephosphorylated DctD activated transcription as efficiently as phosphorylated DctD when it formed a complex with dephosphorylated form of IIA, a component of the glucose-phosphotransferase system. Functional mimicry of this complex with the typical form of transcriptionally active phosphorylated DctD led us to study the molecular characteristics of this heterodimeric complex. Through systematic analyses, it was surprisingly determined that a multimer constituted with 12 complexes gained the ability to hydrolyze ATP and recognize specific upstream activator sequences containing a typical inverted-repeat sequence flanked by distinct nucleotides.
Topics: Adenosine Triphosphate; Bacterial Proteins; DNA-Binding Proteins; Gene Expression Regulation, Bacterial; Phosphorylation; Protein Binding; Protein Multimerization; Transcription Factors; Transcription, Genetic; Transcriptional Activation; Vibrio vulnificus
PubMed: 38564689
DOI: 10.1128/mbio.00330-24 -
Microorganisms Mar 2024With rising infection rates in recent years, poses an increasing threat to public safety in the coastal brackish Baltic Sea. It is therefore important to monitor this...
With rising infection rates in recent years, poses an increasing threat to public safety in the coastal brackish Baltic Sea. It is therefore important to monitor this organism and assess the infection risk on a more regular basis. However, as the coastline of the Baltic Sea is 8000 km long and shared by nine nations, a convenient, fast, inexpensive, yet efficient identification method is essential. We evaluated the effectiveness of a two-step agar-based approach consisting of successive isolation and cultivation on thiosulphate-citrate-bile salt sucrose (TCBS) agar and CHROMagar™ for in comparison with , , and . Our study contains isolates from water and sediment across a broad expanse of the Baltic Sea including 13 locations and two different summers, the time of year during which infections are usually much more frequent. Confirmation of isolate species identity was carried out using molecular analyses. The two-step agar plating method performed well across different locations and timeframes in correctly identifying by more than 80%, but the sensitivity in other species varied. Thus, our approach yielded promising results as a potential tool for early detection across a broad timeframe and transect of the Baltic Sea and potentially other brackish environments.
PubMed: 38543665
DOI: 10.3390/microorganisms12030614 -
Heliyon Mar 2024is a pathogen that can cause serious and fatal infections, primarily associated with a history of contact with the sea or aquatic organisms or products. However, with...
is a pathogen that can cause serious and fatal infections, primarily associated with a history of contact with the sea or aquatic organisms or products. However, with global climate change and increased global seafood trade, . infections are also occurring in non-coastal areas. In this report, we present the successful diagnosis and treatment of a case of necrotizing wound caused by . infection in an inland city in southwest China. In addition, we review the epidemiology and distribution of . in China and related vaccine research, which may provide a reference for the clinical diagnosis and treatment of . infection.
PubMed: 38533013
DOI: 10.1016/j.heliyon.2024.e28012 -
Frontiers in Microbiology 2024is a free-living marine bacterium associated with the contamination of fish and shellfish-the most consumed seafood in Asia. Owing to its potentially lethal clinical...
is a free-living marine bacterium associated with the contamination of fish and shellfish-the most consumed seafood in Asia. Owing to its potentially lethal clinical consequences, the consumption of seafood contaminated with has become a growing public health concern. This systematic review with meta-analysis and meta-regression aimed to integrate data on the prevalence of seafood-borne specifically in Asia and assess the potential risk factors that can influence the outcomes. A comprehensive literature search of four electronic databases yielded 279 relevant studies, among which 38 fulfilled the inclusion criteria. These selected studies were subjected to risk-of-bias assessment and data extraction by three independent researchers. A meta-analysis of the eligible studies estimated the overall prevalence of seafood-borne in Asia to be 10.47% [95% confidence interval (CI): 6.8-15.8%], with bivalve shellfish, such as oysters, mussels, clams, and cockles being the most contaminated seafood. The highest prevalence was reported in Japan, where 47.6% of the seafood samples tested positive for . The subgroup and meta-regression analyses identified three potential covariates-detection method, publication year, and country-associated with between-study heterogeneity. Furthermore, data visualization displayed the variations in prevalence across the studies, associated with differences in sample type, sample size, and sampling stage. This study provides valuable insights into the prevalence of in fish and shellfish across the entire Asian continent and highlights the potential factors that cause variation in the prevalence rates among the studies. These findings underscore the importance of enhancing hygiene measures throughout the seafood supply chain to mitigate infection risks and ensure the safety of consumers.
PubMed: 38511007
DOI: 10.3389/fmicb.2024.1363560 -
BioRxiv : the Preprint Server For... Feb 2024In species, quorum sensing signaling culminates in the production of a TetR-type master transcription factor collectively called the LuxR/HapR family, which regulates...
UNLABELLED
In species, quorum sensing signaling culminates in the production of a TetR-type master transcription factor collectively called the LuxR/HapR family, which regulates genes required for colonization and infection of host organisms. These proteins possess a solvent accessible putative ligand binding pocket. However, a native ligand has not been identified, and the role of ligand binding in LuxR/HapR function in is unknown. To probe the role of the ligand binding pocket, we utilize the small molecule thiophenesulfonamide inhibitor PTSP (3- henyl-1-( hiophen-2-yl ulfonyl)-1 - yrazole) that we previously showed targets LuxR/HapR proteins. Amino acid conservation in the ligand binding pocket determines the specificity and efficacy of PTSP inhibition across species. Here, we used structure-function analyses to identify PTSP-interacting residues in the ligand binding pocket of SmcR - the LuxR/HapR homolog - that are required for PTSP inhibition of SmcR activity . Forward genetic screening combined with X-ray crystallography structural determination of SmcR bound to PTSP identified substitutions at eight residues that were sufficient to reduce or eliminate PTSP-mediated SmcR inhibition. Small-angle X-ray scattering and computational modeling determined that PTSP drives allosteric unfolding at the N-terminal DNA binding domain. We discovered that SmcR is degraded by the ClpAP protease in the presence of PTSP ; substitution of key PTSP-interacting residues stabilized or increased SmcR levels in the cell. This mechanism of inhibition is observed for all thiophenesulfonamide compounds tested and against other species. We conclude that thiophenesulfonamides specifically bind in the ligand binding pocket of LuxR/HapR proteins, promoting protein degradation and thereby suppressing downstream gene expression, implicating ligand binding as a mediator of LuxR/HapR protein stability and function to govern virulence gene expression in pathogens.
SIGNIFICANCE
LuxR/HapR proteins were discovered in the 1990s as central regulators of quorum sensing gene expression and later discovered to be conserved in all studied species. LuxR/HapR homologs regulate a wide range of genes involved in pathogenesis, including but not limited to genes involved in biofilm production and toxin secretion. As archetypal members of the broad class of TetR-type transcription factors, each LuxR/HapR protein has a predicted ligand binding pocket. However, no ligand has been identified for LuxR/HapR proteins that control their function as regulators. Here, we used LuxR/HapR-specific chemical inhibitors to determine that ligand binding drives proteolytic degradation , the first demonstration of LuxR/HapR function connected to ligand binding for this historical protein family.
PubMed: 38405947
DOI: 10.1101/2024.02.15.580527 -
Microorganisms Feb 2024This study aimed to explore the phenotype and relationship of drug resistance genes in livestock and poultry farm wastewater and drinking water reservoirs to provide...
This study aimed to explore the phenotype and relationship of drug resistance genes in livestock and poultry farm wastewater and drinking water reservoirs to provide evidence for the transmission mechanisms of drug resistance genes, in order to reveal the spread of drug resistance genes in wastewater from intensive farms in Central China to urban reservoirs that serve as drinking water sources and provide preliminary data for the treatment of wastewater from animal farms to reduce the threat to human beings. DNA extraction and metagenomic sequencing were performed on eight groups of samples collected from four water reservoirs and four related wastewaters from animal farms in Central China. Metagenomic sequencing showed that the top 20 AROs with the highest abundance were _gene, _gene, , , , _gene_, _gene, , _gene, _gene, , , , , _gene, , _gene, , , and . The resistance genes mentioned above belong to the following categories of drug resistance mechanisms: antibiotic target replacement, antibiotic target protection, antibiotic inactivation, and antibiotic efflux. The resistomes that match the top 20 genes are and ; ; ; and . ; ; and ; and ; , , , , , , , , , and ; and ; , , , , , and ; and ; and ; , , and ; , , , , , , and . Unreported drug resistance genes and drug-resistant bacteria in Central China were identified in 2023. In the transmission path of drug resistance genes, the transmission path from aquaculture wastewater to human drinking water sources cannot be ignored. For the sake of human health and ecological balance, the treatment of aquaculture wastewater needs to be further strengthened, and the effective blocking of drug resistance gene transmission needs to be considered.
PubMed: 38399800
DOI: 10.3390/microorganisms12020396 -
Parasites & Vectors Feb 2024Traditional methods for detecting insect-borne bacterial pathogens are time-consuming and require specialized laboratory facilities, limiting their applicability in...
BACKGROUND
Traditional methods for detecting insect-borne bacterial pathogens are time-consuming and require specialized laboratory facilities, limiting their applicability in areas without access to such resources. Consequently, rapid and efficient detection methods for insect-borne bacterial diseases have become a pressing need in disease prevention and control.
METHODS
We aligned the ribosomal 16S rRNA sequences of seven bacterial species (Staphylococcus aureus, Shigella flexneri, Aeromonas caviae, Vibrio vulnificus, Salmonella enterica, Proteus vulgaris, and Yersinia enterocolitica) by DNASTAR Lasergene software. Using DNASTAR Lasergene and Primer Premier software, we designed universal primers RLB-F and RLB-R, two species-specific probes for each pathogen, and a universal probe (catch-all). The PCR products of seven standard strains were hybridized with specific oligonucleotide probes fixed on the membrane for specific experimental procedures. To evaluate the sensitivity of PCR-RLB, genomic DNA was serially diluted from an initial copy number of 10 to 10 copies/μl in distilled water. These dilutions were utilized as templates for the PCR-RLB sensitivity analysis. Simultaneous detection of seven fly-borne bacterial pathogens from field samples by the established PCR-RLB method was conducted on a total of 1060 houseflies, collected from various environments in Lanzhou, China.
RESULTS
The established PCR-RLB assay is capable of detecting bacterial strains of about 10 copies/μl for S. aureus, 10 copies/μl for S. flexneri, 10 copies/μl for A. caviae, 10 copies/μl for V. vulnificus, 10 copies/μl for S. enterica, 10 copies/μl for P. vulgaris, and 10 copies/μl for Y. enterocolitica. The results demonstrate that the detection rate of the established PCR-RLB method is higher (approximately 100 times) compared to conventional PCR. This method was applied to assess the bacterial carrier status of flies in various environments in Lanzhou, China. Among the seven bacterial pathogens carried by flies, S. enterica (34.57%), S. flexneri (32.1%), and Y. enterocolitica (20.37%) were found to be the predominant species.
CONCLUSIONS
Overall, this research shows that the rapid and efficient PCR-RLB detection technology could be a useful for surveillance and therefore effective prevention and control the spread of insect-borne diseases. Meanwhile, the experimental results indicate that urban sanitation and vector transmission sources are important influencing factors for pathogen transmission.
Topics: Animals; Bacteria; Diptera; Nucleic Acid Hybridization; RNA, Ribosomal, 16S; Sensitivity and Specificity; Staphylococcus aureus
PubMed: 38389104
DOI: 10.1186/s13071-024-06170-3