Targeting the virulence factors of phytopathogenic bacteria is an innovative strategy for alleviating or eliminating the pathogenicity and rapid outbreak of plant microbial diseases. Therefore, ...several types of 1,2,4-triazole thioethers bearing an amide linkage were prepared and screened to develop virulence factor inhibitors. Besides, the 1,2,4-triazole scaffold was exchanged by a versatile 1,3,4-oxadiazole core to expand molecular diversity. Bioassay results revealed that a 1,2,4-triazole thioether
bearing a privileged
-(3-nitrophenyl)acetamide fragment was extremely bioactive against
(Xoo) with an EC
value of 5.01 μg/mL. Label-free quantitative proteomics found that compound
could significantly downregulate the expression of Xoo's type III secretion system (T3SS) and transcription activator-like effector (TALE) correlative proteins. Meanwhile, qRT-PCR detection revealed that the corresponding gene transcription levels of these virulence factor-associated proteins were substantially inhibited after being triggered by compound
. As a result, the hypersensitive response and pathogenicity were strongly depressed, indicating that a novel virulence factor inhibitor (
) was probably discovered. In vivo anti-Xoo trials displayed that compound
yielded practicable control efficiency (54.2-59.6%), which was superior to thiadiazole-copper and bismerthiazol (38.1-44.9%). Additionally, compound
showed an appreciable antiviral activity toward tobacco mosaic virus (TMV) with the curative and protective activities of 54.6 and 76.4%, respectively, which were comparable to ningnanmycin (55.2 and 60.9%). This effect was further validated and visualized by the inoculation test using GFP-labeled TMV, thereby leading to the reduced biosynthesis of green-fluorescent TMV on
. Given the outstanding features of compound
, it should be deeply developed as a versatile agricultural chemical.
Staphylococcus aureus is an opportunistic pathogen that produces many virulence factors. Two major families of which are the staphylococcal superantigens (SAgs) and the Staphylococcal ...Superantigen-Like (SSL) exoproteins. The former are immunomodulatory toxins that induce a Vβ-specific activation of T cells, while the latter are immune evasion molecules that interfere with a wide range of innate immune defences. The superantigenic properties of Staphylococcal enterotoxin-like X (SElX) have recently been established. We now reveal that SElX also possesses functional characteristics of the SSLs. A region of SElX displays high homology to the sialyl-lactosamine (sLacNac)-specific binding site present in a sub-family of SSLs. By analysing the interaction of SElX with sLacNac-containing glycans we show that SElX has an equivalent specificity and host cell binding range to the SSLs. Mutation of key amino acids in this conserved region affects the ability of SElX to bind to cells of myeloid origin and significantly reduces its ability to protect S. aureus from destruction in a whole blood killing (WBK) assay. Like the SSLs, SElX is up-regulated early during infection and is under the control of the S. aureus exotoxin expression (Sae) two component gene regulatory system. Additionally, the structure of SElX in complex with the sLacNac-containing tetrasaccharide sialyl Lewis X (sLeX) reveals that SElX is a unique single-domain SAg. In summary, SElX is an 'SSL-like' SAg.
Genome-wide CRISPR screening is a powerful tool to identify genes required under selective conditions. However, the inherent scale of genome-wide libraries can limit their application in experimental ...settings where cell numbers are restricted, such as in vivo infections or single cell analysis. The use of small scale CRISPR libraries targeting gene subsets circumvents this problem. Here we develop a method for rapid generation of custom guide RNA (gRNA) libraries using arrayed single-stranded oligonucleotides for reproducible pooled cloning of CRISPR/Cas9 libraries. We use this system to generate mutant pools of different sizes in the protozoan parasite Toxoplasma gondi and describe optimised analysis methods for small scale libraries. An in vivo genetic screen in the murine host identifies novel and known virulence factors and we confirm results using cloned knock-out parasites. Our study also reveals a potential trans-rescue of individual knock-out parasites in pools of mutants compared to homogenous knock-out lines of the key virulence factor MYR1.
Extracellular vesicles (EVs) are small membrane-surrounded structures released by different kinds of cells (normal, diseased, and transformed cells)
and
that contain large amounts of important ...substances (such as lipids, proteins, metabolites, DNA, RNA, and non-coding RNA (ncRNA), including miRNA, lncRNA, tRNA, rRNA, snoRNA, and scaRNA) in an evolutionarily conserved manner. EVs, including exosomes, play a role in the transmission of information, and substances between cells that is increasingly being recognized as important. In some infectious diseases such as parasitic diseases, EVs have emerged as a ubiquitous mechanism for mediating communication during host-parasite interactions. EVs can enable multiple modes to transfer virulence factors and effector molecules from parasites to hosts, thereby regulating host gene expression, and immune responses and, consequently, mediating the pathogenic process, which has made us rethink our understanding of the host-parasite interface. Thus, here, we review the present findings regarding EVs (especially exosomes) and recognize the role of EVs in host-parasite interactions. We hope that a better understanding of the mechanisms of parasite-derived EVs may provide new insights for further diagnostic biomarker, vaccine, and therapeutic development.
capsule polysaccharide is an important antiphagocytic virulence factor. The
genes are regulated at the promoter element (P
) upstream of the
operon. P
, which consists of a dominant SigB-dependent ...promoter and a weaker upstream SigA-dependent promoter, is activated by global regulator MgrA. How MgrA activates capsule is unclear. Here, we showed that MgrA directly bound to the P
region and affected the SigA-dependent promoter. Interestingly, an electrophoretic mobility shift assay showed that MgrA bound to a large region of P
, mainly downstream of the SigA-dependent promoter. We further showed that the ArlRS two-component system and the Agr quorum sensing system activated capsule primarily through MgrA in the early growth phases.
The virulence of
depends on the expression of various virulence factors, which is governed by a complex regulatory network. We have been using capsule as a model virulence factor to study virulence gene regulation in
MgrA is one of the regulators of capsule and has a major effect on capsule production. However, how MgrA regulates capsule genes is not understood. In this study, we were able to define the mechanism involving MgrA regulation of capsule. In addition, we also delineated the role of MgrA in capsule regulatory pathways involving the key virulence regulators Agr and Arl. This study further advances our understanding of virulence gene regulation in
, an important human pathogen.
Abstract
Pseudomonas aeruginosa can cause complicated urinary tract infections, particularly in people with catheters, which can lead to pyelonephritis. Whilst some subgroups appear more susceptible ...to infection, such as the elderly and women, the contribution of other host factors and bacterial virulence factors to successful infection remains relatively understudied. In this review, we explore the potential role of P. aeruginosa virulence factors including phenazines, quorum sensing, biofilm formation and siderophores along with host factors such as Tamm-Horsfall protein, osmotic stress and iron specifically on establishment of successful infection in the urinary niche. P. aeruginosa urinary tract infections are highly antibiotic resistant and require costly and intensive treatment. By understanding the infection dynamics of this organism within this specific niche, we may be able to identify novel therapeutic strategies to enhance the use of existing antibiotics.
Pseudomonas aeruginosa causes highly resistant urinary tract infections. It produces an arsenal of virulence factors that aid the infection process. Understanding these is key to the development of novel therapeutics.
Vi capsular polysaccharide, a linear homopolymer of α-1,4-linked N-acetylgalactosaminuronate, is characteristically produced by Salmonella enterica serovar Typhi. The Vi capsule covers the surface of ...the producing bacteria and serves as an virulence factor via inhibition of complement-mediated killing and promoting resistance against phagocytosis. Furthermore, Vi also represents a predominant protective antigen and plays a key role in the development of vaccines against typhoid fever. Herein, we reviewed the latest advances associated with the Vi polysaccharide, from its synthesis and transport within bacterial cells, mechanisms involved in virulence, immunological characteristics, and applications in vaccine, as well as its purification and detection methods.
Botrytis cinerea, a widespread plant pathogen with a necrotrophic lifestyle, causes gray mold disease in many crops. Massive secretion of enzymes and toxins was long considered to be the main driver ...of infection, but recent studies have uncovered a rich toolbox for B. cinerea pathogenicity. The emerging picture is of a multilayered infection process governed by the exchange of factors that collectively contribute to disease development. No plant shows complete resistance against B. cinerea, but pattern-triggered plant immune responses have the potential to significantly reduce disease progression, opening new possibilities for producing B. cinerea-tolerant plants. We examine current B. cinerea infection models, highlight knowledge gaps, and suggest directions for future studies.
Botrytis cinerea infection can proceed by a number of different routes which vary according to the plant species, tissue type, and external conditions.There is no single silver (virulence) bullet; disease development is multilayered and regulated by multiple factors, with subtle contributions from each virulence factor.Infection cushions have emerged as a factory for the production of virulence factors. These structures are likely essential for disease development in tissues with relatively low susceptibility to infection and possibly under suboptimal conditions.A morphogenetic program is essential for pathogenicity; disrupting proper fungal morphogenesis can be detrimental for successful infection.Plant defense is activated early on; despite the lack of complete resistance against B. cinerea, PAMP-triggered immunity (PTI) has the potential to reduce and even prevent disease development.
Antimicrobial resistance (AMR) in soils represents a serious risk to human health through the food chain and human-nature contact. However, the active antibiotic-resistant bacteria (ARB) residing in ...soils that primarily drive AMR dissemination are poorly explored. Here, single-cell Raman-D
O coupled with targeted metagenomics is developed as a culture-independent approach to phenotypically and genotypically profiling active ARB against clinical antibiotics in a wide range of soils. This method quantifies the prevalence (contamination degree) and activity (spread potential) of soil ARB and reveals a clear elevation with increasing anthropogenic activities such as farming and the creation of pollution, thereby constituting a factor that is critical for the assessment of AMR risks. Further targeted sorting and metagenomic sequencing of the most active soil ARB uncover several uncultured genera and a pathogenic strain. Furthermore, the underlying resistance genes, virulence factor genes, and associated mobile genetic elements (including plasmids, insertion sequences, and prophages) are fully deciphered at the single-cell level. This study advances our understanding of the soil active AMR repertoire by linking the resistant phenome to the genome. It will aid in the risk assessment of environmental AMR and guide the combat under the One Health framework.
is a nontuberculous pathogen of poikilothermic fish and an opportunistic human pathogen. Like tuberculous mycobacteria, the
M strain requires the ESX-1 (ESAT-6 system 1) secretion system for ...virulence in host cells. EsxB and EsxA, two major virulence factors exported by the ESX-1 system, are encoded by the
genes within the ESX-1 locus. Deletion of the
genes abrogates ESX-1 export and attenuates
in
and
models of infection. Interestingly, there are several duplications of the
and
genes (
,
,
,
, and
) in the
M genome located outside the ESX-1 locus. We sought to understand if this region, known as ESX-6, contributes to ESX-1-mediated virulence. We found that deletion of the
_
gene alone or the entire ESX-6 locus did not impact ESX-1 export or function, supporting the idea that the
genes present at the ESX-1 locus are the primary contributors to ESX-1-mediated virulence. Nevertheless, overexpression of the
locus complemented ESX-1 function in the Δ
strain, signifying that the two loci are functionally equivalent. Our findings raise questions about why duplicate versions of the
genes are maintained in the
M genome and how these proteins, which are functionally equivalent to virulence factors, contribute to mycobacterial biology.
is the causative agent of the human disease tuberculosis (TB). There are 10.4 million cases and 1.7 million TB-associated deaths annually, making TB a leading cause of death globally. Nontuberculous mycobacteria (NTM) cause chronic human infections that are acquired from the environment. Despite differences in disease etiology, both tuberculous and NTM pathogens use the ESX-1 secretion system to cause disease. The nontubercular mycobacterial species,
, has additional copies of specific ESX-1 genes. Our findings demonstrate that the duplicated genes do not contribute to virulence but can substitute for virulence factors in
These findings suggest that the duplicated genes may play a specific role in NTM biology.
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