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Molecular Biology of the Cell Dec 2015One quarter of all deaths worldwide each year result from infectious diseases caused by microbial pathogens. Pathogens infect and cause disease by producing virulence...
One quarter of all deaths worldwide each year result from infectious diseases caused by microbial pathogens. Pathogens infect and cause disease by producing virulence factors that target host cell molecules. Studying how virulence factors target host cells has revealed fundamental principles of cell biology. These include important advances in our understanding of the cytoskeleton, organelles and membrane-trafficking intermediates, signal transduction pathways, cell cycle regulators, the organelle/protein recycling machinery, and cell-death pathways. Such studies have also revealed cellular pathways crucial for the immune response. Discoveries from basic research on the cell biology of pathogenesis are actively being translated into the development of host-targeted therapies to treat infectious diseases. Thus there are many reasons for cell biologists to incorporate the study of microbial pathogens into their research programs.
Topics: Animals; Bacteria; Cell Biology; Host-Pathogen Interactions; Humans; Infections; Mice; Parasites; Signal Transduction; Virulence; Viruses
PubMed: 26628749
DOI: 10.1091/mbc.E15-03-0144 -
Medical Mycology Journal 2018Aspergillus fumigatus is the predominant fungal pathogen responsible for life-threatening systemic infections in humans. Recently developed high-throughput whole... (Review)
Review
Aspergillus fumigatus is the predominant fungal pathogen responsible for life-threatening systemic infections in humans. Recently developed high-throughput whole genome sequencing (WGS) and RNA-Seq technologies have proven to be powerful tools for systematically investigating pathogenic organisms. In this review, we present new virulence factors obtained through our "omics" researches on A. fumigatus. We first sequenced genomes of A. fumigatus stains isolated from one infected patient at different time points, and made an important finding that although the genome (microsatellites) type of the infected strain remained unchanged, the strain exhibited several genetic changes, including acquiring therapeutic drug resistance, during patient treatment for 1.5 years. Of the various presentations of aspergillosis, pulmonary aspergilloma (PA) is one of the most common forms of A. fumigatus infection, where fungus balls are composed of fungal hyphae, inflammatory cells, fibrin, mucus, and tissue debris. Chronic necrotizing pulmonary aspergillosis (CNPA), also known as semi-invasive or invasive aspergillosis, is locally invasive and predominantly seen in patients with mild immunodeficiency or with a chronic lung disease. We compared genomes of strains individually isolated from eight PA and eight CNPA patients in Japan, and found that the PA and CNPA strains show indiscernible genetic and ancestral backgrounds as far as genomic SNPs of the strains are concerned. The main route of infections caused by A. fumigatus is via inhalation of conidia. Inhaled conidia rapidly adhere to pulmonary epithelial cells. Nevertheless, little is known of the molecular mechanism of adherence in A. fumigatus resting conidia. We assumed corresponding adhesion molecules were highly expressed in high-adhesion conidia during conidia maturation, and exhaustively searched adhesion molecules by comparing gene expression levels in high- and low-adherence strains using the RNA-Seq technique. We found several factors involved in conidial adhesion and suggest that composite actions of these molecules have roles in conidial adhesion to human pulmonary epithelial cells.
Topics: Aspergillus fumigatus; Drug Resistance, Fungal; Genome, Fungal; Humans; Mutation; Pulmonary Alveoli; Virulence
PubMed: 29848910
DOI: 10.3314/mmj.18.005 -
Biochemical Society Transactions Jun 2021Interferon (IFN)-induced guanosine triphosphate hydrolysing enzymes (GTPases) have been identified as cornerstones of IFN-mediated cell-autonomous defence. Upon IFN... (Review)
Review
Interferon (IFN)-induced guanosine triphosphate hydrolysing enzymes (GTPases) have been identified as cornerstones of IFN-mediated cell-autonomous defence. Upon IFN stimulation, these GTPases are highly expressed in various host cells, where they orchestrate anti-microbial activities against a diverse range of pathogens such as bacteria, protozoan and viruses. IFN-induced GTPases have been shown to interact with various host pathways and proteins mediating pathogen control via inflammasome activation, destabilising pathogen compartments and membranes, orchestrating destruction via autophagy and the production of reactive oxygen species as well as inhibiting pathogen mobility. In this mini-review, we provide an update on how the IFN-induced GTPases target pathogens and mediate host defence, emphasising findings on protection against bacterial pathogens.
Topics: Animals; Bacteria; Bacterial Infections; GTP Phosphohydrolases; Host-Pathogen Interactions; Humans; Immunity, Innate; Interferons; Signal Transduction; Virulence
PubMed: 34003245
DOI: 10.1042/BST20200900 -
BMC Genomics Sep 2022Xanthomonas is a genus of gram-negative bacterium containing more than 35 species. Among these pathogenic species, Xanthomonas albilineans (Xal) is of global interest,... (Comparative Study)
Comparative Study
BACKGROUND
Xanthomonas is a genus of gram-negative bacterium containing more than 35 species. Among these pathogenic species, Xanthomonas albilineans (Xal) is of global interest, responsible for leaf scald disease in sugarcane. Another notable Xanthomonas species is Xanthomonas sachari (Xsa), a sugarcane-associated agent of chlorotic streak disease.
RESULT
The virulence of 24 Xanthomonas strains was evaluated by disease index (DI) and Area Under Disease Progress Curve (AUDPC) in the susceptible inoculated plants (GT 46) and clustered into three groups of five highly potent, seven mild virulent, and twelve weak virulent strains. The highly potent strain (X. albilineans, Xal JG43) and its weak virulent related strain (X. sacchari, Xsa DD13) were sequenced, assembled, and annotated in the circular genomes. The genomic size of JG43 was smaller than that of DD13. Both strains (JG43 and DD13) lacked a Type III secretory system (T3SS) and T6SS. However, JG43 possessed Salmonella pathogenicity island-1 (SPI-1). More pathogen-host interaction (PHI) genes and virulent factors in 17 genomic islands (GIs) were detected in JG43, among which six were related to pathogenicity. Albicidin and a two-component system associated with virulence were also detected in JG43. Furthermore, 23 Xanthomonas strains were sequenced and classified into three categories based on Single Nucleotide Polymorphism (SNP) mutation loci and pathogenicity, using JG43 as a reference genome. Transitions were dominant SNP mutations, while structural variation (SV) is frequent intrachromosomal rearrangement (ITX). Two essential genes (rpfC/rpfG) of the two-component system and another gene related to SNP were mutated to understand their virulence effect. The mutation of rpfG resulted in a decrease in pathogenicity.
CONCLUSION
These findings revealed virulence of 24 Xanthomonas strains and variations by 23 Xanthomonas strains. We sequenced, assembled, and annotated the circular genomes of Xal JG43 and Xsa DD13, identifying diversity detected by pathogenic factors and systems. Furthermore, complete genomic sequences and sequenced data will provide a theoretical basis for identifying pathogenic factors responsible for sugarcane leaf scald disease.
Topics: Plant Diseases; Plant Leaves; Saccharum; Virulence; Virulence Factors; Xanthomonas
PubMed: 36162999
DOI: 10.1186/s12864-022-08900-2 -
FEMS Microbiology Reviews Jan 2020Xanthomonas is a well-studied genus of bacterial plant pathogens whose members cause a variety of diseases in economically important crops worldwide. Genomic and... (Review)
Review
Xanthomonas is a well-studied genus of bacterial plant pathogens whose members cause a variety of diseases in economically important crops worldwide. Genomic and functional studies of these phytopathogens have provided significant understanding of microbial-host interactions, bacterial virulence and host adaptation mechanisms including microbial ecology and epidemiology. In addition, several strains of Xanthomonas are important as producers of the extracellular polysaccharide, xanthan, used in the food and pharmaceutical industries. This polymer has also been implicated in several phases of the bacterial disease cycle. In this review, we summarise the current knowledge on the infection strategies and regulatory networks controlling virulence and adaptation mechanisms from Xanthomonas species and discuss the novel opportunities that this body of work has provided for disease control and plant health.
Topics: Adaptation, Physiological; Genome, Bacterial; Host-Pathogen Interactions; Plant Diseases; Plants; Virulence; Xanthomonas
PubMed: 31578554
DOI: 10.1093/femsre/fuz024 -
Molecular Plant Pathology Jun 2017Plant-pathogenic fungi cause diseases to all major crop plants world-wide and threaten global food security. Underpinning fungal diseases are virulence genes... (Review)
Review
Plant-pathogenic fungi cause diseases to all major crop plants world-wide and threaten global food security. Underpinning fungal diseases are virulence genes facilitating plant host colonization that often marks pathogenesis and crop failures, as well as an increase in staple food prices. Fungal molecular genetics is therefore the cornerstone to the sustainable prevention of disease outbreaks. Pathogenicity studies using mutant collections provide immense function-based information regarding virulence genes of economically relevant fungi. These collections are rich in potential targets for existing and new biological control agents. They contribute to host resistance breeding against fungal pathogens and are instrumental in searching for novel resistance genes through the identification of fungal effectors. Therefore, functional analyses of mutant collections propel gene discovery and characterization, and may be incorporated into disease management strategies. In the light of these attributes, mutant collections enhance the development of practical solutions to confront modern agricultural constraints. Here, a critical review of mutant collections constructed by various laboratories during the past decade is provided. We used Magnaporthe oryzae and Fusarium graminearum studies to show how mutant screens contribute to bridge existing knowledge gaps in pathogenicity and fungal-host interactions.
Topics: Fungal Proteins; Fungi; Fusarium; Genome, Fungal; Host-Pathogen Interactions; Magnaporthe; Plant Diseases; Plants; Virulence
PubMed: 27733021
DOI: 10.1111/mpp.12497 -
EBioMedicine Feb 2023Novel therapeutics to manage bacterial infections are urgently needed as the impact and prevalence of antimicrobial resistance (AMR) grows. Antivirulence therapeutics... (Review)
Review
Novel therapeutics to manage bacterial infections are urgently needed as the impact and prevalence of antimicrobial resistance (AMR) grows. Antivirulence therapeutics are an alternative approach to antibiotics that aim to attenuate virulence rather than target bacterial essential functions, while minimizing microbiota perturbation and the risk of AMR development. Beyond known virulence factors, pathogen-associated genes (PAGs; genes found only in pathogens to date) may play an important role in virulence or host association. Many identified PAGs encode uncharacterized hypothetical proteins and represent an untapped wealth of novel drug targets. Here, we review current advances in antivirulence drug research and development, including PAG identification, and provide a comprehensive workflow from the discovery of antivirulence drug targets to drug discovery. We highlight the importance of integrating bioinformatic/genomic-based methods for novel virulence factor discovery, coupled with experimental characterization, into existing drug screening platforms to develop novel and effective antivirulence drugs.
Topics: Humans; Workflow; Anti-Bacterial Agents; Virulence; Virulence Factors; Genetic Association Studies
PubMed: 36628845
DOI: 10.1016/j.ebiom.2022.104429 -
FEMS Yeast Research Jun 2021Candida albicans typically resides in the human gastrointestinal tract and mucosal membranes as a commensal organism. To adapt and cope with the host immune system, it... (Review)
Review
Candida albicans typically resides in the human gastrointestinal tract and mucosal membranes as a commensal organism. To adapt and cope with the host immune system, it has evolved a variety of mechanisms of adaptation such as stress-induced mutagenesis and epigenetic regulation. Niche-specific patterns of gene expression also allow the fungus to fine-tune its response to specific microenvironments in the host and switch from harmless commensal to invasive pathogen. Proteome plasticity produced by CUG ambiguity, on the other hand is emerging as a new layer of complexity in C. albicans adaptation, pathogenesis, and drug resistance. Such proteome plasticity is the result of a genetic code alteration where the leucine CUG codon is translated mainly as serine (97%), but maintains some level of leucine (3%) assignment. In this review, we dissect the link between C. albicans non-standard CUG translation, proteome plasticity, host adaptation and pathogenesis. We discuss published work showing how this pathogen uses the fidelity of protein synthesis to spawn novel virulence traits.
Topics: Adaptation, Physiological; Candida albicans; Codon; Drug Resistance, Fungal; Epigenesis, Genetic; Protein Biosynthesis; Proteome; Virulence
PubMed: 34021562
DOI: 10.1093/femsyr/foab032 -
PloS One 2017The objective of this study was to characterize blaOXA-23 harbouring Acinetobacter indicus-like strains from cattle including genomic and phylogenetic analyses,...
The objective of this study was to characterize blaOXA-23 harbouring Acinetobacter indicus-like strains from cattle including genomic and phylogenetic analyses, antimicrobial susceptibility testing and evaluation of pathogenicity in vitro and in vivo. Nasal and rectal swabs (n = 45) from cattle in Germany were screened for carbapenem-non-susceptible Acinetobacter spp. Thereby, two carbapenem resistant Acinetobacter spp. from the nasal cavities of two calves could be isolated. MALDI-TOF mass spectrometry and 16S rDNA sequencing identified these isolates as A. indicus-like. A phylogenetic tree based on partial rpoB sequences indicated closest relation of the two bovine isolates to the A. indicus type strain A648T and human clinical A. indicus isolates, while whole genome comparison revealed considerable intraspecies diversity. High mimimum inhibitory concentrations were observed for carbapenems and other antibiotics including fluoroquinolones and gentamicin. Whole genome sequencing and PCR mapping revealed that both isolates harboured blaOXA-23 localized on the chromosome and surrounded by interrupted Tn2008 transposon structures. Since the pathogenic potential of A. indicus is unknown, pathogenicity was assessed employing the Galleria (G.) mellonella infection model and an in vitro cytotoxicity assay using A549 human lung epithelial cells. Pathogenicity in vivo (G. mellonella killing assay) and in vitro (cytotoxicity assay) of the two A. indicus-like isolates was lower compared to A. baumannii ATCC 17978 and similar to A. lwoffii ATCC 15309. The reduced pathogenicity of A. indicus compared to A. baumannii correlated with the absence of important virulence genes encoding like phospholipase C1+C2, acinetobactin outer membrane protein BauA, RND-type efflux system proteins AdeRS and AdeAB or the trimeric autotransporter adhesin Ata. The emergence of carbapenem-resistant A. indicus-like strains from cattle carrying blaOXA-23 on transposable elements and revealing genetic relatedness to isolates from human clinical sources requires further investigations regarding the pathogenic potential, genomic characteristics, zoonotic risk and putative additional sources of this new Acinetobacter species.
Topics: Acinetobacter; Acinetobacter Infections; Animals; Carbapenems; Cattle; Microbial Sensitivity Tests; Phylogeny; Virulence; beta-Lactam Resistance
PubMed: 28207789
DOI: 10.1371/journal.pone.0171986 -
Molecular Plant-microbe Interactions :... Apr 2023Extracellular vesicles (EVs) are lipid bilayer-enclosed nanoparticles that deliver bioactive proteins, nucleic acids, lipids, and other small molecules from donor to... (Review)
Review
Extracellular vesicles (EVs) are lipid bilayer-enclosed nanoparticles that deliver bioactive proteins, nucleic acids, lipids, and other small molecules from donor to recipient cells. They have attracted significant interest recently due to their important roles in regulating plant-microbe interaction. During microbial infection, plant EVs play a prominent role in defense by delivering small regulatory RNA into pathogens, resulting in the silencing of pathogen virulence genes. Pathogens also deliver small RNAs into plant cells to silence host immunity genes. Recent evidence indicates that microbial EVs may be involved in pathogenesis and host immunity modulation by transporting RNAs and other biomolecules. However, the biogenesis and function of microbial EVs in plant-microbe interaction remain ill-defined. In this review, we discuss various aspects of microbial EVs, with a particular focus on current methods for EV isolation, composition, biogenesis, and their roles in plant-microbe interaction. We also discussed the potential role of microbial EVs in cross-kingdom RNA trafficking from pathogens to plants, as it is a highly likely possibility to explore in the future. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
Topics: RNA; Extracellular Vesicles; RNA Interference; Biological Transport; Virulence
PubMed: 36574017
DOI: 10.1094/MPMI-08-22-0162-FI