-
F1000Research 2019Morphological changes are critical for the virulence of a range of plant and human fungal pathogens. is a major human fungal pathogen whose ability to switch between... (Review)
Review
Morphological changes are critical for the virulence of a range of plant and human fungal pathogens. is a major human fungal pathogen whose ability to switch between different morphological states is associated with its adaptability and pathogenicity. In particular, can switch from an oval yeast form to a filamentous hyphal form, which is characteristic of filamentous fungi. What mechanisms underlie hyphal growth and how are they affected by environmental stimuli from the host or resident microbiota? These questions are the focus of intensive research, as understanding hyphal growth has broad implications for cell biological and medical research.
Topics: Candida albicans; Humans; Hyphae; Virulence
PubMed: 31131089
DOI: 10.12688/f1000research.18546.1 -
Frontiers in Immunology 2019Brucellosis is one of the most prevalent bacterial zoonosis of worldwide distribution. The disease is caused by spp., facultative intracellular pathogens. Brucellosis... (Review)
Review
Brucellosis is one of the most prevalent bacterial zoonosis of worldwide distribution. The disease is caused by spp., facultative intracellular pathogens. Brucellosis in animals results in abortion of fetuses, while in humans, it frequently manifests flu-like symptoms and a typical undulant fever, being osteoarthritis a common complication of the chronic infection. The two most common ways to acquire the infection in humans are through the ingestion of contaminated dairy products or by inhalation of contaminated aerosols. spp. enter the body mainly through the gastrointestinal and respiratory mucosa; however, most studies of immune response to spp. are performed analyzing models of systemic immunity. It is necessary to better understand the mucosal immune response induced by infection since this is the main entry site for the bacterium. In this review, some virulence factors and the mechanisms needed for pathogen invasion and persistence are discussed. Furthermore, some aspects of local immune responses induced during infection will be reviewed. With this knowledge, better vaccines can be designed focused on inducing protective mucosal immune response.
Topics: Brucella; Brucellosis; Humans; Immunity, Mucosal; Intestinal Mucosa; Respiratory Mucosa; Virulence
PubMed: 31481953
DOI: 10.3389/fimmu.2019.01759 -
Molecular Plant Pathology Jul 2021Plant-pathogenic fungi are a significant threat to economic and food security worldwide. Novel protection strategies are required and therefore it is critical we... (Review)
Review
Plant-pathogenic fungi are a significant threat to economic and food security worldwide. Novel protection strategies are required and therefore it is critical we understand the mechanisms by which these pathogens cause disease. Virulence factors and pathogenicity genes have been identified, but in many cases their roles remain elusive. It is becoming increasingly clear that gene regulation is vital to enable plant infection and transcription factors play an essential role. Efforts to determine their regulatory functions in plant-pathogenic fungi have expanded since the annotation of fungal genomes revealed the ubiquity of transcription factors from a broad range of families. This review establishes the significance of transcription factors as regulatory elements in plant-pathogenic fungi and provides a systematic overview of those that have been functionally characterized. Detailed analysis is provided on regulators from well-characterized families controlling various aspects of fungal metabolism, development, stress tolerance, and the production of virulence factors such as effectors and secondary metabolites. This covers conserved transcription factors with either specialized or nonspecialized roles, as well as recently identified regulators targeting key virulence pathways. Fundamental knowledge of transcription factor regulation in plant-pathogenic fungi provides avenues to identify novel virulence factors and improve our understanding of the regulatory networks linked to pathogen evolution, while transcription factors can themselves be specifically targeted for disease control. Areas requiring further insight regarding the molecular mechanisms and/or specific classes of transcription factors are identified, and direction for future investigation is presented.
Topics: Fungal Proteins; Fungi; Gene Expression Regulation, Fungal; Genome, Fungal; Plant Diseases; Plants; Transcription Factors; Virulence; Virulence Factors
PubMed: 33973705
DOI: 10.1111/mpp.13056 -
Molecular Plant Pathology Jan 2009Successful host-pathogen interactions require the presence, maintenance and expression of gene cassettes called 'pathogenicity islands' (PAIs) and 'metabolic islands'... (Review)
Review
Successful host-pathogen interactions require the presence, maintenance and expression of gene cassettes called 'pathogenicity islands' (PAIs) and 'metabolic islands' (MAIs) in the respective pathogen. The products of these genes confer on the pathogen the means to recognize their host(s) and to efficiently evade host defences in order to colonize, propagate within the host and eventually disseminate from the host. Virulence effectors secreted by type III and type IV secretion systems, among others, play vital roles in sustaining pathogenicity and optimizing host-pathogen interactions. Complete genome sequences of plant pathogenic bacteria have revealed the presence of PAIs and MAIs. The genes of these islands possess mosaic structures with regions displaying differences in nucleotide composition and codon usage in relation to adjacent genome structures, features that are highly suggestive of their acquisition from a foreign donor. These donors can be other bacteria, as well as lower members of the Archaea and Eukarya. Genes that have moved from the domains Archaea and Eukarya to the domain Bacteria are true cases of horizontal gene transfer. They represent interdomain genetic transfer. Genetic exchange between distinct members of the domain Bacteria, however, represents lateral gene transfer, an intradomain event. Both horizontal and lateral gene transfer events have been used to facilitate survival fitness of the pathogen.
Topics: Bacteria; Gene Transfer, Horizontal; Genes, Plant; Plants; Virulence
PubMed: 19161360
DOI: 10.1111/j.1364-3703.2008.00518.x -
Sheng Wu Gong Cheng Xue Bao = Chinese... Sep 2017Biofilms are complex three-dimensional bacterial assemblages that attach to biotic or abiotic solid surfaces, and frequently embed within a self-produced matrix of... (Review)
Review
Biofilms are complex three-dimensional bacterial assemblages that attach to biotic or abiotic solid surfaces, and frequently embed within a self-produced matrix of extracellular polymeric substances. Biofilm formation is a microbial defense response to biotic and abiotic stresses, and a key factor for survival in adverse environments. A wide variety of microorganisms can colonize distant tissues of higher plants, such as leaves, vascular network and roots, and adhere to the surface of the tissues to form biofilms. The dynamic processes in forming biofilms in response to plant internal environment are key steps required for full virulence of phytopathogenic bacteria. Exploring the mechanisms involved in regulation of bacterial biofilms is important for understanding the plant-pathogens interactions. In this review, we summarized the research progresses related to the biofilms of bacterial phytopathogens, including biofilm characteristics, essential regulatory mechanisms and key signals affecting the transition between a planktonic lifestyle and multicellular behavior.
Topics: Bacteria; Biofilms; Host-Pathogen Interactions; Plant Diseases; Plants; Virulence
PubMed: 28956407
DOI: 10.13345/j.cjb.170079 -
Virulence Dec 2019Opportunistic commensal and environmental fungi can cause superficial to systemic diseases in humans. But how did these pathogens adapt to infect us and how does... (Review)
Review
Opportunistic commensal and environmental fungi can cause superficial to systemic diseases in humans. But how did these pathogens adapt to infect us and how does host-pathogen co-evolution shape their virulence potential? During evolution toward pathogenicity, not only do microorganisms gain virulence genes, but they also tend to lose non-adaptive genes in the host niche. Additionally, virulence factors can become detrimental during infection when they trigger host recognition. The loss of non-adaptive genes as well as the loss of the virulence potential of genes by adaptations to the host has been investigated in pathogenic bacteria and phytopathogenic fungi, where they are known as antivirulence and avirulence genes, respectively. However, these concepts are nearly unknown in the field of pathogenic fungi of humans. We think that this unnecessarily limits our view of human-fungal interplay, and that much could be learned if we applied a similar framework to aspects of these interactions. In this review, we, therefore, define and adapt the concepts of antivirulence and avirulence genes for human pathogenic fungi. We provide examples for analogies to antivirulence genes of bacterial pathogens and to avirulence genes of phytopathogenic fungi. Introducing these terms to the field of pathogenic fungi of humans can help to better comprehend the emergence and evolution of fungal virulence and disease.
Topics: Adaptation, Physiological; Animals; Evolution, Molecular; Fungi; Genes, Fungal; Host-Pathogen Interactions; Humans; Mice; Virulence; Virulence Factors
PubMed: 31711357
DOI: 10.1080/21505594.2019.1688753 -
Cold Spring Harbor Perspectives in... Aug 2014We review here recent advances in our understanding of sexual reproduction in fungal pathogens that commonly infect humans, including Candida albicans, Cryptococcus... (Review)
Review
We review here recent advances in our understanding of sexual reproduction in fungal pathogens that commonly infect humans, including Candida albicans, Cryptococcus neoformans/gattii, and Aspergillus fumigatus. Where appropriate or relevant, we introduce findings on other species associated with human infections. In particular, we focus on rapid advances involving genetic, genomic, and population genetic approaches that have reshaped our view of how fungal pathogens evolve. Rather than being asexual, mitotic, and largely clonal, as was thought to be prevalent as recently as a decade ago, we now appreciate that the vast majority of pathogenic fungi have retained extant sexual, or parasexual, cycles. In some examples, sexual and parasexual unions of pathogenic fungi involve closely related individuals, generating diversity in the population but with more restricted recombination than expected from fertile, sexual, outcrossing and recombining populations. In other cases, species and isolates participate in global outcrossing populations with the capacity for considerable levels of gene flow. These findings illustrate general principles of eukaryotic pathogen emergence with relevance for other fungi, parasitic eukaryotic pathogens, and both unicellular and multicellular eukaryotic organisms.
Topics: Drug Resistance, Fungal; Fungi; Humans; Hyphae; Mycoses; Reproduction; Self-Fertilization; Virulence
PubMed: 25085958
DOI: 10.1101/cshperspect.a019281 -
Virulence 2014Until quite recently and since the late 19(th) century, medical microbiology has been based on the assumption that some micro-organisms are pathogens and others are not.... (Review)
Review
Until quite recently and since the late 19(th) century, medical microbiology has been based on the assumption that some micro-organisms are pathogens and others are not. This binary view is now strongly criticized and is even becoming untenable. We first provide a historical overview of the changing nature of host-parasite interactions, in which we argue that large-scale sequencing not only shows that identifying the roots of pathogenesis is much more complicated than previously thought, but also forces us to reconsider what a pathogen is. To address the challenge of defining a pathogen in post-genomic science, we present and discuss recent results that embrace the microbial genetic diversity (both within- and between-host) and underline the relevance of microbial ecology and evolution. By analyzing and extending earlier work on the concept of pathogen, we propose pathogenicity (or virulence) should be viewed as a dynamical feature of an interaction between a host and microbes.
Topics: Animals; Bacteria; Biological Evolution; Fungi; Genetic Variation; Host-Parasite Interactions; Host-Pathogen Interactions; Humans; Virulence; Viruses
PubMed: 25483864
DOI: 10.4161/21505594.2014.960726 -
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 -
Advances in Experimental Medicine and... 2011The family Xanthomonadaceae is a wide-spread family of bacteria belonging to the gamma subdivision of the Gram-negative proteobacteria, including the two... (Review)
Review
The family Xanthomonadaceae is a wide-spread family of bacteria belonging to the gamma subdivision of the Gram-negative proteobacteria, including the two plant-pathogenic genera Xanthomonas and Xylella, and the related genus Stenotrophomonas. Adhesion is a widely conserved virulence mechanism among Gram-negative bacteria, no matter whether they are human, animal or plant pathogens, since attachment to the host tissue is one of the key early steps of the bacterial infection process. Bacterial attachment to surfaces is mediated by surface structures that are anchored in the bacterial outer membrane and cover a broad group of fimbrial and non-fimbrial structures, commonly known as adhesins. In this chapter, we discuss recent findings on candidate adhesins of plant-pathogenic Xanthomonadaceae, including polysaccharidic (lipopolysaccharides, exopolysaccharides) and proteineous structures (chaperone/usher pili, type IV pili, autotransporters, two-partner-secreted and other outer membrane adhesins), their involvement in the formation of biofilms and their mode of regulation via quorum sensing. We then compare the arsenals of adhesins among different Xanthomonas strains and evaluate their mode of selection. Finally, we summarize the sparse knowledge on specific adhesin receptors in plants and the possible role of RGD motifs in binding to integrin-like plant molecules.
Topics: Adhesins, Bacterial; Bacterial Adhesion; Fimbriae, Bacterial; Gram-Negative Bacterial Infections; Host-Pathogen Interactions; Plant Diseases; Plants; Polysaccharides, Bacterial; Receptors, Immunologic; Virulence; Xanthomonadaceae
PubMed: 21557058
DOI: 10.1007/978-94-007-0940-9_5