scholarly journals PLB-985 Neutrophil-Like Cells as a Model To Study Aspergillus fumigatus Pathogenesis

mSphere ◽  
2022 ◽  
Author(s):  
Muhammad Rafiq ◽  
Flora Rivieccio ◽  
Ann-Kathrin Zimmermann ◽  
Corissa Visser ◽  
Alexander Bruch ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Polymorphonuclear Leukocyte ◽  
Fungal Pathogen ◽  
Polymorphonuclear Leukocytes ◽  
Fungal Pathogens ◽  
Model Systems ◽  
Content Type ◽  
Human Polymorphonuclear Leukocyte ◽  
Human Fungal Pathogen

Polymorphonuclear leukocytes are an important defense against human fungal pathogens, yet our model systems to study this group of cells remain very limited in scope. In this study, we established that differentiated PLB-985 cells can serve as a model to recapitulate several important aspects of human polymorphonuclear leukocyte interactions with the important human fungal pathogen Aspergillus fumigatus .

scholarly journals Targeting Methionine Synthase in a Fungal Pathogen Causes a Metabolic Imbalance That Impacts Cell Energetics, Growth, and Virulence

mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Jennifer Scott ◽  
Monica Sueiro-Olivares ◽  
Benjamin P. Thornton ◽  
Rebecca A. Owens ◽  
Howbeer Muhamadali ◽  
...  
Keyword(s):  
Beneficial Effect ◽  
Aspergillus Fumigatus ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Antifungal Drugs ◽  
New Drugs ◽  
Methionine Synthase ◽  
Content Type ◽  
Metabolic Imbalance

ABSTRACT There is an urgent need to develop novel antifungals to tackle the threat fungal pathogens pose to human health. Here, we have performed a comprehensive characterization and validation of the promising target methionine synthase (MetH). We show that in Aspergillus fumigatus the absence of this enzymatic activity triggers a metabolic imbalance that causes a reduction in intracellular ATP, which prevents fungal growth even in the presence of methionine. Interestingly, growth can be recovered in the presence of certain metabolites, which shows that metH is a conditionally essential gene and consequently should be targeted in established infections for a more comprehensive validation. Accordingly, we have validated the use of the tetOFF genetic model in fungal research and improved its performance in vivo to achieve initial validation of targets in models of established infection. We show that repression of metH in growing hyphae halts growth in vitro, which translates into a beneficial effect when targeting established infections using this model in vivo. Finally, a structure-based virtual screening of methionine synthases reveals key differences between the human and fungal structures and unravels features in the fungal enzyme that can guide the design of novel specific inhibitors. Therefore, methionine synthase is a valuable target for the development of new antifungals. IMPORTANCE Fungal pathogens are responsible for millions of life-threatening infections on an annual basis worldwide. The current repertoire of antifungal drugs is very limited and, worryingly, resistance has emerged and already become a serious threat to our capacity to treat fungal diseases. The first step to develop new drugs is often to identify molecular targets in the pathogen whose inhibition during infection can prevent its growth. However, the current models are not suitable to validate targets in established infections. Here, we have characterized the promising antifungal target methionine synthase in great detail, using the prominent fungal pathogen Aspergillus fumigatus as a model. We have uncovered the underlying reason for its essentiality and confirmed its druggability. Furthermore, we have optimized the use of a genetic system to show a beneficial effect of targeting methionine synthase in established infections. Therefore, we believe that antifungal drugs to target methionine synthase should be pursued and additionally, we provide a model that permits gaining information about the validity of antifungal targets in established infections.

scholarly journals Characterization of Extracellular Vesicles Produced by Aspergillus fumigatus Protoplasts

mSphere ◽  
2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Juliana Rizzo ◽  
Thibault Chaze ◽  
Kildare Miranda ◽  
Robert W. Roberson ◽  
Olivier Gorgette ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Aspergillus Fumigatus ◽  
Extracellular Vesicles ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Biologically Active ◽  
Content Type ◽  
Cell Wall Biogenesis

ABSTRACT Extracellular vesicles (EVs) are membranous compartments produced by yeast and mycelial forms of several fungal species. One of the difficulties in perceiving the role of EVs during the fungal life, and particularly in cell wall biogenesis, is caused by the presence of a thick cell wall. One alternative to have better access to these vesicles is to use protoplasts. This approach has been investigated here with Aspergillus fumigatus, one of the most common opportunistic fungal pathogens worldwide. Analysis of regenerating protoplasts by scanning electron microscopy and fluorescence microscopy indicated the occurrence of outer membrane projections in association with surface components and the release of particles with properties resembling those of fungal EVs. EVs in culture supernatants were characterized by transmission electron microscopy and nanoparticle tracking analysis. Proteomic and glycome analysis of EVs revealed the presence of a complex array of enzymes related to lipid/sugar metabolism, pathogenic processes, and cell wall biosynthesis. Our data indicate that (i) EV production is a common feature of different morphological stages of this major fungal pathogen and (ii) protoplastic EVs are promising tools for undertaking studies of vesicle functions in fungal cells. IMPORTANCE Fungal cells use extracellular vesicles (EVs) to export biologically active molecules to the extracellular space. In this study, we used protoplasts of Aspergillus fumigatus, a major fungal pathogen, as a model to evaluate the role of EV production in cell wall biogenesis. Our results demonstrated that wall-less A. fumigatus exports plasma membrane-derived EVs containing a complex combination of proteins and glycans. Our report is the first to characterize fungal EVs in the absence of a cell wall. Our results suggest that protoplasts represent a promising model for functional studies of fungal vesicles.

scholarly journals Global Population Genetic Analysis of Aspergillus fumigatus

mSphere ◽  
2017 ◽  
Vol 2 (1) ◽  
Author(s):  
Eta Ebasi Ashu ◽  
Ferry Hagen ◽  
Anuradha Chowdhary ◽  
Jacques F. Meis ◽  
Jianping Xu
Keyword(s):  
Gene Flow ◽  
Microsatellite Markers ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Management Strategies ◽  
Antifungal Drug ◽  
Drug Pressure ◽  
Content Type ◽  
Human Fungal Pathogen ◽  
Polymorphic Microsatellite

ABSTRACT The genetic diversity and geographic structure of the human fungal pathogen A. fumigatus have been the subject of many studies. However, most previous studies had relatively limited sample ranges and sizes and/or used genetic markers with low-level polymorphisms. In this paper, we characterize a global collection of strains of A. fumigatus using a panel of 9 highly polymorphic microsatellite markers. Using these markers, we analyze 2,026 isolates, which is ~3 times the number of isolates reported so far in previous studies. Our analyses suggest that A. fumigatus contains historically differentiated genetic populations but that its evolution is significantly impacted by contemporary forces such as widespread gene flow and local antifungal drug pressure. In the wake of a global rise in resistance to azoles in fungal pathogens, our findings should aid in developing management strategies to mitigate current increases to azole resistance. Aspergillus fumigatus is a ubiquitous opportunistic fungal pathogen capable of causing invasive aspergillosis, a globally distributed disease with a mortality rate of up to 90% in high-risk populations. Effective control and prevention of this disease require a thorough understanding of its epidemiology. However, despite significant efforts, the global molecular epidemiology of A. fumigatus remains poorly understood. In this study, we analyzed 2,026 A. fumigatus isolates from 13 countries in four continents using nine highly polymorphic microsatellite markers. Genetic cluster analyses suggest that our global sample of A. fumigatus isolates belonged to eight genetic clusters, with seven of the eight clusters showing broad geographic distributions. We found common signatures of sexual recombination within individual genetic clusters and clear evidence of hybridization between several clusters. Limited but statistically significant genetic differentiations were found among geographic and ecological populations. However, there was abundant evidence for gene flow at the local, regional, and global scales. Interestingly, the triazole-susceptible and triazole-resistant populations showed different population structures, consistent with antifungal drug pressure playing a significant role in local adaptation. Our results suggest that global populations of A. fumigatus are shaped by historical differentiation, contemporary gene flow, sexual reproduction, and the localized antifungal drug selection that is driving clonal expansion of genotypes resistant to multiple triazole drugs. IMPORTANCE The genetic diversity and geographic structure of the human fungal pathogen A. fumigatus have been the subject of many studies. However, most previous studies had relatively limited sample ranges and sizes and/or used genetic markers with low-level polymorphisms. In this paper, we characterize a global collection of strains of A. fumigatus using a panel of 9 highly polymorphic microsatellite markers. Using these markers, we analyze 2,026 isolates, which is ~3 times the number of isolates reported so far in previous studies. Our analyses suggest that A. fumigatus contains historically differentiated genetic populations but that its evolution is significantly impacted by contemporary forces such as widespread gene flow and local antifungal drug pressure. In the wake of a global rise in resistance to azoles in fungal pathogens, our findings should aid in developing management strategies to mitigate current increases to azole resistance.

scholarly journals Host Lung Environment Limits Aspergillus fumigatus Germination through an SskA-Dependent Signaling Response

mSphere ◽  
2021 ◽  
Author(s):  
Marina E. Kirkland ◽  
McKenzie Stannard ◽  
Caitlin H. Kowalski ◽  
Dallas Mould ◽  
Alayna Caffrey-Carr ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Fungal Pathogen ◽  
Murine Models ◽  
Content Type ◽  
Human Fungal Pathogen

Aspergillus fumigatus is an important human fungal pathogen particularly in immunocompromised individuals. Initiation of growth by A. fumigatus in the lung is important for its pathogenicity in murine models.

scholarly journals Mixed Infections and In Vivo Evolution in the Human Fungal Pathogen Cryptococcus neoformans

mBio ◽  
2010 ◽  
Vol 1 (1) ◽  
Author(s):  
Marie Desnos-Ollivier ◽  
Sweta Patel ◽  
Adam R. Spaulding ◽  
Caroline Charlier ◽  
Dea Garcia-Hermoso ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Molecular Diversity ◽  
Therapeutic Strategies ◽  
Mixed Infections ◽  
Content Type ◽  
Human Fungal Pathogen ◽  
Life Threatening

ABSTRACTKoch’s postulates are criteria establishing a causal relationship between a microbe and a disease that lead to the assumption that diseases are caused by a single strain or its evolved forms.Cryptococcus neoformansis a life-threatening human fungal pathogen responsible for an estimated 1 million cases of cryptococcosis/year, predominantly meningoencephalitis. To assess the molecular diversity of clinical isolates and gain knowledge ofC. neoformansbiology in the host, we analyzed clinical cultures collected during the prospective CryptoA/D study. Using molecular analysis of unpurified isolates, we demonstrated that mixed infections in humans are more common than previously thought, occurring in almost 20% of patients diagnosed with cryptococcosis. These mixed infections are composed of different mating types, serotypes, and/or genotypes. We also identified genetically related haploid and diploid strains in the same patients. Experimental infections and quantitative PCR show that these ploidy changes can result from endoreplication (duplication of DNA content) and that shuttling between haploid and diploid states can occur, suggestingin vivoevolution. Thus, the concept of one strain/one infection does not hold true forC. neoformansand may apply to other environmentally acquired fungal pathogens. Furthermore, the possibility of mixed and/or evolving infections should be taken into account when developing therapeutic strategies against these pathogens.IMPORTANCECryptococcus  neoformansis a life-threatening human fungal pathogen that is present in the environment and is responsible for an estimated 1 million cases of cryptococcosis/year, predominantly meningoencephalitis in HIV-infected patients. To assess the molecular diversity of clinical isolates and gain knowledge ofC. neoformansbiology in the host, we analyzed clinical cultures collected during a prospective study on cryptococcosis. Using molecular analysis of unpurified isolates, we uncovered an unexpectedly high frequency (almost 20%) of mixed infections. We further demonstrated that these mixed infections could result from infestation by multiple strains acquired from the environment. We also made the serendipitous discovery ofin vivoevolution leading to endoreplication of the yeasts within the host. Thus, the concept of one strain causing one infection does not hold true forC. neoformansand potentially for other environmentally acquired fungal pathogens. The possibility of mixed and/or evolving infections should be taken into account when developing therapeutic strategies against these pathogens.

scholarly journals Aspergillus fumigatus Acetate Utilization Impacts Virulence Traits and Pathogenicity

mBio ◽  
2021 ◽  
Author(s):  
Laure Nicolas Annick Ries ◽  
Patricia Alves de Castro ◽  
Lilian Pereira Silva ◽  
Clara Valero ◽  
Thaila Fernanda dos Reis ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Fungal Pathogen ◽  
Carbon Sources ◽  
Body Fluids ◽  
Peripheral Tissues ◽  
Content Type ◽  
Virulence Traits ◽  
Acetate Utilization ◽  
Opportunistic Fungal Pathogen

Aspergillus fumigatus is an opportunistic fungal pathogen in humans. During infection, A. fumigatus is predicted to use host carbon sources, such as acetate, present in body fluids and peripheral tissues, to sustain growth and promote colonization and invasion.

scholarly journals mSphere of Influence: the Power of Yeast Genetics Still Going Strong!

mSphere ◽  
2019 ◽  
Vol 4 (5) ◽  
Author(s):  
Felipe H. Santiago-Tirado
Keyword(s):  
Genetic Analysis ◽  
Fungal Pathogen ◽  
Cell Biology ◽  
Genetic Manipulation ◽  
Chemical Genetics ◽  
Yeast Genetics ◽  
Content Type ◽  
Human Fungal Pathogen ◽  
Link Type ◽  
Fungal Meningitis

ABSTRACT Felipe Santiago-Tirado studies the cell biology of cryptococcal infections. In this mSphere of Influence article, he reflects on how the papers “Systematic Genetic Analysis of Virulence in the Human Fungal Pathogen Cryptococcus neoformans” (https://doi.org/10.1016/j.cell.2008.07.046) and “Unraveling the Biology of a Fungal Meningitis Pathogen Using Chemical Genetics” (https://doi.org/10.1016/j.cell.2014.10.044) by the Noble and Madhani groups influenced his thinking by showcasing the various modern applications of yeast genetics in an organism where genetic manipulation was difficult.

scholarly journals Pleiotropic Roles of the Msi1-Like Protein Msl1 in Cryptococcus neoformans

2012 ◽  
Vol 11 (12) ◽  
pp. 1482-1495 ◽  
Author(s):  
Dong-Hoon Yang ◽  
Shinae Maeng ◽  
Anna K. Strain ◽  
Anna Floyd ◽  
Kirsten Nielsen ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Stress Responses ◽  
Fungal Pathogens ◽  
Independent Manner ◽  
Content Type ◽  
Antifungal Drug Resistance ◽  
Human Fungal Pathogen ◽  
Assembly Factor ◽  
Life Threatening ◽  
Stress Related Genes

ABSTRACT Msi1-like (MSIL) proteins contain WD40 motifs and have a pleiotropic cellular function as negative regulators of the Ras/cyclic AMP (cAMP) pathway and components of chromatin assembly factor 1 (CAF-1), yet they have not been studied in fungal pathogens. Here we identified and characterized an MSIL protein, Msl1, in Cryptococcus neoformans , which causes life-threatening meningoencephalitis in humans. Notably, Msl1 plays pleiotropic roles in C. neoformans in both cAMP-dependent and -independent manners largely independent of Ras. Msl1 negatively controls antioxidant melanin production and sexual differentiation, and this was repressed by the inhibition of the cAMP-signaling pathway. In contrast, Msl1 controls thermotolerance, diverse stress responses, and antifungal drug resistance in a Ras/cAMP-independent manner. Cac2, which is the second CAF-1 component, appears to play both redundant and distinct functions compared to the functions of Msl1. Msl1 is required for the full virulence of C. neoformans . Transcriptome analysis identified a group of Msl1-regulated genes, which include stress-related genes such as HSP12 and HSP78 . In conclusion, this study demonstrates pleiotropic roles of Msl1 in the human fungal pathogen C. neoformans , providing insight into a potential novel antifungal therapeutic target.

scholarly journals Mechanistic Basis of pH-Dependent 5-Flucytosine Resistance inAspergillus fumigatus

2018 ◽  
Vol 62 (6) ◽  
Author(s):  
Fabio Gsaller ◽  
Takanori Furukawa ◽  
Paul D. Carr ◽  
Bharat Rash ◽  
Christoph Jöchl ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Fungal Pathogens ◽  
Regulatory Protein ◽  
Transcriptional Regulators ◽  
Primary Factor ◽  
Ph Sensing ◽  
Content Type ◽  
Ph Dependent ◽  
Mechanistic Basis

ABSTRACTThe antifungal drug 5-flucytosine (5FC), a derivative of the nucleobase cytosine, is licensed for the treatment of fungal diseases; however, it is rarely used as a monotherapeutic to treatAspergillusinfection. Despite being potent against other fungal pathogens, 5FC has limited activity againstAspergillus fumigatuswhen standardin vitroassays are used to determine susceptibility. However, in modifiedin vitroassays where the pH is set to pH 5, the activity of 5FC increases significantly. Here we provide evidence thatfcyB, a gene that encodes a purine-cytosine permease orthologous to known 5FC importers, is downregulated at pH 7 and is the primary factor responsible for the low efficacy of 5FC at pH 7. We also uncover two transcriptional regulators that are responsible for the repression offcyBand, consequently, mediators of 5FC resistance, the CCAAT binding complex (CBC) and the pH regulatory protein PacC. We propose that the activity of 5FC might be enhanced by the perturbation of factors that repressfcyBexpression, such as PacC or other components of the pH-sensing machinery.

Sign in / Sign up

Export Citation Format

Share Document