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Arturo Casadevall - One of the best experts on this subject based on the ideXlab platform.

  • variation in cell surface hydrophobicity among Cryptococcus neoformans strains influences interactions with amoebas
    mSphere, 2020
    Co-Authors: Raghav Vij, Quigly Dragotakes, Conor J Crawford, Carina Danchik, Arturo Casadevall
    Abstract:

    Cryptococcus neoformans and Cryptococcus gattii are pathogenic fungi that cause significant morbidity and mortality. Cell surface hydrophobicity (CSH) is a biophysical parameter that influences the adhesion of fungal cells or spores to biotic and abiotic surfaces. C. neoformans is encased by polysaccharide capsule that is highly hydrophilic and is a critical determinant of virulence. In this study, we report large differences in the CSH of some C. neoformans and C. gattii strains. The capsular polysaccharides of C. neoformans strains differ in repeating motifs and therefore vary in the number of hydroxyl groups, which, along with higher-order structure of the capsule, may contribute to the variation in hydrophobicity that we observed. We found that cell wall composition, in the context of chitin-chitosan content, does not influence CSH. For C. neoformans, CSH correlated with phagocytosis by natural soil predator Acanthamoeba castellanii Furthermore, capsular binding of the protective antibody (18B7), but not the nonprotective antibody (13F1), altered the CSH of C. neoformans strains. Variability in CSH could be an important characteristic in comparing the biological properties of cryptococcal strains.IMPORTANCE The interaction of a microbial cell with its environment is influenced by the biophysical properties of a cell. The affinity of the cell surface for water, defined by the cell surface hydrophobicity (CSH), is a biophysical parameter that varies among different strains of Cryptococcus neoformans The CSH influences the phagocytosis of the yeast by its natural predator in the soil, the amoeba. Studying variation in biophysical properties like CSH gives us insight into the dynamic host-predator interaction and host-pathogen interaction in a damage-response framework.

  • variation in cell surface hydrophobicity among Cryptococcus neoformans strains influences interactions with amoeba
    bioRxiv, 2019
    Co-Authors: Raghav Vij, Conor J Crawford, Arturo Casadevall
    Abstract:

    ABSTRACT Cryptococcus neoformans and Cryptococcus gattii are pathogenic fungi that cause significant morbidity and mortality. Cell surface hydrophobicity (CSH) is a biophysical parameter that influences the adhesion of fungal cells or spores to biotic and abiotic surfaces. C. neoformans is encased by polysaccharide capsule that is highly hydrophilic and is a critical determinant of virulence. In this study, we report large differences in the CSH of some C. neoformans and C. gattii strains. The capsular polysaccharides of C. neoformans strains differ in repeating motifs, and therefore vary in the number of hydroxyl groups, which along with higher-order structure of the capsule, may contribute to the variation in hydrophobicity that we observed. For C. neoformans, CSH correlated with phagocytosis by natural soil predator Acanthamoeba castellani. Furthermore, capsular binding of the protective antibody (18B7), but not the non-protective (13F1) antibody altered the CSH of C. neoformans strains. Variability in CSH could be an important characteristic when comparing the biological properties of cryptococcal strains. IMPORTANCE The interaction of a microbial cell with its environment is influenced by the biophysical properties of a cell. The affinity of the cell surface for water, defined by the Cell Surface Hydrophobicity (CSH), is a biophysical parameter that varied amongst different strains of Cryptococcus neoformans. The CSH influenced the phagocytosis of the yeast by its natural predator in the soil, Amoeba. Studying variation in biophysical properties like CSH gives us insight into the dynamic host-predator interaction, and host-pathogen interaction in a damage-response framework.

  • The capsule of Cryptococcus neoformans.
    Virulence, 2018
    Co-Authors: Arturo Casadevall, Carolina Coelho, Radames J. B. Cordero, Quigly Dragotakes, Eric H. Jung, Raghav Vij, Maggie P. Wear
    Abstract:

    The capsule of Cryptococcus neoformans is its dominant virulence factor and plays a key role in the biology of this fungus. In this essay, we focus on the capsule as a cellular structure and note the limitations inherent in the current methodologies available for its study. Given that no single method can provide the structure of the capsule, our notions of what is the cryptococcal capsule must be arrived at by synthesizing information gathered from very different methodological approaches including microscopy, polysaccharide chemistry and physical chemistry of macromolecules. The emerging picture is one of a carefully regulated dynamic structure that is constantly rearranged as a response to environmental stimulation and cellular replication. In the environment, the capsule protects the fungus against desiccation and phagocytic predators. In animal hosts the capsule functions in both offensive and defensive modes, such that it interferes with immune responses while providing the fungal cell with a defensive shield that is both antiphagocytic and capable of absorbing microbicidal oxidative bursts from phagocytic cells. Finally, we delineate a set of unsolved problems in the cryptococcal capsule field that could provide fertile ground for future investigations.

  • Opsonin-free, real-time imaging of Cryptococcus neoformans capsule during budding
    2018
    Co-Authors: Hugo Costa Paes, Arturo Casadevall, Stefânia De Oliveira Frazão, Camila Pereira Rosa, Patrícia Albuquerque, Maria Sueli Soares Felipe, André Moraes Nicola
    Abstract:

    Opsonin-free, real-time imaging of Cryptococcus neoformans capsule during buddin

  • the intracellular life of Cryptococcus neoformans
    Annual Review of Pathology-mechanisms of Disease, 2014
    Co-Authors: Carolina Coelho, Anamelia Lorenzetti Bocca, Arturo Casadevall
    Abstract:

    Cryptococcus neoformans is a fungal pathogen with worldwide distribution. Serological studies of human populations show a high prevalence of human infection, which rarely progresses to disease in immunocompetent hosts. However, decreased host immunity places individuals at high risk for cryptococcal disease. The disease can result from acute infection or reactivation of latent infection, in which yeasts within granulomas and host macrophages emerge to cause disease. In this review, we summarize what is known about the cellular recognition, ingestion, and killing of C. neoformans and discuss the unique and remarkable features of its intracellular life, including the proposed mechanisms for fungal persistence and killing in phagocytic cells.

Joseph Heitman - One of the best experts on this subject based on the ideXlab platform.

  • the biology of the Cryptococcus neoformans species complex
    Annual Review of Microbiology, 2006
    Co-Authors: Xiaorong Lin, Joseph Heitman
    Abstract:

    Cryptococcus neoformans is a major cause of fungal meningoencephalitis in immunocompromised patients. Despite recent advances in the genetics and molecular biology of C. neoformans, and improved techniques for molecular epidemiology, aspects of the ecology, population structure, and mode of reproduction of this environmental pathogen remain to be established. Application of recent insights into the life cycle of C. neoformans and its different ways of engaging in sexual reproduction under laboratory conditions has just begun to affect research on the ecology and epidemiology of this human pathogenic fungus. The melding of these disparate disciplines should yield rich dividends in our understanding of the evolution of microbial pathogens, providing insights relevant to diagnosis, treatment, and prevention.

  • deciphering the model pathogenic fungus Cryptococcus neoformans
    Nature Reviews Microbiology, 2005
    Co-Authors: Alexander Idnurm, James A. Fraser, Yong Sun Bahn, Kirsten Nielsen, Xiaorong Lin, Joseph Heitman
    Abstract:

    Cryptococcus neoformans is a basidiomycete fungal pathogen of humans that has diverged considerably from other model fungi such as Neurospora crassa, Aspergillus nidulans, Saccharomyces cerevisiae and the common human fungal pathogen Candida albicans. The recent completion of the genome sequences of two related C. neoformans strains and the ongoing genome sequencing of three other divergent Cryptococcus strains with different virulence phenotypes and environmental distributions should improve our understanding of this important pathogen. We discuss the biology of C. neoformans in light of this genomic data, with a special emphasis on the role that evolution and sexual reproduction have in the complex relationships of the fungus with the environment and the host.

  • specialization of the hog pathway and its impact on differentiation and virulence of Cryptococcus neoformans
    Molecular Biology of the Cell, 2005
    Co-Authors: Yong Sun Bahn, Kaihei Kojima, Gary M Cox, Joseph Heitman
    Abstract:

    The human pathogenic fungus Cryptococcus neoformans has diverged from a common ancestor into three biologically distinct varieties or sibling species over the past 10–40 million years. During evolu...

  • Chromosomal translocation and segmental duplication in Cryptococcus neoformans.
    Eukaryotic cell, 2005
    Co-Authors: James A. Fraser, Johnny C. Huang, Read Pukkila-worley, J. Andrew Alspaugh, Thomas G. Mitchell, Joseph Heitman
    Abstract:

    Large chromosomal events such as translocations and segmental duplications enable rapid adaptation to new environments. Here we marshal genomic, genetic, meiotic mapping, and physical evidence to demonstrate that a chromosomal translocation and segmental duplication occurred during construction of a congenic strain pair in the fungal human pathogen Cryptococcus neoformans. Two chromosomes underwent telomere-telomere fusion, generating a dicentric chromosome that broke to produce a chromosomal translocation, forming two novel chromosomes sharing a large segmental duplication. The duplication spans 62,872 identical nucleotides and generated a second copy of 22 predicted genes, and we hypothesize that this event may have occurred during meiosis. Gene disruption studies of one embedded gene (SMG1) corroborate that this region is duplicated in an otherwise haploid genome. These findings resolve a genome project assembly anomaly and illustrate an example of rapid genome evolution in a fungal genome rich in repetitive elements.

  • gene disruption by biolistic transformation in serotype d strains of Cryptococcus neoformans
    Fungal Genetics and Biology, 2000
    Co-Authors: Robert C Davidson, Ja Alspaugh, M C Cruz, R A L Sia, B Allen, Joseph Heitman
    Abstract:

    Gene disruption by biolistic transformation in serotype D strains of Cryptococcus neoformans. Fungal Genetics and Biology 29, 38-48. Cryptococcus neoformans is an opportunistic fungal pathogen with a defined sexual cycle and well-developed genetic and molecular approaches. Two different transformation systems have been developed, and a number of genes have been disrupted by homologous recombination. However, the frequency of homologous recombination achieved by these approaches has differed dramatically between strains of the A and D serotypes. Transformation by electroporation in serotype D strains results in homologous recombination at frequencies of 1/1000 to 1/100,000, whereas transformation by the biolistic method has resulted in gene disruption at frequencies between 2 and 50% in serotype A strains. We find that gene disruption by homologous recombination can be achieved in the congenic serotype D strain series by biolistic transformation with frequencies of approximately 1 to 4%. By this approach, we have readily disrupted the genes encoding a MAPK homolog (CPK1), the calcineurin A catalytic subunit (CNA1), and a G protein alpha subunit (GPA1). By physical and genetic methods, we show that these mutations result from targeted recombination events without ectopic integrations. Because genetic approaches can be applied in the congenic serotype D strains, our observations represent a significant advance in molecular approaches to understand the physiology and virulence of this important human pathogen.

Ferry Hagen - One of the best experts on this subject based on the ideXlab platform.

  • recognition of seven species in the Cryptococcus gattii Cryptococcus neoformans species complex
    Fungal Genetics and Biology, 2015
    Co-Authors: Ferry Hagen, I Polacheck, Bart Theelen, Kantarawee Khayhan, Anna Kolecka, Edward Sionov, Rama Falk, Sittiporn Parnmen
    Abstract:

    Phylogenetic analysis of 11 genetic loci and results from many genotyping studies revealed significant genetic diversity with the pathogenic Cryptococcus gattii/Cryptococcus neoformans species complex. Genealogical concordance, coalescence-based, and species tree approaches supported the presence of distinct and concordant lineages within the complex. Consequently, we propose to recognize the current C. neoformans var. grubii and C. neoformans var. neoformans as separate species, and five species within C. gattii. The type strain of C. neoformans CBS132 represents a serotype AD hybrid and is replaced. The newly delimited species differ in aspects of pathogenicity, prevalence for patient groups, as well as biochemical and physiological aspects, such as susceptibility to antifungals. MALDI-TOF mass spectrometry readily distinguishes the newly recognized species.

  • consensus multi locus sequence typing scheme for Cryptococcus neoformans and Cryptococcus gattii
    Medical Mycology, 2009
    Co-Authors: Wieland Meyer, Ferry Hagen, Teun Boekhout, Massimo Cogliati, Mara R Diaz, David M Aanensen, M C Esposto, Matthew C Fisher, Felix Gilgado, Sirada Kaocharoen
    Abstract:

    This communication describes the consensus multi-locus typing scheme established by the Cryptococcal Working Group I (Genotyping of Cryptococcus neoformans and C. gattii) of the International Society for Human and Animal Mycology (ISHAM) using seven unlinked genetic loci for global strain genotyping. These genetic loci include the housekeeping genes CAP59,GPD1, LAC1, PLB1, SOD1, URA5 and the IGS1 region. Allele and sequence type information are accessible at http://www.mlst.net/ .

  • aids patient death caused by novel Cryptococcus neoformans c gattii hybrid
    Emerging Infectious Diseases, 2008
    Co-Authors: Marjan Bovers, Ferry Hagen, Eiko E Kuramae, Frana Oise Dromer, Hans L Hoogveld, Guy Stgermain, Teun Boekhout
    Abstract:

    Interspecies hybrids of Cryptococcus neoformans and C. gattii have only recently been reported. We describe a novel C. neoformans × C. gattii hybrid strain (serotype AB) that was previously described as C. gattii and that caused a lethal infection in an AIDS patient from Canada.

  • diversity of the Cryptococcus neoformans Cryptococcus gattii species complex
    Revista Iberoamericana De Micologia, 2008
    Co-Authors: Marjan Bovers, Ferry Hagen, Teun Boekhout
    Abstract:

    Resumen Mas de 110 anos de estudio sobre el complejo de especies Cryptococcus neoformans y Cryptococcus gattii han dado lugar a un gran acumulo de conocimiento basico, aplicado y clinico. En este articulo se describen los avances recientes en la comprension de su diversidad, haciendo enfasis en la complejidad intraespecifica que presenta y que llega a englobar especies, microespecies, hibridos, serotipos y genotipos. Cada uno de estos grupos puede jugar un papel diferente en la enfermedad. Se presenta tambien una vision global de los nombres obsoletos y actuales de estos taxones.

  • Diversity of the Cryptococcus neoformans-Cryptococcus gattii species complex.
    Revista iberoamericana de micologia, 2008
    Co-Authors: Marjan Bovers, Ferry Hagen, Teun Boekhout
    Abstract:

    More than 110 years of study of the Cryptococcus neoformans and Cryptococcus gattii species complex has resulted in an enormous accumulation of fundamental and applied biological and clinical knowledge. Recent developments in our understanding of the diversity within the species complex are presented, emphasizing the intraspecific complexity, which includes species, microspecies, hybrids, serotypes and genotypes. Each of these may have different roles in disease. An overview of obsolete and current names is presented.

Teun Boekhout - One of the best experts on this subject based on the ideXlab platform.

  • consensus multi locus sequence typing scheme for Cryptococcus neoformans and Cryptococcus gattii
    Medical Mycology, 2009
    Co-Authors: Wieland Meyer, Ferry Hagen, Teun Boekhout, Massimo Cogliati, Mara R Diaz, David M Aanensen, M C Esposto, Matthew C Fisher, Felix Gilgado, Sirada Kaocharoen
    Abstract:

    This communication describes the consensus multi-locus typing scheme established by the Cryptococcal Working Group I (Genotyping of Cryptococcus neoformans and C. gattii) of the International Society for Human and Animal Mycology (ISHAM) using seven unlinked genetic loci for global strain genotyping. These genetic loci include the housekeeping genes CAP59,GPD1, LAC1, PLB1, SOD1, URA5 and the IGS1 region. Allele and sequence type information are accessible at http://www.mlst.net/ .

  • aids patient death caused by novel Cryptococcus neoformans c gattii hybrid
    Emerging Infectious Diseases, 2008
    Co-Authors: Marjan Bovers, Ferry Hagen, Eiko E Kuramae, Frana Oise Dromer, Hans L Hoogveld, Guy Stgermain, Teun Boekhout
    Abstract:

    Interspecies hybrids of Cryptococcus neoformans and C. gattii have only recently been reported. We describe a novel C. neoformans × C. gattii hybrid strain (serotype AB) that was previously described as C. gattii and that caused a lethal infection in an AIDS patient from Canada.

  • diversity of the Cryptococcus neoformans Cryptococcus gattii species complex
    Revista Iberoamericana De Micologia, 2008
    Co-Authors: Marjan Bovers, Ferry Hagen, Teun Boekhout
    Abstract:

    Resumen Mas de 110 anos de estudio sobre el complejo de especies Cryptococcus neoformans y Cryptococcus gattii han dado lugar a un gran acumulo de conocimiento basico, aplicado y clinico. En este articulo se describen los avances recientes en la comprension de su diversidad, haciendo enfasis en la complejidad intraespecifica que presenta y que llega a englobar especies, microespecies, hibridos, serotipos y genotipos. Cada uno de estos grupos puede jugar un papel diferente en la enfermedad. Se presenta tambien una vision global de los nombres obsoletos y actuales de estos taxones.

  • Diversity of the Cryptococcus neoformans-Cryptococcus gattii species complex.
    Revista iberoamericana de micologia, 2008
    Co-Authors: Marjan Bovers, Ferry Hagen, Teun Boekhout
    Abstract:

    More than 110 years of study of the Cryptococcus neoformans and Cryptococcus gattii species complex has resulted in an enormous accumulation of fundamental and applied biological and clinical knowledge. Recent developments in our understanding of the diversity within the species complex are presented, emphasizing the intraspecific complexity, which includes species, microspecies, hybrids, serotypes and genotypes. Each of these may have different roles in disease. An overview of obsolete and current names is presented.

  • hybrid genotypes in the pathogenic yeast Cryptococcus neoformans
    Microbiology, 2001
    Co-Authors: Teun Boekhout, Mara R Diaz, Francoise Dromer, Bart Theelen, Jack W Fell, Wim C J Hop, Edwin C A Abeln, Wieland Meyer
    Abstract:

    Amplified fragment length polymorphism (AFLP) genotyping of isolates of the pathogenic fungus Cryptococcus neoformans suggested a considerable genetic divergence between the varieties C. neoformans var. neoformans and C. neoformans var. grubii on the one hand versus C. neoformans var. gattii on the other. This divergence is supported by additional phenotypic, biochemical, clinical and molecular differences. Therefore, the authors propose the existence of two species, C. neoformans (Sanfelice) Vuillemin and C. bacillisporus Kwon-Chung, which differ in geographical distribution, serotypes and ecological origin. Within each species three AFLP genotypes occur, which differ in geographical distribution and serotypes. Differences in ecological origin (AIDS patients, non-AIDS patients, animals or the environment) were found to be statistically not significant. In C. neoformans as well as in C. bacillisporus one of the genotypes represented a hybrid. The occurrence of hybridization has consequences for the reproductive biology of the species, as new genotypes with altered virulence or susceptibility to antifungal drugs may arise through the exchange of genetic material.

Marjan Bovers - One of the best experts on this subject based on the ideXlab platform.