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FEMS Microbiology Letters Nov 2011Histoplasma capsulatum is the leading cause of endemic mycosis in the world. Analyses of clinical isolates from different endemic regions show important diversity within... (Review)
Review
Histoplasma capsulatum is the leading cause of endemic mycosis in the world. Analyses of clinical isolates from different endemic regions show important diversity within the species. Recent molecular studies of two isolates, the Chemotype I NAm2 strain G217B and the Chemotype II Panamanian strain G186A, reveal significant genetic, structural, and molecular differences between these representative Histoplasma strains. Some of these variations have functional consequences, representing distinct molecular mechanisms that facilitate Histoplasma pathogenesis. The realization of Histoplasma strain diversity highlights the importance of characterizing Histoplasma virulence factors in the context of specific clinical strain isolates.
Topics: Endemic Diseases; Genetic Variation; Histoplasma; Histoplasmosis; Humans; Virulence Factors
PubMed: 22092757
DOI: 10.1111/j.1574-6968.2011.02363.x -
Contributions To Microbiology 2000
Review
Topics: Blastomyces; Cysteine; Ecology; Genes, Fungal; HSP70 Heat-Shock Proteins; Histoplasma; Stearoyl-CoA Desaturase; Virulence
PubMed: 10863674
DOI: 10.1159/000060346 -
Current Opinion in Infectious Diseases Aug 2008To define the most appropriate studies for making a diagnosis of histoplasmosis in immunosuppressed patients. (Review)
Review
PURPOSE OF REVIEW
To define the most appropriate studies for making a diagnosis of histoplasmosis in immunosuppressed patients.
RECENT FINDINGS
As is true of all fungal infections in immunosuppressed patients, heightened awareness of the epidemiology and clinical manifestations of histoplasmosis is essential in making an early diagnosis. Increasingly, Histoplasma antigen detection is used to help establish a diagnosis of histoplasmosis. Most of the reported data are on patients with AIDS, but limited data suggest the usefulness of this assay in other immunosuppressed patients as well. False positive reactions occur with other fungal infections, especially blastomycosis, and patients who have histoplasmosis may have a false positive serum Aspergillus galactomannan assay. The identification of the yeast phase of Histoplasma capsulatum in tissue biopsy samples and, uncommonly, in circulating blood phagocytes is also helpful in establishing a diagnosis quickly. PCR techniques have yet to prove useful for the rapid diagnosis of histoplasmosis, and serology is often negative in immunosuppressed patients. Culture remains definitive and should always be performed to confirm the results of the rapid diagnostic studies.
SUMMARY
Rapid techniques, mostly antigen detection in serum and urine and histopathological identification of Histoplasma capsulatum in tissues, are the most important rapid diagnostic tests for histoplasmosis in immunosuppressed patients.
Topics: Antigens, Fungal; Biopsy; False Positive Reactions; HIV Infections; Histoplasma; Histoplasmosis; Humans; Immunocompromised Host
PubMed: 18594296
DOI: 10.1097/QCO.0b013e328306eb8d -
Current Opinion in Microbiology Aug 2008The dimorphism of Histoplasma reflects a developmental switch in morphology and lifestyle that is necessary for virulence. The dimorphism regulating kinase DRK1 and the... (Review)
Review
The dimorphism of Histoplasma reflects a developmental switch in morphology and lifestyle that is necessary for virulence. The dimorphism regulating kinase DRK1 and the Histoplasma WOR1 homolog RYP1 mediate the thermally induced transition to the pathogenic yeast-phase program. The genes expressed as part of this regulon influence the host-pathogen interaction to favor Histoplasma virulence. While surface localized HSP60 supports yeast attachment to host macrophages, yeast alpha-glucan polysaccharides conceal immunostimulatory cell wall beta-glucans from detection by macrophage receptors. Intramacrophage growth of yeast cells is facilitated by CBP a secreted, protease-resistant calcium-binding protein tailored to function within the phagolysosomal environment. In some Histoplasma strains, YPS3 promotes dissemination of yeast from pulmonary infection sites. The Histoplasma yeast-phase program includes additional cell surface and extracellular molecules that potentially function in further aspects of Histoplasma virulence.
Topics: Gene Expression Regulation, Fungal; Histoplasma; Histoplasmosis; Virulence
PubMed: 18573684
DOI: 10.1016/j.mib.2008.05.010 -
Revista Iberoamericana de Micologia 2014Histoplasma capsulatum is a dimorphic fungal pathogen naturally found in the soil. Inhalation of conidia can result in pulmonary histoplasmosis and, in some cases,... (Review)
Review
Histoplasma capsulatum is a dimorphic fungal pathogen naturally found in the soil. Inhalation of conidia can result in pulmonary histoplasmosis and, in some cases, causes severe disseminated disease and death. This fungus is an ascomycete that has an anamorphic or asexual stage and a teleomorphic or sexual stage, known as Ajellomyces capsulatus, which results from (+) and (-) mating types. Sexual reproduction is regulated by a specialized genomic region known as the mating-type (MAT1) locus. The mating process in this heterothallic species is represented by isolates that contain only one of the two different MAT1 locus idiomorphs (MAT1-1 or MAT1-2) that have unrelated sequences encoding different transcription factors. In medically important dimorphic pathogens and in most ascomycete molds, one MAT locus idiomorph encodes a high-mobility-group (HMG) box-domain transcription factor, and the other idiomorph encodes an alpha-box domain transcription factor. There is scarce molecular information about H. capsulatum mating type although recombinant population structures have been reported that could occur in nature and this process has been documented in distinct models such as parasites and other fungi. In this review, we shall focus on published studies on H. capsulatum sexuality, and outline the distribution of the two H. capsulatum mating types in Latin America. This manuscript is part of the series of works presented at the "V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi" (Oaxaca, Mexico, 2012).
Topics: Brazil; Evolution, Molecular; Fungal Proteins; Genes, Mating Type, Fungal; Genetic Variation; HMGB Proteins; Histoplasma; Histoplasmosis; Humans; Mexico; Reproduction; Transcription Factors
PubMed: 24262630
DOI: 10.1016/j.riam.2013.10.002 -
Journal of Microbiology, Immunology,... Dec 2020
Topics: Female; Histoplasma; Histoplasmosis; Humans; Middle Aged; Reinfection; Taiwan
PubMed: 32094075
DOI: 10.1016/j.jmii.2020.02.003 -
Proceedings of the National Academy of... Aug 2000The success of Histoplasma capsulatum as an intracellular pathogen depends completely on successful conversion of the saprophytic mycelial (mold) form of this fungus to... (Review)
Review
The success of Histoplasma capsulatum as an intracellular pathogen depends completely on successful conversion of the saprophytic mycelial (mold) form of this fungus to a parasitic yeast form. It is therefore not surprising that yeast phase-specific genes and gene products are proving to be important for survival and proliferation of H. capsulatum within macrophages. In this study, we have focused on the role and regulation of two yeast-specific characteristics: alpha-(1,3)-glucan, a cell wall polysaccharide modulated by cell-density (quorum) sensing, and a secreted calcium-binding protein (CBP) that is essential for pathogenicity.
Topics: Calcium-Binding Proteins; Cell Wall; Gene Expression Regulation; Glucans; Histoplasma; Phenotype; Virulence
PubMed: 10922037
DOI: 10.1073/pnas.97.16.8794 -
Current Topics in Medicinal Chemistry 2018The thermally-dimorphic systemic fungal group includes several important human pathogens: Blastomyces dermatitides, Coccidioides immitis and C. posadasii, Histoplasma... (Review)
Review
The thermally-dimorphic systemic fungal group includes several important human pathogens: Blastomyces dermatitides, Coccidioides immitis and C. posadasii, Histoplasma capsulatum, Paracoccidioides brasiliensis, P. lutzii, and Talaromyces (Penicillium) marneffei. They usually are geographically restricted and have natural habitats in soil or in plants, and when fungal propagules invade mammalian host by inhalation, they initiate an inflammatory reaction that can result in self-resolution of the infection or cause an acute or chronic disease. In the setting of the AIDS pandemic and the developments in modern medicine, such as immunosuppressive therapy in cancer surgery patients and in transplantation and autoimmune diseases, the incidence of endemic mycoses has progressively increased. Another important factor of the increased incidence of systemic mycoses in certain regions is the progressive devastation of tropical and subtropical forests. In this review, we focus on two of the most important systemic mycoses: paracoccidioidomycosis and histoplasmosis, and their major characteristics in epidemiology, clinical aspects and laboratorial diagnosis.
Topics: Antifungal Agents; Histoplasma; Histoplasmosis; Humans; Microbial Sensitivity Tests; Paracoccidioides; Paracoccidioidomycosis
PubMed: 30277157
DOI: 10.2174/1568026618666181002112231 -
European Journal of Clinical... Jan 2016Histoplasmosis is a systemic mycosis caused by Histoplasma capsulatum, a dimorphic fungal pathogen that can infect both humans and animals. This disease has worldwide... (Review)
Review
Histoplasmosis is a systemic mycosis caused by Histoplasma capsulatum, a dimorphic fungal pathogen that can infect both humans and animals. This disease has worldwide distribution and affects mainly immunocompromised individuals. In the environment, H. capsulatum grows as mold but undergoes a morphologic transition to the yeast morphotype under special conditions. Molecular techniques are important tools to conduct epidemiologic investigations for fungal detection, identification of infection sources, and determination of different fungal genotypes associated to a particular disease symptom. In this study, we performed a systematic review in the PubMed database to improve the understanding about the molecular epidemiology of histoplasmosis. This search was restricted to English and Spanish articles. We included a combination of specific keywords: molecular typing [OR] genetic diversity [OR] polymorphism [AND] H. capsulatum; molecular epidemiology [AND] histoplasmosis; and molecular epidemiology [AND] Histoplasma. In addition, we used the specific terms: histoplasmosis [AND] outbreaks. Non-English or non-Spanish articles, dead links, and duplicate results were excluded from the review. The results reached show that the main methods used for molecular typing of H. capsulatum were: restriction fragment length polymorphism, random amplified polymorphic DNA, microsatellites polymorphism, sequencing of internal transcribed spacers region, and multilocus sequence typing. Different genetic profiles were identified among H. capsulatum isolates, which can be grouped according to their source, geographical origin, and clinical manifestations.
Topics: Animals; Genetic Markers; Genotype; Histoplasma; Histoplasmosis; Humans; Molecular Epidemiology; Molecular Typing; Mycological Typing Techniques
PubMed: 26589702
DOI: 10.1007/s10096-015-2508-5 -
Revista Argentina de Microbiologia 2006Dimorphism and pathogenesis of Hisdistoplasma capsulatum is a dimorphic fungal pathogen with worldwide significance, which causes a broad spectrum of disease. In the... (Review)
Review
Dimorphism and pathogenesis of Hisdistoplasma capsulatum is a dimorphic fungal pathogen with worldwide significance, which causes a broad spectrum of disease. In the saprophytic stage, it lives as a mycelial form consisting of hyphae bearing both macro and microconidia. Infection with H. capsulatum occurs by inhalation of microconidia (1-4 x 2-6 microm) or small mycelia fragments (5-8 microm) in the terminal bronchioles and alveoli of the lung. Inhaled conidia then convert into the yeast form that is responsible for the pathogenesis of histoplasmosis. As a soil fungus with no known requirements for interacting with a mammalian host as a necessary stage of its life cycle, the number of its strategies for successful pathogenesis is particularly remarkable. They include dimorphic mould-yeast transition, entry into host macrophages, subcellular localization, intracellular survival and proliferation during clinically unapparent infection with capacity for reactivation. H. capsulatum became the subject of increasing studies concurrently with the rising prevalence of human immunodeficiency. This paper presents an overall view of advances in the investigation of H. capsulatum dimorphic transition and pathogenesis.
Topics: Bronchi; Calcium; Fungal Proteins; Gene Expression Regulation, Fungal; Histoplasma; Histoplasmosis; Humans; Hydrogen-Ion Concentration; Iron; Lung; Macrophages; Mycelium; Nitric Oxide; Phenotype; Reactive Oxygen Species; Reproduction, Asexual; Vacuoles; Virulence
PubMed: 17370580
DOI: No ID Found