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Sepúlveda VE, Rader JA, Li JJ, Goldman WE, Matute DR. Phenotypic characterization of cryptic species in the fungal pathogen Histoplasma. mSphere 2024:e0000924. [PMID: 38771035 DOI: 10.1128/msphere.00009-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 04/11/2024] [Indexed: 05/22/2024] Open
Abstract
Histoplasmosis is an endemic mycosis that often presents as a respiratory infection in immunocompromised patients. Hundreds of thousands of new infections are reported annually around the world. The etiological agent of the disease, Histoplasma, is a dimorphic fungus commonly found in the soil where it grows as mycelia. Humans can become infected by Histoplasma through inhalation of its spores (conidia) or mycelial particles. The fungi transition into the yeast phase in the lungs at 37°C. Once in the lungs, yeast cells reside and proliferate inside alveolar macrophages. Genomic work has revealed that Histoplasma is composed of at least five cryptic phylogenetic species that differ genetically. Three of those lineages have received new names. Here, we evaluated multiple phenotypic characteristics (colony morphology, secreted proteolytic activity, yeast size, and growth rate) of strains from five of the phylogenetic species of Histoplasma to identify phenotypic traits that differentiate between these species: Histoplasma capsulatum sensu stricto, Histoplasma ohiense, Histoplasma mississippiense, Histoplasma suramericanum, and an African lineage. We report diagnostic traits for three species. The other two species can be identified by a combination of traits. Our results suggest that (i) there are significant phenotypic differences among the cryptic species of Histoplasma and (ii) those differences can be used to positively distinguish those species in a clinical setting and for further study of the evolution of this fungal pathogen.IMPORTANCEIdentifying species boundaries is a critical component of evolutionary biology. Genome sequencing and the use of molecular markers have advanced our understanding of the evolutionary history of fungal pathogens, including Histoplasma, and have allowed for the identification of new species. This is especially important in organisms where morphological characteristics have not been detected. In this study, we revised the taxonomic status of the four named species of the genus Histoplasma, H. capsulatum sensu stricto (ss), H. ohiense, H. mississippiense, and H. suramericanum, and propose the use of species-specific phenotypic traits to aid their identification when genome sequencing is not available. These results have implications not only for evolutionary study of Histoplasma but also for clinicians, as the Histoplasma species could determine the outcome of disease and treatment needed.
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Affiliation(s)
- Victoria E Sepúlveda
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jonathan A Rader
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jingbaoyi Janet Li
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - William E Goldman
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Daniel R Matute
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Ameni G, Messele Kebede A, Zewude A, Girma Abdulla M, Asfaw R, Gobena MM, Kyalo M, Stomeo F, Gumi B, Sori T. Equine Histoplasmosis in Ethiopia: Phylogenetic Analysis by Sequencing of the Internal Transcribed Spacer Region of rRNA Genes. Front Cell Infect Microbiol 2022; 12:789157. [PMID: 35909976 PMCID: PMC9330904 DOI: 10.3389/fcimb.2022.789157] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 03/23/2022] [Indexed: 11/22/2022] Open
Abstract
Equine histoplasmosis commonly known as epizootic lymphangitis (EL) is a neglected granulomatous disease of equine that is endemic to Ethiopia. It is caused by Histoplasma capsulatum variety farciminosum, a dimorphic fungus that is closely related to H. capsulatum variety capsulatum. The objective of this study was to undertake a phylogenetic analysis of H. capsulatum isolated from EL cases of horses in central Ethiopia and evaluate their relationship with H. capsulatum isolates in other countries and/or clades using the internal transcribed spacer (ITS) region of rRNA genes. Clinical and mycological examinations, DNA extraction, polymerase chain reaction (PCR), Sanger sequencing, and phylogenetic analysis were used for undertaking this study. Additionally, sequence data of Histoplasma isolates were retrieved from GenBank and included for a comprehensive phylogenetic analysis. A total of 390 horses were screened for EL and 97 were positive clinically while H. capsulatum was isolated from 60 horses and further confirmed with PCR, of which 54 were sequenced. BLAST analysis of these 54 isolates identified 29 H. capsulatum isolates and 14 isolates from other fungal genera while the remaining 11 samples were deemed insufficient for further downstream analysis. The phylogenetic analysis identified five clades, namely, African, Eurasian, North American 1 and 2, and Latin American A and B. The Ethiopian isolates were closely aggregated with isolates of the Latin American A and Eurasian clades, whereas being distantly related to isolates from North American 1 and 2 clades as well as Latin American B clade. This study highlights the possible origins and transmission routes of Histoplasmosis in Ethiopia.
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Affiliation(s)
- Gobena Ameni
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
- Department of Veterinary Medicine, College of Food and Agriculture, United Arab Emirates University, Al Ain, United Arab Emirates
- *Correspondence: Gobena Ameni, ;
| | | | - Aboma Zewude
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
- Department of Veterinary Medicine, College of Food and Agriculture, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Musse Girma Abdulla
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Rahel Asfaw
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Mesfin Mamo Gobena
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
- College of Veterinary Medicine and Agriculture, Addis Ababa University, Debre Zeit, Ethiopia
| | - Martina Kyalo
- Capacity Building, Biosciences for Eastern and Central Africa-International Livestock Research Institute (BecA-ILRI) Hub, Nairobi, Kenya
| | - Francesca Stomeo
- Capacity Building, Biosciences for Eastern and Central Africa-International Livestock Research Institute (BecA-ILRI) Hub, Nairobi, Kenya
| | - Balako Gumi
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Teshale Sori
- College of Veterinary Medicine and Agriculture, Addis Ababa University, Debre Zeit, Ethiopia
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Jofre GI, Singh A, Mavengere H, Sundar G, D'Agostino E, Chowdhary A, Matute DR. An Indian lineage of Histoplasma with strong signatures of differentiation and selection. Fungal Genet Biol 2022; 158:103654. [PMID: 34942368 DOI: 10.1016/j.fgb.2021.103654] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 12/06/2021] [Accepted: 12/11/2021] [Indexed: 01/04/2023]
Abstract
Histoplasma, a genus of dimorphic fungi, is the etiological agent of histoplasmosis, a pulmonary disease widespread across the globe. Whole genome sequencing has revealed that the genus harbors a previously unrecognized diversity of cryptic species. To date, studies have focused on Histoplasma isolates collected in the Americas with little knowledge of the genomic variation from other localities. In this report, we report the existence of a well-differentiated lineage of Histoplasma occurring in the Indian subcontinent. The group is differentiated enough to satisfy the requirements of a phylogenetic species, as it shows extensive genetic differentiation along the whole genome and has little evidence of gene exchange with other Histoplasma species. Next, we leverage this genetic differentiation to identify genetic changes that are unique to this group and that have putatively evolved through rapid positive selection. We found that none of the previously known virulence factors have evolved rapidly in the Indian lineage but find evidence of strong signatures of selection on other alleles potentially involved in clinically-important phenotypes. Our work serves as an example of the importance of correctly identifying species boundaries to understand the extent of selection in the evolution of pathogenic lineages. IMPORTANCE: Whole genome sequencing has revolutionized our understanding of microbial diversity, including human pathogens. In the case of fungal pathogens, a limiting factor in understanding the extent of their genetic diversity has been the lack of systematic sampling. In this piece, we show the results of a collection in the Indian subcontinent of the pathogenic fungus Histoplasma, the causal agent of a systemic mycosis. We find that Indian samples of Histoplasma form a distinct clade which is highly differentiated from other Histoplasma species. We also show that the genome of this lineage shows unique signals of natural selection. This work exemplifies how the combination of a robust sampling along with population genetics, and phylogenetics can reveal the precise genetic changes that differentiate lineages of fungal pathogens.
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Affiliation(s)
- Gaston I Jofre
- Department of Biology, University of North Carolina, Chapel Hill, NC, United States
| | - Ashutosh Singh
- National Reference Laboratory for Antimicrobial Resistance in Fungal Pathogens, Medical Mycology Unit, Department of Microbiology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | - Heidi Mavengere
- Department of Biology, University of North Carolina, Chapel Hill, NC, United States
| | - Gandhi Sundar
- National Reference Laboratory for Antimicrobial Resistance in Fungal Pathogens, Medical Mycology Unit, Department of Microbiology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | - Emmanuel D'Agostino
- Department of Biology, University of North Carolina, Chapel Hill, NC, United States
| | - Anuradha Chowdhary
- National Reference Laboratory for Antimicrobial Resistance in Fungal Pathogens, Medical Mycology Unit, Department of Microbiology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | - Daniel R Matute
- Department of Biology, University of North Carolina, Chapel Hill, NC, United States.
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Vite-Garín T, Estrada-Bárcenas DA, Gernandt DS, Reyes-Montes MDR, Sahaza JH, Canteros CE, Ramírez JA, Rodríguez-Arellanes G, Serra-Damasceno L, Zancopé-Oliveira RM, Taylor JW, Taylor ML. Histoplasma capsulatum Isolated from Tadarida brasiliensis Bats Captured in Mexico Form a Sister Group to North American Class 2 Clade. J Fungi (Basel) 2021; 7:529. [PMID: 34209122 PMCID: PMC8305335 DOI: 10.3390/jof7070529] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 06/03/2021] [Accepted: 06/11/2021] [Indexed: 01/11/2023] Open
Abstract
Histoplasma capsulatum is a dimorphic fungus associated with respiratory and systemic infections in mammalian hosts that have inhaled infective mycelial propagules. A phylogenetic reconstruction of this pathogen, using partial sequences of arf, H-anti, ole1, and tub1 protein-coding genes, proposed that H. capsulatum has at least 11 phylogenetic species, highlighting a clade (BAC1) comprising three H. capsulatum isolates from infected bats captured in Mexico. Here, relationships for each individual locus and the concatenated coding regions of these genes were inferred using parsimony, maximum likelihood, and Bayesian inference methods. Coalescent-based analyses, a concatenated sequence-types (CSTs) network, and nucleotide diversities were also evaluated. The results suggest that six H. capsulatum isolates from the migratory bat Tadarida brasiliensis together with one isolate from a Mormoops megalophylla bat support a NAm 3 clade, replacing the formerly reported BAC1 clade. In addition, three H. capsulatum isolates from T. brasiliensis were classified as lineages. The concatenated sequence analyses and the CSTs network validate these findings, suggesting that NAm 3 is related to the North American class 2 clade and that both clades could share a recent common ancestor. Our results provide original information on the geographic distribution, genetic diversity, and host specificity of H. capsulatum.
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Affiliation(s)
- Tania Vite-Garín
- Unidad de Micología, Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México 04510, Mexico; (T.V.-G.); (M.d.R.R.-M.); (J.H.S.); (J.A.R.); (G.R.-A.)
| | - Daniel A. Estrada-Bárcenas
- Colección Nacional de Cepas Microbianas y Cultivos Celulares, Centro de Investigación y de Estudios Avanzados, Instituto Politécnico Nacional (CINVESTAV, IPN), Ciudad de México 07360, Mexico;
| | - David S. Gernandt
- Departamento de Botánica, Instituto de Biología, Universidad Nacional Autónoma de México (UNAM), Ciudad de México 04510, Mexico;
| | - María del Rocío Reyes-Montes
- Unidad de Micología, Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México 04510, Mexico; (T.V.-G.); (M.d.R.R.-M.); (J.H.S.); (J.A.R.); (G.R.-A.)
| | - Jorge H. Sahaza
- Unidad de Micología, Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México 04510, Mexico; (T.V.-G.); (M.d.R.R.-M.); (J.H.S.); (J.A.R.); (G.R.-A.)
| | - Cristina E. Canteros
- Departamento de Micología, Instituto Nacional de Enfermedades Infecciosas (INEI), Administración Nacional de Laboratorios e Institutos de Salud (ANLIS) “Dr. Carlos G. Malbrán”, Buenos Aires 1281, Argentina;
| | - José A. Ramírez
- Unidad de Micología, Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México 04510, Mexico; (T.V.-G.); (M.d.R.R.-M.); (J.H.S.); (J.A.R.); (G.R.-A.)
| | - Gabriela Rodríguez-Arellanes
- Unidad de Micología, Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México 04510, Mexico; (T.V.-G.); (M.d.R.R.-M.); (J.H.S.); (J.A.R.); (G.R.-A.)
| | - Lisandra Serra-Damasceno
- Centro de Ciências da Saúde, Departamento de Saúde Comunitária, Universidade Federal do Ceará, Fortaleza 60455-610, Brazil;
| | - Rosely M. Zancopé-Oliveira
- Laboratório de Micologia, Setor Imunodiagnóstico, Instituto Nacional de Infectología Evandro Chagas, Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro 21040-360, Brazil;
| | - John W. Taylor
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA;
| | - Maria Lucia Taylor
- Unidad de Micología, Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México 04510, Mexico; (T.V.-G.); (M.d.R.R.-M.); (J.H.S.); (J.A.R.); (G.R.-A.)
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Sahaza JH, Rodríguez-Arellanez G, Canteros CE, Reyes-Montes MDR, Taylor ML. Thermotolerance of Histoplasma capsulatum at 40 °C predominates among clinical isolates from different Latin American regions. Braz J Infect Dis 2020; 24:44-50. [PMID: 31987782 PMCID: PMC9392019 DOI: 10.1016/j.bjid.2019.12.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 12/13/2019] [Accepted: 12/28/2019] [Indexed: 12/01/2022] Open
Abstract
The yeast phase of 22 Histoplasma capsulatum clinical isolates from Mexico, Argentina, Colombia, and Guatemala and three reference strains, one from Panama and two from the United States of America (USA), were screened for thermosensitivity characteristics using different analyses. Growth curves at 0, 3, 6, 12, 24, and 30 h of incubation at 37 and 40 °C, the growth inhibition percentage at 40 °C, and the doubling time at 37 and 40 °C were determined for all yeasts studied. Most of the isolates examined exhibited thermotolerant phenotypes at 40 °C, whereas a thermosensitive phenotype at 40 °C was only detected in the Downs reference strain from the USA. Growth inhibition values lower than 33.8% supported the predominance of the thermotolerant phenotype at 40 °C. The doubling time means found for the different isolates were 5.14 h ± 1.47 h at 37 °C and 5.55 h ± 1.87 h at 40 °C. This is the first report to underscore the predominance of thermotolerant and delayed doubling time phenotypes in H. capsulatum clinical isolates from different regions of Latin America.
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Affiliation(s)
- Jorge H Sahaza
- Universidad Nacional Autónoma de México (UNAM), Facultad de Medicina, Departamento de Microbiología-Parasitología, Ciudad de México, Mexico; Unidad de Micología Médica y Experimental, Corporación Para Investigaciones Biológicas, Medellín, Colombia
| | - Gabriela Rodríguez-Arellanez
- Universidad Nacional Autónoma de México (UNAM), Facultad de Medicina, Departamento de Microbiología-Parasitología, Ciudad de México, Mexico
| | - Cristina E Canteros
- Departamento Micologı́a, INEI-ANLIS "Dr. Carlos G. Malbrán", Buenos Aires, Argentina
| | - María Del Rocío Reyes-Montes
- Universidad Nacional Autónoma de México (UNAM), Facultad de Medicina, Departamento de Microbiología-Parasitología, Ciudad de México, Mexico.
| | - Maria Lucia Taylor
- Universidad Nacional Autónoma de México (UNAM), Facultad de Medicina, Departamento de Microbiología-Parasitología, Ciudad de México, Mexico.
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6
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Revisiting old friends: Developments in understanding Histoplasma capsulatum pathogenesis. J Microbiol 2016; 54:265-76. [DOI: 10.1007/s12275-016-6044-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 02/02/2016] [Indexed: 12/27/2022]
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Comparison of phylogenetically distinct Histoplasma strains reveals evolutionarily divergent virulence strategies. mBio 2014; 5:e01376-14. [PMID: 24987093 PMCID: PMC4161242 DOI: 10.1128/mbio.01376-14] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Infection with the dimorphic fungus Histoplasma capsulatum results from the inhalation of contaminated soil. Disease outcome is variable and depends on the immune status of the host, number of organisms inhaled, and the H. capsulatum strain. H. capsulatum is divided into seven distinct clades based on phylogenetic analyses, and strains from two separate clades have been identified in North America (denoted as NAm strains). We characterized an H. capsulatum isolate (WU24) from the NAm 1 lineage in relation to two other well-characterized Histoplasma isolates, the Panamanian strain G186A and the NAm 2 strain G217B. We determined that WU24 is a chemotype II strain and requires cell wall α-(1,3)-glucan for successful in vitro infection of macrophages. In a mouse model of histoplasmosis, WU24 exhibited a disease profile that was very similar to that of strain G186A at a high sublethal dose; however, at this dose G217B had markedly different kinetics. Surprisingly, infection with a lower dose mitigated many of the differences during the course of infection. The observed differences in fungal burden, disease kinetics, symptomology, and cytokine responses all indicate that there is a sophisticated relationship between host and fungus that drives the development and progression of histoplasmosis. Importance: Histoplasmosis has a wide range of clinical manifestations, presenting as mild respiratory distress, acute respiratory infection, or a life-threatening disseminated disease most often seen in immunocompromised patients. Additionally, the outcome appears to be dependent on the amount and strain of fungus inhaled. In this study, we characterized a recent clinical H. capsulatum isolate that was collected from an HIV(+) individual in North America. In contrast to other isolates from the same lineage, this strain, WU24, infected both macrophages and wild-type mice. We determined that in contrast to many other North American strains, WU24 infection of macrophages is dependent on the presence of cell wall α-(1,3)-glucan. Surprisingly, comparison of WU24 with two previously characterized isolates revealed that many conclusions regarding relative strain virulence and certain hallmarks of histoplasmosis are dependent on the inoculum size.
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Williams GJ, Price NN, Ushijima B, Aeby GS, Callahan S, Davy SK, Gove JM, Johnson MD, Knapp IS, Shore-Maggio A, Smith JE, Videau P, Work TM. Ocean warming and acidification have complex interactive effects on the dynamics of a marine fungal disease. Proc Biol Sci 2014; 281:20133069. [PMID: 24452029 DOI: 10.1098/rspb.2013.3069] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Diseases threaten the structure and function of marine ecosystems and are contributing to the global decline of coral reefs. We currently lack an understanding of how climate change stressors, such as ocean acidification (OA) and warming, may simultaneously affect coral reef disease dynamics, particularly diseases threatening key reef-building organisms, for example crustose coralline algae (CCA). Here, we use coralline fungal disease (CFD), a previously described CCA disease from the Pacific, to examine these simultaneous effects using both field observations and experimental manipulations. We identify the associated fungus as belonging to the subphylum Ustilaginomycetes and show linear lesion expansion rates on individual hosts can reach 6.5 mm per day. Further, we demonstrate for the first time, to our knowledge, that ocean-warming events could increase the frequency of CFD outbreaks on coral reefs, but that OA-induced lowering of pH may ameliorate outbreaks by slowing lesion expansion rates on individual hosts. Lowered pH may still reduce overall host survivorship, however, by reducing calcification and facilitating fungal bio-erosion. Such complex, interactive effects between simultaneous extrinsic environmental stressors on disease dynamics are important to consider if we are to accurately predict the response of coral reef communities to future climate change.
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Affiliation(s)
- Gareth J Williams
- Scripps Institution of Oceanography, Center for Marine Biodiversity and Conservation, University of California San Diego, , La Jolla, CA 92093, USA, Department of Microbiology, University of California San Diego, , La Jolla, CA 92093, USA, Joint Institute for Marine and Atmospheric Research, University of Hawaii at Manoa, , Honolulu, HI, USA, Hawaii Institute of Marine Biology, , Kaneohe, HI 96744, USA, School of Biological Sciences, Victoria University of Wellington, , PO Box 600, Wellington, New Zealand, Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), , NOAA, 1610 Kapiolani Boulevard, Suite 1110, Honolulu, HI 96814, USA, US Geological Survey, National Wildlife Health Center, , Honolulu Field Station, PO Box 50167, Honolulu, HI 96850, USA
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Vite-Garín T, Estrada-Bárcenas DA, Cifuentes J, Taylor ML. The importance of molecular analyses for understanding the genetic diversity of Histoplasma capsulatum: an overview. Rev Iberoam Micol 2013; 31:11-5. [PMID: 24252830 DOI: 10.1016/j.riam.2013.09.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 09/27/2013] [Indexed: 10/26/2022] Open
Abstract
Advances in the classification of the human pathogen Histoplasma capsulatum (H. capsulatum) (ascomycete) are sustained by the results of several genetic analyses that support the high diversity of this dimorphic fungus. The present mini-review highlights the great genetic plasticity of H. capsulatum. Important records with different molecular tools, mainly single- or multi-locus sequence analyses developed with this fungus, are discussed. Recent phylogenetic data with a multi-locus sequence analysis using 5 polymorphic loci support a new clade and/or phylogenetic species of H. capsulatum for the Americas, which was associated with fungal isolates obtained from the migratory bat Tadarida brasiliensis. 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).
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Affiliation(s)
- Tania Vite-Garín
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), México DF, Mexico
| | - Daniel Alfonso Estrada-Bárcenas
- Colección Nacional de Cultivos Microbianos, Centro de Investigación y de Estudios Avanzados, Instituto Politécnico Nacional, México DF, Mexico
| | - Joaquín Cifuentes
- Herbario FCME (Hongos), Facultad de Ciencias, Universidad Nacional Autónoma de México (UNAM), México DF, Mexico
| | - Maria Lucia Taylor
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), México DF, Mexico.
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Taylor ML, Hernández-García L, Estrada-Bárcenas D, Salas-Lizana R, Zancopé-Oliveira RM, García de la Cruz S, Galvão-Dias MA, Curiel-Quesada E, Canteros CE, Bojórquez-Torres G, Bogard-Fuentes CA, Zamora-Tehozol E. Genetic diversity of Histoplasma capsulatum isolated from infected bats randomly captured in Mexico, Brazil, and Argentina, using the polymorphism of (GA)(n) microsatellite and its flanking regions. Fungal Biol 2011; 116:308-17. [PMID: 22289776 DOI: 10.1016/j.funbio.2011.12.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 11/14/2011] [Accepted: 12/08/2011] [Indexed: 11/29/2022]
Abstract
The genetic diversity of 47 Histoplasma capsulatum isolates from infected bats captured in Mexico, Brazil, and Argentina was studied, using sequence polymorphism of a 240-nucleotides (nt) fragment, which includes the (GA)(n) length microsatellite and its flanking regions within the HSP60 gene. Three human clinical strains were used as geographic references. Based on phylogenetic analyses of 240-nt fragments achieved, the relationships among H. capsulatum isolates were resolved using neighbour-joining and maximum parsimony methods. The tree topologies obtained by both methods were identical and highlighted two major clusters of isolates. Cluster I had three sub-clusters (Ia, Ib, and Ic), all of which contained Mexican H. capsulatum samples, while cluster II consisted of samples from Brazil and Argentina. Sub-cluster Ia included only fungal isolates from the migratory bat Tadarida brasiliensis. An average DNA mutation rate of 2.39 × 10(-9) substitutions per site per year was estimated for the 240-nt fragment for all H. capsulatum isolates. Nucleotide diversity analysis of the (GA)(n) and flanking regions from fungal isolates of each cluster and sub-cluster underscored the high similarity of cluster II (Brazil and Argentina), sub-clusters Ib, and Ic (Mexico). According to the genetic distances among isolates, a network of the 240-nt fragment was graphically represented by (GA)(n) length haplotype. This network showed an association between genetic variation and both the geographic distribution and the ecotype dispersion of H. capsulatum, which are related to the migratory behaviour of the infected bats studied.
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Affiliation(s)
- Maria Lucia Taylor
- Departamento de Microbiología-Parasitología, Universidad Nacional Autónoma de México, México DF 04510, Mexico.
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Edwards JA, Rappleye CA. Histoplasma mechanisms of pathogenesis--one portfolio doesn't fit all. FEMS Microbiol Lett 2011; 324:1-9. [PMID: 22092757 PMCID: PMC3228276 DOI: 10.1111/j.1574-6968.2011.02363.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 07/12/2011] [Accepted: 07/13/2011] [Indexed: 01/15/2023] Open
Abstract
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.
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Affiliation(s)
- Jessica A. Edwards
- Departments of Microbiology and Internal Medicine, The Center for Microbial Interface Biology, Ohio State University, 484 W. 12Avenue, Columbus, OH 43210, USA
| | - Chad A. Rappleye
- Departments of Microbiology and Internal Medicine, The Center for Microbial Interface Biology, Ohio State University, 484 W. 12Avenue, Columbus, OH 43210, USA
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12
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Detection of Latin American strains of Histoplasma in a murine model by use of a commercially available antigen test. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2010; 17:802-6. [PMID: 20357054 DOI: 10.1128/cvi.00043-10] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During a Histoplasma outbreak in a colony of fruit bats at a southern United States zoo, it was observed that although Histoplasma was recovered in culture from multiple sites at necropsy, none of the samples collected from those bats tested positive for Histoplasma antigen (HAg). Five of the Histoplasma isolates from the bats were subsequently identified as Latin American (LA) clade A, restriction fragment length polymorphism (RFLP) class 6. These observations raised concern as to whether the commercially available HAg test could detect Histoplasma antigen not of the North American clade upon which the HAg test had been developed. To evaluate this concern, a murine model of disseminated histoplasmosis was established, and mice were infected with multiple LA Histoplasma isolates, including clinical isolates recovered from Brazilian AIDS patients (RFLP class 5 and class 6) and isolates recovered from the bats during the outbreak (RFLP class 6). Histoplasma antigen was detected in all infected mice in our experiments, even when Histoplasma was not recovered in culture. Because the currently available HAg test is able to detect Histoplasma antigen in mice infected with Latin American isolates, this suggests that bat host factors rather than differences among Histoplasma RFLP classes were responsible for the inability to detect HAg in infected bats.
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13
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Bonifaz A, Chang P, Moreno K, Fernández-Fernández V, Montes de Oca G, Araiza J, Ponce RM. Disseminated cutaneous histoplasmosis in acquired immunodeficiency syndrome: report of 23 cases. Clin Exp Dermatol 2009; 34:481-6. [DOI: 10.1111/j.1365-2230.2008.02974.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Taylor ML, Chávez-Tapia CB, Rojas-Martínez A, del Rocio Reyes-Montes M, del Valle MB, Zúñiga G. Geographical distribution of genetic polymorphism of the pathogen Histoplasma capsulatum isolated from infected bats, captured in a central zone of Mexico. ACTA ACUST UNITED AC 2005; 45:451-8. [PMID: 16061361 DOI: 10.1016/j.femsim.2005.05.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2005] [Accepted: 05/27/2005] [Indexed: 10/25/2022]
Abstract
Fourteen Histoplasma capsulatum isolates recovered from infected bats captured in Mexican caves and two human H. capsulatum reference strains were analyzed using random amplification of polymorphic DNA PCR-based and partial DNA sequences of four genes. Cluster analysis of random amplification of polymorphic DNA-patterns revealed differences for two H. capsulatum isolates of one migratory bat Tadarida brasiliensis. Three groups were identified by distance and maximum-parsimony analyses of arf, H-anti, ole, and tub1 H. capsulatum genes. Group I included most isolates from infected bats and one clinical strain from central Mexico; group II included the two isolates from T. brasiliensis; the human G-217B reference strain from USA formed an independent group III. Isolates from group II showed diversity in relation to groups I and III, suggesting a different H. capsulatum population.
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Affiliation(s)
- Maria Lucia Taylor
- Laboratorio de Inmunología de Hongos, Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad Universitaria.
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15
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Bohse ML, Woods JP. Surface localization of the Yps3p protein of Histoplasma capsulatum. EUKARYOTIC CELL 2005; 4:685-93. [PMID: 15821128 PMCID: PMC1087815 DOI: 10.1128/ec.4.4.685-693.2005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The YPS3 gene of Histoplasma capsulatum encodes a protein that is both resident in the cell wall and also released into the culture medium. This protein is produced only during the pathogenic yeast phase of infection and is also expressed differently in H. capsulatum strains that differ in virulence. We investigated the cellular localization of Yps3p. We demonstrated that the cell wall fraction of Yps3p was surface localized in restriction fragment length polymorphism class 2 strains. We also established that Yps3p released into the G217B culture supernatant binds to the surface of strains that do not naturally express the protein. This binding was saturable and occurred within 5 min of exposure and occurred similarly with live and heat-killed H. capsulatum. Flow cytometric analysis of H. capsulatum after enzymatic treatments was consistent with Yps3p binding to chitin, a carbohydrate polymer that is a component of fungal cell walls. Polysaccharide binding assays demonstrated that chitin but not cellulose binds to and extracts Yps3p from culture supernatants.
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Affiliation(s)
- Megan L Bohse
- Department of Medical Microbiology and Immunology, University of Wisconsin Medical School, Madison, Wisconsin 53706-1532, USA
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16
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Kasuga T, White TJ, Koenig G, McEwen J, Restrepo A, Castañeda E, Da Silva Lacaz C, Heins-Vaccari EM, De Freitas RS, Zancopé-Oliveira RM, Qin Z, Negroni R, Carter DA, Mikami Y, Tamura M, Taylor ML, Miller GF, Poonwan N, Taylor JW. Phylogeography of the fungal pathogen Histoplasma capsulatum. Mol Ecol 2004; 12:3383-401. [PMID: 14629354 DOI: 10.1046/j.1365-294x.2003.01995.x] [Citation(s) in RCA: 230] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Until recently, Histoplasma capsulatum was believed to harbour three varieties, var. capsulatum (chiefly a New World human pathogen), var. duboisii (an African human pathogen) and var. farciminosum (an Old World horse pathogen), which varied in clinical manifestations and geographical distribution. We analysed the phylogenetic relationships of 137 individuals representing the three varieties from six continents using DNA sequence variation in four independent protein-coding genes. At least eight clades were idengified: (i) North American class 1 clade; (ii) North American class 2 clade; (iii) Latin American group A clade; (iv) Latin American group B clade; (v) Australian clade; (vi) Netherlands (Indonesian?) clade; (vii) Eurasian clade and (viii) African clade. Seven of eight clades represented genetically isolated groups that may be recognized as phylogenetic species. The sole exception was the Eurasian clade which originated from within the Latin American group A clade. The phylogenetic relationships among the clades made a star phylogeny. Histoplasma capsulatum var. capsulatum individuals were found in all eight clades. The African clade included all of the H. capsulatum var. duboisii individuals as well as individuals of the other two varieties. The 13 individuals of var. farciminosum were distributed among three phylogenetic species. These findings suggest that the three varieties of Histoplasma are phylogenetically meaningless. Instead we have to recognize the existence of genetically distinct geographical populations or phylogenetic species. Combining DNA substitution rates of protein-coding genes with the phylogeny suggests that the radiation of Histoplasma started between 3 and 13 million years ago in Latin America.
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Affiliation(s)
- Takao Kasuga
- Department of Plant and Microbial Biology, 321 Koshland Hall, University of California, Berkeley, CA 94720, USA.
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17
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Carter DA, Taylor JW, Dechairo B, Burt A, Koenig GL, White TJ. Amplified single-nucleotide polymorphisms and a (GA)(n) microsatellite marker reveal genetic differentiation between populations of Histoplasma capsulatum from the Americas. Fungal Genet Biol 2001; 34:37-48. [PMID: 11567550 DOI: 10.1006/fgbi.2001.1283] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Histoplasma capsulatum has a worldwide distribution but is particularly concentrated in the midwestern United States and throughout Central and South America. Genetic differences between isolates resident in separate parts of the world have been reported, but the relationship between the isolates and the level of migration between different endemic foci has not been clear. In this study we used multilocus genotypes based on amplified polymorphic loci and one microsatellite to quantify the level of genetic differentiation occurring between North and South American populations of H. capsulatum. Significant genetic differentiation occurred between isolates obtained from Indiana and Alabama, and a marked division was seen between the Indiana population and the Class 1 isolates from St. Louis. Strong genetic differentiation occurred between the two North American populations and the Colombian population. This study supports the separation of North and South American H. capsulatum into different species, which has been proposed under the phylogenetic species concept.
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Affiliation(s)
- D A Carter
- Roche Molecular Systems, Alameda, California 94501, USA
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18
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Taylor JW, Jacobson DJ, Kroken S, Kasuga T, Geiser DM, Hibbett DS, Fisher MC. Phylogenetic species recognition and species concepts in fungi. Fungal Genet Biol 2000; 31:21-32. [PMID: 11118132 DOI: 10.1006/fgbi.2000.1228] [Citation(s) in RCA: 1131] [Impact Index Per Article: 47.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The operational species concept, i.e., the one used to recognize species, is contrasted to the theoretical species concept. A phylogenetic approach to recognize fungal species based on concordance of multiple gene genealogies is compared to those based on morphology and reproductive behavior. Examples where Phylogenetic Species Recognition has been applied to fungi are reviewed and concerns regarding Phylogenetic Species Recognition are discussed.
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Affiliation(s)
- J W Taylor
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720-3102, USA
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19
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Taylor ML, Chávez-Tapia CB, Reyes-Montes MR. Molecular typing of Histoplasma capsulatum isolated from infected bats, captured in Mexico. Fungal Genet Biol 2000; 30:207-12. [PMID: 11035942 DOI: 10.1006/fgbi.2000.1219] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present paper represents data on the genetic polymorphism of 13 Histoplasma capsulatum isolates recovered from infected bats randomly captured in the Mexican states of Morelos, Puebla, and Oaxaca. The polymorphic DNA patterns were analyzed by two-primer RAPD-PCR (random amplified polymorphic DNA-polymerase chain reaction) method. To amplify the fungal genome by PCR, the following primer arrangements were used: 5'-AACGCGCAAC-3' and 5'-AAGAGCCCGT-3'; 5'-AACGCGCAAC-3' and 5'-GTTTCCGCCC-3'; or 5'-AACGCGCAAC-3' and 5'-GCGATCCCCA-3'. A common polymorphic DNA pattern of H. capsulatum was revealed in different assays. This pattern is shared by 7 H. capsulatum isolates recovered from different specimens of nonmigratory bats (Artibeus hirsutus) captured in a cave in Morelos, by 5 isolates recovered from infected migratory bats (Leptonycteris nivalis) captured in Morelos and Puebla, and by 1 isolate from another migratory bat (L. curasoae) captured in Oaxaca. This polymorphic DNA pattern of H. capsulatum could represent fungal markers for the geographic areas studied, and considering its distribution in three different states of the Mexican Republic, the role of bats as responsible for H. capsulatum spreading in nature, in relation to their movements and migrations besides their shelter habits, is suggested. Analyses of DNA patterns of H. capsulatum isolated from infected bats, from clinical cases, and from blackbird excreta, have shown a major relatedness between bats and clinical isolates, in contrast to those isolates from bird excreta.
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Affiliation(s)
- M L Taylor
- Departamento de Microbiología-Parasitología, Universidad Nacional Autónoma de México, Mexico City, Mexico.
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20
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Jiang B, Bartlett MS, Allen SD, Smith JW, Wheat LJ, Connolly PA, Lee CH. Typing of Histoplasma capsulatum isolates based on nucleotide sequence variation in the internal transcribed spacer regions of rRNA genes. J Clin Microbiol 2000; 38:241-5. [PMID: 10618094 PMCID: PMC88702 DOI: 10.1128/jcm.38.1.241-245.2000] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nucleotide sequences of internal transcribed spacer (ITS) regions of rRNA genes of 24 isolates of Histoplasma capsulatum were examined. The results indicate that the sequences of ITS regions in different isolates are not identical. Sequence variations were found at 20 positions in the 496 bp that were sequenced. Ten different sequence patterns, designated types A through H, were observed when the sequences from the 24 isolates were aligned. Twelve isolates from Indianapolis were classified into four different types. Two isolates from New York belonged to type G. Three isolates from different cities were type F. The remaining six isolates were of different types.
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Affiliation(s)
- B Jiang
- Department of Pathology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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21
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Retallack DM, Woods JP. Molecular epidemiology, pathogenesis, and genetics of the dimorphic fungus Histoplasma capsulatum. Microbes Infect 1999; 1:817-25. [PMID: 10816087 DOI: 10.1016/s1286-4579(99)80084-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Histoplasma capsulatum, the causative agent of the most common systemic fungal infection, histoplasmosis, has become subject to increasing study in parallel with rising prevalence of human immunodeficiency. This review presents a summary of the advances made in the investigation of H. capsulatum genomics, molecular epidemiology, pathogenesis, and molecular genetics.
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Affiliation(s)
- D M Retallack
- Department of Medical Microbiology and Immunology, University of Wisconsin Medical School, Madison 53706, USA
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22
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Abstract
Fungal infections, especially those caused by opportunistic species, have become substantially more common in recent decades. Numerous species cause human infections, and several new human pathogens are discovered yearly. This situation has created an increasing interest in fungal taxonomy and has led to the development of new methods and approaches to fungal biosystematics which have promoted important practical advances in identification procedures. However, the significance of some data provided by the new approaches is still unclear, and results drawn from such studies may even increase nomenclatural confusion. Analyses of rRNA and rDNA sequences constitute an important complement of the morphological criteria needed to allow clinical fungi to be more easily identified and placed on a single phylogenetic tree. Most of the pathogenic fungi so far described belong to the kingdom Fungi; two belong to the kingdom Chromista. Within the Fungi, they are distributed in three phyla and in 15 orders (Pneumocystidales, Saccharomycetales, Dothideales, Sordariales, Onygenales, Eurotiales, Hypocreales, Ophiostomatales, Microascales, Tremellales, Poriales, Stereales, Agaricales, Schizophyllales, and Ustilaginales).
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Affiliation(s)
- J Guarro
- Unitat de Microbiologia, Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, 43201 Reus, Spain.
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23
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Reyes-Montes MR, Bobadilla-Del Valle M, Martínez-Rivera MA, Rodríguez-Arellanes G, Maravilla E, Sifuentes-Osornio J, Taylor ML. Relatedness analyses of Histoplasma capsulatum isolates from Mexican patients with AIDS-associated histoplasmosis by using histoplasmin electrophoretic profiles and randomly amplified polymorphic DNA patterns. J Clin Microbiol 1999; 37:1404-8. [PMID: 10203495 PMCID: PMC84786 DOI: 10.1128/jcm.37.5.1404-1408.1999] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The present paper analyzes the histoplasmin electrophoretic profiles and the randomly amplified polymorphic DNA (RAPD) patterns of the fungus Histoplasma capsulatum isolated from Mexican patients with AIDS-associated histoplasmosis. Clinical isolates from Guatemala, Colombia, and Panama, as well as H. capsulatum isolates from different sources in nature, were also processed. All histoplasmin samples shared four antigenic fractions of 200, 49, 10.5, and 8.5 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). According to their percentage of relatedness, based on SDS-PAGE histoplasmin electrophoretic image analysis, H. capsulatum isolates were divided in two groups: group A contained all AIDS-associated isolates studied and two human reference strains from Mexican histoplasmosis patients without AIDS; group B included bat guano, infected bat, and cock excreta isolates from the State of Guerrero, Mexico, plus three human histoplasmosis strains from Guatemala, Panama, and Colombia. Polymorphic DNA patterns evaluated by RAPD-PCR showed three major bands of 4.4, 3.2, and 2.3 kb in most H. capsulatum isolates studied. Four groups were related by DNA polymorphisms: group I was formed by most of the AIDS-associated H. capsulatum isolates studied, one human histoplasmosis strain from Colombia, two human reference strains from Mexican patients without AIDS, and one human histoplasmosis strain from Guatemala. Group II consisted of only a single strain from Panama. Group III included three strains: one from a Mexican patient with AIDS and two isolated from nature in Guerrero (cock excreta and bat guano). The last, group IV, consisted of only one strain isolated from an infected bat, captured in Guerrero. A tight relationship between phenotypic and genotypic characterization was observed, and both analyses could be useful tools for typing H. capsulatum from different sources and geographic origins.
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Affiliation(s)
- M R Reyes-Montes
- Departamento de Microbiología-Parasitología, Facultad de Medicina, UNAM, Mexico City, Mexico
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24
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Kasuga T, Taylor JW, White TJ. Phylogenetic relationships of varieties and geographical groups of the human pathogenic fungus Histoplasma capsulatum Darling. J Clin Microbiol 1999; 37:653-63. [PMID: 9986828 PMCID: PMC84508 DOI: 10.1128/jcm.37.3.653-663.1999] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The phylogeny of 46 geographically diverse Histoplasma capsulatum isolates representing the three varieties capsulatum, duboisii, and farciminosum was evaluated using partial DNA sequences of four protein coding genes. Parsimony and distance analysis of the separate genes were generally congruent and analysis of the combined data identified six clades: (i) class 1 North American H. capsulatum var. capsulatum, (ii) class 2 North American H. capsulatum var. capsulatum, (iii) Central American H. capsulatum var. capsulatum, (iv) South American H. capsulatum var. capsulatum group A, (v) South American H. capsulatum var. capsulatum group B, and (vi) H. capsulatum var. duboisii. Although the clades were generally well supported, the relationships among them were not resolved and the nearest outgroups (Blastomyces and Paracoccidioides) were too distant to unequivocally root the H. capsulatum tree. H. capsulatum var. farciminosum was found within the South American H. capsulatum var. capsulatum group A clade. With the exception of the South American H. capsulatum var. capsulatum group A clade, genetic distances within clades were an order of magnitude lower than those between clades, and each clade was supported by a number of shared derived nucleotide substitutions, leading to the conclusion that each clade was genetically isolated from the others. Under a phylogenetic species concept based on possession of multiple shared derived characters, as well as concordance of four gene genealogies, H. capsulatum could be considered to harbor six species instead of three varieties.
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Affiliation(s)
- T Kasuga
- Roche Molecular Systems, Alameda, California 94501, USA.
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25
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Poonwan N, Imai T, Mekha N, Yazawa K, Mikami Y, Ando A, Nagata Y. Genetic analysis of Histoplasma capsulatum strains isolated from clinical specimens in thailand by a PCR-based random amplified polymorphic DNA method. J Clin Microbiol 1998; 36:3073-6. [PMID: 9738073 PMCID: PMC105117 DOI: 10.1128/jcm.36.10.3073-3076.1998] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thirteen strains of Histoplasma capsulatum were isolated from clinical specimens, including those from AIDS patients, in Thailand. Random amplified polymorphic DNA (RAPD) analysis with three different PCR primers showed that the DNA fingerprint patterns of the Thai isolates were very similar to each other and homogeneous, with only one exceptional strain, although the patterns were clearly different from those of a reference North American strain with all primers tested. Although the difference in the DNA fingerprinting patterns was minor, Thai isolates could be classified into two to four groups. A common PCR band (about 700 bp) in the patterns of all H. capsulatum strains was extracted, and its DNA sequence was determined. A new PCR primer set for the identification of H. capsulatum species was developed based on this sequence information. This primer set was 100% successful in the identification of the reference strain as well as all Thai isolates. The results of specificity tests of the primer set for the identification of the fungus are also discussed.
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Affiliation(s)
- N Poonwan
- Department of Medical Sciences, National Institute of Health, Nonthaburi, Thailand
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26
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Pernice I, Lo Passo C, Criseo G, Pernice A, Todaro-Luck F. Molecular subtyping of clinical and environmental strains of Cryptococcus neoformans variety neoformans serotype A isolated from southern Italy. Mycoses 1998; 41:117-24. [PMID: 9670763 DOI: 10.1111/j.1439-0507.1998.tb00312.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Analysis of ribosomal DNA (rDNA) restriction fragment-length polymorphism (RFLP) and random amplification of polymorphic DNA (RAPD) was used to investigate the genetic variability and biogeographic distribution of clinical and environmental strains of Cryptococcus neoformans isolated from a limited area of southern Italy, where the selection of a predominant cryptococcal genotype could be expected. All isolates belonged to the species Cr. neoformans variety neoformans serotype A. RFLP analysis of a specific rDNA fragment allowed the distinction of strains of Cr. neoformans from closely related fungal reference species, but neither intraspecies nor intravarieties polymorphism was detected. On the contrary, RAPD fingerprints produced by priming with four different primers [(GTG)5, (GACA)4, M13 core sequence and the 8-mer oligonucleotide (GCGGACGG)] were able to characterize the isolates up to the individual level, indicating the presence of marked heterogeneity among Cr. neoformans serotype A strains in southern Italy.
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Affiliation(s)
- I Pernice
- Institute of Microbiology, University of Messina School of Science, Italy
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27
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Dahl KM, Keath EJ, Fraser VJ, Powderly WG. Molecular epidemiology of mucosal candidiasis in HIV-positive women. AIDS Res Hum Retroviruses 1997; 13:485-91. [PMID: 9100990 DOI: 10.1089/aid.1997.13.485] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Mucosal candidiasis is a common complication of HIV infection and HIV-positive women may develop both oropharyngeal and vaginal disease. Colonization with Candida albicans and related species at either site is a common preceding event in asymptomatic women. To examine the molecular epidemiology of colonizing yeast strains in HIV-positive women, concurrent oropharyngeal and vaginal cultures were obtained from 32 women (mean CD4 count 392 cells/mm3, range 0-1319). Positive oropharyngeal cultures were obtained in 18 (56%) and positive vaginal cultures in 10 (31%). Candida species were isolated from both sites simultaneously in nine (28%) women. All strains were evaluated for restriction fragment length polymorphisms (RFLPs) at the ribosomal DNA locus (using a heterologous 8.4-kb NotI probe from H. capsulatum) and with a C. albicans-specific repetitive DNA probe. Isolates were grouped into three classes by the NotI probe and then members of each class were evaluated with the C. albicans-specific probe. Isolates were subsequently evaluated by random amplified polymorphic DNA (RAPD) PCR with four arbitrary primers to detect strain-specific differences. All isolates tested were unique and could be discriminated by RFLP or RAPD PCR. Vaginal and oropharyngeal isolates from the same individual in all nine cases were dissimilar, suggesting that the dominant strain of Candida colonizing different body sites is different. These findings suggest that the epidemiology of Candida infection in HIV disease is complex, that the development of oropharyngeal and vaginal disease may be disassociated, and that HIV-positive patients are each infected by their own unique strains of Candida.
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Affiliation(s)
- K M Dahl
- Washington University School of Medicine, St. Louis, Missouri 63110, USA
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28
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Lo Passo C, Pernice I, Gallo M, Barbara C, Luck FT, Criseo G, Pernice A. Genetic relatedness and diversity of Cryptococcus neoformans strains in the Maltese Islands. J Clin Microbiol 1997; 35:751-5. [PMID: 9041427 PMCID: PMC229665 DOI: 10.1128/jcm.35.3.751-755.1997] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The genetic relatedness of clinical and environmental Cryptococcus neoformans strains in the Maltese Islands was investigated by randomly amplified polymorphic DNA fingerprinting with four primers. The clinical strains isolate over the course of 1 year from AIDS patients showed identical fingerprints. The electrophoretic patterns of the two clinical strains were also the most common patterns among the environmental strains, but the patterns among the environmental strains showed a wide variability and no correlation with the site of isolation.
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Affiliation(s)
- C Lo Passo
- Istituto di Microbiologia, Facoltà di Scienze, Università di Messina, Italy
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29
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Carter DA, Burt A, Taylor JW, Koenig GL, White TJ. Clinical isolates of Histoplasma capsulatum from Indianapolis, Indiana, have a recombining population structure. J Clin Microbiol 1996; 34:2577-84. [PMID: 8880523 PMCID: PMC229321 DOI: 10.1128/jcm.34.10.2577-2584.1996] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
A sample of 30 clinical isolates of Histoplasma capsulatum was analyzed to determine (i) whether genetic exchange is important in the life cycle of this fungus and (ii) whether distinct subpopulations which correlate with disease severity or host immune status exist. Eleven biallelic molecular markers were developed, with the frequency of the least common allele at each molecular locus ranging from 10 to 50%. Every isolate had a different, unique multilocus genotype. Data analysis indicated that frequent recombination occurs within the Indianapolis, Ind., population. There were no associations between isolates from the immunocompromised population or from those with different clinical manifestations of histoplasmosis.
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Affiliation(s)
- D A Carter
- Roche Molecular Systems, Alameda, California 94501, USA.
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30
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Affiliation(s)
- A Espinel-Ingroff
- Medical Mycology Research Laboratory, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298, USA
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31
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Ikeda T, Little JR. Deactivation of macrophage oxidative burst in vitro by different strains of Histoplasma capsulatum. Mycopathologia 1995; 132:133-41. [PMID: 8684427 DOI: 10.1007/bf01103978] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
It was previously reported that Histoplasma capsulatum (Hc) yeast not only failed to stimulate a murine macrophage oxidative burst (OB), but they also blunted or abolished OB stimulation by a subsequent encounter with potent stimuli such as zymosan or phorbol 12-myristate 13-acetate (PMA). The present studies show that macrophage deactivation is proportional to the time of incubation and the dose of Hc yeast that induce the deactivated state. Hc yeast derived from a virulent strain (G217B) are more efficient inducers of macrophage deactivation than similar preparations derived from the avirulent Downs Hc strain. Yeast cells of two other pathogenic fungi, Candida albicans and Cryptococcus neoformans are shown to stimulate rather than deactivate a macrophage OB.
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Affiliation(s)
- T Ikeda
- Department of Veterinary Microbiology, Azabu University, Kanagawa, Japan
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Mukherjee J, Scharff MD, Casadevall A. Variable efficacy of passive antibody administration against diverse Cryptococcus neoformans strains. Infect Immun 1995; 63:3353-9. [PMID: 7642262 PMCID: PMC173461 DOI: 10.1128/iai.63.9.3353-3359.1995] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The efficacy of monoclonal antibody (MAb 2H1) against diverse strains of Cryptococcus neoformans was studied in a murine model of intravenous infection. For six of eight strains, administration of MAb prior to infection prolonged survival of mice. For two strains, 371 and SB4A, administration of MAb prior to infection did not prolong survival in multiple experiments with inocula ranging from 10(2) to 10(6) yeast cells per mouse. Mice infected with strains 371 and SB4A had fewer CFU than non-MAb-treated controls, but the CFU reduction was not sufficient to affect survival. Serum glucuronoxylomannan (GXM) levels varied for the different C. neoformans strains. For mice that did not receive MAb 2H1, there was a positive correlation between lung fungal burden and serum GXM levels. MAb 2H1-treated mice had significantly reduced serum GXM levels. The results indicate that the efficacy of MAb 2H1 administration in prolonging survival and/or reducing organ CFU varies with the C. neoformans strain.
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Affiliation(s)
- J Mukherjee
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Krunic A, Calonje E, Jeftovic D, Berger S, Milinkovic M, Lausevic Z, Martinovic N, Kokai D. Primary localized cutaneous histoplasmosis in a patient with acquired immunodeficiency syndrome. Int J Dermatol 1995; 34:558-62. [PMID: 7591438 DOI: 10.1111/j.1365-4362.1995.tb02954.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- A Krunic
- Department of Dermatology, Medical School, University of Belgrade, Yugoslavia
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Tsang PC, Samaranayake LP, Philipsen HP, McCulloug M, Reichart PA, Schmidt-Westhausen A, Scully C, Porter SR. Biotypes of oral Candida albicans isolates in human immunodeficiency virus-infected patients from diverse geographic locations. J Oral Pathol Med 1995; 24:32-6. [PMID: 7722918 DOI: 10.1111/j.1600-0714.1995.tb01126.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Oral Candida albicans isolates from HIV-infected individuals in Hong Kong, Australia, Germany and England were characterised using a biotyping system based on enzyme profiles, carbohydrate assimilation patterns and boric acid resistance of the yeasts. A total of 44 biotypes were found amongst the 117 oral C. albicans isolates examined. The major biotype A1R accounted for 17.9% of all isolates while the second commonest biotype was A1S (11.1% of isolates). Whereas these two biotypes were isolated from all the regions studied, there were a number of other biotypes unique to individual countries. The data indicate that there are many different sub-strains of oral C. albicans in HIV-infected patients, some of which are globally prevalent. However, further work is required to ascertain the diversity of oral C. albicans biotypes, if any, in health and disease.
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Affiliation(s)
- P C Tsang
- Oral Biology Unit, University of Kong
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Abstract
OBJECTIVE To review the pharmacotherapy of disseminated histoplasmosis (DH) in patients with AIDS. The article provides an overview of the pathophysiology, epidemiology, clinical presentation and diagnosis of this disease. Clinical trials reporting intervention with antifungal therapy are reviewed, with an emphasis on efficacy and toxicity of these agents. DATA SOURCES A MEDLINE search from 1976 to the present was performed to identify pertinent biomedical literature, including reviews. STUDY SELECTION All available reviews and clinical trials in AIDS patients were evaluated, as were all available case series and interventional clinical trials. DATA SYNTHESIS DH in patients with HIV infection is an AIDS-defining opportunistic infection caused by Histoplasma capsulatum. It is most frequently observed in HIV-infected patients living in or traveling to endemic regions. The clinical presentation most often includes fever and weight loss, but may be complicated by comorbid illness such as other opportunistic infections. Diagnosis is best established by histologic examination of peripheral blood smear or bone marrow aspirate, or isolation of the organism in cultures of blood, bone marrow, and respiratory secretions. Serologic examinations may provide supportive diagnostic information. Detection of histoplasma polysaccharide antigen (HPA) in serum or urine may prove to be a promising approach for the rapid diagnosis and therapeutic monitoring of DH in AIDS patients. In contrast to immunocompetent hosts, high relapse rates are reported after therapy in AIDS patients. Therefore, initial (induction) therapy is routinely followed by long-term (maintenance) therapy to prevent relapse. Issues regarding the selection, dosage, and duration of therapy, as well as prophylaxis of patients at highest risk, still need to be addressed by controlled clinical trials. CONCLUSIONS Amphotericin B is presently the drug of choice for induction therapy. Maintenance therapy with either amphotericin B or an oral azole antifungal agent active against H. capsulatum is necessary to prevent relapse. Itraconazole, a triazole antifungal agent, may provide effective alternative therapy for both induction and maintenance treatment of DH.
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Affiliation(s)
- R H Drew
- Division of Infectious Diseases, Duke University Medical Center, Durham, NC 27710
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Woods JP, Kersulyte D, Goldman WE, Berg DE. Fast DNA isolation from Histoplasma capsulatum: methodology for arbitrary primer polymerase chain reaction-based epidemiological and clinical studies. J Clin Microbiol 1993; 31:463-4. [PMID: 8432840 PMCID: PMC262791 DOI: 10.1128/jcm.31.2.463-464.1993] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The arbitrary primer polymerase chain reaction (also called random amplified polymorphic DNA, or RAPD) is a DNA fingerprinting method that provides an efficient, sensitive way of discriminating between independent isolates of Histoplasma capsulatum, but its widespread application has been hampered by the arduous 2-day procedure traditionally used to extract DNA from H. capsulatum. We present here a quick (approximately 2-h) extraction method and show that the resultant DNA is suitable for sensitive and reproducible identification of individual strains of this pathogenic fungus.
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Affiliation(s)
- J P Woods
- Department of Molecular Microbiology, Washington University Medical School, St. Louis, Missouri 63110
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Kersulyte D, Woods JP, Keath EJ, Goldman WE, Berg DE. Diversity among clinical isolates of Histoplasma capsulatum detected by polymerase chain reaction with arbitrary primers. J Bacteriol 1992; 174:7075-9. [PMID: 1429430 PMCID: PMC207395 DOI: 10.1128/jb.174.22.7075-7079.1992] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Clinical isolates of the fungal respiratory and systemic pathogen Histoplasma capsulatum have been placed in several different classes by using genomic restriction fragment length polymorphisms (RFLPs), but in general have not been distinguished further. We report here that a polymerase chain reaction (PCR)-based DNA fingerprinting method that has been termed arbitrary primer or random amplified polymorphic DNA (RAPD) PCR can distinguish among isolates in a single RFLP class. In this method, arbitrarily chosen oligonucleotides are used to prime DNA synthesis from genomic sites that they fortuitously match, or almost match, to generate strain-specific arrays of DNA fragments. Each of 29 isolates of RFLP class 2, the group endemic in the American Midwest, was distinguished by using just three arbitrary primers. In contrast, laboratory-derived S and E colony morphology variants of two strains were not distinguished from their R parents by using 18 such primers. Thus, the clinical isolates of H. capsulatum are quite diverse, but their genomes remain stable during laboratory culture. These outcomes suggest new possibilities for epidemiological analysis and studies of fungal populations in infected hosts.
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Affiliation(s)
- D Kersulyte
- Department of Molecular Microbiology, Washington University Medical School, St. Louis, Missouri 63110
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Keath EJ, Kobayashi GS, Medoff G. Typing of Histoplasma capsulatum by restriction fragment length polymorphisms in a nuclear gene. J Clin Microbiol 1992; 30:2104-7. [PMID: 1354224 PMCID: PMC265451 DOI: 10.1128/jcm.30.8.2104-2107.1992] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously described yps-3, a Histoplasma-specific nuclear gene probe useful in the identification of Histoplasma capsulatum. By using restriction fragment length polymorphisms (RFLPs) of DNA detected by the yps-3 gene and mitochondrial DNA, 76 clinical and soil isolates of H. capsulatum were classified. The majority of North American isolates obtained from endemic regions of the midwestern United States were members of the previously characterized class 2, although four clinical isolates from different patients with AIDS from that region were grouped in class 1 with the temperature-sensitive Downs strain. A Florida soil isolate (FLS1) was placed in class 4 on the basis of RFLP with both probes. Two American Type Culture Collection strains (G184B and G186B) from Panama were grouped into class 3 by this analysis. A group of five H. capsulatum isolates obtained from patients with AIDS in New York City were typed into a new class 5 on the basis of yps-3 polymorphisms; those organisms fell into two broad mitochondrial DNA patterns, designated 5b and 5c. Two new isolates from Panama were also members of this broad yps-3 class 5 group, but they exhibited a distinct mitochondrial DNA profile (class 5a). A sixth class was detected in DNA obtained from a patient with AIDS from Panama; that DNA had unique RFLP profiles with respect to both probes. These observations suggest that the Histoplasma-specific yps-3 gene probe is a sensitive tool for typing H. capsulatum in clinical specimens. Additionally, these studies provide molecular support for the hypothesis that AIDS-associated histoplasmosis in nonendemic areas is due to reactivation of a previously acquired infection.
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Affiliation(s)
- E J Keath
- Department of Biology, Saint Louis University, Missouri 63103
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Spitzer ED, Spitzer SG. Use of a dispersed repetitive DNA element to distinguish clinical isolates of Cryptococcus neoformans. J Clin Microbiol 1992; 30:1094-7. [PMID: 1349898 PMCID: PMC265231 DOI: 10.1128/jcm.30.5.1094-1097.1992] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We isolated a recombinant phage from a Cryptococcus neoformans genomic library that contains a member of a dispersed family of repetitive DNA elements. This clone, CNRE-1, hybridized to at least seven chromosomes in C. neoformans on the basis of pulsed-field gel analysis. Hybridization of CNRE-1 to restriction digests of genomic DNA confirmed that there are multiple copies of this element and that restriction fragment length polymorphisms are present in strains from different serotypes of C. neoformans. The utility of this probe as an epidemiologic marker was determined by testing cryptococcal isolates from a single hospital. Five isolates from four patients were closely related to a serotype A reference strain, whereas five other isolates from four additional patients exhibited distinct patterns. In two patients, the isolates obtained during recurrent cryptococcal infections were identical to the original isolates.
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Affiliation(s)
- E D Spitzer
- Department of Pathology, School of Medicine, State University of New York, Stony Brook 11794-8691
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Abstract
The rapid and thus far generally inexorable rise in HIV infections has led to a series of opportunistic infection that includes those caused by bacteria, yeasts, and members of the Eumycetes. The infections range in prevalence from occasional to highly prevalent, in severity from trivial to fatal, and in anatomic areas involved from local to disseminated. They occur as isolated, concurrent, or sequential infections with regard to other opportunistic diseases. Some vary in their geographic distribution. They may be newly acquired or reactivated and occur early or late in the course of HIV infection. Bacterial infections are usually easily treated, although they frequently disseminate and often recur after seemingly appropriate treatment. In contrast, all but the mildest fungal infections are difficult to treat and even more difficult or impossible to eradicate. The diagnosis of bacterial and fungal infections begins with clinical suspicion and involves relatively standard methodology. Treatment of the systemic mycoses and some bacterial infections in HIV infected patients is punctuated by exaggerated side effects of therapy, frequent relapses, and the need for maintenance suppressive therapy.
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Affiliation(s)
- E S Daar
- Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California
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Eissenberg LG, Goldman WE. Histoplasma variation and adaptive strategies for parasitism: new perspectives on histoplasmosis. Clin Microbiol Rev 1991; 4:411-21. [PMID: 1747859 PMCID: PMC358209 DOI: 10.1128/cmr.4.4.411] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
This review summarizes the biology of Histoplasma capsulatum in relation to a wide variety of corresponding pathologies in histoplasmosis. Features of these disease syndromes can be explained in part by natural variations within the fungal population and adaptations made by individual organisms to specific environments. H. capsulatum grows as mycelia and conidia in the soil; once inhaled, the organism undergoes a dramatic morphological and physiological conversion to a yeast form. The yeasts proliferate within the phagolysosomes of macrophages, using a variety of specific strategies for intracellular survival. Even avirulent strains or variants are able to avoid being killed by macrophages and instead establish inapparent or persistent infections. The ingested avirulent organisms assume enlarged shapes similar in appearance to those seen in histological sections of tissues from patients with histoplasmosis. Respiratory tract epithelial cells also appear to play a role in persistence: within them yeasts undergo phenotypic switching akin to the phase variation observed in other pathogens. This particular change involves the loss or modification of cell wall alpha-(1,3)-glucan, which is also correlated with the spontaneous appearance of avirulent variants. The repertoire of adaptive responses and natural variations within this species probably evolved from the need to adjust to a wide range of dynamic environments. In combination with the immune status of the host, these characteristics of H. capsulatum appear to influence the epidemiology, extent, and persistence of histoplasmosis.
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Affiliation(s)
- L G Eissenberg
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110
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Polak A, Hartman PG. Antifungal chemotherapy--are we winning? PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 1991; 37:181-269. [PMID: 1763183 DOI: 10.1007/978-3-0348-7139-6_5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- A Polak
- F. Hoffmann-La Roche Ltd, Basel, Switzerland
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