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Cogliati M, Chidebelu PE, Hitchcock M, Chen M, Rickerts V, Ackermann S, Desnos Ollivier M, Inácio J, Nawrot U, Florek M, Kwon-Chung KJ, Yang DH, Firacative C, Puime CA, Escandon P, Bertout S, Roger F, Xu J. Multi-locus sequence typing and phylogenetics of Cryptococcus neoformans AD hybrids. Fungal Genet Biol 2024; 170:103861. [PMID: 38128716 DOI: 10.1016/j.fgb.2023.103861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 12/06/2023] [Accepted: 12/18/2023] [Indexed: 12/23/2023]
Abstract
Hybrid AD strains of the human pathogenic Cryptococcus neoformans species complex have been reported from many parts of the world. However, their origin, diversity, and evolution are incompletely understood. In this study, we analyzed 102 AD hybrid strains representing 21 countries on five continents. For each strain, we obtained its mating type and its allelic sequences at each of the seven loci that have been used for genotyping haploid serotypes A and D strains of the species complex by the Cryptococcus research community. Our results showed that most AD hybrids exhibited loss of heterozygosity at one or more of the seven analyzed loci. Phylogenetic and population genetic analyses of the allelic sequences revealed multiple origins of the hybrids within each continent, dating back to one million years ago in Africa and up to the present in other continents. We found evidence for clonal reproduction and long-distance dispersal of these hybrids in nature. Comparisons with the global haploid serotypes A and D strains identified new alleles and new haploid multi-locus genotypes in AD hybrids, consistent with the presence of yet-to-be discovered genetic diversity in haploid populations of this species complex in nature. Together, our results indicate that AD hybrids can be effectively genotyped using the same multi-locus sequencing type approach as that established for serotypes A and D strains. Our comparisons of the AD hybrids among each other as well as with the global haploid serotypes A and D strains revealed novel genetic diversity as well as evidence for multiple origins and dynamic evolution of these hybrids in nature.
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Affiliation(s)
- M Cogliati
- Lab. Medical Mycology, Dept. Biomedical Sciences for Health, Università degli Studi di Milano, Milano, Italy.
| | - P E Chidebelu
- Department of Microbiology, University of Nigeria, Nsukka, Enugu State, Nigeria
| | - M Hitchcock
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - M Chen
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Chanzheng Hospital, Second Military Medical University, Shanghai, China
| | | | | | - M Desnos Ollivier
- Institut Pasteur, Université de Paris, CNRS UMR2000, Molecular Mycology Unit, National Reference Center for Invasive Mycoses and Antifungals, Paris, France
| | - J Inácio
- School of Applied Sciences, University of Brighton, Brighton, UK
| | - U Nawrot
- Department of Pharmaceutical Microbiology and Parasitology, Wroclaw Medical University, Wroclaw, Poland
| | - M Florek
- Department of Pathology, Faculty of Veterinary Medicine, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
| | - K J Kwon-Chung
- Molecular Microbiology Section, Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases NIH, Bethesda, USA
| | - D-H Yang
- Molecular Microbiology Section, Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases NIH, Bethesda, USA
| | - C Firacative
- Studies in Translational Microbiology and Emerging Diseases (MICROS) Research Group, School of Medicine and Health Sciences, Universidad de Rosario, Bogotá, Colombia
| | - C A Puime
- Unidad de Parasitología y Micología, Departamento de Laboratorios de Salud Pública, Ministerio de Salud Pública, Montevideo, Uruguay
| | - P Escandon
- Grupo de Microbiología, Instituto Nacional de Salud, Bogotá, Colombia
| | - S Bertout
- Laboratoire de Parasitologie et Mycologie Médicale, UMI 233 TransVIHMI, University of Montpellier, IRD, INSERM, Montpellier, France
| | - F Roger
- Laboratoire de Parasitologie et Mycologie Médicale, UMI 233 TransVIHMI, University of Montpellier, IRD, INSERM, Montpellier, France
| | - J Xu
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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2
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Zhang L, Wang S, Hong N, Li M, Liu Y, Zhou T, Peng Y, Hu C, Li X, Zhang Z, Guo M, Cogliati M, Hitchcock M, Xu J, Chen M, Liao G. Genotypic diversity and antifungal susceptibility of Cryptococcus neoformans species complex from China, including the diploid VNIII isolates from HIV-infected patients in Chongqing region. Med Mycol 2023; 61:myad119. [PMID: 37985734 DOI: 10.1093/mmy/myad119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 11/07/2023] [Accepted: 11/15/2023] [Indexed: 11/22/2023] Open
Abstract
Although previous studies on the genotypic diversity and antifungal susceptibility of the Cryptococcus neoformans species complex (CNSC) isolates from China revealed ST5 genotype isolates being dominant, the information about the CNSC isolates from Chinese HIV-infected patients is limited. In this study, 171 CNSC isolates from HIV-infected patients in the Chongqing region of Southwest China were genotyped using the International Society for Human and Animal Mycology-multilocus sequence typing consensus scheme, and their antifungal drug susceptibilities were determined following CLSI M27-A3 guidelines. Among 171 isolates, six sequence types (STs) were identified, including the dominant ST5 isolates, the newly reported ST15, and four diploid VNIII isolates (ST632/ST636). Moreover, a total of 1019 CNSC isolates with STs and HIV-status information were collected and analyzed from Mainland China in the present study. A minimum spanning analysis grouped these 1019 isolates into three main subgroups, which were dominated by the ST5 clonal complex (CC5), followed by the ST31 clonal complex (CC31) and ST93 clonal complex (CC93). The trend of resistance or decreasing susceptibility of clinical CNSC isolates to azole agents within HIV-infected patients from the Chongqing region is increasing, especially resistance to fluconazole.
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Affiliation(s)
- Lanyu Zhang
- College of Pharmaceutical Sciences, Southwest University, Chongqing, China
| | - Saisai Wang
- College of Pharmaceutical Sciences, Southwest University, Chongqing, China
| | - Nan Hong
- Department of Dermatology, Jinling Hospital, School of Medicine of Nanjing University, Nanjing, China
| | - Muyuan Li
- College of Pharmaceutical Sciences, Southwest University, Chongqing, China
| | - Yiting Liu
- Graduate School, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Tao Zhou
- College of Pharmaceutical Sciences, Southwest University, Chongqing, China
| | - Yan Peng
- College of Pharmaceutical Sciences, Southwest University, Chongqing, China
| | - Changhua Hu
- College of Pharmaceutical Sciences, Southwest University, Chongqing, China
| | - Xiaoxu Li
- The Medical Research Institute (MRI), Southwest University, Chongqing, China
| | - Zhen Zhang
- Department of Clinical Laboratory, Chongqing General Hospital, Chongqing, China
| | - Mengzhu Guo
- Department of Dermatology, General Hospital of Southern Theatre Command, Guangzhou, China
| | - Massimo Cogliati
- Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milano, Italy
| | - Megan Hitchcock
- Department of Biology, McMaster University, Hamilton, Canada
| | - Jianping Xu
- Department of Biology, McMaster University, Hamilton, Canada
| | - Min Chen
- Department of Dermatology, Shanghai Key Laboratory of Molecular Medical Mycology, Changzheng Hospital, Shanghai, China
| | - Guojian Liao
- College of Pharmaceutical Sciences, Southwest University, Chongqing, China
- The Medical Research Institute (MRI), Southwest University, Chongqing, China
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3
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Agustinho DP, Brown HL, Chen G, Gaylord EA, Geddes-McAlister J, Brent MR, Doering TL. Unbiased discovery of natural sequence variants that influence fungal virulence. Cell Host Microbe 2023; 31:1910-1920.e5. [PMID: 37898126 PMCID: PMC10842055 DOI: 10.1016/j.chom.2023.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 08/18/2023] [Accepted: 10/02/2023] [Indexed: 10/30/2023]
Abstract
Isolates of Cryptococcus neoformans, a fungal pathogen that kills over 112,000 people each year, differ from a 19-Mb reference genome at a few thousand up to almost a million DNA sequence positions. We used bulked segregant analysis and association analysis, genetic methods that require no prior knowledge of sequence function, to address the key question of which naturally occurring sequence variants influence fungal virulence. We identified a region containing such variants, prioritized them, and engineered strains to test our findings in a mouse model of infection. At one locus, we identified a 4-nt variant in the PDE2 gene that occurs in common laboratory strains and severely truncates the encoded phosphodiesterase. The resulting loss of phosphodiesterase activity significantly impacts virulence. Our studies demonstrate a powerful and unbiased strategy for identifying key genomic regions in the absence of prior information and provide significant sequence and strain resources to the community.
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Affiliation(s)
- Daniel Paiva Agustinho
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Holly Leanne Brown
- Department of Computer Science & Engineering, Washington University, St. Louis, MO 63130, USA
| | - Guohua Chen
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Elizabeth Anne Gaylord
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | | - Michael Richard Brent
- Department of Computer Science & Engineering, Washington University, St. Louis, MO 63130, USA; Department of Genetics and Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Tamara Lea Doering
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Howard-Jones AR, Sparks R, Pham D, Halliday C, Beardsley J, Chen SCA. Pulmonary Cryptococcosis. J Fungi (Basel) 2022; 8:1156. [PMID: 36354923 PMCID: PMC9696922 DOI: 10.3390/jof8111156] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 10/26/2022] [Accepted: 10/29/2022] [Indexed: 07/25/2023] Open
Abstract
Pulmonary cryptococcosis describes an invasive lung mycosis caused by Cryptococcus neoformans or Cryptococcus gattii complex. It is often a high-consequence disease in both immunocompromised and immunocompetent populations, and may be misdiagnosed as pulmonary malignancy, leading to a delay in therapy. Epidemiology follows that of cryptococcal meningoencephalitis, with C. gattii infection more common in certain geographic regions. Diagnostic tools include histopathology, microscopy and culture, and the detection of cryptococcal polysaccharide antigen or Cryptococcus-derived nucleic acids. All patients with lung cryptococcosis should have a lumbar puncture and cerebral imaging to exclude central nervous system disease. Radiology is key, both as an adjunct to laboratory testing and as the initial means of detection in asymptomatic patients or those with non-specific symptoms. Pulmonary cryptococcomas (single or multiple) may also be associated with disseminated disease and/or cryptococcal meningitis, requiring prolonged treatment regimens. Optimal management for severe disease requires extended induction (amphotericin B and flucytosine) and consolidation therapy (fluconazole) with close clinical monitoring. Susceptibility testing is of value for epidemiology and in regions where relatively high minimum inhibitory concentrations to azoles (particularly fluconazole) have been noted. Novel diagnostic tools and therapeutic agents promise to improve the detection and treatment of cryptococcosis, particularly in low-income settings where the disease burden is high.
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Affiliation(s)
- Annaleise R. Howard-Jones
- Centre for Infectious Diseases & Microbiology Laboratory Services, New South Wales Health Pathology—Institute of Clinical Pathology & Medical Research, Westmead Hospital, Westmead, NSW 2145, Australia
- Faculty of Medicine and Health, University of Sydney, Camperdown, NSW 2145, Australia
- Sydney Institute for Infectious Diseases, The University of Sydney, Sydney, NSW 2006, Australia
| | - Rebecca Sparks
- Centre for Infectious Diseases & Microbiology Laboratory Services, New South Wales Health Pathology—Institute of Clinical Pathology & Medical Research, Westmead Hospital, Westmead, NSW 2145, Australia
| | - David Pham
- Centre for Infectious Diseases & Microbiology Laboratory Services, New South Wales Health Pathology—Institute of Clinical Pathology & Medical Research, Westmead Hospital, Westmead, NSW 2145, Australia
| | - Catriona Halliday
- Centre for Infectious Diseases & Microbiology Laboratory Services, New South Wales Health Pathology—Institute of Clinical Pathology & Medical Research, Westmead Hospital, Westmead, NSW 2145, Australia
| | - Justin Beardsley
- Faculty of Medicine and Health, University of Sydney, Camperdown, NSW 2145, Australia
- Sydney Institute for Infectious Diseases, The University of Sydney, Sydney, NSW 2006, Australia
- Westmead Institute for Medical Research, Westmead, NSW 2145, Australia
| | - Sharon C.-A. Chen
- Centre for Infectious Diseases & Microbiology Laboratory Services, New South Wales Health Pathology—Institute of Clinical Pathology & Medical Research, Westmead Hospital, Westmead, NSW 2145, Australia
- Faculty of Medicine and Health, University of Sydney, Camperdown, NSW 2145, Australia
- Sydney Institute for Infectious Diseases, The University of Sydney, Sydney, NSW 2006, Australia
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Michelotti LA, Sun S, Heitman J, James TY. Clonal evolution in serially passaged Cryptococcus neoformans × deneoformans hybrids reveals a heterogenous landscape of genomic change. Genetics 2022; 220:iyab142. [PMID: 34849836 PMCID: PMC8733418 DOI: 10.1093/genetics/iyab142] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 08/25/2021] [Indexed: 11/14/2022] Open
Abstract
Cryptococcus neoformans × deneoformans hybrids (also known as serotype AD hybrids) are basidiomycete yeasts that are common in a clinical setting. Like many hybrids, the AD hybrids are largely locked at the F1 stage and are mostly unable to undergo normal meiotic reproduction. However, these F1 hybrids, which display a high (∼10%) sequence divergence are known to genetically diversify through mitotic recombination and aneuploidy, and this diversification may be adaptive. In this study, we evolved a single AD hybrid genotype in six diverse environments by serial passaging and then used genome resequencing of evolved clones to determine evolutionary mechanisms of adaptation. The evolved clones generally increased fitness after passaging, accompanied by an average of 3.3 point mutations, 2.9 loss of heterozygosity (LOH) events, and 0.7 trisomic chromosomes per clone. LOH occurred through nondisjunction of chromosomes, crossing over consistent with break-induced replication, and gene conversion, in that order of prevalence. The breakpoints of these recombination events were significantly associated with regions of the genome with lower sequence divergence between the parents and clustered in sub-telomeric regions, notably in regions that had undergone introgression between the two parental species. Parallel evolution was observed, particularly through repeated homozygosity via nondisjunction, yet there was little evidence of environment-specific parallel change for either LOH, aneuploidy, or mutations. These data show that AD hybrids have both a remarkable genomic plasticity and yet are challenged in the ability to recombine through sequence divergence and chromosomal rearrangements, a scenario likely limiting the precision of adaptive evolution to novel environments.
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Affiliation(s)
- Lucas A Michelotti
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Timothy Y James
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
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6
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Boekhout T, Aime MC, Begerow D, Gabaldón T, Heitman J, Kemler M, Khayhan K, Lachance MA, Louis EJ, Sun S, Vu D, Yurkov A. The evolving species concepts used for yeasts: from phenotypes and genomes to speciation networks. FUNGAL DIVERS 2021; 109:27-55. [PMID: 34720775 PMCID: PMC8550739 DOI: 10.1007/s13225-021-00475-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 05/31/2021] [Indexed: 12/12/2022]
Abstract
Here we review how evolving species concepts have been applied to understand yeast diversity. Initially, a phenotypic species concept was utilized taking into consideration morphological aspects of colonies and cells, and growth profiles. Later the biological species concept was added, which applied data from mating experiments. Biophysical measurements of DNA similarity between isolates were an early measure that became more broadly applied with the advent of sequencing technology, leading to a sequence-based species concept using comparisons of parts of the ribosomal DNA. At present phylogenetic species concepts that employ sequence data of rDNA and other genes are universally applied in fungal taxonomy, including yeasts, because various studies revealed a relatively good correlation between the biological species concept and sequence divergence. The application of genome information is becoming increasingly common, and we strongly recommend the use of complete, rather than draft genomes to improve our understanding of species and their genome and genetic dynamics. Complete genomes allow in-depth comparisons on the evolvability of genomes and, consequently, of the species to which they belong. Hybridization seems a relatively common phenomenon and has been observed in all major fungal lineages that contain yeasts. Note that hybrids may greatly differ in their post-hybridization development. Future in-depth studies, initially using some model species or complexes may shift the traditional species concept as isolated clusters of genetically compatible isolates to a cohesive speciation network in which such clusters are interconnected by genetic processes, such as hybridization.
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Affiliation(s)
- Teun Boekhout
- Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands
- Institute of Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, Amsterdam, The Netherlands
| | - M. Catherine Aime
- Dept Botany and Plant Pathology, College of Agriculture, Purdue University, West Lafayette, IN 47907 USA
| | - Dominik Begerow
- Evolution of Plants and Fungi, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Toni Gabaldón
- Barcelona Supercomputing Centre (BSC–CNS), Jordi Girona, 29, 08034 Barcelona, Spain
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, 08028 Barcelona, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), Barcelona, Spain
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710 USA
| | - Martin Kemler
- Evolution of Plants and Fungi, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Kantarawee Khayhan
- Department of Microbiology and Parasitology, Faculty of Medical Sciences, University of Phayao, Phayao, 56000 Thailand
| | - Marc-André Lachance
- Department of Biology, University of Western Ontario, London, ON N6A 5B7 Canada
| | - Edward J. Louis
- Department of Genetics and Genome Biology, Genetic Architecture of Complex Traits, University of Leicester, Leicester, LE1 7RH UK
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710 USA
| | - Duong Vu
- Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands
| | - Andrey Yurkov
- German Collection of Microorganisms and Cell Cultures, Leibniz Institute DSMZ, Brunswick, Germany
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Maufrais C, de Oliveira L, Bastos RW, Moyrand F, Reis FCG, Valero C, Gimenez B, Josefowicz LJ, Goldman GH, Rodrigues ML, Janbon G. Population genomic analysis of Cryptococcus Brazilian isolates reveals an African type subclade distribution. G3 (BETHESDA, MD.) 2021; 11:jkab107. [PMID: 33822048 PMCID: PMC8495746 DOI: 10.1093/g3journal/jkab107] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 03/29/2021] [Indexed: 12/22/2022]
Abstract
The genomes of a large number of Cryptococcus neoformans isolates have been sequenced and analyzed in recent years. These genomes have been used to understand the global population structure of this opportunistic pathogen. However, only a small number of South American isolates have been considered in these studies, and the population structure of C. neoformans in this part of the world remains elusive. Here, we analyzed the genomic sequences of 53 Brazilian Cryptococcus isolates and deciphered the C. neoformans population structure in this country. Our data reveal an African-like structure that suggested repeated intercontinental transports from Africa to South America. We also identified a mutator phenotype in one VNBII Brazilian isolate, exemplifying how fast-evolving isolates can shape the Cryptococcus population structure. Finally, phenotypic analyses revealed wide diversity but not lineage specificity in the expression of classical virulence traits within the set of isolates.
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Affiliation(s)
- Corinne Maufrais
- Unité Biologie des ARN des Pathogènes Fongiques, Département de Mycologie, Institut Pasteur, F-75015 Paris, France
- Institut Pasteur, HUB Bioinformatique et Biostatistique, C3BI, USR 3756 IP CNRS, F-75015 Paris, France
| | - Luciana de Oliveira
- Unité Biologie des ARN des Pathogènes Fongiques, Département de Mycologie, Institut Pasteur, F-75015 Paris, France
| | - Rafael W Bastos
- Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, 14040-903 Ribeirão Preto, Brazil
| | - Frédérique Moyrand
- Unité Biologie des ARN des Pathogènes Fongiques, Département de Mycologie, Institut Pasteur, F-75015 Paris, France
| | - Flavia C G Reis
- Instituto Carlos Chagas, Fundação Oswaldo Cruz (FIOCRUZ), 81310-020 Curitiba, Brazil
- Centro de Desenvolvimento Tecnologico em Saude (CDTS-Fiocruz), 21040-361 Rio de Janeiro, Brazil
| | - Clara Valero
- Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, 14040-903 Ribeirão Preto, Brazil
| | - Bianca Gimenez
- Instituto Carlos Chagas, Fundação Oswaldo Cruz (FIOCRUZ), 81310-020 Curitiba, Brazil
| | - Luisa J Josefowicz
- Instituto Carlos Chagas, Fundação Oswaldo Cruz (FIOCRUZ), 81310-020 Curitiba, Brazil
| | - Gustavo H Goldman
- Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, 14040-903 Ribeirão Preto, Brazil
| | - Marcio L Rodrigues
- Instituto Carlos Chagas, Fundação Oswaldo Cruz (FIOCRUZ), 81310-020 Curitiba, Brazil
- Instituto de Microbiologia Paulo de Góes (IMPG), Universidade Federal do Rio de Janeiro, 21941-902 Rio de Janeiro, Brazil
| | - Guilhem Janbon
- Unité Biologie des ARN des Pathogènes Fongiques, Département de Mycologie, Institut Pasteur, F-75015 Paris, France
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You M, Xu J. What Are the Best Parents for Hybrid Progeny? An Investigation into the Human Pathogenic Fungus Cryptococcus. J Fungi (Basel) 2021; 7:jof7040299. [PMID: 33920829 PMCID: PMC8071107 DOI: 10.3390/jof7040299] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 04/12/2021] [Accepted: 04/14/2021] [Indexed: 12/13/2022] Open
Abstract
Hybridization between more divergent organisms is likely to generate progeny with more novel genetic interactions and genetic variations. However, the relationship between parental genetic divergence and progeny phenotypic variation remains largely unknown. Here, using strains of the human pathogenic Cryptococcus, we investigated the patterns of such a relationship. Twenty-two strains with up to 15% sequence divergence were mated. Progeny were genotyped at 16 loci. Parental strains and their progeny were phenotyped for growth ability at two temperatures, melanin production at seven conditions, and susceptibility to the antifungal drug fluconazole. We observed three patterns of relationships between parents and progeny for each phenotypic trait, including (i) similar to one of the parents, (ii) intermediate between the parents, and (iii) outside the parental phenotypic range. We found that as genetic distance increases between parental strains, progeny showed increased fluconazole resistance and growth at 37 °C but decreased melanin production under various oxidative and nitrosative stresses. Our findings demonstrate that, depending on the traits, both evolutionarily more similar strains and more divergent strains may be better parents to generate progeny with hybrid vigor. Together, the results indicate the enormous potential of Cryptococcus hybrids in their evolution and adaptation to diverse conditions.
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9
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Okurut S, Boulware DR, Olobo J, Meya DB. Landmark clinical observations and immunopathogenesis pathways linked to HIV and Cryptococcus fatal central nervous system co-infection. Mycoses 2020; 63:840-853. [PMID: 32472727 PMCID: PMC7416908 DOI: 10.1111/myc.13122] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 05/21/2020] [Accepted: 05/22/2020] [Indexed: 12/13/2022]
Abstract
Cryptococcal meningitis remains one of the leading causes of death among HIV-infected adults in the fourth decade of HIV era in sub-Saharan Africa, contributing to 10%-20% of global HIV-related deaths. Despite widespread use and early induction of ART among HIV-infected adults, incidence of cryptococcosis remains significant in those with advanced HIV disease. Cryptococcus species that causes fatal infection follows systemic spread from initial environmental acquired infection in lungs to antigenaemia and fungaemia in circulation prior to establishment of often fatal disease, cryptococcal meningitis in the CNS. Cryptococcus person-to-person transmission is uncommon, and deaths related to blood infection without CNS involvement are rare. Keen to the persistent high mortality associated with HIV-cryptococcal meningitis, seizures are common among a third of the patients, altered mental status is frequent, anaemia is prevalent with ensuing brain hypoxia and at autopsy, brain fibrosis and infarction are evident. In addition, fungal burden is 3-to-4-fold higher in those with seizures. And high immune activation together with exacerbated inflammation and elevated PD-1/PD-L immune checkpoint expression is immunomodulated phenotypes elevated in CSF relative to blood. Lastly, though multiple Cryptococcus species cause disease in this setting, observations are mostly generalised to cryptococcal infection/meningitis or regional dominant species (C neoformans or gattii complex) that may limit our understanding of interspecies differences in infection, progression, treatment or recovery outcome. Together, these factors and underlying mechanisms are hypotheses generating for research to find targets to prevent infection or adequate therapy to prevent persistent high mortality with current optimal therapy.
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Affiliation(s)
- Samuel Okurut
- Research DepartmentInfectious Diseases InstituteMakerere UniversityKampalaUganda
- Department of MicrobiologySchool of Biomedical SciencesCollege of Health SciencesMakerere UniversityKampalaUganda
| | - David R. Boulware
- Division of Infectious Diseases and International MedicineDepartment of MedicineUniversity of MinnesotaMinneapolisMinnesota
| | - Joseph Olobo
- Department of Immunology and Molecular BiologySchool of Biomedical SciencesCollege of Health SciencesMakerere UniversityKampalaUganda
| | - David B. Meya
- Research DepartmentInfectious Diseases InstituteMakerere UniversityKampalaUganda
- Division of Infectious Diseases and International MedicineDepartment of MedicineUniversity of MinnesotaMinneapolisMinnesota
- Department of MedicineSchool of MedicineCollege of Health SciencesMakerere UniversityKampalaUganda
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10
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Wang Y, Xu J. Mitochondrial Genome Polymorphisms in the Human Pathogenic Fungus Cryptococcus neoformans. Front Microbiol 2020; 11:706. [PMID: 32373103 PMCID: PMC7186387 DOI: 10.3389/fmicb.2020.00706] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 03/26/2020] [Indexed: 12/11/2022] Open
Abstract
The Cryptococcus complex consists of at least seven evolutionary divergent lineages and causes ∼200,000 fatal human infections each year worldwide. The dominant lineage is Cryptococcus neoformans which consists of three haploid clades VNI, VNII, and VNB, their haploid hybrids, and various diploids derived from intra- and inter-clade mating events. In this study, we analyzed the mitogenomes of 184 strains of C. neoformans. Our analyses revealed that all 184 mitogenomes contained the same 15 protein-coding genes in the same gene order. However, their mitogenome sizes varied between 24,740 and 31,327 bp, primarily due to differences in the number and size of mitochondrial introns. Twelve nucleotide sites within five mitochondrial genes were found to contain introns in at least one of the 184 strains, ranging from 2 to 7 introns within each mitogenome. The concatenated mitochondrial exon sequences of the 15 protein-coding genes and two rRNA genes showed that VNI, VNII, and VNB strains were separated into distinct clades or sub-clades, largely consistent with results based on nuclear genome SNPs. However, several novel findings were observed. First, one strain of the VNB clade contained mitogenome exon sequences identical to the main VNI mitogenome type but was distant to other VNB mitogenomes. Second, hybrids among clades VNI, VNII, and VNB identified based on their nuclear genome SNPs contained mitogenomes from different clades, with evidence of their mitogenomes inherited from either the MAT a or the MAT α parents. Third, the eight diploid VNB (C. neoformans) × VNIV (C. deneoformans) hybrids contained recombinant mitogenomes. Fourth, analyses of intron distribution and the paired exon-intron phylogenies for each of the 12 exon-intron pairs suggested frequent gains and losses of mitochondrial introns during the evolution of C. neoformans. The combined mitogenome exon-based phylogeny and intron distributions suggested that clades VNI, VNII and VNB could be further divided into sub-clades. Together, our results revealed a dynamic evolution of mitochondrial genomes in this important human fungal pathogen.
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Affiliation(s)
- Yue Wang
- Department of Biology, McMaster University, Hamilton, ON, Canada
| | - Jianping Xu
- Department of Biology, McMaster University, Hamilton, ON, Canada
- Institute of Bast Fiber Crops and Center of Southern Economic Crops, Chinese Academy of Agricultural Sciences, Changsha, China
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11
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Coelho C, Farrer RA. Pathogen and host genetics underpinning cryptococcal disease. ADVANCES IN GENETICS 2020; 105:1-66. [PMID: 32560785 DOI: 10.1016/bs.adgen.2020.02.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cryptococcosis is a severe fungal disease causing 220,000 cases of cryptococcal meningitis yearly. The etiological agents of cryptococcosis are taxonomically grouped into at least two species complexes belonging to the genus Cryptococcus. All of these yeasts are environmentally ubiquitous fungi (often found in soil, leaves and decaying wood, tree hollows, and associated with bird feces especially pigeon guano). Infection in a range of animals including humans begins following inhalation of spores or aerosolized yeasts. Recent advances provide fundamental insights into the factors from both the pathogen and its hosts which influence pathogenesis and disease. The complex interactions leading to disease in mammalian hosts have also updated from the availability of better genomic tools and datasets. In this review, we discuss recent genetic research on Cryptococcus, covering the epidemiology, ecology, and evolution of Cryptococcus pathogenic species. We also discuss the insights into the host immune response obtained from the latest genetic modified host models as well as insights from monogenic disorders in humans. Finally we highlight outstanding questions that can be answered in the near future using bioinformatics and genomic tools.
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Affiliation(s)
- Carolina Coelho
- Medical Research Council Centre for Medical Mycology at the University of Exeter, Exeter, United Kingdom
| | - Rhys A Farrer
- Medical Research Council Centre for Medical Mycology at the University of Exeter, Exeter, United Kingdom.
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12
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Hybridization Facilitates Adaptive Evolution in Two Major Fungal Pathogens. Genes (Basel) 2020; 11:genes11010101. [PMID: 31963231 PMCID: PMC7017293 DOI: 10.3390/genes11010101] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/02/2020] [Accepted: 01/14/2020] [Indexed: 01/13/2023] Open
Abstract
Hybridization is increasingly recognized as an important force impacting adaptation and evolution in many lineages of fungi. During hybridization, divergent genomes and alleles are brought together into the same cell, potentiating adaptation by increasing genomic plasticity. Here, we review hybridization in fungi by focusing on two fungal pathogens of animals. Hybridization is common between the basidiomycete yeast species Cryptococcus neoformans × Cryptococcus deneoformans, and hybrid genotypes are frequently found in both environmental and clinical settings. The two species show 10-15% nucleotide divergence at the genome level, and their hybrids are highly heterozygous. Though largely sterile and unable to mate, these hybrids can propagate asexually and generate diverse genotypes by nondisjunction, aberrant meiosis, mitotic recombination, and gene conversion. Under stress conditions, the rate of such genetic changes can increase, leading to rapid adaptation. Conversely, in hybrids formed between lineages of the chytridiomycete frog pathogen Batrachochytrium dendrobatidis (Bd), the parental genotypes are considerably less diverged (0.2% divergent). Bd hybrids are formed from crosses between lineages that rarely undergo sex. A common theme in both species is that hybrids show genome plasticity via aneuploidy or loss of heterozygosity and leverage these mechanisms as a rapid way to generate genotypic/phenotypic diversity. Some hybrids show greater fitness and survival in both virulence and virulence-associated phenotypes than parental lineages under certain conditions. These studies showcase how experimentation in model species such as Cryptococcus can be a powerful tool in elucidating the genotypic and phenotypic consequences of hybridization.
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Samarasinghe H, Vogan A, Pum N, Xu J. Patterns of allele distribution in a hybrid population of the Cryptococcus neoformans species complex. Mycoses 2019; 63:275-283. [PMID: 31774582 DOI: 10.1111/myc.13040] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 11/18/2019] [Accepted: 11/22/2019] [Indexed: 11/28/2022]
Abstract
BACKGROUND The sister yeast species Cryptococcus neoformans (serotype A) and Cryptococcus deneoformans (serotype D) are causative agents of deadly cryptococcosis and fungal meningoencephalitis. These haploid yeasts can hybridise in nature, giving rise to AD hybrids that are predominantly diploid or aneuploid. Despite their increasing prevalence in clinical settings, much remains unknown about the allelic distribution patterns in AD hybrid strains. OBJECTIVES This study aims to characterise allele distributions in AD hybrids derived from the same basidium as well as from multiple basidia in a laboratory-derived C neoformans × C deneoformans hybrid cross. METHODS We dissected a total of 1625 basidiospores from 31 basidia. The 297 basidiospores that successfully germinated were genotyped by molecular characterisation of 33 markers using PCR-RFLP, with at least two markers on each of the 14 chromosomes in the genome. RESULTS Of the 297 strains, 294 contained at least one heterozygous locus, with a mean heterozygosity of ~30% per strain. Most hybrid genomes and chromosomes displayed significantly distorted allele distributions, with offspring originating from the same basidium tended to have alleles at different loci from the same parent. More basidia were skewed in favour of C deneoformans alleles, the mitochondria-donor parent, than the C neoformans alleles. CONCLUSIONS The divergence between C neoformans and C deneoformans genomes has likely created co-adapted allelic combinations, with their co-segregation in hybrid offspring imparting a significant fitness benefit. However, the diversity of genotypes recovered here in a single hybridisation event indicates the enormous capacity of AD hybrids for adaptation and diversification.
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Affiliation(s)
| | - Aaron Vogan
- Department of Biology, McMaster University, Hamilton, ON, Canada
| | - Nicole Pum
- Department of Biology, McMaster University, Hamilton, ON, Canada
| | - Jianping Xu
- Department of Biology, McMaster University, Hamilton, ON, Canada
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Ergin Ç, Şengül M, Aksoy L, Döğen A, Sun S, Averette AF, Cuomo CA, Seyedmousavi S, Heitman J, Ilkit M. Cryptococcus neoformans Recovered From Olive Trees ( Olea europaea) in Turkey Reveal Allopatry With African and South American Lineages. Front Cell Infect Microbiol 2019; 9:384. [PMID: 31788454 PMCID: PMC6856141 DOI: 10.3389/fcimb.2019.00384] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 10/25/2019] [Indexed: 11/13/2022] Open
Abstract
Cryptococcus species are life-threatening human fungal pathogens that cause cryptococcal meningoencephalitis in both immunocompromised and healthy hosts. The natural environmental niches of Cryptococcus include pigeon (Columba livia) guano, soil, and a variety of tree species such as Eucalyptus camaldulensis, Ceratonia siliqua, Platanus orientalis, and Pinus spp. Genetic and genomic studies of extensive sample collections have provided insights into the population distribution and composition of different Cryptococcus species in geographic regions around the world. However, few such studies examined Cryptococcus in Turkey. We sampled 388 Olea europaea (olive) and 132 E. camaldulensis trees from seven locations in coastal and inland areas of the Aegean region of Anatolian Turkey in September 2016 to investigate the distribution and genetic diversity present in the natural Cryptococcus population. We isolated 84 Cryptococcus neoformans strains (83 MATα and 1 MAT a) and 3 Cryptococcus deneoformans strains (all MATα) from 87 (22.4% of surveyed) O. europaea trees; a total of 32 C. neoformans strains were isolated from 32 (24.2%) of the E. camaldulensis trees, all of which were MATα. A statistically significant difference was observed in the frequency of C. neoformans isolation between coastal and inland areas (P < 0.05). Interestingly, the MAT a C. neoformans isolate was fertile in laboratory crosses with VNI and VNB MATα tester strains and produced robust hyphae, basidia, and basidiospores, thus suggesting potential sexual reproduction in the natural population. Sequencing analyses of the URA5 gene identified at least five different genotypes among the isolates. Population genetics and genomic analyses revealed that most of the isolates in Turkey belong to the VNBII lineage of C. neoformans, which is predominantly found in southern Africa; these isolates are part of a distinct minor clade within VNBII that includes several isolates from Zambia and Brazil. Our study provides insights into the geographic distribution of different C. neoformans lineages in the Mediterranean region and highlights the need for wider geographic sampling to gain a better understanding of the natural habitats, migration, epidemiology, and evolution of this important human fungal pathogen.
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Affiliation(s)
- Çağri Ergin
- Department of Microbiology, Faculty of Medicine, Pamukkale University, Denizli, Turkey
| | - Mustafa Şengül
- Department of Microbiology, Faculty of Medicine, Pamukkale University, Denizli, Turkey
| | - Levent Aksoy
- Department of Microbiology, Faculty of Medicine, Pamukkale University, Denizli, Turkey
| | - Aylin Döğen
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Mersin, Mersin, Turkey
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States
| | - Anna F Averette
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States
| | - Christina A Cuomo
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, United States
| | - Seyedmojtaba Seyedmousavi
- Microbiology Service, Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, MD, United States
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States
| | - Macit Ilkit
- Division of Mycology, Department of Microbiology, Faculty of Medicine, University of Çukurova, Adana, Turkey
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15
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Rickerts V. [Climate change and systemic fungal infections]. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz 2019; 62:646-651. [PMID: 30923845 DOI: 10.1007/s00103-019-02931-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Climate change may cause profound and complex changes in the prevalence of infectious diseases. Obligate pathogenic fungi causing endemic mycoses and the agents of cryptococcosis are environmental pathogens adapted to environmental niches. They may be exposed to changing climatic conditions, which may change the epidemiology of human infections. OBJECTIVES To review documented changes in the epidemiology of endemic fungal infections and cryptococcosis. To review evidence that changing climate is a potential mechanism for changes in the epidemiology of these infections. METHODS A selective literature review focusing on endemic mycoses and cryptococcosis. RESULTS Changes in endemic regions of infections caused by C. gattii and selected endemic mycoses have been well documented. Significant increases in the incidence of infections have been demonstrated for some areas. Climatic factors (temperature, precipitation, and extreme weather events), changes in land use, distribution of potential host animals, and global trade routes are discussed as contributory factors. CONCLUSIONS Improved surveillance of fungal infections of humans and animals including molecular typing of clinical and environmental isolates is necessary to understand the epidemiology of these infections. The characterization of environmental niches, mechanisms of distribution of fungi, and fungal adaptation mechanisms are needed to guide prevention strategies.
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Affiliation(s)
- Volker Rickerts
- FG 16, Erreger von Mykosen, Mykobakteriosen und Parasitosen, Konsiliarlabor für Kryptokokkose und seltene Systemmykosen, Robert Koch-Institut, Seestraße 10, 13353, Berlin, Deutschland.
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16
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Samarasinghe H, Xu J. Hybrids and hybridization in the Cryptococcus neoformans and Cryptococcus gattii species complexes. INFECTION GENETICS AND EVOLUTION 2018; 66:245-255. [PMID: 30342094 DOI: 10.1016/j.meegid.2018.10.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 09/28/2018] [Accepted: 10/16/2018] [Indexed: 12/29/2022]
Abstract
The basidiomycetous yeasts of the Cryptococcus neoformans and Cryptococcus gattii species complexes (CNSC and CGSC respectively) are the causative agents of cryptococcosis, a set of life-threatening diseases affecting the central nervous system, lungs, skin, and other body sites of humans and other mammals. Both the CNSC and CGSC can be subdivided into varieties, serotypes, molecular types, and lineages based on structural variations, molecular characteristics and genetic sequences. Hybridization between the haploid lineages within and between the two species complexes is known to occur in natural and clinical settings, giving rise to intraspecific and interspecific diploid/aneuploid hybrid strains. Since their initial discovery in 1977, cryptococcal hybrids have been increasingly discovered in both clinical and environmental settings with over 30% of all cryptococcal infections in some regions of Europe being caused by hybrid strains. This review summarizes the major findings to date on cryptococcal hybrids, including their possible origins, prevalence, genomic profiles and phenotypic characteristics. Our analyses suggest that CNSC and CGSC can be an excellent model system for studying fungal hybridization.
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Affiliation(s)
- Himeshi Samarasinghe
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada
| | - Jianping Xu
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada.
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17
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Andrade-Silva LE, Ferreira-Paim K, Ferreira TB, Vilas-Boas A, Mora DJ, Manzato VM, Fonseca FM, Buosi K, Andrade-Silva J, Prudente BDS, Araujo NE, Sales-Campos H, da Silva MV, Júnior VR, Meyer W, Silva-Vergara ML. Genotypic analysis of clinical and environmental Cryptococcus neoformans isolates from Brazil reveals the presence of VNB isolates and a correlation with biological factors. PLoS One 2018; 13:e0193237. [PMID: 29505557 PMCID: PMC5837091 DOI: 10.1371/journal.pone.0193237] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 02/07/2018] [Indexed: 11/19/2022] Open
Abstract
Cryptococcal infections are mainly caused by members of the Cryptococcus neoformans species complex (molecular types VNI, VNII, VNB, VNIV and the AD hybrid VNIII). PCR of the mating type loci and MLST typing using the ISHAM-MLST consensus scheme were used to evaluate the genetic relationship of 102 (63 clinical and 39 environmental) C. neoformans isolates from Uberaba, Brazil and to correlate the obtained genotypes with clinical, antifungal susceptibility and virulence factor data. All isolates were mating type alpha. MLST identified 12 known and five new sequence types (ST). Fourteen STs were identified within the VNI isolates, with ST93 (57/102, 56%) and ST77 (19/102, 19%) being the most prevalent. From the nine VNII isolates previously identify by URA5-RFLP only four (ST40) were confirmed by MLST. The remaining five grouped within the VNB clade in the phylogenetic analysis corresponding to the sequence type ST504. Other two environmental isolates also grouped within VNB clade with the new sequence type ST527. The four VNII/ST40 isolates were isolated from CSF. The two VNIV sequence types (ST11 and ST160) were isolated from blood cultures. Two of six patients evaluated with more than one isolates had mixed infections. Amongst the VNI isolates 4 populations were identified, which showed differences in their susceptibility profiles, clinical outcome and virulence factors. These results reinforce that ST93 is the most prevalent ST in HIV-infected patients in the Southeastern region of Brazil. The finding of the VNB molecular type amongst environmental Brazilian isolates highlights that this genotype is not restricted to the African continent.
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Affiliation(s)
- Leonardo Euripedes Andrade-Silva
- Infectious Disease Department, Triangulo Mineiro Federal University, Uberaba, Brazil
- Clinical Pathology Department, Triangulo Mineiro Federal University, Uberaba, Brazil
| | - Kennio Ferreira-Paim
- Infectious Disease Department, Triangulo Mineiro Federal University, Uberaba, Brazil
- Clinical Pathology Department, Triangulo Mineiro Federal University, Uberaba, Brazil
- Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Marie Bashir Institute for Emerging Infectious Diseases and Biosecurity, Sydney Medical School-Westmead Hospital, The University of Sydney, Westmead Institute for Medical Research, Sydney, Australia
| | | | - Anderson Vilas-Boas
- Infectious Disease Department, Triangulo Mineiro Federal University, Uberaba, Brazil
| | - Delio José Mora
- Infectious Disease Department, Triangulo Mineiro Federal University, Uberaba, Brazil
| | | | | | - Kelli Buosi
- Infectious Disease Department, Triangulo Mineiro Federal University, Uberaba, Brazil
| | - Juliana Andrade-Silva
- Infectious Disease Department, Triangulo Mineiro Federal University, Uberaba, Brazil
| | | | - Natalia Evelyn Araujo
- Infectious Disease Department, Triangulo Mineiro Federal University, Uberaba, Brazil
| | | | | | | | - Wieland Meyer
- Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Marie Bashir Institute for Emerging Infectious Diseases and Biosecurity, Sydney Medical School-Westmead Hospital, The University of Sydney, Westmead Institute for Medical Research, Sydney, Australia
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Tracing Genetic Exchange and Biogeography of Cryptococcus neoformans var. grubii at the Global Population Level. Genetics 2017; 207:327-346. [PMID: 28679543 PMCID: PMC5586382 DOI: 10.1534/genetics.117.203836] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 06/28/2017] [Indexed: 11/18/2022] Open
Abstract
Cryptococcus neoformans var. grubii is the causative agent of cryptococcal meningitis, a significant source of mortality in immunocompromised individuals, typically human immunodeficiency virus/AIDS patients from developing countries. Despite the worldwide emergence of this ubiquitous infection, little is known about the global molecular epidemiology of this fungal pathogen. Here we sequence the genomes of 188 diverse isolates and characterize the major subdivisions, their relative diversity, and the level of genetic exchange between them. While most isolates of C. neoformans var. grubii belong to one of three major lineages (VNI, VNII, and VNB), some haploid isolates show hybrid ancestry including some that appear to have recently interbred, based on the detection of large blocks of each ancestry across each chromosome. Many isolates display evidence of aneuploidy, which was detected for all chromosomes. In diploid isolates of C. neoformans var. grubii (serotype AA) and of hybrids with C. neoformans var. neoformans (serotype AD) such aneuploidies have resulted in loss of heterozygosity, where a chromosomal region is represented by the genotype of only one parental isolate. Phylogenetic and population genomic analyses of isolates from Brazil reveal that the previously "African" VNB lineage occurs naturally in the South American environment. This suggests migration of the VNB lineage between Africa and South America prior to its diversification, supported by finding ancestral recombination events between isolates from different lineages and regions. The results provide evidence of substantial population structure, with all lineages showing multi-continental distributions; demonstrating the highly dispersive nature of this pathogen.
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Hagen F, Lumbsch HT, Arsic Arsenijevic V, Badali H, Bertout S, Billmyre RB, Bragulat MR, Cabañes FJ, Carbia M, Chakrabarti A, Chaturvedi S, Chaturvedi V, Chen M, Chowdhary A, Colom MF, Cornely OA, Crous PW, Cuétara MS, Diaz MR, Espinel-Ingroff A, Fakhim H, Falk R, Fang W, Herkert PF, Ferrer Rodríguez C, Fraser JA, Gené J, Guarro J, Idnurm A, Illnait-Zaragozi MT, Khan Z, Khayhan K, Kolecka A, Kurtzman CP, Lagrou K, Liao W, Linares C, Meis JF, Nielsen K, Nyazika TK, Pan W, Pekmezovic M, Polacheck I, Posteraro B, de Queiroz Telles F, Romeo O, Sánchez M, Sampaio A, Sanguinetti M, Sriburee P, Sugita T, Taj-Aldeen SJ, Takashima M, Taylor JW, Theelen B, Tomazin R, Verweij PE, Wahyuningsih R, Wang P, Boekhout T. Importance of Resolving Fungal Nomenclature: the Case of Multiple Pathogenic Species in the Cryptococcus Genus. mSphere 2017; 2:e00238-17. [PMID: 28875175 PMCID: PMC5577652 DOI: 10.1128/msphere.00238-17] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cryptococcosis is a major fungal disease caused by members of the Cryptococcus gattii and Cryptococcus neoformans species complexes. After more than 15 years of molecular genetic and phenotypic studies and much debate, a proposal for a taxonomic revision was made. The two varieties within C. neoformans were raised to species level, and the same was done for five genotypes within C. gattii. In a recent perspective (K. J. Kwon-Chung et al., mSphere 2:e00357-16, 2017, https://doi.org/10.1128/mSphere.00357-16), it was argued that this taxonomic proposal was premature and without consensus in the community. Although the authors of the perspective recognized the existence of genetic diversity, they preferred the use of the informal nomenclature "C. neoformans species complex" and "C. gattii species complex." Here we highlight the advantage of recognizing these seven species, as ignoring these species will impede deciphering further biologically and clinically relevant differences between them, which may in turn delay future clinical advances.
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Affiliation(s)
- Ferry Hagen
- Department of Medical Microbiology and Infectious Diseases, Canisius-Wilhelmina Hospital, Nijmegen, The Netherlands
- Centre of Expertise in Mycology Radboudumc/CWZ, Nijmegen, The Netherlands
| | | | | | - Hamid Badali
- Department of Medical Mycology and Parasitology/Invasive Fungi Research Center (IFRC), Mazandaran University of Medical Sciences, Sari, Iran
| | - Sebastien Bertout
- Unité Mixte Internationale Recherches Translationnelles sur l’Infection à VIH et les Maladies Infectieuses, Laboratoire de Parasitologie et Mycologie Médicale, UFR Pharmacie, Université Montpellier, Montpellier, France
| | - R. Blake Billmyre
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - M. Rosa Bragulat
- Veterinary Mycology Group, Department of Animal Health and Anatomy, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - F. Javier Cabañes
- Veterinary Mycology Group, Department of Animal Health and Anatomy, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - Mauricio Carbia
- Departamento de Parasitología y Micología, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Arunaloke Chakrabarti
- Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Sudha Chaturvedi
- Mycology Laboratory, Wadsworth Center, New York State Department of Health, Albany, New York, USA
| | - Vishnu Chaturvedi
- Mycology Laboratory, Wadsworth Center, New York State Department of Health, Albany, New York, USA
| | - Min Chen
- Shanghai Key Laboratory of Molecular Medical Mycology, Shanghai Institute of Medical Mycology, Second Military Medical University, Shanghai, China
- Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Anuradha Chowdhary
- Department of Medical Mycology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | | | - Oliver A. Cornely
- CECAD Cluster of Excellence, University of Cologne, Cologne, Germany
- Department I for Internal Medicine, University Hospital of Cologne, Cologne, Germany
- Center for Clinical Trials, University Hospital Cologne, Cologne, Germany
| | - Pedro W. Crous
- Phytopathology Research, Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands
- Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai, Thailand
- Department of Microbiology and Plant Pathology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa
| | - Maria S. Cuétara
- Department of Microbiology, Hospital Severo Ochoa, Madrid, Spain
| | - Mara R. Diaz
- University of Miami, NSF NIEHS Oceans and Human Health Center, Miami, Florida, USA
- Rosentiel School of Marine and Atmospheric Science, Division of Marine Biology and Fisheries, University of Miami, Miami, Florida, USA
| | | | - Hamed Fakhim
- Department of Medical Parasitology and Mycology/Cellular and Molecular Research Center, Urmia University of Medical Sciences, Urmia, Iran
| | - Rama Falk
- Department of Clinical Microbiology and Infectious Diseases, Hadassah-Hebrew University Medical Center, Ein Kerem, Jerusalem, Israel
- Department of Fisheries and Aquaculture, Ministry of Agriculture and Rural Development, Nir-David, Israel
| | - Wenjie Fang
- Shanghai Key Laboratory of Molecular Medical Mycology, Shanghai Institute of Medical Mycology, Second Military Medical University, Shanghai, China
- Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Patricia F. Herkert
- Department of Medical Microbiology and Infectious Diseases, Canisius-Wilhelmina Hospital, Nijmegen, The Netherlands
- Postgraduate Program in Microbiology, Parasitology and Pathology, Biological Sciences, Department of Basic Pathology, Federal University of Parana, Curitiba, Brazil
| | | | - James A. Fraser
- Australian Infectious Diseases Research Centre, School of Chemistry & Molecular Biosciences, University of Queensland, Brisbane, Australia
| | - Josepa Gené
- Unitat de Micologia, Facultat de Medicina i Ciències de la Salut, IISPV, Universitat Rovira i Virgili, Reus, Spain
| | - Josep Guarro
- Unitat de Micologia, Facultat de Medicina i Ciències de la Salut, IISPV, Universitat Rovira i Virgili, Reus, Spain
| | - Alexander Idnurm
- School of BioSciences, BioSciences 2, University of Melbourne, Melbourne, Australia
| | | | - Ziauddin Khan
- Department of Microbiology, Faculty of Medicine, Kuwait University, Safat, Kuwait
| | - Kantarawee Khayhan
- Department of Microbiology and Parasitology, Faculty of Medical Sciences, University of Phayao, Phayao, Thailand
- Yeast Research, Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands
| | - Anna Kolecka
- Yeast Research, Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands
| | - Cletus P. Kurtzman
- Mycotoxin Prevention and Applied Microbiology Research Unit, National Center for Agricultural Utilization Research, USDA-ARS, Peoria, Illinois, USA
| | - Katrien Lagrou
- Department of Laboratory Medicine, University Hospitals Leuven, Leuven, Belgium
- Department of Microbiology and Immunology, KU Leuven - University of Leuven, Leuven, Belgium
| | - Wanqing Liao
- Shanghai Key Laboratory of Molecular Medical Mycology, Shanghai Institute of Medical Mycology, Second Military Medical University, Shanghai, China
- Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Carlos Linares
- Medical School, Universidad Miguel Hernández, Alicante, Spain
| | - Jacques F. Meis
- Department of Medical Microbiology and Infectious Diseases, Canisius-Wilhelmina Hospital, Nijmegen, The Netherlands
- Centre of Expertise in Mycology Radboudumc/CWZ, Nijmegen, The Netherlands
| | - Kirsten Nielsen
- Department of Microbiology and Immunology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Tinashe K. Nyazika
- Department of Medical Microbiology, College of Health Sciences, University of Zimbabwe, Harare, Zimbabwe
- Malawi-Liverpool-Wellcome Trust, College of Medicine, University of Malawi, Blantyre, Malawi
- School of Tropical Medicine, Liverpool, United Kingdom
| | - Weihua Pan
- Shanghai Key Laboratory of Molecular Medical Mycology, Shanghai Institute of Medical Mycology, Second Military Medical University, Shanghai, China
- Department of Dermatology, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | | | - Itzhack Polacheck
- Department of Clinical Microbiology and Infectious Diseases, Hadassah-Hebrew University Medical Center, Ein Kerem, Jerusalem, Israel
| | - Brunella Posteraro
- Institute of Public Health (Section of Hygiene), Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario Agostino Gemelli, Rome, Italy
| | - Flavio de Queiroz Telles
- Department of Communitarian Health, Hospital de Clínicas, Federal University of Parana, Curitiba, Brazil
| | - Orazio Romeo
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
- IRCCS Centro Neurolesi Bonino-Pulejo, Messina, Italy
| | - Manuel Sánchez
- Medical School, Universidad Miguel Hernández, Alicante, Spain
| | - Ana Sampaio
- Centro de Investigação e de Tecnologias Agro-ambientais e Biológicas (CITAB), Universidade de Trás-os-Montes e Alto Douro (UTAD), Quinta dos Prados, Vila Real, Portugal
| | - Maurizio Sanguinetti
- Institute of Microbiology, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario Agostino Gemelli, Rome, Italy
| | - Pojana Sriburee
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Takashi Sugita
- Department of Microbiology, Meiji Pharmaceutical University, Noshio, Kiyose, Tokyo, Japan
| | - Saad J. Taj-Aldeen
- Mycology Unit, Microbiology Division, Department of Laboratory Medicine and Pathology, Hamad Medical Corporation, Doha, Qatar
| | - Masako Takashima
- Japan Collection of Microorganisms, RIKEN BioResource Center, Koyadai, Tsukuba, Ibaraki, Japan
| | - John W. Taylor
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, USA
| | - Bart Theelen
- Yeast Research, Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands
| | - Rok Tomazin
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Paul E. Verweij
- Centre of Expertise in Mycology Radboudumc/CWZ, Nijmegen, The Netherlands
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Retno Wahyuningsih
- Department of Parasitology, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia
- Department of Parasitology, School of Medicine, Universitas Kristen Indonesia, Jakarta, Indonesia
| | - Ping Wang
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
- Department of Pediatrics, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Teun Boekhout
- Institute of Biodiversity and Ecosystems Dynamics (IBED), University of Amsterdam, Amsterdam, The Netherlands
- Yeast Research, Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands
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Ferreira-Paim K, Andrade-Silva L, Fonseca FM, Ferreira TB, Mora DJ, Andrade-Silva J, Khan A, Dao A, Reis EC, Almeida MTG, Maltos A, Junior VR, Trilles L, Rickerts V, Chindamporn A, Sykes JE, Cogliati M, Nielsen K, Boekhout T, Fisher M, Kwon-Chung J, Engelthaler DM, Lazéra M, Meyer W, Silva-Vergara ML. MLST-Based Population Genetic Analysis in a Global Context Reveals Clonality amongst Cryptococcus neoformans var. grubii VNI Isolates from HIV Patients in Southeastern Brazil. PLoS Negl Trop Dis 2017; 11:e0005223. [PMID: 28099434 PMCID: PMC5242430 DOI: 10.1371/journal.pntd.0005223] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 12/01/2016] [Indexed: 12/16/2022] Open
Abstract
Cryptococcosis is an important fungal infection in immunocompromised individuals, especially those infected with HIV. In Brazil, despite the free availability of antiretroviral therapy (ART) in the public health system, the mortality rate due to Cryptococcus neoformans meningitis is still high. To obtain a more detailed picture of the population genetic structure of this species in southeast Brazil, we studied 108 clinical isolates from 101 patients and 35 environmental isolates. Among the patients, 59% had a fatal outcome mainly in HIV-positive male patients. All the isolates were found to be C. neoformans var. grubii major molecular type VNI and mating type locus alpha. Twelve were identified as diploid by flow cytometry, being homozygous (AαAα) for the mating type and by PCR screening of the STE20, GPA1, and PAK1 genes. Using the ISHAM consensus multilocus sequence typing (MLST) scheme, 13 sequence types (ST) were identified, with one being newly described. ST93 was identified from 81 (75%) of the clinical isolates, while ST77 and ST93 were identified from 19 (54%) and 10 (29%) environmental isolates, respectively. The southeastern Brazilian isolates had an overwhelming clonal population structure. When compared with populations from different continents based on data extracted from the ISHAM-MLST database (mlst.mycologylab.org) they showed less genetic variability. Two main clusters within C. neoformans var. grubii VNI were identified that diverged from VNB around 0.58 to 4.8 million years ago. The members of the Cryptococcus neoformans / Cryptococcus gattii species complex are the cause of cryptococcosis, a life-threatening human disease responsible for 624,000 deaths annually. Infection is acquired through inhalation of dehydrated yeast cells from environmental sources. After reaching the lungs, the fungus disseminates to the central nervous system causing meningoencephalitis. The majority of meningitis cases in HIV-infected patients are caused by C. neoformans, a species well studied in regions with a high prevalence of HIV infection, such as Asia and Africa. A similar high prevalence has been reported from Brazil however the epidemiology of these infections is less well understood. We studied clinical and environmental isolates from the southeast region of Brazil using MLST. The results that we obtained showed a clonal population structure of C. neoformans var. grubii VNI, with low variability when compared against populations from different continents. This lower variability is probably the result of multiple recent dispersal events from Africa to the Americas. The majority of clinical isolates were of one sequence type (ST93), which was also found in environmental samples. By expanding the analysis to isolates from around the globe, it was possible to identify two major groups among C. neoformans var. grubii VNI.
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Affiliation(s)
- Kennio Ferreira-Paim
- Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Marie Bashir Institute for Emerging Infectious Diseases and Biosecurity, Sydney Medical School-Westmead Hospital, The Westmead Institute for Medical Research, The University of Sydney, Sydney, Australia
- Infectious Disease Department, Triangulo Mineiro Federal University, Uberaba, Brazil
| | | | | | - Thatiana B. Ferreira
- Infectious Disease Department, Triangulo Mineiro Federal University, Uberaba, Brazil
| | - Delio J. Mora
- Infectious Disease Department, Triangulo Mineiro Federal University, Uberaba, Brazil
| | - Juliana Andrade-Silva
- Infectious Disease Department, Triangulo Mineiro Federal University, Uberaba, Brazil
| | - Aziza Khan
- Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Marie Bashir Institute for Emerging Infectious Diseases and Biosecurity, Sydney Medical School-Westmead Hospital, The Westmead Institute for Medical Research, The University of Sydney, Sydney, Australia
| | - Aiken Dao
- Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Marie Bashir Institute for Emerging Infectious Diseases and Biosecurity, Sydney Medical School-Westmead Hospital, The Westmead Institute for Medical Research, The University of Sydney, Sydney, Australia
| | - Eduardo C. Reis
- Infectious Disease Department, Faculty of Medicine of São José do Rio Preto, São José do Rio Preto, Brazil
| | - Margarete T. G. Almeida
- Infectious Disease Department, Faculty of Medicine of São José do Rio Preto, São José do Rio Preto, Brazil
| | - Andre Maltos
- Infectious Disease Department, Triangulo Mineiro Federal University, Uberaba, Brazil
| | - Virmondes R. Junior
- Infectious Disease Department, Triangulo Mineiro Federal University, Uberaba, Brazil
| | - Luciana Trilles
- Evandro Chagas National Institute of Infectious Diseases, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
| | | | - Ariya Chindamporn
- Mycology Unit, Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Jane E. Sykes
- Department of Medicine and Epidemiology, University of California, Davis, United States of America
| | - Massimo Cogliati
- Laboratorio Micologia Medica, Dip. Scienze Biomediche per la Salute, Università degli Studi di Milano, Milano, Italy
| | - Kirsten Nielsen
- Department of Microbiology and Immunology, Medical School, University of Minnesota, Minneapolis, Mississippi, United States of America
| | - Teun Boekhout
- Department of Yeast and Basidiomycete Research, CBS-KNAW Fungal Biodiversity Centre, Utrecht, The Netherlands
| | - Matthew Fisher
- Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, United Kingdom
| | - June Kwon-Chung
- Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institute of Health, Bethesda, Maryland, United States of America
| | - David M. Engelthaler
- Translational Genomics Research Institute, Flagstaff, Arizona, United States of America
| | - Marcia Lazéra
- Evandro Chagas National Institute of Infectious Diseases, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
| | - Wieland Meyer
- Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Marie Bashir Institute for Emerging Infectious Diseases and Biosecurity, Sydney Medical School-Westmead Hospital, The Westmead Institute for Medical Research, The University of Sydney, Sydney, Australia
- * E-mail:
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Aminnejad M, Cogliati M, Duan S, Arabatzis M, Tintelnot K, Castañeda E, Lazéra M, Velegraki A, Ellis D, Sorrell TC, Meyer W. Identification and Characterization of VNI/VNII and Novel VNII/VNIV Hybrids and Impact of Hybridization on Virulence and Antifungal Susceptibility Within the C. neoformans/C. gattii Species Complex. PLoS One 2016; 11:e0163955. [PMID: 27764108 PMCID: PMC5072701 DOI: 10.1371/journal.pone.0163955] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 09/16/2016] [Indexed: 12/14/2022] Open
Abstract
Cryptococcus neoformans and C. gattii are pathogenic basidiomycetous yeasts and the commonest cause of fungal infection of the central nervous system. Cryptococci are typically haploid but several inter-species, inter-varietal and intra-varietal hybrids have been reported. It has a bipolar mating system with sexual reproduction occurring normally between two individuals with opposite mating types, α and a. This study set out to characterize hybrid isolates within the C. neoformans/C. gattii species complex: seven unisexual mating intra-varietal VNI/VNII (αAAα) and six novel inter-varietal VNII/VNIV (aADα). The URA5-RFLP pattern for VNII/VNIV (aADα) differs from the VNIII (αADa) hybrids. Analysis of the allelic patterns of selected genes for AD hybrids showed 79% or more heterozygosis for the studied loci except for CBS132 (VNIII), which showed 50% of heterozygosity. MALDI-TOF MS was applied to hybrids belonging to different sero/mating type allelic patterns. All hybrid isolates were identified as belonging to the same hybrid group with identification scores ranging between 2.101 to 2.634. All hybrids were virulent when tested in the Galleria mellonella (wax moth) model, except for VNII/VNIV (aADα) hybrids. VNI/VGII hybrids were the most virulent hybrids. Hybrids recovered from larvae manifested a significant increase in capsule and total cell size and produced a low proportion (5-10%) of giant cells compared with the haploid control strains. All strains expressed the major virulence factors-capsule, melanin and phospholipase B-and grew well at 37°C. The minimal inhibitory concentration of nine drugs was measured by micro-broth dilution and compared with published data on haploid strains. MICs were similar amongst hybrids and haploid parental strains. This is the first study reporting natural same sex αAAα intra-varietal VNI/VNII hybrids and aADα inter-varietal VNII/VNIV hybrids.
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Affiliation(s)
- Mojgan Aminnejad
- Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Sydney Medical School – Westmead Hospital, Marie Bashir Institute for Infectious Diseases and Biosecurity, The University of Sydney, Westmead Institute for Medical Research, Sydney, Australia
| | - Massimo Cogliati
- Laboratory Micologia Medica, Dip. Scienze Biomediche per la Salute, Università degli Studi di Milano, Milano, Italy
| | - Shuyao Duan
- Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Sydney Medical School – Westmead Hospital, Marie Bashir Institute for Infectious Diseases and Biosecurity, The University of Sydney, Westmead Institute for Medical Research, Sydney, Australia
| | - Michael Arabatzis
- Mycology Research Laboratory, Department of Microbiology, Medical School, National Kapodistrian University of Athens, Athens, Greece
| | | | | | - Marcia Lazéra
- Mycology Laboratory, National Institute of Infectious Diseases, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
| | - Aristea Velegraki
- Mycology Research Laboratory, Department of Microbiology, Medical School, National Kapodistrian University of Athens, Athens, Greece
| | - David Ellis
- School of Molecular & Biomedical Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Tania C. Sorrell
- Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Sydney Medical School – Westmead Hospital, Marie Bashir Institute for Infectious Diseases and Biosecurity, The University of Sydney, Westmead Institute for Medical Research, Sydney, Australia
| | - Wieland Meyer
- Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Sydney Medical School – Westmead Hospital, Marie Bashir Institute for Infectious Diseases and Biosecurity, The University of Sydney, Westmead Institute for Medical Research, Sydney, Australia
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Forsythe A, Vogan A, Xu J. Genetic and environmental influences on the germination of basidiospores in the Cryptococcus neoformans species complex. Sci Rep 2016; 6:33828. [PMID: 27644692 PMCID: PMC5028750 DOI: 10.1038/srep33828] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 08/30/2016] [Indexed: 12/12/2022] Open
Abstract
In basidiomycetous fungi, the viability of basidiospores is an important component of sexual fitness. However, relatively little is known about the genetic and environmental factors influencing basidiospore germination. In this study, we used human opportunistic yeast pathogens, Cryptococcus neoformans and Cryptococcus deneoformans, as models to investigate the potential effects of selected genetic and environmental factors on basidiospore germination. A total of five strains with known genome structure were used to construct six crosses, three of which were between strains within the same species, while the remaining three were hybrid crosses between C. neoformans and C. deneoformans. Offspring from these crosses were incubated on two media (a nutrient-limiting and a nutrient-rich) and three temperatures (23 °C, 30 °C, and 37 °C). In general, spores from intra-specific crosses had greater germination rates than those from inter-specific crosses. Of the two environmental factors, temperature showed a greater influence than nutrient medium, with the 37 °C environment yielding lower germination rates than at 23 °C and 30 °C environments in most crosses. Furthermore, there were notable interaction effects between environmental factors and parental strains or strain pairs on basidiospore germination. We discuss the implications of these results on pathogenesis and speciation in this human fungal pathogen.
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Affiliation(s)
- Adrian Forsythe
- Department of Biology, McMaster University, 1280 Main St West, Hamilton, Ontario, L8S 4K1, Canada
| | - Aaron Vogan
- Department of Biology, McMaster University, 1280 Main St West, Hamilton, Ontario, L8S 4K1, Canada
| | - Jianping Xu
- Department of Biology, McMaster University, 1280 Main St West, Hamilton, Ontario, L8S 4K1, Canada
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Gago S, Serrano C, Alastruey-Izquierdo A, Cuesta I, Martín-Mazuelos E, Aller AI, Gómez-López A, Mellado E. Molecular identification, antifungal resistance and virulence ofCryptococcus neoformansandCryptococcus deneoformansisolated in Seville, Spain. Mycoses 2016; 60:40-50. [DOI: 10.1111/myc.12543] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 07/09/2016] [Accepted: 07/11/2016] [Indexed: 11/26/2022]
Affiliation(s)
- Sara Gago
- Mycology Reference Laboratory; Centro Nacional de Microbiología; Instituto de Salud Carlos III; Madrid Spain
- Manchester Fungal Infection Group; Institute of Inflammation and Repair; University of Manchester; Manchester UK
| | - Carmen Serrano
- Sección Micología; Hospital San Juan de Dios del Aljarafe; Sevilla Spain
| | - Ana Alastruey-Izquierdo
- Mycology Reference Laboratory; Centro Nacional de Microbiología; Instituto de Salud Carlos III; Madrid Spain
- Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015); Instituto de Salud Carlos III; Madrid Spain
| | - Isabel Cuesta
- Mycology Reference Laboratory; Centro Nacional de Microbiología; Instituto de Salud Carlos III; Madrid Spain
- Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015); Instituto de Salud Carlos III; Madrid Spain
| | | | - Ana Isabel Aller
- Unidad de Gestión de Enfermedades Infecciosas y Microbiología; Hospital de Valme; Sevilla Spain
| | - Alicia Gómez-López
- Mycology Reference Laboratory; Centro Nacional de Microbiología; Instituto de Salud Carlos III; Madrid Spain
- Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015); Instituto de Salud Carlos III; Madrid Spain
| | - Emilia Mellado
- Mycology Reference Laboratory; Centro Nacional de Microbiología; Instituto de Salud Carlos III; Madrid Spain
- Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015); Instituto de Salud Carlos III; Madrid Spain
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Identification of QTLs Associated with Virulence Related Traits and Drug Resistance in Cryptococcus neoformans. G3-GENES GENOMES GENETICS 2016; 6:2745-59. [PMID: 27371951 PMCID: PMC5015932 DOI: 10.1534/g3.116.029595] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cryptococcus neoformans is a basidiomycete fungus capable of causing deadly meningoenchephilitis, primarily in immunocompromised individuals. Formerly, C. neoformans was composed of two divergent lineages, but these have recently been elevated to species status, now C. neoformans (formerly C. neoformans var. grubii) and C. deneoformans (formerly C. neoformans var. neoformans). While both species can cause deadly infections in humans, C. neoformans is much more prevalent in clinical settings than C. deneoformans. However, the genetic factors contributing to their significant differences in virulence remain largely unknown. Quantitative trait locus (QTL) mapping is a powerful tool that can be used to identify genomic regions associated with phenotypic differences between strains. Here, we analyzed a hybrid cross between these two species and identified a total of 23 QTL, including five for melanin production, six for cell size, one for cell wall thickness, five for the frequency of capsule production, three for minimal inhibitory concentration (MIC) of fluconazole in broth, and three for MIC on solid medium. For the fluconazole resistance-associated QTL, three showed environment and/or concentration-specific effects. Our results provide a large number of candidate gene regions from which to explore the molecular bases for phenotypic differences between C. neoformans and C. deneoformans.
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Abstract
Cryptococcosis is a globally distributed invasive fungal infection that is caused by species within the genus Cryptococcus which presents substantial therapeutic challenges. Although natural human-to-human transmission has never been observed, recent work has identified multiple virulence mechanisms that enable cryptococci to infect, disseminate within and ultimately kill their human host. In this Review, we describe these recent discoveries that illustrate the intricacy of host-pathogen interactions and reveal new details about the host immune responses that either help to protect against disease or increase host susceptibility. In addition, we discuss how this improved understanding of both the host and the pathogen informs potential new avenues for therapeutic development.
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Beale MA, Sabiiti W, Robertson EJ, Fuentes-Cabrejo KM, O’Hanlon SJ, Jarvis JN, Loyse A, Meintjes G, Harrison TS, May RC, Fisher MC, Bicanic T. Genotypic Diversity Is Associated with Clinical Outcome and Phenotype in Cryptococcal Meningitis across Southern Africa. PLoS Negl Trop Dis 2015; 9:e0003847. [PMID: 26110902 PMCID: PMC4482434 DOI: 10.1371/journal.pntd.0003847] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 05/24/2015] [Indexed: 12/21/2022] Open
Abstract
Cryptococcal meningitis is a major cause of mortality throughout the developing world, yet little is known about the genetic markers underlying Cryptococcal virulence and patient outcome. We studied a cohort of 230 Cryptococcus neoformans (Cn) isolates from HIV-positive South African clinical trial patients with detailed clinical follow-up using multi-locus sequence typing and in vitro phenotypic virulence assays, correlating these data with clinical and fungal markers of disease in the patient. South African Cn displayed high levels of genetic diversity and locus variability compared to globally distributed types, and we identified 50 sequence types grouped within the main molecular types VNI, VNII and VNB, with 72% of isolates typed into one of seven 'high frequency' sequence types. Spatial analysis of patients’ cryptococcal genotype was not shown to be clustered geographically, which might argue against recent local acquisition and in favour of reactivation of latent infection. Through comparison of MLST genotyping data with clinical parameters, we found a relationship between genetic lineage and clinical outcome, with patients infected with the VNB lineage having significantly worse survival (n=8, HR 3.35, CI 1.51-7.20, p=0.003), and this was maintained even after adjustment for known prognostic indicators and treatment regimen. Comparison of fungal genotype with in vitro phenotype (phagocytosis, laccase activity and CSF survival) performed on a subset of 89 isolates revealed evidence of lineage-associated virulence phenotype, with the VNII lineage displaying increased laccase activity (p=0.001) and ex vivo CSF survival (p=0.0001). These findings show that Cryptococcus neoformans is a phenotypically heterogeneous pathogen, and that lineage plays an important role in cryptococcal virulence during human infection. Furthermore, a detailed understanding of the genetic diversity in Southern Africa will support further investigation into how genetic diversity is structured across African environments, allowing assessment of the risks different ecotypes pose to infection. Cryptococcus neoformans (Cn) is a yeast that commonly causes meningitis in HIV infected individuals in Africa, where it may account for up to 500,000 deaths every year. In this highly translational and multidisciplinary study, we used genetic analysis techniques to show that Cryptococcus found in Southern Africa represents a hotspot of genetic diversity. We combined this data with the results of microbiological techniques that assess the natural virulence traits that the yeast uses to survive and infect humans to further show that genetic diversity is associated with differences in cryptococcal phenotype. Finally, we analysed detailed clinical data on patients to investigate the clinical effects of infection with different lineages, and showed that one genetic lineage (VNB) is significantly associated with worse survival. Whilst much of our prior knowledge regarding the genetic basis of virulence is derived from studies on laboratory-adapted cryptococcal strains, our findings from this large and comprehensive MLST genotyping study of clinical isolates—linking genotype, phenotype, clinical presentation and outcome—provide direct insights into the contribution of pathogen lineage to virulence in human cryptococcal meningitis.
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Affiliation(s)
- Mathew A. Beale
- Institute of Infection and Immunity, St. George’s University London, London, United Kingdom
- Department of Infectious Disease Epidemiology, Imperial College School of Public Health, London, United Kingdom
| | - Wilber Sabiiti
- Institute of Infection and Immunity, St. George’s University London, London, United Kingdom
- School of Medicine University of St. Andrews, St. Andrews, United Kingdom
| | - Emma J. Robertson
- Institute of Infection and Immunity, St. George’s University London, London, United Kingdom
| | | | - Simon J. O’Hanlon
- Department of Infectious Disease Epidemiology, Imperial College School of Public Health, London, United Kingdom
| | - Joseph N. Jarvis
- Botswana-UPenn Partnership, Gaborone, Botswana
- Division of Infectious Diseases, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Angela Loyse
- Institute of Infection and Immunity, St. George’s University London, London, United Kingdom
| | - Graeme Meintjes
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, University of Cape Town, Cape Town, South Africa
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
| | - Thomas S. Harrison
- Institute of Infection and Immunity, St. George’s University London, London, United Kingdom
| | - Robin C. May
- Institute of Microbiology and Infection and the School of Biosciences, University of Birmingham, Birmingham, United Kingdom
- National Institute for Health Research (NIHR) Surgical Reconstruction and Microbiology Research Centre, University Hospitals of Birmingham National Health Service (NHS) Foundation Trust, Queen Elizabeth Hospital Birmingham, Birmingham, United Kingdom
| | - Matthew C. Fisher
- Department of Infectious Disease Epidemiology, Imperial College School of Public Health, London, United Kingdom
- * E-mail: (MCF); (TB)
| | - Tihana Bicanic
- Institute of Infection and Immunity, St. George’s University London, London, United Kingdom
- * E-mail: (MCF); (TB)
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Abstract
Cryptococcus neoformans is a human opportunistic fungal pathogen causing severe disseminated meningoencephalitis, mostly in patients with cellular immune defects. This species is divided into three serotypes: A, D, and the AD hybrid. Our objectives were to compare population structures of serotype A and D clinical isolates and to assess whether infections with AD hybrids differ from infections with the other serotypes. For this purpose, we analyzed 483 isolates and the corresponding clinical data from 234 patients enrolled during the CryptoA/D study or the nationwide survey on cryptococcosis in France. Isolates were characterized in terms of ploidy, serotype, mating type, and genotype, utilizing flow cytometry, serotype- and mating type-specific PCR amplifications, and multilocus sequence typing (MLST) methods. Our results suggest that C. neoformans serotypes A and D have different routes of multiplication (primarily clonal expansion versus recombination events for serotype A and serotype D, respectively) and important genomic differences. Cryptococcosis includes a high proportion of proven or probable infections (21.5%) due to a mixture of genotypes, serotypes, and/or ploidies. Multivariate analysis showed that parameters independently associated with failure to achieve cerebrospinal fluid (CSF) sterilization by week 2 were a high serum antigen titer, the lack of flucytosine during induction therapy, and the occurrence of mixed infection, while infections caused by AD hybrids were more likely to be associated with CSF sterilization. Our study provides additional evidence for the possible speciation of C. neoformans var. neoformans and grubii and highlights the importance of careful characterization of causative isolates. Cryptococcus neoformans is an environmental fungus causing severe disease, estimated to be responsible for 600,000 deaths per year worldwide. This species is divided into serotypes A and D and an AD hybrid, and these could be considered two different species and an interspecies hybrid. The objectives of our study were to compare population structures of serotype A and serotype D and to assess whether infections with AD hybrids differ from infections with serotype A or D isolates in terms of clinical presentation and outcome. For this purpose, we used clinical data and strains from patients diagnosed with cryptococcosis in France. Our results suggest that, according to the serotype, isolates have different routes of multiplication and high genomic differences, confirming the possible speciation of serotypes A and D. Furthermore, we observed a better prognosis for infections caused by AD hybrid than those caused by serotype A or D, at least for those diagnosed in France.
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28
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Beardsley J, Thanh LT, Day J. A Model CNS Fungal Infection: Cryptococcal Meningitis. CURRENT CLINICAL MICROBIOLOGY REPORTS 2015. [DOI: 10.1007/s40588-015-0016-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Hagen F, Khayhan K, Theelen B, Kolecka A, Polacheck I, Sionov E, Falk R, Parnmen S, Lumbsch HT, Boekhout T. Recognition of seven species in the Cryptococcus gattii/Cryptococcus neoformans species complex. Fungal Genet Biol 2015; 78:16-48. [PMID: 25721988 DOI: 10.1016/j.fgb.2015.02.009] [Citation(s) in RCA: 452] [Impact Index Per Article: 50.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 02/12/2015] [Accepted: 02/15/2015] [Indexed: 02/08/2023]
Abstract
Phylogenetic analysis of 11 genetic loci and results from many genotyping studies revealed significant genetic diversity with the pathogenic Cryptococcus gattii/Cryptococcus neoformans species complex. Genealogical concordance, coalescence-based, and species tree approaches supported the presence of distinct and concordant lineages within the complex. Consequently, we propose to recognize the current C. neoformans var. grubii and C. neoformans var. neoformans as separate species, and five species within C. gattii. The type strain of C. neoformans CBS132 represents a serotype AD hybrid and is replaced. The newly delimited species differ in aspects of pathogenicity, prevalence for patient groups, as well as biochemical and physiological aspects, such as susceptibility to antifungals. MALDI-TOF mass spectrometry readily distinguishes the newly recognized species.
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Affiliation(s)
- Ferry Hagen
- CBS-KNAW Fungal Biodiversity Centre, Basidiomycete and Yeast Research, Utrecht, The Netherlands; Department of Medical Microbiology and Infectious Diseases, Canisius-Wilhelmina Hospital, Nijmegen, The Netherlands
| | - Kantarawee Khayhan
- CBS-KNAW Fungal Biodiversity Centre, Basidiomycete and Yeast Research, Utrecht, The Netherlands; Department of Microbiology and Parasitology, Faculty of Medical Sciences, University of Phayao, Phayao, Thailand
| | - Bart Theelen
- CBS-KNAW Fungal Biodiversity Centre, Basidiomycete and Yeast Research, Utrecht, The Netherlands
| | - Anna Kolecka
- CBS-KNAW Fungal Biodiversity Centre, Basidiomycete and Yeast Research, Utrecht, The Netherlands
| | - Itzhack Polacheck
- Department of Clinical Microbiology and Infectious Diseases, Hadassah-Hebrew University Medical Center, Ein Kerem, Jerusalem, Israel
| | - Edward Sionov
- Department of Clinical Microbiology and Infectious Diseases, Hadassah-Hebrew University Medical Center, Ein Kerem, Jerusalem, Israel; Department of Food Quality & Safety, Institute for Postharvest and Food Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
| | - Rama Falk
- Department of Clinical Microbiology and Infectious Diseases, Hadassah-Hebrew University Medical Center, Ein Kerem, Jerusalem, Israel; Department of Fisheries and Aquaculture, Ministry of Agriculture and Rural Development, Nir-David, Israel
| | - Sittiporn Parnmen
- Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand
| | | | - Teun Boekhout
- CBS-KNAW Fungal Biodiversity Centre, Basidiomycete and Yeast Research, Utrecht, The Netherlands; Shanghai Key Laboratory of Molecular Medical Mycology, Changzheng Hospital, Second Military Medical University, Shanghai, China; Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
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Abstract
Sexual reproduction is ubiquitous throughout the eukaryotic kingdom, but the capacity of pathogenic fungi to undergo sexual reproduction has been a matter of intense debate. Pathogenic fungi maintained a complement of conserved meiotic genes but the populations appeared to be clonally derived. This debate was resolved first with the discovery of an extant sexual cycle and then unisexual reproduction. Unisexual reproduction is a distinct form of homothallism that dispenses with the requirement for an opposite mating type. Pathogenic and nonpathogenic fungi previously thought to be asexual are able to undergo robust unisexual reproduction. We review here recent advances in our understanding of the genetic and molecular basis of unisexual reproduction throughout fungi and the impact of unisex on the ecology and genomic evolution of fungal species.
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Affiliation(s)
- Kevin C Roach
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
| | - Marianna Feretzaki
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
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Heitman J, Carter DA, Dyer PS, Soll DR. Sexual reproduction of human fungal pathogens. Cold Spring Harb Perspect Med 2014; 4:4/8/a019281. [PMID: 25085958 DOI: 10.1101/cshperspect.a019281] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We review here recent advances in our understanding of sexual reproduction in fungal pathogens that commonly infect humans, including Candida albicans, Cryptococcus neoformans/gattii, and Aspergillus fumigatus. Where appropriate or relevant, we introduce findings on other species associated with human infections. In particular, we focus on rapid advances involving genetic, genomic, and population genetic approaches that have reshaped our view of how fungal pathogens evolve. Rather than being asexual, mitotic, and largely clonal, as was thought to be prevalent as recently as a decade ago, we now appreciate that the vast majority of pathogenic fungi have retained extant sexual, or parasexual, cycles. In some examples, sexual and parasexual unions of pathogenic fungi involve closely related individuals, generating diversity in the population but with more restricted recombination than expected from fertile, sexual, outcrossing and recombining populations. In other cases, species and isolates participate in global outcrossing populations with the capacity for considerable levels of gene flow. These findings illustrate general principles of eukaryotic pathogen emergence with relevance for other fungi, parasitic eukaryotic pathogens, and both unicellular and multicellular eukaryotic organisms.
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Affiliation(s)
- Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710
| | - Dee A Carter
- School of Molecular Bioscience, University of Sydney, Sydney NSW 2006, Australia
| | - Paul S Dyer
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, United Kingdom
| | - David R Soll
- Department of Biology, University of Iowa, Iowa City, Iowa 52242
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32
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Sabiiti W, May RC. Mechanisms of infection by the human fungal pathogen Cryptococcus neoformans. Future Microbiol 2013; 7:1297-313. [PMID: 23075448 DOI: 10.2217/fmb.12.102] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Brain infection by the fungus Cryptococcus neoformans results in inflammation of the meninges and brain parenchyma, a condition known as meningoencephalitis. One million people are estimated to suffer cryptococcal meningitis globally and >60% of these cases die within 3 months of diagnosis. Humans are believed to contract infection by inhalation of spores or dried yeast cells, which subsequently colonize the lung tissue. In the lungs, cryptococci may be cleared by the lung phagocytes, stay latent, cause pulmonary infection and/or disseminate to other body parts, preferentially the brain, culminating in cryptococcal meningoencephalitis. In this review, we discuss the pathogenesis of C. neoformans from the environment to the brain, the current understanding of the mechanisms of cryptococcal transmission into the brain and cryptococcal meningitis. We also give an insight into future cryptococcosis research and the development of novel therapies.
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Affiliation(s)
- Wilber Sabiiti
- Infection & Immunity, Clinical Sciences Division, St Georges' University of London, London SW17 0RE, UK
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Morrow CA, Fraser JA. Ploidy variation as an adaptive mechanism in human pathogenic fungi. Semin Cell Dev Biol 2013; 24:339-46. [PMID: 23380396 DOI: 10.1016/j.semcdb.2013.01.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 01/25/2013] [Accepted: 01/25/2013] [Indexed: 12/24/2022]
Abstract
Changes in ploidy have a profound and usually negative influence on cellular viability and proliferation, yet the vast majority of cancers and tumours exhibit an aneuploid karyotype. Whether this genomic plasticity is a cause or consequence of malignant transformation remains uncertain. Systemic fungal pathogens regularly develop aneuploidies in a similar manner during human infection, often far in excess of the natural rate of chromosome nondisjunction. As both processes fundamentally represent cells evolving under selective pressures, this suggests that changes in chromosome number may be a concerted mechanism to adapt to the hostile host environment. Here, we examine the mechanisms by which aneuploidy and polyploidy are generated in the fungal pathogens Candida albicans and Cryptococcus neoformans and investigate whether these represent an adaptive strategy under severe stress through the rapid generation of large-scale mutations. Insights into fungal ploidy changes, strategies for tolerating aneuploidies and proliferation during infection may yield novel targets for both antifungal and anticancer therapies.
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Affiliation(s)
- Carl A Morrow
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane QLD 4072, Australia
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Morales L, Dujon B. Evolutionary role of interspecies hybridization and genetic exchanges in yeasts. Microbiol Mol Biol Rev 2012; 76:721-39. [PMID: 23204364 PMCID: PMC3510521 DOI: 10.1128/mmbr.00022-12] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Forced interspecific hybridization has been used in yeasts for many years to study speciation or to construct artificial strains with novel fermentative and metabolic properties. Recent genome analyses indicate that natural hybrids are also generated spontaneously between yeasts belonging to distinct species, creating lineages with novel phenotypes, varied genetic stability, or altered virulence in the case of pathogens. Large segmental introgressions from evolutionarily distant species are also visible in some yeast genomes, suggesting that interspecific genetic exchanges occur during evolution. The origin of this phenomenon remains unclear, but it is likely based on weak prezygotic barriers, limited Dobzhansky-Muller (DM) incompatibilities, and rapid clonal expansions. Newly formed interspecies hybrids suffer rapid changes in the genetic contribution of each parent, including chromosome loss or aneuploidy, translocations, and loss of heterozygosity, that, except in a few recently studied cases, remain to be characterized more precisely at the genomic level by use of modern technologies. We review here known cases of natural or artificially formed interspecies hybrids between yeasts and discuss their potential importance in terms of genome evolution. Problems of meiotic fertility, ploidy constraint, gene and gene product compatibility, and nucleomitochondrial interactions are discussed and placed in the context of other known mechanisms of yeast genome evolution as a model for eukaryotes.
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Affiliation(s)
- Lucia Morales
- Institut Pasteur, Unité de Génétique Moléculaire des Levures CNRS UMR3525, University Pierre and Marie Curie UFR927, Paris, France.
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Henk DA, Shahar-Golan R, Devi KR, Boyce KJ, Zhan N, Fedorova ND, Nierman WC, Hsueh PR, Yuen KY, Sieu TPM, Kinh NV, Wertheim H, Baker SG, Day JN, Vanittanakom N, Bignell EM, Andrianopoulos A, Fisher MC. Clonality despite sex: the evolution of host-associated sexual neighborhoods in the pathogenic fungus Penicillium marneffei. PLoS Pathog 2012; 8:e1002851. [PMID: 23055919 PMCID: PMC3464222 DOI: 10.1371/journal.ppat.1002851] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 06/25/2012] [Indexed: 12/04/2022] Open
Abstract
Molecular genetic approaches typically detect recombination in microbes regardless of assumed asexuality. However, genetic data have shown the AIDS-associated pathogen Penicillium marneffei to have extensive spatial genetic structure at local and regional scales, and although there has been some genetic evidence that a sexual cycle is possible, this haploid fungus is thought to be genetically, as well as morphologically, asexual in nature because of its highly clonal population structure. Here we use comparative genomics, experimental mixed-genotype infections, and population genetic data to elucidate the role of recombination in natural populations of P. marneffei. Genome wide comparisons reveal that all the genes required for meiosis are present in P. marneffei, mating type genes are arranged in a similar manner to that found in other heterothallic fungi, and there is evidence of a putatively meiosis-specific mutational process. Experiments suggest that recombination between isolates of compatible mating types may occur during mammal infection. Population genetic data from 34 isolates from bamboo rats in India, Thailand and Vietnam, and 273 isolates from humans in China, India, Thailand, and Vietnam show that recombination is most likely to occur across spatially and genetically limited distances in natural populations resulting in highly clonal population structure yet sexually reproducing populations. Predicted distributions of three different spatial genetic clusters within P. marneffei overlap with three different bamboo rat host distributions suggesting that recombination within hosts may act to maintain population barriers within P. marneffei.
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Affiliation(s)
- Daniel A Henk
- Department of Infectious Disease Epidemiology, Imperial College, Norfolk Place, London, United Kingdom.
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Gene conversion occurs within the mating-type locus of Cryptococcus neoformans during sexual reproduction. PLoS Genet 2012; 8:e1002810. [PMID: 22792079 PMCID: PMC3390403 DOI: 10.1371/journal.pgen.1002810] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 05/23/2012] [Indexed: 12/30/2022] Open
Abstract
Meiotic recombination of sex chromosomes is thought to be repressed in organisms with heterogametic sex determination (e.g. mammalian X/Y chromosomes), due to extensive divergence and chromosomal rearrangements between the two chromosomes. However, proper segregation of sex chromosomes during meiosis requires crossing-over occurring within the pseudoautosomal regions (PAR). Recent studies reveal that recombination, in the form of gene conversion, is widely distributed within and may have played important roles in the evolution of some chromosomal regions within which recombination was thought to be repressed, such as the centromere cores of maize. Cryptococcus neoformans, a major human pathogenic fungus, has an unusually large mating-type locus (MAT, >100 kb), and the MAT alleles from the two opposite mating-types show extensive nucleotide sequence divergence and chromosomal rearrangements, mirroring characteristics of sex chromosomes. Meiotic recombination was assumed to be repressed within the C. neoformans MAT locus. A previous study identified recombination hot spots flanking the C. neoformans MAT, and these hot spots are associated with high GC content. Here, we investigated a GC-rich intergenic region located within the MAT locus of C. neoformans to establish if this region also exhibits unique recombination behavior during meiosis. Population genetics analysis of natural C. neoformans isolates revealed signals of homogenization spanning this GC-rich intergenic region within different C. neoformans lineages, consistent with a model in which gene conversion of this region during meiosis prevents it from diversifying within each lineage. By analyzing meiotic progeny from laboratory crosses, we found that meiotic recombination (gene conversion) occurs around the GC-rich intergenic region at a frequency equal to or greater than the meiotic recombination frequency observed in other genomic regions. We discuss the implications of these findings with regards to the possible functional and evolutionary importance of gene conversion within the C. neoformans MAT locus and, more generally, in fungi. Recombination has been thought to be repressed within sex chromosomes, as well as within the mating-type (MAT) loci in many fungi, due to the highly diverged and rearranged nature between alleles defining opposite sexes or mating-types. However, it has long been appreciated that recombination can occur within these presumptive recombinational “cold spots,” and recent studies reveal that recombination, including gene conversion, can occur at a frequency higher than previously appreciated and could play important roles in shaping evolution of these chromosomal regions. Here, we provide evidence that, during sexual reproduction of the human pathogenic fungus Cryptococcus neoformans, recombination (gene conversion) occurs across a GC-rich intergenic region within the MAT locus. The frequency of this gene conversion is comparable to those of typical meiotic recombination events observed in other chromosomal regions. This is in accord with population genetics analyses, which indicate homogenization between alleles of opposite mating-types within the intergenic region. Gene conversion within these highly rearranged chromosomal regions may serve to ensure proper meiosis and/or rejuvenate genes/chromosomal regions within MAT that are otherwise facing irreversible evolutionary decay. In conclusion, our study provides further experimental evidence that at least some recombinational “cold spots” are not that cold, after all.
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Firacative C, Trilles L, Meyer W. MALDI-TOF MS enables the rapid identification of the major molecular types within the Cryptococcus neoformans/C. gattii species complex. PLoS One 2012; 7:e37566. [PMID: 22666368 PMCID: PMC3362595 DOI: 10.1371/journal.pone.0037566] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 04/20/2012] [Indexed: 12/14/2022] Open
Abstract
Background The Cryptococcus neoformans/C. gattii species complex comprises two sibling species that are divided into eight major molecular types, C. neoformans VNI to VNIV and C. gattii VGI to VGIV. These genotypes differ in host range, epidemiology, virulence, antifungal susceptibility and geographic distribution. The currently used phenotypic and molecular identification methods for the species/molecular types are time consuming and expensive. As Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) offers an effective alternative for the rapid identification of microorganisms, the objective of this study was to examine its potential for the identification of C. neoformans and C. gattii strains at the intra- and inter-species level. Methodology Protein extracts obtained via the formic acid extraction method of 164 C. neoformans/C. gattii isolates, including four inter-species hybrids, were studied. Results The obtained mass spectra correctly identified 100% of all studied isolates, grouped each isolate according to the currently recognized species, C. neoformans and C. gattii, and detected potential hybrids. In addition, all isolates were clearly separated according to their major molecular type, generating greater spectral differences among the C. neoformans molecular types than the C. gattii molecular types, most likely reflecting a closer phylogenetic relationship between the latter. The number of colonies used and the incubation length did not affect the results. No spectra were obtained from intact yeast cells. An extended validated spectral library containing spectra of all eight major molecular types was established. Conclusions MALDI-TOF MS is a rapid identification tool for the correct recognition of the two currently recognized human pathogenic Cryptococcus species and offers a simple method for the separation of the eight major molecular types and the detection of hybrid strains within this species complex in the clinical laboratory. The obtained mass spectra provide further evidence that the major molecular types warrant variety or even species status.
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Affiliation(s)
- Carolina Firacative
- Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, Sydney Medical School–Westmead, The University of Sydney, Westmead Hospital, Sydney, Australia
- Grupo de Microbiología, Instituto Nacional de Salud, Bogotá, Colombia
| | - Luciana Trilles
- Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, Sydney Medical School–Westmead, The University of Sydney, Westmead Hospital, Sydney, Australia
- Laboratório de Micologia, Instituto de Pesquisa Clínica Evandro Chagas, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Wieland Meyer
- Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, Sydney Medical School–Westmead, The University of Sydney, Westmead Hospital, Sydney, Australia
- * E-mail:
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38
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Function of Cryptococcus neoformans KAR7 (SEC66) in karyogamy during unisexual and opposite-sex mating. EUKARYOTIC CELL 2012; 11:783-94. [PMID: 22544906 DOI: 10.1128/ec.00066-12] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The human basidiomycetous fungal pathogen Cryptococcus neoformans serves as a model fungus to study sexual development and produces infectious propagules, basidiospores, via the sexual cycle. Karyogamy is the process of nuclear fusion and an essential step to complete mating. Therefore, regulation of nuclear fusion is central to understanding sexual development of C. neoformans. However, our knowledge of karyogamy genes was limited. In this study, using a BLAST search with the Saccharomyces cerevisiae KAR genes, we identified five C. neoformans karyogamy gene orthologs: CnKAR2, CnKAR3, CnKAR4, CnKAR7 (or CnSEC66), and CnKAR8. There are no apparent orthologs of the S. cerevisiae genes ScKAR1, ScKAR5, and ScKar9 in C. neoformans. Karyogamy involves the congression of two nuclei followed by nuclear membrane fusion, which results in diploidization. ScKar7 (or ScSec66) is known to be involved in nuclear membrane fusion. In C. neoformans, kar7 mutants display significant defects in hyphal growth and basidiospore chain formation during both a-α opposite and α-α unisexual reproduction. Fluorescent nuclear imaging revealed that during kar7 × kar7 bilateral mutant matings, the nuclei congress but fail to fuse in the basidia. These results demonstrate that the KAR7 gene plays an integral role in both opposite-sex and unisexual mating, indicating that proper control of nuclear dynamics is important. CnKAR2 was found to be essential for viability, and its function in mating is not known. No apparent phenotypes were observed during mating of kar3, kar4, or kar8 mutants, suggesting that the role of these genes may be dispensable for C. neoformans mating, which demonstrates a different evolutionary trajectory for the KAR genes in C. neoformans compared to those in S. cerevisiae.
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Litvintseva AP, Mitchell TG. Population genetic analyses reveal the African origin and strain variation of Cryptococcus neoformans var. grubii. PLoS Pathog 2012; 8:e1002495. [PMID: 22383873 PMCID: PMC3285590 DOI: 10.1371/journal.ppat.1002495] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Anastasia P Litvintseva
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA.
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Genetic Diversity and Genomic Plasticity of Cryptococcus neoformans AD Hybrid Strains. G3-GENES GENOMES GENETICS 2012; 2:83-97. [PMID: 22384385 PMCID: PMC3276195 DOI: 10.1534/g3.111.001255] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2001] [Accepted: 11/09/2011] [Indexed: 01/05/2023]
Abstract
Natural hybridization between two strains, varieties, or species is a common phenomenon in both plants and animals. Although hybridization may skew established gene pools, it generates population diversity efficiently and sometimes results in the emergence of newly adapted genotypes. Cryptococcus neoformans, which causes the most frequent opportunistic fungal infection in immunocompromised hosts, has three serotypes: A, D, and AD. Serotype-specific multilocus sequence typing and serotype-specific comparative genome hybridization were applied to investigate the genetic variability and genomic organization of C. neoformans serotype AD isolates. We confirm that C. neoformans serotype AD isolates are hybrids of serotype A and D strains. Compared with haploid strains, most AD hybrid isolates exhibit unique multilocus sequence typing genotypes, suggesting that multiple independent hybridization events punctuated the origin and evolutionary trajectory of AD hybrids. The MATa alleles from both haploid and AD hybrid isolates group closely to form a cluster or subcluster in both the serotype A and D populations. The rare and unique distribution of MATa alleles may restrict sexual reproduction between isolates of opposite mating types. The genetic diversity of the serotype D population, including haploid strains and serotype D genomes of the AD hybrid, is significantly greater than that of serotype A, and there are signatures of recombination within the serotype D population. Given that MATa isolates are relatively rare, both opposite-sex and same-sex mating may contribute to genetic recombination of serotype D in nature. Extensive chromosome loss was observed in AD hybrid isolates, which results in loss of heterozygosity in the otherwise-heterozygous AD hybrid genome. Most AD hybrid isolates exhibit hybrid vigor and are resistant to the antifungal drug FK506. In addition, the C. neoformans AD hybrid genome is highly dynamic, with continuous chromosome loss, which may be a facile route for pathogen evolution through which genotypic and phenotypic variation is generated.
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Hu G, Wang J, Choi J, Jung WH, Liu I, Litvintseva AP, Bicanic T, Aurora R, Mitchell TG, Perfect JR, Kronstad JW. Variation in chromosome copy number influences the virulence of Cryptococcus neoformans and occurs in isolates from AIDS patients. BMC Genomics 2011; 12:526. [PMID: 22032296 PMCID: PMC3221739 DOI: 10.1186/1471-2164-12-526] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 10/27/2011] [Indexed: 11/25/2022] Open
Abstract
Background The adaptation of pathogenic fungi to the host environment via large-scale genomic changes is a poorly characterized phenomenon. Cryptococcus neoformans is the leading cause of fungal meningoencephalitis in HIV/AIDS patients, and we recently discovered clinical strains of the fungus that are disomic for chromosome 13. Here, we examined the genome plasticity and phenotypes of monosomic and disomic strains, and compared their virulence in a mouse model of cryptococcosis Results In an initial set of strains, melanin production was correlated with monosomy at chromosome 13, and disomic variants were less melanized and attenuated for virulence in mice. After growth in culture or passage through mice, subsequent strains were identified that varied in melanin formation and exhibited copy number changes for other chromosomes. The correlation between melanin and disomy at chromosome 13 was observed for some but not all strains. A survey of environmental and clinical isolates maintained in culture revealed few occurrences of disomic chromosomes. However, an examination of isolates that were freshly collected from the cerebrospinal fluid of AIDS patients and minimally cultured provided evidence for infections with multiple strains and copy number variation. Conclusions Overall, these results suggest that the genome of C. neoformans exhibits a greater degree of plasticity than previously appreciated. Furthermore, the expression of an essential virulence factor and the severity of disease are associated with genome variation. The occurrence of chromosomal variation in isolates from AIDS patients, combined with the observed influence of disomy on virulence, indicates that genome plasticity may have clinical relevance.
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Affiliation(s)
- Guanggan Hu
- The Michael Smith Laboratories, Department of Microbiology and Immunology, and Faculty of Land and Food Systems, University of British Columbia, Vancouver, B.C. V6T 1Z4, Canada
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Litvintseva AP, Carbone I, Rossouw J, Thakur R, Govender NP, Mitchell TG. Evidence that the human pathogenic fungus Cryptococcus neoformans var. grubii may have evolved in Africa. PLoS One 2011; 6:e19688. [PMID: 21589919 PMCID: PMC3092753 DOI: 10.1371/journal.pone.0019688] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 04/04/2011] [Indexed: 12/15/2022] Open
Abstract
Most of the species of fungi that cause disease in mammals, including Cryptococcus neoformans var. grubii (serotype A), are exogenous and non-contagious. Cryptococcus neoformans var. grubii is associated worldwide with avian and arboreal habitats. This airborne, opportunistic pathogen is profoundly neurotropic and the leading cause of fungal meningitis. Patients with HIV/AIDS have been ravaged by cryptococcosis – an estimated one million new cases occur each year, and mortality approaches 50%. Using phylogenetic and population genetic analyses, we present evidence that C. neoformans var. grubii may have evolved from a diverse population in southern Africa. Our ecological studies support the hypothesis that a few of these strains acquired a new environmental reservoir, the excreta of feral pigeons (Columba livia), and were globally dispersed by the migration of birds and humans. This investigation also discovered a novel arboreal reservoir for highly diverse strains of C. neoformans var. grubii that are restricted to southern Africa, the mopane tree (Colophospermum mopane). This finding may have significant public health implications because these primal strains have optimal potential for evolution and because mopane trees contribute to the local economy as a source of timber, folkloric remedies and the edible mopane worm.
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Affiliation(s)
- Anastasia P Litvintseva
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America.
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43
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Gupta G, Fries BC. Variability of phenotypic traits in Cryptococcus varieties and species and the resulting implications for pathogenesis. Future Microbiol 2010; 5:775-87. [PMID: 20441549 DOI: 10.2217/fmb.10.44] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Variability of phenotypic characteristics in Cryptococcus neoformans var. grubii and var. neoformans as well as Cryptococcus gattii can have diverse effects on the virulence of these fungi and are thus important for pathogenesis. This article summarizes the diverse phenotypic changes that these fungi can manifest. We divide changes into those that affect the entire fungal population and are predominantly induced by environmental signals, and those that involve subpopulations of the fungal population and have to be selected. Last, the article summarizes the experimental evidence that epitopes on the polysaccharide capsule also vary, which may have implications for the pathogenesis as these findings would further diversify the fungal population.
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Affiliation(s)
- Gunjan Gupta
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
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Abstract
Human fungal pathogens are associated with diseases ranging from dandruff and skin colonization to invasive bloodstream infections. The major human pathogens belong to the Candida, Aspergillus, and Cryptococcus clades, and infections have high and increasing morbidity and mortality. Many human fungal pathogens were originally assumed to be asexual. However, recent advances in genome sequencing, which revealed that many species have retained the genes required for the sexual machinery, have dramatically influenced our understanding of the biology of these organisms. Predictions of a rare or cryptic sexual cycle have been supported experimentally for some species. Here, I examine the evidence that human pathogens reproduce sexually. The evolution of the mating-type locus in ascomycetes (including Candida and Aspergillus species) and basidiomycetes (Malassezia and Cryptococcus) is discussed. I provide an overview of how sex is suppressed in different species and discuss the potential associations with pathogenesis.
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Olivares LRC, Martínez KM, Cruz RMB, Rivera MAM, Meyer W, Espinosa RAA, Martínez RL, Santos GMRPY. Genotyping of Mexican Cryptococcus neoformans and C. gattii isolates by PCR-fingerprinting. Med Mycol 2010; 47:713-21. [PMID: 19888804 DOI: 10.3109/13693780802559031] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Cryptococcosis in México is caused by both species of the Cryptococcus species complex i.e., Cryptococcus neoformans and C. gattii. The current study was aimed to determine genetic variability of 72 Mexican clinical isolates using PCR-fingerprinting with the primer M13. PCR fingerprinting revealed 55 VNI, five VNII, three VNIII, one VNIV, two VGI, two VGII, two VGIII and two VGIV isolates among those studied. The results show that most cryptococcosis cases in México are AIDS related and are caused by C. neoformans var. grubii, genotypes VNI and VNII. In addition this study revealed for the first time the presence of genotypes VNIV and VGII among Mexican clinical isolates. The present data show that all genotypes that have been described for the Cryptococcus species complex are found in México, indicating a much wider geographic distribution of genotypes than previously reported. The molecular analysis of Mexican cryptococcal isolates generated PCR-fingerprinting patterns which will provide references for future typing studies to allow the integration of Mexican cryptococcal genotypes into the ongoing global genotyping study of the Cryptococcus species complex.
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Affiliation(s)
- L R Castañón Olivares
- Departamento de Microbiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Distrito Federal, México C. P. 04510.
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Genetic diversity of the Cryptococcus species complex suggests that Cryptococcus gattii deserves to have varieties. PLoS One 2009; 4:e5862. [PMID: 19517012 PMCID: PMC2690690 DOI: 10.1371/journal.pone.0005862] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Accepted: 05/13/2009] [Indexed: 01/02/2023] Open
Abstract
The Cryptococcus species complex contains two sibling taxa, Cryptococcus neoformans and Cryptococcus gattii. Both species are basidiomycetous yeasts and major pathogens of humans and other mammals. Genotyping methods have identified major haploid molecular types of C. neoformans (VNI, VNII, VNB and VNIV) and of C. gattii (VGI, VGII, VGIII and VGIV). To investigate the phylogenetic relationships among these haploid genotypes, we selected 73 strains from 2000 globally collected isolates investigated in our previous typing studies, representing each of these genotypes and carried out multigene sequence analyses using four genetically unlinked nuclear loci, ACT1, IDE, PLB1 and URA5. The separate or combined sequence analyses of all four loci revealed seven clades with significant support for each molecular type. However, three strains of each species revealed some incongruence between the original molecular type and the sequence-based type obtained here. The topology of the individual gene trees was identical for each clade of C. neoformans but incongruent for the clades of C. gattii indicating recent recombination events within C. gattii. There was strong evidence of recombination in the global VGII population. Both parsimony and likelihood analyses supported three major clades of C. neoformans (VNI/VNB, VNII and VNIV) and four major clades of C. gattii (VGI, VGII, VGIII and VGIV). The sequence variation between VGI, VGIII and VGIV was similar to that between VNI/VNB and VNII. MATa was for the first time identified for VGIV. The VNIV and VGII clades are basal to the C. neoformans or the C. gattii clade, respectively. Divergence times among the seven haploid monophyletic lineages in the Cryptococcus species complex were estimated by applying the hypothesis of the molecular clock. The genetic variation found among all of these haploid monophyletic lineages indicates that they warrant varietal status.
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James TY, Litvintseva AP, Vilgalys R, Morgan JAT, Taylor JW, Fisher MC, Berger L, Weldon C, du Preez L, Longcore JE. Rapid global expansion of the fungal disease chytridiomycosis into declining and healthy amphibian populations. PLoS Pathog 2009; 5:e1000458. [PMID: 19478871 PMCID: PMC2680619 DOI: 10.1371/journal.ppat.1000458] [Citation(s) in RCA: 171] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 04/29/2009] [Indexed: 01/27/2023] Open
Abstract
The fungal disease chytridiomycosis, caused by Batrachochytrium dendrobatidis, is enigmatic because it occurs globally in both declining and apparently healthy (non-declining) amphibian populations. This distribution has fueled debate concerning whether, in sites where it has recently been found, the pathogen was introduced or is endemic. In this study, we addressed the molecular population genetics of a global collection of fungal strains from both declining and healthy amphibian populations using DNA sequence variation from 17 nuclear loci and a large fragment from the mitochondrial genome. We found a low rate of DNA polymorphism, with only two sequence alleles detected at each locus, but a high diversity of diploid genotypes. Half of the loci displayed an excess of heterozygous genotypes, consistent with a primarily clonal mode of reproduction. Despite the absence of obvious sex, genotypic diversity was high (44 unique genotypes out of 59 strains). We provide evidence that the observed genotypic variation can be generated by loss of heterozygosity through mitotic recombination. One strain isolated from a bullfrog possessed as much allelic diversity as the entire global sample, suggesting the current epidemic can be traced back to the outbreak of a single clonal lineage. These data are consistent with the current chytridiomycosis epidemic resulting from a novel pathogen undergoing a rapid and recent range expansion. The widespread occurrence of the same lineage in both healthy and declining populations suggests that the outcome of the disease is contingent on environmental factors and host resistance.
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Sun S, Xu J. Chromosomal rearrangements between serotype A and D strains in Cryptococcus neoformans. PLoS One 2009; 4:e5524. [PMID: 19436753 PMCID: PMC2677675 DOI: 10.1371/journal.pone.0005524] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Accepted: 01/18/2009] [Indexed: 12/30/2022] Open
Abstract
Cryptococcus neoformans is a major human pathogenic fungus that can cause meningoencephalitis in immunocompromised hosts. It contains two divergent varieties, var. grubii (serotype A) and var. neoformans (serotype D), as well as hybrids (serotype AD) between these two varieties. In this study, we investigated the extent of chromosomal rearrangements between the two varieties, estimated the effects of chromosomal rearrangements on recombination frequencies, and surveyed the potential polymorphisms of the rearrangements among natural strains of the three serotypes. Through the analyses of two sequenced genomes from strains H99 (representing var. grubii) and JEC21 (representing var. neoformans), we revealed a total of 32 unambiguous chromosome rearrangements, including five translocations, nine simple inversions, and 18 complex rearrangements. Our analyses identified that overall, rearranged regions had recombination frequencies about half of those around syntenic regions. Using a direct PCR screening strategy, we examined the potential polymorphisms of 11 rearrangements among 64 natural C. neoformans strains from five countries. We found no polymorphism within var. neoformans and very limited polymorphism within var. grubii. However, strains of serotype AD showed significant polymorphism, consistent with their hybrid origins coupled with differential loss of heterozygosity. We discuss the implications of these results on the genome structure, ecology, and evolution of C. neoformans.
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Affiliation(s)
- Sheng Sun
- Department of Biology, McMaster University, Hamilton, Ontario, Canada.
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49
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Abstract
Cryptococcus neoformans and Cryptococcus gattii are the cause of life-threatening meningoencephalitis in immunocompromised and immunocompetent individuals respectively. The increasing incidence of cryptococcal infection as a result of the AIDS epidemic, the recent emergence of a hypervirulent cryptococcal strain in Canada and the fact that mortality from cryptococcal disease remains high have stimulated intensive research into this organism. Here we outline recent advances in our understanding of C. neoformans and C. gattii, including intraspecific complexity, virulence factors, and key signaling pathways. We discuss the molecular basis of cryptococcal virulence and the interaction between these pathogens and the host immune system. Finally, we discuss future challenges in the study and treatment of cryptococcosis.
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Affiliation(s)
- Hansong Ma
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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50
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Lin X, Patel S, Litvintseva AP, Floyd A, Mitchell TG, Heitman J. Diploids in the Cryptococcus neoformans serotype A population homozygous for the alpha mating type originate via unisexual mating. PLoS Pathog 2009; 5:e1000283. [PMID: 19180236 PMCID: PMC2629120 DOI: 10.1371/journal.ppat.1000283] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Accepted: 12/30/2008] [Indexed: 01/03/2023] Open
Abstract
The ubiquitous environmental human pathogen Cryptococcus neoformans is traditionally considered a haploid fungus with a bipolar mating system. In nature, the α mating type is overwhelmingly predominant over a. How genetic diversity is generated and maintained by this heterothallic fungus in a largely unisexual α population is unclear. Recently it was discovered that C. neoformans can undergo same-sex mating under laboratory conditions generating both diploid intermediates and haploid recombinant progeny. Same-sex mating (α-α) also occurs in nature as evidenced by the existence of natural diploid αADα hybrids that arose by fusion between two α cells of different serotypes (A and D). How significantly this novel sexual style contributes to genetic diversity of the Cryptococcus population was unknown. In this study, ∼500 natural C. neoformans isolates were tested for ploidy and close to 8% were found to be diploid by fluorescence flow cytometry analysis. The majority of these diploids were serotype A isolates with two copies of the α MAT locus allele. Among those, several are intra-varietal allodiploid hybrids produced by fusion of two genetically distinct α cells through same-sex mating. The majority, however, are autodiploids that harbor two seemingly identical copies of the genome and arose via either endoreplication or clonal mating. The diploids identified were isolated from different geographic locations and varied genotypically and phenotypically, indicating independent non-clonal origins. The present study demonstrates that unisexual mating produces diploid isolates of C. neoformans in nature, giving rise to populations of hybrids and mixed ploidy. Our findings underscore the importance of same-sex mating in shaping the current population structure of this important human pathogenic fungus, with implications for mechanisms of selfing and inbreeding in other microbial pathogens. Although sex typically involves partners of opposite mating type (sexuality), it can also occur with just one mating type and even single individuals (parthenogenesis, homothallism). However, from a population perspective, sexual reproduction occurs by either outcrossing or inbreeding regardless of the partners' sexuality. Here the impact of sex was studied for Cryptococcus neoformans, a pathogen that causes fungal meningitis. While sex in the laboratory is known to occur via opposite-sex-mating, the population is largely unisexual (α) in nature. Recently, an unusual α-α unisexual mating process involving only mating type α was discovered in the lab, but the impact of unisexual mating in nature was unknown. The global survey of this typically haploid organism reveals ∼8% diploids in the population produced by unisexual α-α mating. Some diploids result from fusion of two genetically distinct parents while other diploids arise via sibling mating or genome duplication. Although hybrid fitness is well-documented, how sex between identical isolates benefits the population is a conundrum. The diploid state may confer growth advantages or serve as a capacitor for evolution, allowing mutations to arise that would be deleterious on their own in the haploid, and then releasing these in novel combinations by meiosis and sporulation.
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Affiliation(s)
- Xiaorong Lin
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Sweta Patel
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Anastasia P. Litvintseva
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Anna Floyd
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Thomas G. Mitchell
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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