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Vlasova-St. Louis I, Mohei H. Molecular Diagnostics of Cryptococcus spp. and Immunomics of Cryptococcosis-Associated Immune Reconstitution Inflammatory Syndrome. Diseases 2024; 12:101. [PMID: 38785756 PMCID: PMC11120354 DOI: 10.3390/diseases12050101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 05/05/2024] [Accepted: 05/10/2024] [Indexed: 05/25/2024] Open
Abstract
Cryptococcal infection poses a significant global public health challenge, particularly in regions near the equator. In this review, we offer a succinct exploration of the Cryptococcus spp. genome and various molecular typing methods to assess the burden and genetic diversity of cryptococcal pathogens in the environment and clinical isolates. We delve into a detailed discussion on the molecular pathogenesis and diagnosis of immune reconstitution inflammatory syndrome (IRIS) associated with cryptococcosis, with a specific emphasis on cryptococcal meningitis IRIS (CM-IRIS). Our examination includes the recent literature on CM-IRIS, covering host cellulomics, proteomics, transcriptomics, and genomics.
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Affiliation(s)
| | - Hesham Mohei
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA;
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2
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Roosen L, Maes D, Musetta L, Himmelreich U. Preclinical Models for Cryptococcosis of the CNS and Their Characterization Using In Vivo Imaging Techniques. J Fungi (Basel) 2024; 10:146. [PMID: 38392818 PMCID: PMC10890286 DOI: 10.3390/jof10020146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/24/2024] [Accepted: 01/30/2024] [Indexed: 02/24/2024] Open
Abstract
Infections caused by Cryptococcus neoformans and Cryptococcus gattii remain a challenge to our healthcare systems as they are still difficult to treat. In order to improve treatment success, in particular for infections that have disseminated to the central nervous system, a better understanding of the disease is needed, addressing questions like how it evolves from a pulmonary to a brain disease and how novel treatment approaches can be developed and validated. This requires not only clinical research and research on the microorganisms in a laboratory environment but also preclinical models in order to study cryptococci in the host. We provide an overview of available preclinical models, with particular emphasis on models of cryptococcosis in rodents. In order to further improve the characterization of rodent models, in particular the dynamic aspects of disease manifestation, development, and ultimate treatment, preclinical in vivo imaging methods are increasingly used, mainly in research for oncological, neurological, and cardiac diseases. In vivo imaging applications for fungal infections are rather sparse. A second aspect of this review is how research on models of cryptococcosis can benefit from in vivo imaging methods that not only provide information on morphology and tissue structure but also on function, metabolism, and cellular properties in a non-invasive way.
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Affiliation(s)
- Lara Roosen
- Biomedical MRI, Department of Imaging and Pathology, KU Leuven, 3000 Leuven, Belgium
| | - Dries Maes
- Biomedical MRI, Department of Imaging and Pathology, KU Leuven, 3000 Leuven, Belgium
| | - Luigi Musetta
- Biomedical MRI, Department of Imaging and Pathology, KU Leuven, 3000 Leuven, Belgium
| | - Uwe Himmelreich
- Biomedical MRI, Department of Imaging and Pathology, KU Leuven, 3000 Leuven, Belgium
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3
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Giamberardino C, Perfect JR. The Rabbit Model of Cryptococcal Meningitis. Methods Mol Biol 2024; 2775:13-27. [PMID: 38758308 DOI: 10.1007/978-1-0716-3722-7_2] [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] [Indexed: 05/18/2024]
Abstract
Cryptococcal meningitis (CM) is a fungal disease caused by the invasion of Cryptococcus yeast cells into the central nervous system. The organism is thought to enter the body through the lungs and then escape due to dysregulation of the immune response. Multiple animal species have been used to model the infection and characterize CM including mice, rats, dogs, guinea pigs, and rabbits. The rabbit model has over 40 years of data and has been used to study host-pathogen interactions and the efficacy of antifungal therapeutics. The model begins with immune suppression to eliminate the lymphocytic cell population followed by direct infection of the central nervous system via an injection of a suspension of yeast cells into the cisterna magna. The organism remains in the CNS during the course of infection, and cerebrospinal fluid can be repeatedly sampled to quantify the burden of organism, measure drug levels in the CSF, profile the immune response in the CSF, and/or characterize the yeast cells. The rabbit model of infection is a robust experimental model for better understanding CM and Cryptococcus cellular behavior.
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Affiliation(s)
- Charles Giamberardino
- Duke University School of Medicine, Department of Medicine, Division of Infectious Diseases, Durham, NC, USA.
| | - John R Perfect
- Duke University School of Medicine, Department of Medicine, Division of Infectious Diseases, Durham, NC, USA
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4
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Sephton-Clark P, Temfack E, Tenor JL, Toffaletti DL, Loyse A, Molloy SF, Perfect JR, Bicanic T, Harrison TS, Lortholary O, Kouanfack C, Cuomo CA. Genetic diversity and microevolution in clinical Cryptococcus isolates from Cameroon. Med Mycol 2023; 61:myad116. [PMID: 37952096 PMCID: PMC10709296 DOI: 10.1093/mmy/myad116] [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: 08/22/2023] [Revised: 11/03/2023] [Accepted: 11/09/2023] [Indexed: 11/14/2023] Open
Abstract
Cryptococcal meningitis is the second most common cause of death in people living with HIV/AIDS, yet we have a limited understanding of how cryptococcal isolates change over the course of infection. Cryptococcal infections are environmentally acquired, and the genetic diversity of these infecting isolates can also be geographically linked. Here, we employ whole genome sequences for 372 clinical Cryptococcus isolates from 341 patients with HIV-associated cryptococcal meningitis obtained via a large clinical trial, across both Malawi and Cameroon, to enable population genetic comparisons of isolates between countries. We see that isolates from Cameroon are highly clonal, when compared to those from Malawi, with differential rates of disruptive variants in genes with roles in DNA binding and energy use. For a subset of patients (22) from Cameroon, we leverage longitudinal sampling, with samples taken at days 7 and 14 post-enrollment, to interrogate the genetic changes that arise over the course of infection, and the genetic diversity of isolates within patients. We see disruptive variants arising over the course of infection in several genes, including the phagocytosis-regulating transcription factor GAT204. In addition, in 13% of patients sampled longitudinally, we see evidence for mixed infections. This approach identifies geographically linked genetic variation, signatures of microevolution, and evidence for mixed infections across a clinical cohort of patients affected by cryptococcal meningitis in Central Africa.
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Affiliation(s)
- Poppy Sephton-Clark
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Elvis Temfack
- Internal Medicine Unit, Douala General Hospital, Douala, Cameroon
- Institut Pasteur, Molecular Mycology Unit, CNRS UMR 2000, Paris, France
| | - Jennifer L Tenor
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
| | - Dena L Toffaletti
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
| | - Angela Loyse
- Institute of Infection and Immunity, St George's University of London, London, UK
- Clinical Academic Group in Infection, St George's University Hospital, London, UK
| | - Síle F Molloy
- Institute of Infection and Immunity, St George's University of London, London, UK
| | - John R Perfect
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
| | - Tihana Bicanic
- Institute of Infection and Immunity, St George's University of London, London, UK
- Clinical Academic Group in Infection, St George's University Hospital, London, UK
| | - Thomas S Harrison
- Institute of Infection and Immunity, St George's University of London, London, UK
- MRC Centre for Medical Mycology, University of Exeter, Exeter, UK
| | - Olivier Lortholary
- Department of Infectious Diseases and Tropical Medicine, Paris Cité University, Necker-Enfants Malades Hospital, AP-HP, IHU Imagine, Paris, France
- Mycology Department and National Reference Center for Invasive Mycoses and Antifungals, Institut Pasteur, Paris, France
| | - Charles Kouanfack
- Department of Public Health, Faculty of Medicine and Pharmaceutical Sciences, University of Dschang, Dschang, Cameroon
- Day Hospital, Hospital Central Yaoundé, Yaoundé, Cameroon
- Research Center for Emerging and Re-emerging Diseases, Cameroon Baptist Convention Health Services (CBCHS), Yaoundé, Cameroon
| | - Christina A Cuomo
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
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5
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Boyce KJ. The Microevolution of Antifungal Drug Resistance in Pathogenic Fungi. Microorganisms 2023; 11:2757. [PMID: 38004768 PMCID: PMC10673521 DOI: 10.3390/microorganisms11112757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 10/30/2023] [Accepted: 10/30/2023] [Indexed: 11/26/2023] Open
Abstract
The mortality rates of invasive fungal infections remain high because of the limited number of antifungal drugs available and antifungal drug resistance, which can rapidly evolve during treatment. Mutations in key resistance genes such as ERG11 were postulated to be the predominant cause of antifungal drug resistance in the clinic. However, recent advances in whole genome sequencing have revealed that there are multiple mechanisms leading to the microevolution of resistance. In many fungal species, resistance can emerge through ERG11-independent mechanisms and through the accumulation of mutations in many genes to generate a polygenic resistance phenotype. In addition, genome sequencing has revealed that full or partial aneuploidy commonly occurs in clinical or microevolved in vitro isolates to confer antifungal resistance. This review will provide an overview of the mutations known to be selected during the adaptive microevolution of antifungal drug resistance and focus on how recent advances in genome sequencing technology have enhanced our understanding of this process.
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Affiliation(s)
- Kylie J Boyce
- School of Science, RMIT University, Melbourne, VIC 3085, Australia
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6
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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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7
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Ristow LC, Jezewski AJ, Chadwick BJ, Stamnes MA, Lin X, Krysan DJ. Cryptococcus neoformans adapts to the host environment through TOR-mediated remodeling of phospholipid asymmetry. Nat Commun 2023; 14:6587. [PMID: 37852972 PMCID: PMC10584969 DOI: 10.1038/s41467-023-42318-y] [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: 04/17/2023] [Accepted: 10/06/2023] [Indexed: 10/20/2023] Open
Abstract
Cryptococcus spp. are environmental fungi that first must adapt to the host environment before they can cause life-threatening meningitis in immunocompromised patients. Host CO2 concentrations are 100-fold higher than the external environment and strains unable to grow at host CO2 concentrations are not pathogenic. Using a genetic screening and transcriptional profiling approach, we report that the TOR pathway is critical for C. neoformans adaptation to host CO2 partly through Ypk1-dependent remodeling of phosphatidylserine asymmetry at the plasma membrane. We also describe a C. neoformans ABC/PDR transporter (PDR9) that is highly expressed in CO2-sensitive environmental strains, suppresses CO2-induced phosphatidylserine/phospholipid remodeling, and increases susceptibility to host concentrations of CO2. Interestingly, regulation of plasma membrane lipid asymmetry by the TOR-Ypk1 axis is distinct in C. neoformans compared to S. cerevisiae. Finally, host CO2 concentrations suppress the C. neoformans pathways that respond to host temperature (Mpk1) and pH (Rim101), indicating that host adaptation requires a stringent balance among distinct stress responses.
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Affiliation(s)
- Laura C Ristow
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Andrew J Jezewski
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | | | - Mark A Stamnes
- Department of Molecular Physiology and Biophysics, Caver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Xiaorong Lin
- Department of Plant Biology, University of Georgia, Athens, GA, 30602, USA
- Department of Microbiology, University of Georgia, Athens, GA, 30602, USA
| | - Damian J Krysan
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA.
- Department of Molecular Physiology and Biophysics, Caver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA.
- Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA.
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8
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Hilbert ZA, Bednarek JM, Schwiesow MJW, Chung KY, Moreau CT, Brown JCS, Elde NC. Distinct pathways of adaptive evolution in Cryptococcus neoformans reveal a mutation in adenylyl cyclase with trade-offs for pathogenicity. Curr Biol 2023; 33:4136-4149.e9. [PMID: 37708888 PMCID: PMC10592076 DOI: 10.1016/j.cub.2023.08.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 07/13/2023] [Accepted: 08/17/2023] [Indexed: 09/16/2023]
Abstract
Pathogenic fungi populate a wide range of environments and infect a diversity of host species. Despite this substantial biological flexibility, the impact of interactions between fungi and their hosts on the evolution of pathogenicity remains unclear. We studied how repeated interactions between the fungus Cryptococcus neoformans and relevant environmental and mammalian host cells-amoeba and mouse macrophages-shape the evolution of this model fungal pathogen. First, using a collection of clinical and environmental isolates of C. neoformans, we characterized a range of survival phenotypes for these strains when exposed to host cells of different species. We then performed serial passages of an environmentally isolated C. neoformans strain through either amoeba or macrophages for ∼75 generations to observe how these interactions select for improved replication within hosts. In one adapted population, we identified a single point mutation in the adenylyl cyclase gene, CAC1, that swept to fixation and confers a strong competitive advantage for growth inside macrophages. Strikingly, this growth advantage in macrophages is inversely correlated with disease severity during mouse infections, suggesting that adaptation to specific host niches can markedly reduce the pathogenicity of these fungi. These results raise intriguing questions about the influence of cyclic AMP (cAMP) signaling on pathogenicity and highlight the role of seemingly small adaptive changes in promoting fundamental shifts in the intracellular behavior and virulence of these important human pathogens.
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Affiliation(s)
- Zoë A Hilbert
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA; Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
| | - Joseph M Bednarek
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Mara J W Schwiesow
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA; Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Krystal Y Chung
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Christian T Moreau
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Jessica C S Brown
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Nels C Elde
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA; Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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9
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Sephton-Clark P, Nguyen T, Hoa NT, Ashton P, van Doorn HR, Ly VT, Le T, Cuomo CA. Impact of pathogen genetics on clinical phenotypes in a population of Talaromyces marneffei from Vietnam. Genetics 2023; 224:iyad100. [PMID: 37226893 PMCID: PMC10411598 DOI: 10.1093/genetics/iyad100] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 03/29/2023] [Accepted: 05/12/2023] [Indexed: 05/26/2023] Open
Abstract
Talaromycosis, a severe and invasive fungal infection caused by Talaromyces marneffei, is difficult to treat and impacts those living in endemic regions of Southeast Asia, India, and China. While 30% of infections result in mortality, our understanding of the genetic basis of pathogenesis for this fungus is limited. To address this, we apply population genomics and genome-wide association study approaches to a cohort of 336 T. marneffei isolates collected from patients who enrolled in the Itraconazole vs Amphotericin B for Talaromycosis trial in Vietnam. We find that isolates from northern and southern Vietnam form two distinct geographical clades, with isolates from southern Vietnam associated with increased disease severity. Leveraging longitudinal isolates, we identify multiple instances of disease relapse linked to unrelated strains, highlighting the potential for multistrain infections. In more frequent cases of persistent talaromycosis caused by the same strain, we identify variants arising over the course of patient infections that impact genes predicted to function in the regulation of gene expression and secondary metabolite production. By combining genetic variant data with patient metadata for all 336 isolates, we identify pathogen variants significantly associated with multiple clinical phenotypes. In addition, we identify genes and genomic regions under selection across both clades, highlighting loci undergoing rapid evolution, potentially in response to external pressures. With this combination of approaches, we identify links between pathogen genetics and patient outcomes and identify genomic regions that are altered during T. marneffei infection, providing an initial view of how pathogen genetics affects disease outcomes.
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Affiliation(s)
- Poppy Sephton-Clark
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Thu Nguyen
- Division of Infectious Diseases and International Health, Duke University School of Medicine, Durham, NC 27710, USA
| | - Ngo Thi Hoa
- Oxford University Clinical Research Unit, Oxford University, Ho Chi Minh City 749000, Vietnam
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford OX37LG, UK
- Microbiology department and Biological Research Center, Pham Ngoc Thach University of Medicine, Ho Chi Minh City 740500, Vietnam
| | - Philip Ashton
- Veterinary and Ecological Sciences, Institute of Infection, University of Liverpool, Liverpool CH647TE, UK
| | - H Rogier van Doorn
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford OX37LG, UK
- Oxford University Clinical Research Unit, Oxford University, Hanoi 113000, Vietnam
| | - Vo Trieu Ly
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford OX37LG, UK
- Department of Medicine and Pharmacy, Hospital for Tropical Diseases, Ho Chi Minh City 749000, Vietnam
| | - Thuy Le
- Division of Infectious Diseases and International Health, Duke University School of Medicine, Durham, NC 27710, USA
- Tropical Medicine Research Center for Talaromycosis, Pham Ngoc Thach University of Medicine, Ho Chi Minh City 740500, Vietnam
| | - Christina A Cuomo
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
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10
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Mao Y, Solis NV, Filler SG, Mitchell AP. Functional Dichotomy for a Hyphal Repressor in Candida albicans. mBio 2023; 14:e0013423. [PMID: 36883818 PMCID: PMC10127614 DOI: 10.1128/mbio.00134-23] [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: 01/15/2023] [Accepted: 02/20/2023] [Indexed: 03/09/2023] Open
Abstract
Nrg1 is a repressor of hypha formation and hypha-associated gene expression in the fungal pathogen Candida albicans. It has been well studied in the genetic background of the type strain SC5314. Here, we tested Nrg1 function in four other diverse clinical isolates through an analysis of nrg1Δ/Δ mutants, with SC5314 included as a control. In three strains, nrg1Δ/Δ mutants unexpectedly produced aberrant hyphae under inducing conditions, as assayed by microscopic observation and endothelial cell damage. The nrg1Δ/Δ mutant of strain P57055 had the most severe defect. We examined gene expression features under hypha-inducing conditions by RNA-sequencing (RNA-Seq) for the SC5314 and P57055 backgrounds. The SC5314 nrg1Δ/Δ mutant expressed six hypha-associated genes at reduced levels compared with wild-type SC5314. The P57055 nrg1Δ/Δ mutant expressed 17 hypha-associated genes at reduced levels compared with wild-type P57055, including IRF1, RAS2, and ECE1. These findings indicate that Nrg1 has a positive role in hypha-associated gene expression and that this role is magnified in strain P57055. Remarkably, the same hypha-associated genes affected by the nrg1Δ/Δ mutation in strain P57055 were also naturally expressed at lower levels in wild-type P57055 than those in wild-type SC5314. Our results suggest that strain P57055 is defective in a pathway that acts in parallel with Nrg1 to upregulate the expression of several hypha-associated genes. IMPORTANCE Hypha formation is a central virulence trait of the fungal pathogen Candida albicans. Control of hypha formation has been studied in detail in the type strain but not in other diverse C. albicans clinical isolates. Here, we show that the hyphal repressor Nrg1 has an unexpected positive role in hypha formation and hypha-associated gene expression, as revealed by the sensitized P57055 strain background. Our findings indicate that reliance on a single type strain limits understanding of gene function and illustrate that strain diversity is a valuable resource for C. albicans molecular genetic analysis.
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Affiliation(s)
- Yinhe Mao
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Norma V. Solis
- Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
| | - Scott G. Filler
- Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
- David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Aaron P. Mitchell
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
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11
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Sephton-Clark P, Nguyen T, Hoa NT, Ashton P, van Doorn HR, Ly VT, Le T, Cuomo CA. Impact of pathogen genetics on clinical phenotypes in a population of Talaromyces marneffei from Vietnam. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.30.534926. [PMID: 37034632 PMCID: PMC10081260 DOI: 10.1101/2023.03.30.534926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
Talaromycosis, a severe and invasive fungal infection caused by Talaromyces marneffei , is difficult to treat and impacts those living in endemic regions of southeast Asia, India, and China. While 30% of infections result in mortality, our understanding of the genetic basis of pathogenesis for this fungus is limited. To address this, we apply population genomics and genome wide association study approaches to a cohort of 336 T. marneffei isolates collected from patients who enrolled in the Itraconazole versus Amphotericin B for Talaromycosis (IVAP) trial in Vietnam. We find that isolates from northern and southern Vietnam form two distinct geographical clades, with isolates from southern Vietnam associated with increased disease severity. Leveraging longitudinal isolates, we identify multiple instances of disease relapse linked to unrelated strains, highlighting the potential for multi-strain infections. In more frequent cases of persistent talaromycosis caused by the same strain, we identify variants arising over the course of patient infections that impact genes predicted to function in the regulation of gene expression and secondary metabolite production. By combining genetic variant data with patient metadata for all 336 isolates, we identify pathogen variants significantly associated with multiple clinical phenotypes. In addition, we identify genes and genomic regions under selection across both clades, highlighting loci undergoing rapid evolution, potentially in response to external pressures. With this combination of approaches, we identify links between pathogen genetics and patient outcomes and identify genomic regions that are altered during T. marneffei infection, providing an initial view of how pathogen genetics affects disease outcomes.
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Affiliation(s)
- Poppy Sephton-Clark
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA 02142
| | - Thu Nguyen
- Division of Infectious Diseases and International Health, Duke University School of Medicine, Durham, North Carolina, USA 27710
| | - Ngo Thi Hoa
- Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom OX37LG
- Microbiology department and Biological Research Center, Pham Ngoc Thach University of Medicine, Ho Chi Minh City, Vietnam
| | - Philip Ashton
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, UK CH647TE
| | - H. Rogier van Doorn
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom OX37LG
- Oxford University Clinical Research Unit, Hanoi, Vietnam
| | - Vo Trieu Ly
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom OX37LG
- Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | - Thuy Le
- Division of Infectious Diseases and International Health, Duke University School of Medicine, Durham, North Carolina, USA 27710
- Tropical Medicine Research Center for Talaromycosis, Pham Ngoc Thach University of Medicine, Ho Chi Minh City, Vietnam
| | - Christina A. Cuomo
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA 02142
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12
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Jackson KM, Ding M, Nielsen K. Importance of Clinical Isolates in Cryptococcus neoformans Research. J Fungi (Basel) 2023; 9:364. [PMID: 36983532 PMCID: PMC10056780 DOI: 10.3390/jof9030364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 03/09/2023] [Accepted: 03/13/2023] [Indexed: 03/19/2023] Open
Abstract
The human pathogenic fungus Cryptococcus neoformans is a global health concern. Previous research in the field has focused on studies using reference strains to identify virulence factors, generate mutant libraries, define genomic structures, and perform functional studies. In this review, we discuss the benefits and drawbacks of using reference strains to study C. neoformans, describe how the study of clinical isolates has expanded our understanding of pathogenesis, and highlight how studies using clinical isolates can further develop our understanding of the host-pathogen interaction during C. neoformans infection.
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Affiliation(s)
| | | | - Kirsten Nielsen
- Department of Microbiology and Immunology, University of Minnesota, Minneapolis, MN 55455, USA
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