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Edrich ESM, Duvenage L, Gourlay CW. Alternative Oxidase - Aid or obstacle to combat the rise of fungal pathogens? Biochim Biophys Acta Bioenerg 2024; 1865:149031. [PMID: 38195037 DOI: 10.1016/j.bbabio.2024.149031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 11/16/2023] [Accepted: 01/03/2024] [Indexed: 01/11/2024]
Abstract
Fungal pathogens present a growing threat to both humans and global health security alike. Increasing evidence of antifungal resistance in fungal populations that infect both humans and plant species has increased reliance on combination therapies and shown the need for new antifungal therapeutic targets to be investigated. Here, we review the roles of mitochondria and fungal respiration in pathogenesis and discuss the role of the Alternative Oxidase enzyme (Aox) in both human fungal pathogens and phytopathogens. Increasing evidence exists for Aox within mechanisms that underpin fungal virulence. Aox also plays important roles in adaptability that may prove useful within dual targeted fungal-specific therapeutic approaches. As improved fungal specific mitochondrial and Aox inhibitors are under development we may see this as an emerging target for future approaches to tackling the growing challenge of fungal infection.
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Affiliation(s)
| | - Lucian Duvenage
- CMM AFRICA Medical Mycology Research Unit, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Campbell W Gourlay
- Kent Fungal Group, School of Biosciences, University of Kent, Kent CT2 9HY, UK.
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Nev OA, Duvenage L, Brown AJP, Dangarembizi R, Hoving JC. Slicing through the challenge of maintaining Pneumocystis in the laboratory. mBio 2024; 15:e0327723. [PMID: 38345378 PMCID: PMC10936409 DOI: 10.1128/mbio.03277-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/29/2024] Open
Abstract
Pneumocystis jirovecii is a major fungal pathogen of humans that causes life-threatening lung infections in immunocompromised individuals. Despite its huge global impact upon human health, our understanding of the pathobiology of this deadly fungus remains extremely limited, largely because it is not yet possible to cultivate Pneumocystis in vitro, independently of the host. However, a recent paper by Munyonho et al. offers a major step forward (F. T. Munyonho, R. D. Clark, D. Lin, M. S. Khatun, et al., 2023, mBio 15:e01464-23, https://doi.org/10.1128/mbio.01464-23). They show that it is possible to maintain both the trophozoite and cyst forms of the mouse pathogen, Pneumocystis murina, in precision-cut lung slices for several weeks. Furthermore, they demonstrate that this offers the exciting opportunity to examine potential virulence factors such as possible biofilm formation as well as antifungal drug responses in the lung.
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Affiliation(s)
- Olga A. Nev
- Biosciences and Living Systems Institute, University of Exeter, Exeter, United Kingdom
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
| | - Lucian Duvenage
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
- CMM AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa
- Department of Pathology, Division of Immunology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Alistair J. P. Brown
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
| | - Rachael Dangarembizi
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
- CMM AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa
- Department of Human Biology, Division of Physiological Sciences, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
- Neuroscience Institute, Faculty of Health Sciences, University of Cape Town, Groote Schuur Hospital, Cape Town, South Africa
| | - Jennifer Claire Hoving
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
- CMM AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa
- Department of Pathology, Division of Immunology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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Höft MA, Duvenage L, Salie S, Keeton R, Botha A, Schwartz IS, Govender NP, Brown GD, Hoving JC. The pathogenesis of experimental Emergomycosis in mice. PLoS Negl Trop Dis 2024; 18:e0011850. [PMID: 38198478 PMCID: PMC10805315 DOI: 10.1371/journal.pntd.0011850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 01/23/2024] [Accepted: 12/07/2023] [Indexed: 01/12/2024] Open
Abstract
Emergomyces africanus is a recently identified thermally-dimorphic fungal pathogen that causes disseminated infection in people living with advanced HIV disease. Known as emergomycosis, this disseminated disease is associated with very high case fatality rates. Over the last decade, improved diagnostics and fungal identification in South Africa resulted in a dramatic increase in the number of reported cases. Although the true burden of disease is still unknown, emergomycosis is among the most frequently diagnosed dimorphic fungal infections in Southern Africa; and additional species in the genus have been identified on four continents. Little is known about the pathogenesis and the host's immune response to this emerging pathogen. Therefore, we established a murine model of pulmonary infection using a clinical isolate, E. africanus (CBS 136260). Both conidia and yeast forms caused pulmonary and disseminated infection in mice with organisms isolated in culture from lung, spleen, liver, and kidney. Wild-type C57BL/6 mice demonstrated a drop in body weight at two weeks post-infection, corresponding to a peak in fungal burden in the lung, spleen, liver, and kidney. An increase in pro-inflammatory cytokine production was detected in homogenized lung supernatants including IFN-γ, IL-1β, IL-6, IL12-p40 and IL-17 at three- and four-weeks post-infection. No significant differences in TNF, IL-12p70 and IL-10 were observed in wild-type mice between one and four-weeks post-infection. Rag-1-deficient mice, lacking mature T-and B-cells, had an increased fungal burden associated with reduced IFN-γ production. Together our data support a protective T-helper type-1 immune response to E. africanus infection. This may provide a possible explanation for the susceptibility of only a subset of people living with advanced HIV disease despite hypothesized widespread environmental exposure. In summary, we have established a novel murine model of E. africanus disease providing critical insights into the host immune components required for eliminating the infection.
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Affiliation(s)
- Maxine A. Höft
- CMM AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine (IDM), University of Cape Town, Cape Town, South Africa
- Division of Immunology, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Lucian Duvenage
- CMM AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine (IDM), University of Cape Town, Cape Town, South Africa
- Division of Immunology, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Sumayah Salie
- CMM AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine (IDM), University of Cape Town, Cape Town, South Africa
- Division of Immunology, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Roanne Keeton
- Division of Immunology, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Alfred Botha
- Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa
| | - Ilan S. Schwartz
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Nelesh P. Govender
- CMM AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine (IDM), University of Cape Town, Cape Town, South Africa
- National Institute for Communicable Diseases, Division of the National Health Laboratory Service, Johannesburg, South Africa; School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Medical Research Council Centre for Medical Mycology at the University of Exeter, Geoffrey Pope Building Stocker Road, Exeter, United Kingdom
| | - Gordon D. Brown
- CMM AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine (IDM), University of Cape Town, Cape Town, South Africa
- Medical Research Council Centre for Medical Mycology at the University of Exeter, Geoffrey Pope Building Stocker Road, Exeter, United Kingdom
| | - Jennifer Claire Hoving
- CMM AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine (IDM), University of Cape Town, Cape Town, South Africa
- Division of Immunology, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
- Medical Research Council Centre for Medical Mycology at the University of Exeter, Geoffrey Pope Building Stocker Road, Exeter, United Kingdom
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Azimova D, Herrera N, Duvenage L, Voorhies M, Rodriguez RA, English BC, Hoving JC, Rosenberg O, Sil A. Cbp1, a fungal virulence factor under positive selection, forms an effector complex that drives macrophage lysis. PLoS Pathog 2022; 18:e1010417. [PMID: 35731824 PMCID: PMC9255746 DOI: 10.1371/journal.ppat.1010417] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 07/05/2022] [Accepted: 03/07/2022] [Indexed: 12/03/2022] Open
Abstract
Intracellular pathogens secrete effectors to manipulate their host cells. Histoplasma capsulatum (Hc) is a fungal intracellular pathogen of humans that grows in a yeast form in the host. Hc yeasts are phagocytosed by macrophages, where fungal intracellular replication precedes macrophage lysis. The most abundant virulence factor secreted by Hc yeast cells is Calcium Binding Protein 1 (Cbp1), which is absolutely required for macrophage lysis. Here we take an evolutionary, structural, and cell biological approach to understand Cbp1 function. We find that Cbp1 is present only in the genomes of closely related dimorphic fungal species of the Ajellomycetaceae family that lead primarily intracellular lifestyles in their mammalian hosts (Histoplasma, Paracoccidioides, and Emergomyces), but not conserved in the extracellular fungal pathogen Blastomyces dermatitidis. We observe a high rate of fixation of non-synonymous substitutions in the Cbp1 coding sequences, indicating that Cbp1 is under positive selection. We determine the de novo structures of Hc H88 Cbp1 and the Paracoccidioides americana (Pb03) Cbp1, revealing a novel "binocular" fold consisting of a helical dimer arrangement wherein two helices from each monomer contribute to a four-helix bundle. In contrast to Pb03 Cbp1, we show that Emergomyces Cbp1 orthologs are unable to stimulate macrophage lysis when expressed in the Hc cbp1 mutant. Consistent with this result, we find that wild-type Emergomyces africanus yeast are able to grow within primary macrophages but are incapable of lysing them. Finally, we use subcellular fractionation of infected macrophages and indirect immunofluorescence to show that Cbp1 localizes to the macrophage cytosol during Hc infection, making this the first instance of a phagosomal human fungal pathogen directing an effector into the cytosol of the host cell. We additionally show that Cbp1 forms a complex with Yps-3, another known Hc virulence factor that accesses the cytosol. Taken together, these data imply that Cbp1 is a fungal virulence factor under positive selection that localizes to the cytosol to trigger host cell lysis.
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Affiliation(s)
- Dinara Azimova
- University of California San Francisco, San Francisco, California, United States of America
| | - Nadia Herrera
- University of California San Francisco, San Francisco, California, United States of America
| | - Lucian Duvenage
- AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa
| | - Mark Voorhies
- University of California San Francisco, San Francisco, California, United States of America
| | - Rosa A. Rodriguez
- University of California San Francisco, San Francisco, California, United States of America
| | - Bevin C. English
- University of California Davis, Davis, California, United States of America
| | - Jennifer C. Hoving
- AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa
| | - Oren Rosenberg
- University of California San Francisco, San Francisco, California, United States of America
| | - Anita Sil
- University of California San Francisco, San Francisco, California, United States of America
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Abstract
Exposure to fungal pathogens from the environment is inevitable and with the number of at-risk populations increasing, the prevalence of invasive fungal infection is on the rise. An interesting group of fungal organisms known as thermally dimorphic fungi predominantly infects immunocompromised individuals. These potential pathogens are intriguing in that they survive in the environment in one form, mycelial phase, but when entering the host, they are triggered by the change in temperature to switch to a new pathogenic form. Considering the growing prevalence of infection and the need for improved diagnostic and treatment approaches, studies identifying key components of fungal recognition and the innate immune response to these pathogens will significantly contribute to our understanding of disease progression. This review focuses on key endemic dimorphic fungal pathogens that significantly contribute to disease, including Histoplasma, Coccidioides and Talaromyces species. We briefly describe their prevalence, route of infection and clinical presentation. Importantly, we have reviewed the major fungal cell wall components of these dimorphic fungi, the host pattern recognition receptors responsible for recognition and important innate immune responses supporting adaptive immunity and fungal clearance or the failure thereof.
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Affiliation(s)
- Maxine A. Höft
- CMM AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine (IDM), University of Cape Town, Cape Town 7925, South Africa
- Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa
- MRC Centre for Medical Mycology at the University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK
| | - Lucian Duvenage
- CMM AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine (IDM), University of Cape Town, Cape Town 7925, South Africa
- Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa
- MRC Centre for Medical Mycology at the University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK
| | - J. Claire Hoving
- CMM AFRICA Medical Mycology Research Unit, Institute of Infectious Diseases and Molecular Medicine (IDM), University of Cape Town, Cape Town 7925, South Africa
- Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa
- MRC Centre for Medical Mycology at the University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK
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Duvenage L, Munro CA, Gourlay CW. High Resolution Respirometry in Candida albicans. Bio Protoc 2019; 9:e3361. [PMID: 33654859 DOI: 10.21769/bioprotoc.3361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/24/2019] [Accepted: 08/26/2019] [Indexed: 01/30/2023] Open
Abstract
Many Candida species, such as the opportunistic human pathogen Candida albicans, are Crabtree-Negative yeasts and are therefore highly dependent on the energy generated through oxidative phosphorylation. Respiration control is linked to a range of aspects of C. albicans cell physiology that appear to be important for virulence, most notably its ability to switch from yeast to hyphal forms and the maintenance of the cell wall. The following protocol allows for the measurement and characterization of respiration in C. albicans using high resolution respirometry. We outline how addition of respiration inhibitors can be used to assay the "mode" of respiration, mitochondrial health and the level of electron transport that is coupled to ATP synthase activity in living cell cultures. These data provide useful insight into the effects of external factors, such as exposure to anti-fungal compounds, or internal changes such as genetic alterations on respiratory performance.
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Affiliation(s)
- Lucian Duvenage
- Kent Fungal Group, School of Biosciences, University of Kent, Kent, CT2 9HY, UK
| | - Carol A Munro
- MRC Centre for Medical Mycology at the University of Aberdeen, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD
| | - Campbell W Gourlay
- Kent Fungal Group, School of Biosciences, University of Kent, Kent, CT2 9HY, UK
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Duvenage L, Hitzeroth II, Meyers AE, Rybicki EP. Expression in tobacco and purification of beak and feather disease virus capsid protein fused to elastin-like polypeptides. J Virol Methods 2013; 191:55-62. [PMID: 23578703 DOI: 10.1016/j.jviromet.2013.03.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 03/20/2013] [Accepted: 03/25/2013] [Indexed: 02/05/2023]
Abstract
Psittacine beak and feather disease, caused by beak and feather disease virus (BFDV), is a threat to endangered psittacine species. There is currently no vaccine against BFDV, which necessitates the development of safe and affordable vaccine candidates. A subunit vaccine based on BFDV capsid protein (CP), the major antigenic determinant, expressed in the inexpensive and highly scalable plant expression system could satisfy these requirements. Full-length CP and a truncated CP (ΔN40 CP) were transiently expressed in tobacco (Nicotiana benthamiana) as fusions to elastin-like polypeptide (ELP). These two proteins were fused to ELPs of different lengths in order to increase expression levels and to provide a simple means of purification. The ELP fusion proteins were purified by inverse transition cycling (ITC) and it was found that a membrane filtration-based ITC method improved the recovery of ΔN40 CP-ELP51 fusion protein relative to a centrifugation-based method.
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Affiliation(s)
- Lucian Duvenage
- Department of Molecular and Cell Biology, University of Cape Town, Rondebosch 7700, South Africa
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