The pbrB gene encodes a laccase required for DHN-melanin synthesis in conidia of Talaromyces (Penicillium) marneffei.
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ABSTRACT:
SUBMITTER: Sapmak A
PROVIDER: S-EPMC4395095 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Talaromyces (Penicillium) marneffei is an emerging opportunistic pathogen associated with HIV infection, particularly in Southeast Asia and southern China. The rapid uptake and killing of T. marneffei conidia by phagocytic cells along with the effective induction of an inflammatory response by the host is essential for disease control. T. marneffei produces a number of different laccases linked to fungal virulence. To understand the role of the various laccases in T. marneffei, laccase-encoding genes were investigated. Targeted single, double and triple gene deletions of laccases encoding lacA, lacB, and lacC showed no significant phenotypic effects suggesting redundancy of function. When a fourth laccase-encoding gene, pbrB, was deleted in the ?lacA ?lacB ?lacC background, the quadruple mutant displayed delayed conidiation and the conidia were more sensitive to H2O2, sodium dodecyl sulfate (SDS), and antifungal agents than wild-type and other transformants. Conidia of the quadruple mutant showed marked differences in their interaction with the human monocyte cell line, THP-1 such that phagocytosis was significantly higher when compared with the wild-type at one and 2 hours of incubation while the phagocytic index was significantly different from 15 to 120 minutes. In addition, killing of the quadruple mutant by THP-1 cells was more efficient at 2 and 4 hours of incubation. The levels of the proinflammatory cytokines TNF-?, IL-1? and IL-6 from THP-1 cells infected with the quadruple mutant were also significantly increased in comparison with wild-type. The results demonstrate that production of laccases by T. marneffei actually promotes the pathogen's resistance to innate host defenses.
| S-EPMC4991349 | biostudies-literature
Project description:Talaromyces (Penicillium) marneffei is an important pathogenic thermally dimorphic fungus causing systemic mycosis in Southeast Asia. The clinical significance of T. marneffei became evident when the human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome epidemic arrived in Southeast Asia in 1988. Subsequently, a decline in the incidence of T. marneffei infection among HIV-infected patients was seen in regions with access to highly active antiretroviral therapy and other control measures for HIV. Since the 1990s, an increasing number of T. marneffei infections have been reported among non-HIV-infected patients with impaired cell-mediated immunity. Their comorbidities included primary adult-onset immunodeficiency due to anti-interferon-gamma autoantibodies and secondary immunosuppressive conditions including other autoimmune diseases, solid organ and hematopoietic stem cell transplantations, T-lymphocyte-depleting immunsuppressive drugs and novel anti-cancer targeted therapies such as anti-CD20 monoclonal antibodies and kinase inhibitors. Moreover, improved immunological diagnostics identified more primary immunodeficiency syndromes associated with T. marneffei infection in children. The higher case-fatality rate of T. marneffei infection in non-HIV-infected than HIV-infected patients might be related to delayed diagnosis due to the lack of clinical suspicion. Correction of the underlying immune defects and early use of antifungals are important treatment strategies. Clinicians should be familiar with the changing epidemiology and clinical management of T. marneffei infection among non-HIV-infected patients.
| S-EPMC4820671 | biostudies-other
Project description:BackgroundTalaromyces marneffei is an opportunistic dimorphic fungus prevalent in Southeast Asia. We previously demonstrated that Mp1p is an immunogenic surface and secretory mannoprotein of T. marneffei. Since Mp1p is a surface protein that can generate protective immunity, we hypothesized that Mp1p and/or its homologs are virulence factors.Methodology/principal findingsWe examined the pathogenic roles of Mp1p and its homologs in a mouse model. All mice died 21 and 30 days after challenge with wild-type T. marneffei PM1 and MP1 complemented mutant respectively. None of the mice died 60 days after challenge with MP1 knockout mutant (P<0.0001). Seventy percent of mice died 60 days after challenge with MP1 knockdown mutant (P<0.0001). All mice died after challenge with MPLP1 to MPLP13 knockdown mutants, suggesting that only Mp1p plays a significant role in virulence. The mean fungal loads of PM1 and MP1 complemented mutant in the liver, lung, kidney and spleen were significantly higher than those of the MP1 knockout mutant. Similarly, the mean load of PM1 in the liver, lung and spleen were significantly higher than that of the MP1 knockdown mutant. Histopathological studies showed an abundance of yeast in the kidney, spleen, liver and lung with more marked hepatic and splenic necrosis in mice challenged with PM1 compared to MP1 knockout and MP1 knockdown mutants. Likewise, a higher abundance of yeast was observed in the liver and spleen of mice challenged with MP1 complemented mutant compared to MP1 knockout mutant. PM1 and MP1 complemented mutant survived significantly better than MP1 knockout mutant in macrophages at 48 hours (P<0.01) post-infection. The mean fungal counts of Pichia pastoris GS115-MP1 in the liver (P<0.001) and spleen (P<0.05) of mice were significantly higher than those of GS115 at 24 hours post-challenge.Conclusions/significanceMp1p is a key virulence factor of T. marneffei. Mp1p mediates virulence by improving the survival of T. marneffei in macrophages.
| S-EPMC4999278 | biostudies-literature
Project description:Neutrophils and macrophages provide the first line of cellular defence against pathogens once physical barriers are breached, but can play very different roles for each specific pathogen. This is particularly so for fungal pathogens, which can occupy several niches in the host. We developed an infection model of talaromycosis in zebrafish embryos with the thermally-dimorphic intracellular fungal pathogen Talaromyces marneffei and used it to define different roles of neutrophils and macrophages in infection establishment. This system models opportunistic human infection prevalent in HIV-infected patients, as zebrafish embryos have intact innate immunity but, like HIV-infected talaromycosis patients, lack a functional adaptive immune system. Importantly, this new talaromycosis model permits thermal shifts not possible in mammalian models, which we show does not significantly impact on leukocyte migration, phagocytosis and function in an established Aspergillus fumigatus model. Furthermore, the optical transparency of zebrafish embryos facilitates imaging of leukocyte/pathogen interactions in vivo. Following parenteral inoculation, T. marneffei conidia were phagocytosed by both neutrophils and macrophages. Within these different leukocytes, intracellular fungal form varied, indicating that triggers in the intracellular milieu can override thermal morphological determinants. As in human talaromycosis, conidia were predominantly phagocytosed by macrophages rather than neutrophils. Macrophages provided an intracellular niche that supported yeast morphology. Despite their minor role in T. marneffei conidial phagocytosis, neutrophil numbers increased during infection from a protective CSF3-dependent granulopoietic response. By perturbing the relative abundance of neutrophils and macrophages during conidial inoculation, we demonstrate that the macrophage intracellular niche favours infection establishment by protecting conidia from a myeloperoxidase-dependent neutrophil fungicidal activity. These studies provide a new in vivo model of talaromycosis with several advantages over previous models. Our findings demonstrate that limiting T. marneffei's opportunity for macrophage parasitism and thereby enhancing this pathogen's exposure to effective neutrophil fungicidal mechanisms may represent a novel host-directed therapeutic opportunity.
| S-EPMC6010348 | biostudies-literature
Project description:Dectin-1 and ephrin type-A receptor 2 (EphA2) receptors recognize β-glucan present in the fungal cell wall. Inhibition of Dectin-1 with the monoclonal 2a11 antibody was shown to reduce internalization of conidia of the human pathogen Aspergillus fumigatus into epithelial cells. In this study, we investigated the role of the EphA2 receptor present on A549 epithelial type II lung cells in the interaction with A. fumigatus conidia. We assessed whether EphA2 is involved in association and internalization of conidia by receptor inhibition by an antibody or by using the kinase inhibitor dasatinib. A 50% reduction of internalization of conidia was observed when this receptor was blocked with either the EphA2-specific monoclonal antibody or dasatinib, which was similar when Dectin-1 was inhibited with the 2a11 monoclonal antibody. Inhibition of both receptors reduced the internalization to 40%. EphA2 inhibition was also assessed in a hydrophobin deletion strain (ΔrodA) that exposes more β-glucan and a dihydroxynaphthalene (DHN)-melanin deletion strain (ΔpksP) that exposes more glucosamine and glycoproteins. The ΔrodA strain behaved similar to the wild-type strain with or without EphA2 inhibition. In contrast, the ΔpksP mutant showed an increase in association to the A549 cells and a decrease in internalization. Internalization was not further decreased by EphA2 inhibition. Taken together, the presence of DHN-melanin in the spore cell wall results in an EphA2-dependent internalization of conidia of A. fumigatus into A549 cells.
| S-EPMC7573251 | biostudies-literature
Project description:Talaromyces (Penicillium) marneffei is a thermally dimorphic fungus that can cause opportunistic systemic mycoses in patients infected with the human immunodeficiency virus (HIV). It has also been reported among patients with other causes of immunodeficiency, such as systemic lupus erythematosus, cancer, organ transplanted patients receiving immunosuppressive drug and adult onset immunodeficiency syndromes. Recent studies indicate that the clinical manifestations, laboratory findings and treatment strategies of talaromycosis (penicilliosis) marneffei are different between patients with and without HIV infection. Therefore early and accurate diagnosis of talaromycosis marneffei is crucial to the proper management and treatment. Since current diagnostic methods are currently inadequate, the aim of this study was to develop an immunochromatographic test (ICT) for the detection of T. marneffei yeast antigens in urine samples. The highly T. marneffei-specific monoclonal antibody 4D1 (MAb 4D1) conjugated with gold colloid at pH 6.5 was used as signal generator. The nitrocellulose membrane was lined with T. marneffei cytoplasmic yeast antigen (TM CYA) to serve as the test line, and rabbit anti-mouse IgG was the control line. Subjecting the assembled test strip to urine samples containing T. marneffei antigen produced a visible result within 20 minutes. The sensitivity limit of the assay was 3.125?g/ml of TM CYA. The ICT was used to test urine samples from 66 patients with blood culture confirmed talaromycosis marneffei, 42 patients with other fungal or bacterial infections, and 70 normal healthy individuals from endemic area of T. marneffei. The test exhibited sensitivity, specificity and accuracy of 87.87%, 100% and 95.5%, respectively. This rapid, user-friendly test holds great promise for the serodiagnosis of T. marneffei infection.
| S-EPMC5895032 | biostudies-literature
Project description:Talaromyces marneffei, formerly Penicillium marneffei, is a thermally dimorphic fungus. It causes a fatal disseminated disease in patients infected with the human immunodeficiency virus (HIV). Studies on the stress defense mechanism of T. marneffei can lead to a better understanding of the pathogenicity and the progression of the disease due to this fungus. The basic leucine-zipper (bZip) transcription factor gene in Saccharomyces cerevisiae, named yap1 (yeast activating protein-1), is known as a crucial central regulator of stress responses including those caused by oxidative agents, cadmium, and drugs. An ortholog of yap1, designated yapA, was identified in T. marneffei. We found that the yapA gene was involved in growth and fungal cell development. The yapA deletion mutant exhibited delays in the rate of growth, germination, and conidiation. Surprisingly, the yapA gene was also involved in the pigmentation of T. marneffei. Moreover, the mutant was sensitive to oxidative stressors such as H2O2 and menadione, similar to S. cerevisiae yap1 mutant, as well as the nitrosative stressor NaNO2. In addition, the yapA mutant demonstrated significantly decreased survival in human macrophage THP-1 compared to wild-type and complemented strains. This study reveals the role of yapA in fungal growth, cell development, stress response, and potential virulence in T. marneffei.
| S-EPMC5051730 | biostudies-literature
Project description:Fungi are adept at occupying specific environmental niches and often exploit numerous secondary metabolites generated by the cytochrome P450 (CYP) monoxygenases. This report describes the characterization of a yeast-specific CYP encoded by simA ("survival in macrophages"). Deletion of simA does not affect yeast growth at 37°C in vitro but is essential for yeast cell production during macrophage infection. The ΔsimA strain exhibits reduced conidial germination and intracellular growth of yeast in macrophages, suggesting that the enzymatic product of SimA is required for normal fungal growth in vivo. Intracellular ΔsimA yeast cells exhibit cell wall defects, and metabolomic and chemical sensitivity data suggest that SimA may promote chitin synthesis or deposition in vitro. In vivo, ΔsimA yeast cells subsequently lyse and are degraded, suggesting that SimA may increase resistance to and/or suppress host cell biocidal effectors. The results suggest that simA synthesizes a secondary metabolite that allows T. marneffei to occupy the specific intracellular environmental niche within the macrophage. IMPORTANCE This study in a dimorphic fungal pathogen uncovered a role for a yeast-specific cytochrome P450 (CYP)-encoding gene in the ability of T. marneffei to grow as yeast cells within the host macrophages. This report will inspire further research into the role of CYPs and secondary metabolite synthesis during fungal pathogenic growth.
| S-EPMC5863032 | biostudies-literature
Project description:Penicillium marneffei can cause a fatal systemic mycosis in patients infected with the HIV. Infections are endemic in the tropical regions of southeast Asia. Here, we report the genome sequences of the type strains of P. marneffei and its avirulent near relative, Talaromyces stipitatus.
| S-EPMC4333666 | biostudies-literature
Project description:Asexual spores (conidia) are the infectious propagules of many pathogenic fungi, and the capacity to sense the host environment and trigger conidial germination is a key pathogenicity determinant. Germination of conidia requires the de novo establishment of a polarised growth axis and consequent germ tube extension. The molecular mechanisms that control polarisation during germination are poorly understood. In the dimorphic human pathogenic fungus Penicillium marneffei, conidia germinate to produce one of two cell types that have very different fates in response to an environmental cue. At 25 degrees C, conidia germinate to produce the saprophytic cell type, septate, multinucleate hyphae that have the capacity to undergo asexual development. At 37 degrees C, conidia germinate to produce the pathogenic cell type, arthroconidiating hyphae that liberate uninucleate yeast cells. This study shows that the p21-activated kinase pakA is an essential component of the polarity establishment machinery during conidial germination and polarised growth of yeast cells at 37 degrees C but is not required for germination or polarised growth at 25 degrees C. Analysis shows that the heterotrimeric G protein alpha subunit GasC and the CDC42 orthologue CflA lie upstream of PakA for germination at both temperatures, while the Ras orthologue RasA only functions at 25 degrees C. These findings suggest that although some proteins that regulate the establishment of polarised growth in budding yeast are conserved in filamentous fungi, the circuitry and downstream effectors are differentially regulated to give rise to distinct cell types.
| S-EPMC2048533 | biostudies-literature