scholarly journals Characterization of a novel yeast phase-specific antigen expressed during in vitro thermal phase transition of Talaromyces marneffei

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Kritsada Pruksaphon ◽  
Mc Millan Nicol Ching ◽  
Joshua D. Nosanchuk ◽  
Anna Kaltsas ◽  
Kavi Ratanabanangkoon ◽  
...  
Keyword(s):  
Phase Transition ◽  
Therapeutic Potential ◽  
Specific Antigen ◽  
Human Monocyte ◽  
Host Cells ◽  
Yeast Cells ◽  
Fungal Pathogenesis ◽  
Dimorphic Fungus ◽  
Talaromyces Marneffei

AbstractTalaromyces marneffei is a dimorphic fungus that has emerged as an opportunistic pathogen particularly in individuals with HIV/AIDS. Since its dimorphism has been associated with its virulence, the transition from mold to yeast-like cells might be important for fungal pathogenesis, including its survival inside of phagocytic host cells. We investigated the expression of yeast antigen of T.marneffei using a yeast-specific monoclonal antibody (MAb) 4D1 during phase transition. We found that MAb 4D1 recognizes and binds to antigenic epitopes on the surface of yeast cells. Antibody to antigenic determinant binding was associated with time of exposure, mold to yeast conversion, and mammalian temperature. We also demonstrated that MAb 4D1 binds to and recognizes conidia to yeast cells’ transition inside of a human monocyte-like THP-1 cells line. Our studies are important because we demonstrated that MAb 4D1 can be used as a tool to study T.marneffei virulence, furthering the understanding of the therapeutic potential of passive immunity in this fungal pathogenesis.

scholarly journals Paracoccidioides brasiliensis Enolase Is a Surface Protein That Binds Plasminogen and Mediates Interaction of Yeast Forms with Host Cells

2010 ◽  
Vol 78 (9) ◽  
pp. 4040-4050 ◽  
Author(s):  
Sarah Veloso Nogueira ◽  
Fernanda L. Fonseca ◽  
Marcio L. Rodrigues ◽  
Vasanth Mundodi ◽  
Erika A. Abi-Chacra ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Paracoccidioides Brasiliensis ◽  
Surface Protein ◽  
Host Cells ◽  
Yeast Cells ◽  
Soluble Form ◽  
Dimorphic Fungus ◽  
Systemic Disorder ◽  
Fibronectin Binding Protein

ABSTRACT Paracoccidioidomycosis (PCM), caused by the dimorphic fungus Paracoccidioides brasiliensis, is a disseminated, systemic disorder that involves the lungs and other organs. The ability of the pathogen to interact with host components, including extracellular matrix (ECM) proteins, is essential to further colonization, invasion, and growth. Previously, enolase (EC 4.2.1.11) was characterized as a fibronectin binding protein in P. brasiliensis. Interaction of surface-bound enolase with plasminogen has been incriminated in tissue invasion for pathogenesis in several pathogens. In this paper, enolase was expressed in Escherichia coli as a recombinant glutathione S-transferase (GST) fusion protein (recombinant P. brasiliensis enolase [rPbEno]). The P. brasiliensis native enolase (PbEno) was detected at the fungus surface and cytoplasm by immunofluorescence with an anti-rPbEno antibody. Immobilized purified rPbEno bound plasminogen in a specific, concentration-dependent fashion. Both native enolase and rPbEno activated conversion of plasminogen to plasmin through tissue plasminogen activator. The association between PbEno and plasminogen was lysine dependent. In competition experiments, purified rPbEno, in its soluble form, inhibited plasminogen binding to fixed P. brasiliensis, suggesting that this interaction required surface-localized PbEno. Plasminogen-coated P. brasiliensis yeast cells were capable of degrading purified fibronectin, providing in vitro evidence for the generation of active plasmin on the fungus surface. Exposure of epithelial cells and phagocytes to enolase was associated with an increased expression of surface sites of adhesion. In fact, the association of P. brasiliensis with epithelial cells and phagocytes was increased in the presence of rPbEno. The expression of PbEno was upregulated in yeast cells derived from mouse-infected tissues. These data indicate that surface-associated PbEno may contribute to the pathogenesis of P. brasiliensis.

The ultrastructure of Candida albicans infections

1981 ◽  
Vol 27 (11) ◽  
pp. 1156-1164 ◽  
Author(s):  
Thomas J. Marrie ◽  
J. William Costerton
Keyword(s):  
Candida Albicans ◽  
Oral Candidiasis ◽  
Ruthenium Red ◽  
Host Cells ◽  
Yeast Cells ◽  
Positive Matrix ◽  
Urine Sediment ◽  
Bacteria Adhesion

Scrapings of Candida albicans plaques from the tongue and buccal mucosa of patients with oral candidiasis were examined electron microscopy. In addition, urine sediment from patients with infection of their catheterized urinary tracts was similar examined. Three types of C. albicans – oral epithelial cell interactions were noted: a loose adherence apparently mediated by ruthenium red positive matrix, a "tight" adherence where no space could be seen between the host and yeast cell, and invasions host cells by yeast hyphal elements. Adhesion of Candida blastospores to hyphal elements and adhesion of bacteria to Candida cells was also frequently observed.Urine sediments from patients with mixed bacteria–yeast infections demonstrated adhesion of the bacteria to the yeast cells. This phenomenon was also demonstrated in in vitro experiments and fibrous ruthenium red material invariably occupied the zo*** of adhesion.Phagocytosis of yeast by polymorphonuclear leukocytes was found in urinary, but not in oral, candidiasis. Our in vivo and vitro observations indicate that a ruthenium red positive matrix covers the surfaces involved in the yeast to yeast, yeast to ho and yeast to bacteria adhesion.

scholarly journals The N-terminal half of the core protein of hepatitis C virus is sufficient for nucleocapsid formation

2004 ◽  
Vol 85 (4) ◽  
pp. 971-981 ◽  
Author(s):  
Nathalie Majeau ◽  
Valérie Gagné ◽  
Annie Boivin ◽  
Marilène Bolduc ◽  
Josée-Anne Majeau ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Core Protein ◽  
Host Cells ◽  
Yeast Cells ◽  
Main Function ◽  
C Protein ◽  
Multifunctional Protein ◽  
The Core

The core (C) protein of hepatitis C virus (HCV) appears to be a multifunctional protein that is involved in many viral and cellular processes. Although its effects on host cells have been extensively discussed in the literature, little is known about its main function, the assembly and packaging of the viral genome. We have studied the in vitro assembly of several deleted versions of recombinant HCV C protein expressed in E. coli. We demonstrated that the 75 N-terminal residues of the C protein were sufficient to assemble and generate nucleocapsid-like particles (NLPs) in vitro. However, homogeneous particles of regular size and shape were observed only when NLPs were produced from at least the first 79 N-terminal amino acids of the C protein. This small protein unit fused to the endoplasmic reticulum-anchoring domain also generated NLPs in yeast cells. These data suggest that the N-terminal half of the C protein is important for formation of NLPs. Similarities between the HCV C protein and C proteins of other members of the Flaviviridae are discussed.

scholarly journals In-vivo Protection from SARS-CoV-2 infection by ATN-161 in k18-hACE2 transgenic mice

2021 ◽  
Author(s):  
Amruta Narayanappa ◽  
Elizabeth B Engler-Chiurazzi ◽  
Isabel C Murray-Brown ◽  
Timothy E Gressett ◽  
Ifechukwude J Biose ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Viral Entry ◽  
Therapeutic Potential ◽  
Host Cells ◽  
Spike Protein ◽  
Cell Infection ◽  
Integrin Alpha5beta1 ◽  
Chemokine Ligand

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an infectious disease that has spread worldwide. Current treatments are limited in both availability and efficacy, such that improving our understanding of the factors that facilitate infection is urgently needed to more effectively treat infected individuals and to curb the pandemic. We and others have previously demonstrated the significance of interactions between the SARS-CoV-2 spike protein, integrin alpha5beta1 and human ACE2 to facilitate viral entry into host cells in vitro. We previously found that inhibition of integrin alpha5beta1 by the clinically validated small peptide ATN-161 inhibits these spike protein interactions and cell infection in vitro. In continuation with our previous findings, here we have further evaluated the therapeutic potential of ATN-161 on SARS-CoV-2 infection in k18-hACE2 transgenic (SARS-CoV-2 susceptible) mice in vivo. We discovered that treatment with single- or repeated intravenous doses of ATN-161 (1 mg/kg) within 48 hours after intranasal inoculation with SARS-CoV-2 lead to a reduction of lung viral load, viral immunofluorescence and improved lung histology in a majority of mice 72 hours post-infection. Furthermore, ATN-161 reduced SARS-CoV-2-induced increased expression of lung integrin alpha 5 and alpha v (an alpha 5-related integrin that has also been implicated in SARS-CoV-2 interactions) as well as the C-X-C motif chemokine ligand 10 (Cxcl10), further supporting the potential involvement of these integrins, and the anti-inflammatory potential of ATN-161, respectively, in SARS-CoV-2 infection. To the best of our knowledge, this is the first study demonstrating the potential therapeutic efficacy of targeting integrin alpha5beta1 in SARS-CoV-2 infection in vivo and supports the development of ATN-161 as a novel SARS-CoV-2 therapy.

scholarly journals Regulation of type 1 fimbriae synthesis and biofilm formation by the transcriptional regulator LrhA of Escherichia coli

Microbiology ◽  
2005 ◽  
Vol 151 (10) ◽  
pp. 3287-3298 ◽  
Author(s):  
Caroline Blumer ◽  
Alexandra Kleefeld ◽  
Daniela Lehnen ◽  
Margit Heintz ◽  
Ulrich Dobrindt ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Invertible Element ◽  
Transcriptional Regulator ◽  
Host Cells ◽  
Yeast Cells ◽  
Type 1 Fimbriae ◽  
Biofilm Development

Type 1 fimbriae of Escherichia coli facilitate attachment to the host mucosa and promote biofilm formation on abiotic surfaces. The transcriptional regulator LrhA, which is known as a repressor of flagellar, motility and chemotaxis genes, regulates biofilm formation and expression of type 1 fimbriae. Whole-genome expression profiling revealed that inactivation of lrhA results in an increased expression of structural components of type 1 fimbriae. In vitro, LrhA bound to the promoter regions of the two fim recombinases (FimB and FimE) that catalyse the inversion of the fimA promoter, and to the invertible element itself. Translational lacZ fusions with these genes and quantification of fimE transcript levels by real-time PCR showed that LrhA influences type 1 fimbrial phase variation, primarily via activation of FimE, which is required for the ON-to-OFF transition of the fim switch. Enhanced type 1 fimbrial expression as a result of lrhA disruption was confirmed by mannose-sensitive agglutination of yeast cells. Biofilm formation was stimulated by lrhA inactivation and completely suppressed upon LrhA overproduction. The effects of LrhA on biofilm formation were exerted via the changed levels of surface molecules, most probably both flagella and type 1 fimbriae. Together, the data show a role for LrhA as a repressor of type 1 fimbrial expression, and thus as a regulator of the initial stages of biofilm development and, presumably, bacterial adherence to epithelial host cells also.

scholarly journals A 32-Kilodalton Hydrolase Plays an Important Role in Paracoccidioides brasiliensis Adherence to Host Cells and Influences Pathogenicity

2010 ◽  
Vol 78 (12) ◽  
pp. 5280-5286 ◽  
Author(s):  
Orville Hernández ◽  
Agostinho J. Almeida ◽  
Angel Gonzalez ◽  
Ana Maria Garcia ◽  
Diana Tamayo ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Paracoccidioides Brasiliensis ◽  
Protein A ◽  
Host Cells ◽  
Yeast Cells ◽  
Dimorphic Fungus ◽  
Morphological Alterations ◽  
Cell Vitality ◽  
Initial Interaction ◽  
Mouse Model Of Infection

ABSTRACT One of the most crucial events during infection with the dimorphic fungus Paracoccidioides brasiliensis is adhesion to pulmonary epithelial cells, a pivotal step in the establishment of disease. In this study, we have evaluated the relevance of a 32-kDa protein, a putative adhesion member of the haloacid dehalogenase (HAD) superfamily of hydrolases, in the virulence of this fungus. Protein sequence analyses have supported the inclusion of PbHad32p as a hydrolase and have revealed a conserved protein only among fungal dimorphic and filamentous pathogens that are closely phylogenetically related. To evaluate its role during the host-pathogen interaction, we have generated mitotically stable P. brasiliensis HAD32 (PbHAD32) antisense RNA (aRNA) strains with consistently reduced gene expression. Knockdown of PbHAD32 did not alter cell vitality or viability but induced morphological alterations in yeast cells. Moreover, yeast cells with reduced PbHAD32 expression were significantly affected in their capacity to adhere to human epithelial cells and presented decreased virulence in a mouse model of infection. These data support the hypothesis that PbHad32p binds to extracellular matrix (ECM) proteins and modulates the initial immune response for evasion of host defenses. Our findings point to PbHAD32 as a novel virulence factor active during the initial interaction with host cells in P. brasiliensis.

scholarly journals Sustained Nitric Oxide-Releasing Nanoparticles Induce Cell Death in Candida albicans Yeast and Hyphal Cells, Preventing Biofilm FormationIn Vitroand in a Rodent Central Venous Catheter Model

2016 ◽  
Vol 60 (4) ◽  
pp. 2185-2194 ◽  
Author(s):  
Mohammed S. Ahmadi ◽  
Hiu Ham Lee ◽  
David A. Sanchez ◽  
Adam J. Friedman ◽  
Moses T. Tar ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Candida Albicans ◽  
Flow Cytometric Analysis ◽  
Extracellular Polysaccharide ◽  
Host Cells ◽  
Yeast Cells ◽  
Central Venous ◽  
Content Type ◽  
Biofilm Development

ABSTRACTCandida albicansis a leading nosocomial pathogen. Today, candidal biofilms are a significant cause of catheter infections, and such infections are becoming increasingly responsible for the failure of medical-implanted devices.C. albicansforms biofilms in which fungal cells are encased in an autoproduced extracellular polysaccharide matrix. Consequently, the enclosed fungi are protected from antimicrobial agents and host cells, providing a unique niche conducive to robust microbial growth and a harbor for recurring infections. Here we demonstrate that a recently developed platform comprised of nanoparticles that release therapeutic levels of nitric oxide (NO-np) inhibits candidal biofilm formation, destroys the extracellular polysaccharide matrices of mature fungal biofilms, and hinders biofilm development on surface biomaterials such as the lumen of catheters. We found NO-np to decrease both the metabolic activity of biofilms and the cell viability ofC. albicansin vitroandin vivo. Furthermore, flow cytometric analysis found NO-np to induce apoptosis in biofilm yeast cellsin vitro. Moreover, NO-np behave synergistically when used in combination with established antifungal drug therapies. Here we propose NO-np as a novel treatment modality, especially in combination with standard antifungals, for the prevention and/or remediation of fungal biofilms on central venous catheters and other medical devices.

scholarly journals Heterogeneous distribution of Candida albicans cell-surface antigens demonstrated with an Als1-specific monoclonal antibody

Microbiology ◽  
2010 ◽  
Vol 156 (12) ◽  
pp. 3645-3659 ◽  
Author(s):  
David A. Coleman ◽  
Soon-Hwan Oh ◽  
Xiaomin Zhao ◽  
Lois L. Hoyer
Keyword(s):  
Candida Albicans ◽  
Cell Surface ◽  
Spatial Localization ◽  
Host Cells ◽  
Yeast Cells ◽  
Cell Surface Antigens ◽  
Heterogeneous Distribution ◽  
Germ Tubes

Despite an abundance of data describing expression of genes in the Candida albicans ALS (agglutinin-like sequence) gene family, little is known about the production of Als proteins on individual cells, their spatial localization or stability. Als proteins are most commonly discussed with respect to function in adhesion of C. albicans to host and abiotic surfaces. Development of a mAb specific for Als1, one of the eight large glycoproteins encoded by the ALS family, provided the opportunity to detect Als1 during growth of yeast and hyphae, both in vitro and in vivo, and to demonstrate the utility of the mAb in blocking C. albicans adhesion to host cells. Although most C. albicans yeast cells in a saturated culture are Als1-negative by indirect immunofluorescence, Als1 is detected on the surface of nearly all cells shortly after transfer into fresh growth medium. Als1 covers the yeast cell surface, with the exception of bud scars. Daughters of the inoculum cells, and sometimes granddaughters, also have detectable Als1, but Als1 is not detectable on cells from subsequent generations. On germ tubes and hyphae, most Als1 is localized proximal to the mother yeast. Once deposited on yeasts or hyphae, Als1 persists long after the culture has reached saturation. Growth stage-dependent production of Als1, coupled with its persistence on the cell surface, results in a heterogeneous population of cells within a C. albicans culture. Anti-Als1 immunolabelling patterns vary depending on the source of the C. albicans cells, with obvious differences between cells recovered from culture and those from a murine model of disseminated candidiasis. Results from this work highlight the temporal parallels for ALS1 expression and Als1 production in yeasts and germ tubes, the specialized spatial localization and persistence of Als1 on the C. albicans cell surface, and the differences in Als1 localization that occur in vitro and in vivo.

scholarly journals Discordant Influence of Blastomyces dermatitidis Yeast-Phase-Specific Gene BYS1 on Morphogenesis and Virulence

2010 ◽  
Vol 78 (6) ◽  
pp. 2522-2528 ◽  
Author(s):  
Theerapong Krajaejun ◽  
Marcel Wüthrich ◽  
Gregory M. Gauthier ◽  
Thomas F. Warner ◽  
Thomas D. Sullivan ◽  
...  
Keyword(s):  
Signal Sequence ◽  
Yeast Cells ◽  
Blastomyces Dermatitidis ◽  
Mouse Lung ◽  
Specific Gene ◽  
Dimorphic Fungus ◽  
Yeast Phase ◽  
Different Strains

ABSTRACT Blastomyces dermatitidis is a thermally induced dimorphic fungus capable of causing lung and systemic infections in immunocompetent animal hosts. With the publication of genomic sequences from three different strains of B. dermatitidis and the development of RNA interference as a gene-silencing tool, it has become possible to easily ascertain the virulence and morphological effects of knocking down the expression of candidate genes of interest. BYS1 (Blastomyces yeast-phase-specific 1), first identified by Burg and Smith, is expressed at high levels in yeast cells and is undetectable in mold. The deduced protein sequence of BYS1 has a putative signal sequence at its N terminus, opening the possibility that the BYS1-encoded protein is associated with the yeast cell wall. Herein, strains of B. dermatitidis with silenced expression of BYS1 were engineered and tested for morphology and virulence. The silenced strains produced rough-surfaced cultures on agar medium and demonstrated a propensity to form pseudohyphal cells on prolonged culture in vitro and in vivo, as measured in the mouse lung. Tests using a mouse model of blastomycosis with either yeast or spore inocula showed that the bys1-silenced strains were as virulent as control strains. Thus, although silencing of BYS1 alters morphology at 37°C, it does not appear to impair the pathogenicity of B. dermatitidis.

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