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

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.

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The ultrastructure of Candida albicans infections

Canadian Journal of Microbiology ◽

10.1139/m81-181 ◽

1981 ◽

Vol 27 (11) ◽

pp. 1156-1164 ◽

Cited By ~ 36

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.

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Interactions of Candida albicans Yeast Cells, Germ Tubes and Hyphae with Human Polymorphonuclear Leucocytes in vitro

Microbiology ◽

10.1099/00221287-130-3-465 ◽

1984 ◽

Vol 130 (3) ◽

pp. 465-471 ◽

Cited By ~ 5

Author(s):

A. COCKAYNE ◽

F. C. ODDS

Keyword(s):

Candida Albicans ◽

Yeast Cells ◽

Polymorphonuclear Leucocytes ◽

Germ Tubes

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Proteoglycans in host–pathogen interactions: molecular mechanisms and therapeutic implications

Expert Reviews in Molecular Medicine ◽

10.1017/s1462399409001367 ◽

2010 ◽

Vol 12 ◽

Cited By ~ 62

Author(s):

Allison H. Bartlett ◽

Pyong Woo Park

Keyword(s):

Cell Surface ◽

Virulence Factors ◽

Molecular Mechanisms ◽

Biological Significance ◽

Host Cells ◽

Microbial Pathogens ◽

Therapeutic Implications ◽

Core Proteins

Many microbial pathogens subvert proteoglycans for their adhesion to host tissues, invasion of host cells, infection of neighbouring cells, dissemination into the systemic circulation, and evasion of host defence mechanisms. Where studied, specific virulence factors mediate these proteoglycan–pathogen interactions, which are thus thought to affect the onset, progression and outcome of infection. Proteoglycans are composites of glycosaminoglycan (GAG) chains attached covalently to specific core proteins. Proteoglycans are expressed ubiquitously on the cell surface, in intracellular compartments, and in the extracellular matrix. GAGs mediate the majority of ligand-binding activities of proteoglycans, and many microbial pathogens elaborate cell-surface and secreted factors that interact with GAGs. Some pathogens also modulate the expression and function of proteoglycans through known virulence factors. Several GAG-binding pathogens can no longer attach to and invade host cells whose GAG expression has been reduced by mutagenesis or enzymatic treatment. Furthermore, GAG antagonists have been shown to inhibit microbial attachment and host cell entry in vitro and reduce virulence in vivo. Together, these observations underscore the biological significance of proteoglycan–pathogen interactions in infectious diseases.

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Reduced Virulence of HWP1-Deficient Mutants of Candida albicans and Their Interactions with Host Cells

Infection and Immunity ◽

10.1128/iai.68.4.1997-2002.2000 ◽

2000 ◽

Vol 68 (4) ◽

pp. 1997-2002 ◽

Cited By ~ 84

Author(s):

Noboru Tsuchimori ◽

Laura L. Sharkey ◽

William A. Fonzi ◽

Samuel W. French ◽

John E. Edwards ◽

...

Keyword(s):

Candida Albicans ◽

Cell Injury ◽

Gene Dosage ◽

Surface Protein ◽

Host Cells ◽

Null Mutant ◽

Gene Dosage Effect ◽

Hyphal Development

ABSTRACT The Candida albicans gene HWP1 encodes a surface protein that is required for normal hyphal development in vitro. We used mutants lacking one or both alleles of HWP1to investigate the role of this gene in virulence. Mice infected intravenously with the homozygous hwp1 null mutant, CAL3, survived a median of >14 days, whereas mice infected with a control strain containing two functional alleles of HWP1 survived only 3.5 days. After 1 day of infection, all strains produced similar levels of infection in the kidneys, spleen, and blood. However, after 2 and 3 days, there was a significant decrease in the number of organisms in the kidneys of the mice infected with CAL3. This finding suggests that the hwp1 homozygous null mutant is normal in its ability to initiate infection but deficient in its capacity to maintain infection. CAL3 also germinated minimally in the kidneys. The ability of the heterozygous null mutant to germinate and cause mortality in mice was intermediate to CAL3, suggesting a gene dosage effect. To investigate potential mechanisms for the diminished virulence of CAL3, we examined its interactions with endothelial cells and neutrophils in vitro. CAL3 caused less endothelial cell injury than the heterozygoushwp1 mutant. We conclude that the HWP1 gene product is important for both in vivo hyphal development and pathogenicity of C. albicans. Also, the ability to form filaments may be critical for candidal virulence by enabling the fungus to induce cellular injury and maintain a deep-seated infection.

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Effect of Prolonged Fluconazole Treatment on Candida albicans in Diffusion Chambers Implanted into Mice

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.46.10.3175-3179.2002 ◽

2002 ◽

Vol 46 (10) ◽

pp. 3175-3179

Author(s):

Peter G. Sohnle ◽

Beth L. Hahn

Keyword(s):

Candida Albicans ◽

Inflammatory Response ◽

Inflammatory Cells ◽

Model System ◽

Antifungal Drugs ◽

Yeast Cells ◽

In Vitro Susceptibility ◽

Bonferroni Test

ABSTRACT Fluconazole is an azole agent with primarily fungistatic activity in standard in vitro susceptibility tests. The present study was undertaken to develop a diffusion chamber model system in mice in order to study the in vivo effects of prolonged fluconazole treatment on Candida albicans. Chambers containing 100 C. albicans yeast cells were implanted subcutaneously on the flanks of C57BL/6 mice and were then retrieved 6 or 14 weeks later (after fluconazole treatment for 4 or 12 weeks, respectively). Leukocyte counts demonstrated that implantation of the chambers did elicit an inflammatory response but that only small numbers of inflammatory cells were able to enter the chamber interior. Treatment with fluconazole at 10 mg/kg of body weight/day for 12 weeks not only reduced the numbers of viable organisms within the chambers compared to those in untreated mice (mean ± standard deviation of log10 CFU of 0.7 ± 1.2 versus 2.3 ± 2.0; P < 0.001 by the Bonferroni test) but also increased the numbers of chambers that became sterile over the treatment period (14 of 16 versus 6 of 19; P = 0.0009 by the chi-square test). However, treatment for only 4 weeks had minimal effects on the numbers of chamber CFU, and none of the chambers became sterile during this period. Distribution of retrieved organisms between interior fluid and the chamber filters was approximately equal in all the treatment groups. This model system appears to be useful for evaluating the effects of antifungal drugs over prolonged periods in vivo. Its use in the present study demonstrates that fluconazole can increase the rate of sterilization of C. albicans foci that are protected from the host's inflammatory response.

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Cell surface and intracellular expression of two Candida albicans antigens during in vitro and in vivo growth

Microbial Pathogenesis ◽

10.1016/0882-4010(87)90123-9 ◽

1987 ◽

Vol 2 (4) ◽

pp. 249-257 ◽

Cited By ~ 8

Author(s):

Diane L. Brawner ◽

Jim E. Cutler

Keyword(s):

Candida Albicans ◽

Cell Surface ◽

Intracellular Expression ◽

In Vivo Growth

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Function of Candida albicans Adhesin Hwp1 in Biofilm Formation

Eukaryotic Cell ◽

10.1128/ec.00194-06 ◽

2006 ◽

Vol 5 (10) ◽

pp. 1604-1610 ◽

Cited By ~ 212

Author(s):

Clarissa J. Nobile ◽

Jeniel E. Nett ◽

David R. Andes ◽

Aaron P. Mitchell

Keyword(s):

Candida Albicans ◽

Cell Surface ◽

Biofilm Formation ◽

Tight Binding ◽

Surface Protein ◽

Venous Catheter ◽

Cell Surface Protein ◽

Additional Support

ABSTRACT Hwp1 is a well-characterized Candida albicans cell surface protein, expressed only on hyphae, that mediates tight binding to oral epithelial cells. Prior studies indicate that HWP1 expression is dependent upon Bcr1, a key regulator of biofilm formation. Here we test the hypothesis that Hwp1 is required for biofilm formation. In an in vitro model, the hwp1/hwp1 mutant produces a thin biofilm that lacks much of the hyphal mass found in the hwp1/HWP1 reconstituted strain. In a biofilm cell retention assay, we find that the hwp1/hwp1 mutant is defective in retention of nonadherent bcr1/bcr1 mutant cells. In an in vivo rat venous catheter model, the hwp1/hwp1 mutant has a severe biofilm defect, yielding only yeast microcolonies in the catheter lumen. These properties of the hwp1/hwp1 mutant are consistent with its role as a hypha-specific adhesin and indicate that it is required for normal biofilm formation. Overexpression of HWP1 in a bcr1/bcr1 mutant background improves adherence in the in vivo catheter model. This finding provides additional support for the model that Hwp1 is critical for biofilm adhesion. Hwp1 is the first cell surface protein known to be required for C. albicans biofilm formation in vivo and is thus an excellent therapeutic target.

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Role of G2-S16 Polyanionic Carbosilane Dendrimer in the Prevention of Respiratory Syncytial Virus Infection In Vitro and In Vivo in Mice

Polymers ◽

10.3390/polym13132141 ◽

2021 ◽

Vol 13 (13) ◽

pp. 2141

Author(s):

Ignacio Rodriguez-Izquierdo ◽

Rafael Ceña-Diez ◽

Maria Jesús Serramia ◽

Rosa Rodriguez-Fernández ◽

Isidoro Martínez ◽

...

Keyword(s):

Respiratory Syncytial Virus ◽

Cell Surface ◽

Host Cells ◽

Carbosilane Dendrimer ◽

Rsv Infection ◽

Host Cell Surface ◽

Syncytial Virus

The respiratory syncytial virus (RSV) causes respiratory infection and bronchiolitis, requiring hospitalization mainly in infants. The interaction between RSV, envelope glycoproteins G and F, and cell surface heparan sulfate proteoglycans (HSPG) is required for binding and entry into the host cells. A G2-S16 polyanionic carbosilane dendrimer was identified as a possible RSV inhibitor. We speculated that the G2-S16 dendrimer adheres to the host cell-surface HSPG, acts through binding to HS receptors, and prevents further RSV infection. The G2-S16 dendrimer was non-toxic when applied intranasally to Balb/c mice, and interestingly enough, this G2-S16 dendrimer inhibits 85% RSV. Therefore, our G2-S16 dendrimer could be a candidate for developing a new possible therapy against RSV infection.

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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

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02659-15 ◽

2016 ◽

Vol 60 (4) ◽

pp. 2185-2194 ◽

Cited By ~ 18

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.

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