scholarly journals Gene Overexpression/Suppression Analysis of Candidate Virulence Factors of Candida albicans

2008 ◽  
Vol 7 (3) ◽  
pp. 483-492 ◽  
Author(s):  
Yue Fu ◽  
Guanpingsheng Luo ◽  
Brad J. Spellberg ◽  
John E. Edwards ◽  
Ashraf S. Ibrahim
Keyword(s):  
Candida Albicans ◽  
Virulence Factors ◽  
Surface Proteins ◽  
Screening Tests ◽  
Vaginal Candidiasis ◽  
Loss Of Function ◽  
Genes Encoding ◽  
Gpi Proteins ◽  
Protein Cell

ABSTRACT We developed a conditional overexpression/suppression genetic strategy in Candida albicans to enable simultaneous testing of gain or loss of function in order to identify new virulence factors. The strategy involved insertion of a strong, tetracycline-regulated promoter in front of the gene of interest. To validate the strategy, a library of genes encoding glycosylphosphatidylinositol (GPI)-anchored surface proteins was screened for virulence phenotypes in vitro. During the screening, overexpression of IFF4 was found to increase the adherence of C. albicans to plastic and to human epithelial cells, but not endothelial cells. Consistent with the in vitro results, IFF4 overexpression modestly increased the tissue fungal burden during murine vaginal candidiasis. In addition to the in vitro screening tests, IFF4 overexpression was found to increase C. albicans susceptibility to neutrophil-mediated killing. Furthermore, IFF4 overexpression decreased the severity of hematogenously disseminated candidiasis in normal mice, but not in neutropenic mice, again consistent with the in vitro phenotype. Overexpression of 12 other GPI proteins did not affect normal GPI protein cell surface accumulation, demonstrating that the overexpression strategy did not affect the cell capacity for making such proteins. These data indicate that the same gene can increase or decrease candidal virulence in distinct models of infection, emphasizing the importance of studying virulence genes in different anatomical contexts. Finally, these data validate the use of a conditional overexpression/suppression genetic strategy to identify candidal virulence factors.

Interaction of Candida albicans with genital mucosa: effect of sex hormones on adherence of yeasts in vitro

1988 ◽  
Vol 34 (3) ◽  
pp. 224-228 ◽  
Author(s):  
Aliza Kalo ◽  
Esther Segal
Keyword(s):  
Candida Albicans ◽  
Hela Cell ◽  
Sex Hormones ◽  
Hela Cells ◽  
Cell Types ◽  
Vaginal Candidiasis ◽  
Genital Mucosa ◽  
Hela Cell Lines ◽  
I Cells

Findings from our previous studies revealed a correlation between the level of adherence in vitro of Candida albicans to human exfoliated vaginal epithelial cells (VEC) and the hormonal status of the cell donors. In the present study we investigated the effect of the sex hormones estradiol, estriol, progesterone, and testosterone on the binding of the yeasts to HeLa cell lines and VEC in vitro. Monolayers of HeLa cells were exposed to the hormones and yeasts under controlled conditions. The number of adherent yeasts per square millimetre of HeLa cell monolayers and the percentage of VEC with adherent yeasts was estimated by microscopic counts. The results showed that the tested sex hormones affected at various degrees the adhesion of yeasts to HeLa cells or VEC. Progesterone had the most marked effect, leading to a significant increase in the number of adherent yeasts to HeLa cells or in the percentage of adhesion of VEC. In addition, VEC were separated on Percoll gradients into the two cell types: superficial (S) and intermediate (I), cell types which appear physiologically under increased serum levels of estradiol or progesterone, respectively. Adhesion assays with the separated cell populations revealed an increased binding capacity of the I cells. The finding that progesterone increased the adherence of yeasts to genital mucosa and that VEC of the I type have a higher capacity to adhere the yeasts is compatible with our previous observation that increased numbers of I cells, appearing under high level of progesterone, are found in situations known to have predisposition to vaginal candidiasis. Thus, our data point to a possible involvement of the hormone progesterone in the adherence of C. albicans to genital epithelium.

scholarly journals Antimicrobial Photodynamic Inactivation Inhibits Candida albicans Virulence Factors and ReducesIn VivoPathogenicity

2012 ◽  
Vol 57 (1) ◽  
pp. 445-451 ◽  
Author(s):  
Ilka Tiemy Kato ◽  
Renato Araujo Prates ◽  
Caetano Padial Sabino ◽  
Beth Burgwyn Fuchs ◽  
George P. Tegos ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Virulence Factors ◽  
Sodium Dodecyl ◽  
Systemic Infection ◽  
Tube Formation ◽  
Photodynamic Inactivation ◽  
Content Type ◽  
Daughter Cells

ABSTRACTThe objective of this study was to evaluate whetherCandida albicansexhibits altered pathogenicity characteristics following sublethal antimicrobial photodynamic inactivation (APDI) and if such alterations are maintained in the daughter cells.C. albicanswas exposed to sublethal APDI by using methylene blue (MB) as a photosensitizer (0.05 mM) combined with a GaAlAs diode laser (λ 660 nm, 75 mW/cm2, 9 to 27 J/cm2).In vitro, we evaluated APDI effects onC. albicansgrowth, germ tube formation, sensitivity to oxidative and osmotic stress, cell wall integrity, and fluconazole susceptibility.In vivo, we evaluatedC. albicanspathogenicity with a mouse model of systemic infection. Animal survival was evaluated daily. Sublethal MB-mediated APDI reduced the growth rate and the ability ofC. albicansto form germ tubes compared to untreated cells (P< 0.05). Survival of mice systemically infected withC. albicanspretreated with APDI was significantly increased compared to mice infected with untreated yeast (P< 0.05). APDI increasedC. albicanssensitivity to sodium dodecyl sulfate, caffeine, and hydrogen peroxide. The MIC for fluconazole forC. albicanswas also reduced following sublethal MB-mediated APDI. However, none of those pathogenic parameters was altered in daughter cells ofC. albicanssubmitted to APDI. These data suggest that APDI may inhibit virulence factors and reducein vivopathogenicity ofC. albicans. The absence of alterations in daughter cells indicates that APDI effects are transitory. The MIC reduction for fluconazole following APDI suggests that this antifungal could be combined with APDI to treatC. albicansinfections.

scholarly journals A genomic and proteomic analysis of surface proteins in bovine-adapted lineages of Staphylococcus aureus

2020 ◽  
Vol 2 (7A) ◽  
Author(s):  
Shauna D. Drumm ◽  
Rebecca Owens ◽  
Jennifer Mitchell ◽  
Orla M. Keane
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Surface Proteins ◽  
Host Cells ◽  
Mass Spectrometry Analysis ◽  
In Vitro Assays ◽  
Immune Recognition ◽  
Independent Manner ◽  
Genes Encoding

In Ireland, Staphylococcus aureus is the most common cause of intramammary infection (IMI) in cattle with the bovine-adapted lineages CC151 and CC97 most commonly found. Surface proteins play a major role in establishing and maintaining the infection. A previous study revealed that a strain from the CC151 lineage showed significant decay in genes encoding predicted surface proteins. Twenty-three S. aureus strains, twelve belonging to CC151 and eleven belonging to CC97, isolated from clinical IMI, were sequenced and genes encoding cell wall anchored (CWA) proteins predicted. Analysis showed that a minority of genes encoding putative CWA proteins were intact in the CC151 strains compared to CC97. Of the 26 known CWA proteins in S. aureus, the CC151 strains only encoded 10 intact genes while CC97 encoded on average 18 genes. Also within the CC97 lineage, the repertoire of genes varied depending on individual strains, with strains encoding between 17-20 intact genes. Although CC151 is reported to internalize within bovine host cells, it does so in a fibronectin-binding protein (FnBPA and FnBPB) independent manner. In-vitro assays were performed and results showed that strains from CC151, and surprisingly also CC97, weakly bound bovine fibronectin and that the FnBPs were poorly expressed in both these lineages. Mass spectrometry analysis of cell wall extracts revealed that SdrE and AdsA were the most highly expressed CWA proteins in both lineages. These results demonstrate significant differences between CC151 and CC97 in their repertoire of genes encoding CWA proteins, which may impact immune recognition of these strains and their interactions with host cells.

scholarly journals Fungicidal Activity of Fluconazole against Candida albicans in a Synthetic Vagina-Simulative Medium

2004 ◽  
Vol 48 (1) ◽  
pp. 161-167 ◽  
Author(s):  
Mahomed-Yunus S. Moosa ◽  
Jack D. Sobel ◽  
Hussain Elhalis ◽  
Wenjin Du ◽  
Robert A. Akins
Keyword(s):  
Acetic Acid ◽  
Candida Albicans ◽  
Drug Development ◽  
Carboxylic Acids ◽  
Fungicidal Activity ◽  
Vaginal Candidiasis ◽  
Ph Range ◽  
Cure Rates ◽  
Systemic Infections

ABSTRACT Fluconazole (FLZ) has emerged as a highly successful agent in the management of systemic infections of Candida. Cure rates for symptomatic candidiasis following single 150-mg FLZ dose therapy exceed 90%. In vitro, however, FLZ is fungistatic only in a narrow pH range and is not effective at vaginal pH, 4.2. This study evaluated the effect of FLZ on Candida albicans under in vitro conditions resembling the vaginal microenvironment, using vagina-simulative medium (VS). We found that FLZ was fungicidal for C. albicans in VS, but not in other media at the same pH, 4.2. In VS, FLZ was fungicidal at concentrations of ≥8 μg/ml and reduced viability by greater than 99.9%. Analysis of the components of VS indicated that 17 mM acetic acid, a concentration achieved in the vagina, was responsible for the synergistic, fungicidal effect. This effect was not seen at neutral pH. Other substrates were not effective substitutes for acetic acid; however, short-chained carboxylic acids, glyoxylate and malonate, were effective. Most strains of C. albicans that were resistant to FLZ under standard conditions were killed by FLZ plus acetate. Other species of Candida were also killed, except C. krusei and C. glabrata. This study shows that FLZ has fungicidal activity for Candida species under in vitro conditions that mimic the vaginal microenvironment. This raises the possibility that FLZ may also have fungicidal effects during treatment of vaginal candidiasis. Elucidating the mechanism by which FLZ and acetate interact may disclose vulnerable pathways that could be exploited in drug development.

scholarly journals Effect of β-1,6-Glucan Inhibitors on the Invasion Process of Candida albicans: Potential Mechanism of Their In Vivo Efficacy

2009 ◽  
Vol 53 (9) ◽  
pp. 3963-3971 ◽  
Author(s):  
Akihiro Kitamura ◽  
Saito Higuchi ◽  
Masato Hata ◽  
Katsuhiro Kawakami ◽  
Kumi Yoshida ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Critical Role ◽  
Vaginal Candidiasis ◽  
Specific Cell ◽  
Cell Wall Proteins ◽  
Invasion Process ◽  
In Vivo Efficacy

ABSTRACT β-1,6-Glucan is a fungus-specific cell wall component that is essential for the retention of many cell wall proteins. We recently reported the discovery of a small molecule inhibitor of β-1,6-glucan biosynthesis in yeasts. In the course of our study of its derivatives, we found a unique feature in their antifungal profile. D21-6076, one of these compounds, exhibited potent in vitro and in vivo antifungal activities against Candida glabrata. Interestingly, although it only weakly reduced the growth of Candida albicans in conventional media, it significantly prolonged the survival of mice infected by the pathogen. Biochemical evaluation of D21-6076 indicated that it inhibited β-1,6-glucan synthesis of C. albicans, leading the cell wall proteins, which play a critical role in its virulence, to be released from the cell. Correspondingly, adhesion of C. albicans cells to mammalian cells and their hyphal elongation were strongly reduced by the drug treatment. The results of the experiment using an in vitro model of vaginal candidiasis showed that D21-6076 strongly inhibited the invasion process of C. albicans without a significant reduction in its growth in the medium. These evidences suggested that D21-6076 probably exhibited in vivo efficacy against C. albicans by inhibiting its invasion process.

scholarly journals Comparative RNA-seq-Based Transcriptome Analysis of the Virulence Characteristics of Methicillin-Resistant and -Susceptible Staphylococcus pseudintermedius Strains Isolated from Small Animals

2015 ◽  
Vol 60 (2) ◽  
pp. 962-967 ◽  
Author(s):  
Natacha Couto ◽  
Adriana Belas ◽  
Manuela Oliveira ◽  
Paulo Almeida ◽  
Carla Clemente ◽  
...  
Keyword(s):  
Virulence Genes ◽  
Expression Profiles ◽  
Brain Heart Infusion ◽  
Surface Proteins ◽  
Rna Seq ◽  
Staphylococcus Pseudintermedius ◽  
Methicillin Resistant ◽  
Content Type ◽  
Genes Encoding

ABSTRACTStaphylococcus pseudintermediusis often associated with pyoderma, which can turn into a life-threatening disease. The dissemination of highly resistant isolates has occurred in the last 10 years and has challenged antimicrobial treatment of these infections considerably. We have compared the carriage of virulence genes and biofilm formation between methicillin-resistant and methicillin-susceptibleS. pseudintermedius(MRSP and MSSP, respectively) isolates and theirin vitrogene expression profiles by transcriptome sequencing (RNA-seq). Isolates were relatively unevenly distributed among the fouragrgroups, andagrtype III predominated in MRSP. Five virulence genes were detected in all isolates. Only thespsOgene was significantly associated with MSSP isolates (P= 0.04). All isolates produced biofilm in brain heart infusion broth (BHIB)–4% NaCl. MSSP isolates produced more biofilm on BHIB and BHIB–1% glucose media than MRSP isolates (P= 0.03 andP= 0.02, respectively). Virulence genes encoding surface proteins and toxins (spsA,spsB,spsD,spsK,spsL,spsN,nucC,coa, andluk-I) and also prophage genes (encoding phage capsid protein, phage infection protein, two phage portal proteins, and a phage-like protein) were highly expressed in the MRSP isolate (compared with the MSSP isolate), suggesting they may play a role in the rapid and widespread dissemination of MRSP. This study indicates that MRSP may upregulate surface proteins, which may increase the adherence of MRSP isolates (especially sequence type 71 [ST71]) to corneocytes. MSSP isolates may have an increased ability to form biofilm under acidic circumstances, through upregulation of the entirearcoperon. Complete understanding ofS. pseudintermediuspathogenesis and host-pathogen signal interaction during infections is critical for the treatment and prevention ofS. pseudintermediusinfections.

scholarly journals Application of Hydro-ethanol Extract of Tithonia diversifolia (Hemsl) in the Treatment of Experimental Murine Oral Candidiasis

2019 ◽  
pp. 1-10
Author(s):  
Oluwole Moses David ◽  
Margaret Olutayo Alese ◽  
Tobi Oyewole ◽  
Oluwole Ojo Alese ◽  
Adekunle Adegbuyi ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Virulence Factors ◽  
Oral Candidiasis ◽  
Ethanolic Extract ◽  
Alcoholic Extract ◽  
Tithonia Diversifolia ◽  
Candida Spp ◽  
Oral Infections

Background: Oral infection caused by Candida spp. is a major healthcare problem in dental and oral care. Treatment failure has been reported in cases of oral candidiasis as a result of resistance to common antifungals. Aim and Objective: In this study, the in vitro and in vivo activities of extract of Tithonia diversifolia against virulence factor-borne and antifungal resistant-Candida albicans were investigated. Candida albicans was isolated from the saliva of patients attending a tertiary hospital in Ekiti State. Methodology: Standard methods were used to determine the presence of virulence factors in the isolates. In vitro and in vivo anti-candidal activities of the hydro-ethanolic extract of T. diversifolia were also tested on the test fungus. Results: The virulence factors have varying percentage of occurrence in all the isolates with catalase having the highest. Itraconazole and nystatin were not effective against the isolates. Out of the six isolates selected (based on antifungal resistance) only three produced strong biofilm. The reduction in the population of the test organisms by the extract was time and concentration dependent. At the end of candidal challenge and treatment assays, extract of T. diversifolia has lower anti-candidal property compared to nystatin. Conclusion: This study has shown that C. albicans associated with the mouth carries virulence factors and are resistant to common antifungals. In this work, we noticed antifungal effects of hydro-alcoholic extract of T. diversifolia on C. albicans associated with oral infections.

scholarly journals Antagonism of Azole Activity against Candida albicans following Induction of Multidrug Resistance Genes by Selected Antimicrobial Agents

1999 ◽  
Vol 43 (8) ◽  
pp. 1968-1974 ◽  
Author(s):  
Karl W. Henry ◽  
M. Cristina Cruz ◽  
Santosh K. Katiyar ◽  
Thomas D. Edlind
Keyword(s):  
Candida Albicans ◽  
Antimicrobial Agents ◽  
Fold Increase ◽  
Antagonistic Effect ◽  
General Mechanism ◽  
Drug Induced ◽  
Genes Encoding ◽  
Efflux Proteins

ABSTRACT Antifungal azoles (e.g., fluconazole) are widely used for prophylaxis or treatment of Candida albicans infections in immunocompromised individuals, such as those with AIDS. These individuals are frequently treated with a variety of additional antimicrobial agents. Potential interactions between three azoles and 16 unrelated drugs (antiviral, antibacterial, antifungal, and antiprotozoal agents) were examined in vitro. Two compounds, tested at concentrations achievable in serum, demonstrated an antagonistic effect on azole activity against C. albicans. At fluconazole concentrations two to four times the 50% inhibitory concentration,C. albicans growth (relative to treatment with fluconazole alone) increased 3- to 18-fold in the presence of albendazole (2 μg/ml) or sulfadiazine (50 μg/ml). Antagonism (3- to 78-fold) of ketoconazole and itraconazole activity by these compounds was also observed. Since azole resistance has been correlated with overexpression of genes encoding efflux proteins, we hypothesized that antagonism results from drug-induced overexpression of these same genes. Indeed, brief incubation of C. albicans with albendazole or sulfadiazine resulted in a 3-to->10-fold increase in RNAs encoding multidrug transporter Cdr1p or Cdr2p. Zidovudine, trimethoprim, and isoniazid, which were not antagonistic with azoles, did not induce these RNAs. Fluphenazine, a known substrate for Cdr1p and Cdr2p, strongly induced their RNAs and, consistent with our hypothesis, strongly antagonized azole activity. Finally, antagonism was shown to require a functional Cdr1p. The possibility that azole activity against C. albicans is antagonized in vivo as well as in vitro in the presence of albendazole and sulfadiazine warrants investigation. Drug-induced overexpression of efflux proteins represents a new and potentially general mechanism for drug antagonism.

scholarly journals Cloning and Characterization of PRA1, a Gene Encoding a Novel pH-Regulated Antigen of Candida albicans

1998 ◽  
Vol 180 (2) ◽  
pp. 282-289 ◽  
Author(s):  
Maria Sentandreu ◽  
M. Victoria Elorza ◽  
Rafael Sentandreu ◽  
William A. Fonzi
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Immunoblot Analysis ◽  
Surface Proteins ◽  
Cell Fractionation ◽  
Expression Library ◽  
Gene Encoding ◽  
Genes Encoding ◽  
Surface Localization ◽  
Opportunistic Fungal Pathogen

ABSTRACT Candida albicans is an opportunistic fungal pathogen of humans. The cell wall of the organism defines the interface between the pathogen and host tissues and is likely to play an essential and pivotal role in the host-pathogen interaction. The components of the cell wall critical to this interaction are undefined. Immunoscreening of a lambda expression library with sera raised against mycelial cell walls of C. albicans was used to identify genes encoding cell surface proteins. One of the positive clones represented a candidal gene that was differentially expressed in response to changes in the pH of the culture medium. Maximal expression occurred at neutral pH, with no expression detected below pH 6.0. On the basis of the expression pattern, the corresponding gene was designatedPRA1, for pH-regulated antigen. The protein predicted from the nucleotide sequence was 299 amino acids long with motifs characteristic of secreted glycoproteins. The predicted surface localization and N glycosylation of the protein were directly demonstrated by cell fractionation and immunoblot analysis. Deletion of the gene imparted a temperature-dependent defect in hypha formation, indicating a role in morphogenesis. The PRA1 protein was homologous to surface antigens of Aspergillus spp. which react with serum from aspergillosis patients, suggesting that thePRA1 protein may have a role in the host-parasite interaction during candidal infection.

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