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ABSTRACT: The adhesion of fungi to host cells is an important area of study. Knowledge of the molecular mechanisms involved in these
interactions can be used to devise methods to interfere with them. Similar to many pathogens, loss of fungal adhesion to epithelial
or endothelial cell surfaces results in a marked decrease in virulence when evaluated in both in vivo and in vitro disease
models. This review emphasizes literature from the past year and focuses on the molecular mechanisms by which fungi in the
genera Candida, Cryptococcus, Sporothrix, Pneumocystis, and Aspergillus adhere to epithelial and/or endothelial host surfaces. The methodologies used to conduct these studies are also discussed.
Current Fungal Infection Reports 04/2012; 2(3):165-171.
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ABSTRACT: The Candida albicans agglutinin-like sequence (ALS) family encodes large cell surface glycoproteins that function in adhesion of the fungus to host and abiotic surfaces. Monoclonal antibodies (mAbs) specific for each Als protein were developed to study Als localization on the C. albicans surface. An anti-Als4 mAb demonstrated that Als4 covers the surface of yeast cells, with a greater abundance of Als4 on cells grown at 30 °C compared to 37 °C. On germ tubes, Als4 is localized in a restricted area proximal to the mother yeast. Immunolabeling with several anti-Als mAbs showed overlapping localization of Als1 and Als4 on yeast cells and Als1, Als3 and Als4 on germ tubes. Overlapping localization of Als proteins was also observed on yeast and hyphae recovered from mouse models of disseminated and oral candidiasis. Differences between Als localization in vivo and in vitro suggested changes in regulation of Als production in the host compared to the culture flask. Characterization with the anti-Als mAbs reveals the simultaneous presence and differences in relative abundance of Als proteins, creating an accurate image of Als representation and localization that can be used to guide conclusions regarding individual and collective Als protein function.
FEMS Immunology & Medical Microbiology 11/2011; 64(3):321-33. · 2.44 Impact Factor
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ABSTRACT: The Candida albicans ALS family has eight genetic loci, each encoding a large glycoprotein. Als protein function is discussed most frequently in terms of adhesion to host and abiotic surfaces. Analyses of C. albicans strain WO-1 indicated variation within the ALS1 locus compared with other isolates such as SC5314. Investigation revealed a recombination between the contiguous ALS5 and ALS1 loci to generate a new coding region, named ALS51, because it encodes the 5' domain of ALS5 fused in-frame to the tandem repeat region and 3' domain of ALS1. ALS51 was detected in 11 isolates (4.6%) from a collection of 239 C. albicans strains of diverse origin and clade assignment. The 12 ALS51-positive strains identified in this study represented three different ALS family genotypes with respect to the presence and copy number of ALS51, ALS5 and ALS1. ALS51 transcription was detected by real-time reverse-transcription-PCR in WO-1. Although the cell-surface abundance of Als51 on WO-1 and Als5 on SC5314 was too low to visualize by indirect immunofluorescence using an anti-Als5 monoclonal antibody, both proteins were observed on Western blots of β-1,6-glucanase-digested C. albicans cell walls. Characterization of ALS51 illustrates one of the recombination mechanisms that generate diversity within C. albicans gene families.
FEMS Immunology & Medical Microbiology 01/2011; 61(3):245-57. · 2.44 Impact Factor
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ABSTRACT: 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.
Microbiology 12/2010; 156(Pt 12):3645-59. · 3.06 Impact Factor
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Geraldine Butler,
Matthew D Rasmussen,
Michael F Lin,
Manuel A S Santos,
Sharadha Sakthikumar,
Carol A Munro,
Esther Rheinbay,
Manfred Grabherr,
Anja Forche,
Jennifer L Reedy, [......],
Thyagarajan Srikantha,
Qiandong Zeng,
Judith Berman,
Matthew Berriman,
Joseph Heitman,
Neil A R Gow,
Michael C Lorenz,
Bruce W Birren,
Manolis Kellis,
Christina A Cuomo
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ABSTRACT: Candida species are the most common cause of opportunistic fungal infection worldwide. Here we report the genome sequences of six Candida species and compare these and related pathogens and non-pathogens. There are significant expansions of cell wall, secreted and transporter gene families in pathogenic species, suggesting adaptations associated with virulence. Large genomic tracts are homozygous in three diploid species, possibly resulting from recent recombination events. Surprisingly, key components of the mating and meiosis pathways are missing from several species. These include major differences at the mating-type loci (MTL); Lodderomyces elongisporus lacks MTL, and components of the a1/2 cell identity determinant were lost in other species, raising questions about how mating and cell types are controlled. Analysis of the CUG leucine-to-serine genetic-code change reveals that 99% of ancestral CUG codons were erased and new ones arose elsewhere. Lastly, we revise the Candida albicans gene catalogue, identifying many new genes.
Nature 07/2009; 459(7247):657-62. · 36.28 Impact Factor
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ABSTRACT: Two monoclonal antibodies (MAbs) were raised against the Candida albicans cell-surface glycoprotein Als3 using the N-terminal domain of the protein as the immunogen. ELISA was used to demonstrate the specificity of the MAbs for the Als3 fragment, but not for the corresponding N-terminal domain fragments from other proteins in the Als family. The anti-Als3 MAbs immunolabeled the surface of germ tubes from a diverse collection of wild-type C. albicans isolates, but did not label yeast cells, an als3Delta/als3Delta deletion mutant strain, nor isolates of other Candida species associated with human disease. Als3 was visualized readily in fresh and formalin-fixed, paraffin-embedded kidney tissue from a murine model of candidiasis. The anti-Als3 MAbs were also useful for immunogold electron microscopy and Western blotting. Both MAbs blocked C. albicans adhesion to vascular endothelial cells and buccal epithelial cells. These versatile MAbs are a valuable addition to the reagents available to study C. albicans cell surface dynamics and interaction of the fungus with host cells.
Journal of microbiological methods 06/2009; 78(1):71-8. · 2.43 Impact Factor
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ABSTRACT: Monoclonal antibody 3D9.3 (MAb 3D9.3) reacts with the surface of Candida albicans germ tubes and recognizes a protein epitope. We used a two-step chromatography procedure to purify and identify the antigen (3D9) from C. albicans strain 66396 germ tubes. MAb 3D9.3 recognized two intense protein bands at 140 and 180 kDa. A comparative analysis between theoretical and experimental mass spectrum peaks showed that both bands corresponded to Als3. This conclusion was supported by lack of reactivity between MAb 3D9.3 and an als3Delta/als3Delta mutant strain, and the fact that an immunoglobulin preparation enriched for Als3 specificity recognized the purified 3D9 antigen. PCR demonstrated that C. albicans strain 66396 has two different-sized ALS3 alleles that correspond to the two purified protein bands. Strain- and species-specificity of the 3D9 epitope were studied with various C. albicans strains and Candida species, such as closely related Candida dubliniensis. The 3D9 epitope was detected only in C. albicans, demonstrating the utility of MAb 3D9.3 for differentiation between C. albicans and C. dubliniensis. Adhesion assays demonstrated that MAb 3D9.3 blocks adhesion of C. albicans germ tubes to human buccal epithelial cells and vascular endothelial cells.
FEMS Immunology & Medical Microbiology 05/2009; 55(3):314-23. · 2.44 Impact Factor
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ABSTRACT: Due to their predatory nature, raptor species may serve as important indicators of environmental contamination with antimicrobial-resistant bacteria. Raptors prey on small rodents and birds that have diverse habitat ranges, including urban and rural environments, and their intestinal microflora can reflect that of the animals on which they feed. Enterococcus spp. were selected as target organisms because they have been isolated from the avian gastrointestinal tract, can be conferred by prey items, and because they are capable of multiple resistance patterns. They are also a concerning source of human antimicrobial resistance. In this study fecal cultures were obtained from 15 May 2004 to 31 August 2004, from 21 free-living raptors and four captive raptors. Enterococcus was isolated from 21 (84%) of the 25 birds, and 54 isolates were chosen for further study based upon unique colony morphology. The most common isolate recovered was Enterococcus faecalis (95%, 95% confidence interval [CI]: 89-100). One bird in the study was determined to have Enterococcus gallinarum. Two distinct ribotypes of E. faecalis were identified, one with unique bands at 11 and 13 kb and the other with unique bands at 14 and 20 kb. Both ribotypes were found in free-living and captive birds. The Enterococcus isolates in this study demonstrated a variety of antimicrobial-resistance characteristics, including almost complete resistance to amikacin, first-generation cephalosporins, spectinomycin, and sulphadimethoxime. Isolates demonstrated variable resistance to chloramphenicol, gentamicin, enrofloxacin, erythromycin, and ticarcillin. No phenotypically vancomycin-resistant E. faecalis isolates were recovered from any of the raptors; three isolates had intermediate level susceptibility. A significantly higher number of isolates collected from captive birds demonstrated resistance to chloramphenicol than those obtained from free-living birds. This trend was not duplicated with any of the remaining 18 antimicrobial drugs tested. The results of this study suggest that raptors in central Illinois are coming into contact with antimicrobials, prey exposed to antimicrobials, or bacteria that are capable of transferring resistance genes. Further study is needed to determine the source of antimicrobial-resistant Enterococcus in free-living raptors but the limited data reflecting few differences between birds with and without antimicrobial exposure suggests that treatment and release of treated wild raptors is not contributing significantly to antimicrobial resistance in the environment.
Journal of wildlife diseases 05/2009; 45(2):302-13. · 1.08 Impact Factor
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Tae Kyung Kim,
Susan M Thomas,
Mengfei Ho,
Shobha Sharma,
Claudia I Reich,
Jeremy A Frank,
Kathleen M Yeater,
Diana R Biggs,
Noriko Nakamura,
Rebecca Stumpf,
Steven R Leigh,
Richard I Tapping,
Steven R Blanke,
James M Slauch,
H Rex Gaskins,
Jon S Weisbaum,
Gary J Olsen, Lois L Hoyer,
Brenda A Wilson
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ABSTRACT: Recent culture-independent studies have revealed that a healthy vaginal ecosystem harbors a surprisingly complex assemblage of microorganisms. However, the spatial distribution and composition of vaginal microbial populations have not been investigated using molecular methods. Here, we evaluated site-specific microbial composition within the vaginal ecosystem and examined the influence of sampling technique in detection of the vaginal microbiota. 16S rRNA gene clone libraries were prepared from samples obtained from different locations (cervix, fornix, outer vaginal canal) and by different methods (swabbing, scraping, lavaging) from the vaginal tracts of eight clinically healthy, asymptomatic women. The data reveal that the vaginal microbiota is not homogenous throughout the vaginal tract but differs significantly within an individual with regard to anatomical site and sampling method used. Thus, this study illuminates the complex structure of the vaginal ecosystem and calls for the consideration of microenvironments when sampling vaginal microbiota as a clinical predictor of vaginal health.
Journal of clinical microbiology 02/2009; 47(4):1181-9. · 4.16 Impact Factor
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ABSTRACT: This study explored whether wildlife species serve as the reservoir for human Candida albicans strains in a given geographic area. C. albicans isolates were collected from nonmigratory wildlife admitted to the University of Illinois Wildlife Medical Clinic. A geographically and temporally matched set of C. albicans oral isolates was collected from healthy human volunteers. Multilocus sequence typing was used to assign strains to genetic clades. Clade 1 isolates, particularly diploid sequence type 69 (DST 69), were most common in humans. Clade 1 strains were less frequently recovered from wildlife, while clade 8 strains, particularly DST 90, were overrepresented in the wildlife collection. All instances where a wildlife and human isolate shared the same DST occurred within clade 1. Clade distributions between human and wildlife isolates were significantly different, demonstrating population isolation between the groups. These differences may indicate limited strain transfer between groups or differential selection of C. albicans isolates in humans and wildlife. Wildlife strains had an amphotericin B MIC significantly lower than that of human isolates; strains with increased susceptibility were from several clades. C. albicans isolates were collected from domestic animals to provide comparisons with human and wildlife data sets. C. albicans isolation from canine and feline oral and anal swabs was infrequent; companion animal isolates were closely related to clade 1 human isolates. Collectively, the data suggest a greater likelihood of C. albicans transfer from humans to animals than from animals to humans. The nontransient human population may maintain the connection between geography and the C. albicans genetic groups recovered from humans.
Eukaryotic Cell 08/2008; 7(9):1475-86. · 3.60 Impact Factor
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Future Microbiology 06/2008; 3(3):271-3. · 3.82 Impact Factor
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ABSTRACT: The agglutinin-like sequence (ALS) family of Candida albicans includes eight genes that encode large cell-surface glycoproteins. The high degree of sequence relatedness between the ALS genes and the tremendous allelic variability often present in the same C. albicans strain complicated definition and characterization of the gene family. The main hypothesis driving ALS family research is that the genes encode adhesins, primarily involved in host-pathogen interactions. Although adhesive function has been demonstrated for several Als proteins, the challenge of studying putative adhesins in a highly adhesive organism like C. albicans has led to varying ideas about how best to pursue such investigations, and results that are sometimes contradictory. Recent analysis of alsdelta/alsdelta strains suggested roles for Als proteins outside of adhesion to host surfaces, and a broader scope of Als protein function than commonly believed. The availability and use of experimental methodologies to study C. albicans at the genomic level, and the ALS family en masse, have advanced knowledge of these genes and emphasized their importance in C. albicans biology and pathogenesis.
Medical Mycology 03/2008; 46(1):1-15. · 2.46 Impact Factor
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ABSTRACT: The Candida albicans ALS (agglutinin-like sequence) gene family encodes eight cell-surface glycoproteins, some of which function in adhesion to host surfaces. ALS genes have a central tandem repeat-encoding domain comprised entirely of head-to-tail copies of a conserved 108-bp sequence. The number of copies of the tandemly repeated sequence varies between C. albicans strains and often between alleles within the same strain. Because ALS alleles can encode different-sized proteins that may have different functional characteristics, defining the range of allelic variability is important. Genomic DNA from C. albicans strains representing the major genetic clades was PCR amplified to determine the number of tandemly repeated sequence copies within the ALS5 and ALS6 central domain. ALS5 alleles had 2-10 tandem repeat sequence copies (mean=4.82 copies) while ALS6 alleles had 2-8 copies (mean=4.00 copies). Despite this variability, tandem repeat copy number was stable in C. albicans strains passaged for 3000 generations. Prevalent alleles and allelic distributions varied among the clades for ALS5 and ALS6. Overall, ALS6 exhibited less variability than ALS5. ALS5 deletions can occur naturally in C. albicans via direct repeats flanking the ALS5 locus. Deletion of both ALS5 alleles was associated particularly with clades III and SA. ALS5 exhibited allelic polymorphisms in the coding region 5' of the tandem repeats; some alleles resembled ALS1, suggesting recombination between these contiguous loci. Natural deletion of ALS5 and the sequence variation within its coding region suggest relaxed selective pressure on this locus, and that Als5p function may be dispensable in C. albicans or redundant within the Als family.
Fungal Genetics and Biology 01/2008; 44(12):1298-309. · 3.74 Impact Factor
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ABSTRACT: Microarrays were used to identify changes in gene expression associated with Candida albicans biofilm development. Two biofilm substrates (denture and catheter), and two C. albicans strains for each substrate, were tested to remove model- and strain-dependent variability from the overall dataset. Three biofilm developmental phases were examined: early (6 h), intermediate (12 h), and mature (48 h). Planktonic specimens were collected at the same time points. Data analysis focused primarily on gene expression changes over the time-course of biofilm development. Glycolytic and non-glycolytic carbohydrate assimilation, amino acid metabolism, and intracellular transport mechanisms were important during the early phase of biofilm formation. These early events increase intracellular pools of pyruvate, pentoses and amino acids, which prepare the biofilm for the large biomass increase that begins around 12 h of development. This developmental stage demands energy and utilizes specific transporters for amino acids, sugars, ions, oligopeptides and lactate/pyruvate. At mature phase (48 h), few genes were differentially expressed compared with the 12 h time point, suggesting a relative lack of initiation of new metabolic activity. Data analysis to assess biofilm model-specific gene expression showed more dynamic changes in the denture model than in the catheter model. Data analysis to identify gene expression changes that are associated with each strain/substrate combination identified the same types of genes that were identified in the analysis of the entire dataset. Collectively, these data suggest that genes belonging to different, but interconnected, functional categories regulate the morphology and phenotype of C. albicans biofilm.
Microbiology 09/2007; 153(Pt 8):2373-85. · 3.06 Impact Factor
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ABSTRACT: Candida albicans yeast forms deleted for ALS5, ALS6 or ALS7 are more adherent than a relevant control strain to human vascular endothelial cell monolayers and buccal epithelial cells. In the buccal and vaginal reconstituted human epithelium (RHE) disease models, however, mutant and control strains caused a similar degree of tissue destruction. Deletion of ALS5 or ALS6 significantly slowed growth of the mutant strain; this phenotype was not affected by addition of excess uridine to the culture medium. These studies demonstrate similar phenotypic characteristics for the als5Delta/als5Delta, als6Delta/als6Delta and als7Delta/als7Delta strains that are not observed in any of the other C. albicans alsDelta/alsDelta isolates.
Medical Mycology 09/2007; 45(5):429-34. · 2.46 Impact Factor
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ABSTRACT: The Candida albicans ALS (agglutinin-like sequence) family includes eight genes (ALS1 to ALS7, and ALS9) that share a common general organization, consisting of a relatively conserved 5' domain, a central domain of tandemly repeated sequence units, and a 3' domain of relatively variable length and sequence. To test the hypothesis that the cell-surface glycoproteins encoded by the ALS genes mediate contact between the fungal cell and host surfaces, a set of C. albicans mutant strains was systematically constructed, each lacking one of the ALS sequences. Phenotypes of the mutant strains were evaluated, primarily using adhesion assays. ALS9 is unique within the ALS family due to extensive allelic sequence variation within the 5' domain that may result in functional differences between proteins encoded by ALS9-1 and ALS9-2. Deletion of ALS9 significantly reduces C. albicans adhesion to human vascular endothelial cell monolayers. The mutation was complemented by reintegration of a wild-type copy of ALS9-2, but not ALS9-1, suggesting allelic functional differences. Complementation of the mutation with a gene fusion between the 5' domain of ALS9-2 and the tandem repeats and 3' domain of ALS9-1 also restored wild-type adhesion levels. Analysis of the als9Delta/als9Delta mutant phenotype in other assays demonstrated no significant difference from a control strain for adhesion to buccal epithelial cells or laminin-coated plastic plates. The als9Delta/als9Delta mutant did not show significant differences from the control for adhesion to or destruction of cells in the reconstituted human epithelium (RHE) disease model, or for cell-wall defects, germ-tube formation or biofilm formation in a catheter model. Analysis of ALS9 allelic frequency in a collection of geographically diverse clinical isolates showed a distinct preference for ALS9-2 allelic sequences, within both the 5' and the 3' domain of the ALS9 coding region. These data suggest greater selective pressure to maintain the ALS9-2 allele in C. albicans isolates and imply its greater relative importance in host-pathogen interactions.
Microbiology 08/2007; 153(Pt 7):2342-50. · 3.06 Impact Factor
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ABSTRACT: The Salmonella typhimurium LT2 sialidase (neuraminidase, EC 3.2.1.18) structural gene, nanH, has been cloned and sialidase overproduced from multicopy plasmids in Escherichia coli. Sialidase expression was regulated positively by cAMP. In contrast, certain Tn 1000 insertions located upstream of nanH coding sequences reduced sialidase activity. A nanH chromosomal insertion mutation constructed by marker exchange demonstrated a single sialidase gene copy In S. typhimurium LT2. The complete nucleotide sequence of nanH, encoding a 41 300 dalton polypeptide, was determined and the derived primary structure was similar to sialidases from Clostridium perfringens, Clostridium sordellii, Bacteroides fragills, and Trypanosoma cruzi. Comparative sequence analysis, including codon usage and secondary structure predictions, indicated that the S. typhimurium and clostridial sialidases are homologous, strongly suggestive of an interspecies gene transfer event. At least two primary sequence motifs of the bacterial enzymes were detected in influenza A virus sialidases. The predicted secondary structure ol the bacterial enzymes was strikingly similar to viral sialidase. From the population distribution of nanH detected within a collection of salmonellae, it was apparent that S. typhimurium obtained its nanH copy most recently from Salmonella arizonae. S. typhimurium LT2 is thus a genetic mosaic that differs from other strains of even the same serotype by nanH plus potentially additional characters linked to nanH. These results have relevance to the evolution and function of sialidases in pathogenic microbes, and to the origin of the sialic acids.
Molecular Microbiology 10/2006; 6(7):873 - 884. · 5.01 Impact Factor
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ABSTRACT: Candida albicans ALS3 encodes a large cell-surface glycoprotein that has adhesive properties. Immunostaining of cultured C. albicans germ tubes showed that Als3p is distributed diffusely across the germ tube surface. Two-photon laser scanning microscopy of model catheter biofilms grown using a PALS3-green fluorescent protein (GFP) reporter strain showed GFP production in hyphae throughout the biofilm structure while biofilms grown using a PTPI1-GFP reporter strain showed GFP in both hyphae and yeast-form cells. Model catheter biofilms formed by an als3 Delta/als3 Delta strain were weakened structurally and had approximately half the biomass of a wild-type biofilm. Reintegration of a wild-type ALS3 allele restored biofilm mass and wild-type biofilm structure. Production of an Als3p-Ag alpha 1p fusion protein under control of the ALS3 promoter in the als3 Delta/als3 Delta strain restored some of the wild-type biofilm structural features, but not the wild-type biofilm mass. Despite its inability to restore wild-type biofilm mass, the Als3p-Ag alpha 1p fusion protein mediated adhesion of the als3 Delta/als3 Delta C. albicans strain to human buccal epithelial cells (BECs). The adhesive role of the Als3p N-terminal domain was further demonstrated by blocking adhesion of C. albicans to BECs with immunoglobulin reactive against the Als3p N-terminal sequences. Together, these data suggest that portions of Als3p that are important for biofilm formation may be different from those that are important in BEC adhesion, and that Als3p may have multiple functions in biofilm formation. Overexpression of ALS3 in an efg1 Delta/efg1 Delta strain that was deficient for filamentous growth and biofilm formation resulted in growth of elongated C. albicans cells, even under culture conditions that do not favour filamentation. In the catheter biofilm model, the ALS3 overexpression strain formed biofilm with a mass similar to that of a wild-type control. However, C. albicans cells in the biofilm had yeast-like morphology. This result uncouples the effect of cellular morphology from biofilm formation and underscores the importance of Als3p in biofilm development on silicone elastomer surfaces.
Microbiology 09/2006; 152(Pt 8):2287-99. · 3.06 Impact Factor
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ABSTRACT: ALS gene expression was studied in the hyposalivatory rat model of oral candidiasis and in clinical specimens collected from HIV-positive patients to assess similarities in expression patterns between the model system and clinical isolates. Two Candida albicans strains, SC5314 and OY-2-76, were used in the rat model system and infection progressed for 3 or 5 days. The strains produced similar oral lesions at 3 days. At 5 days, strain OY-2-76 produced more superficial lesions containing relatively more yeast forms compared to invasive hyphal forms observed for strain SC5314. For all infections, the most severe lesions were observed on the tongue and gingiva overlying the mandible. ALS transcripts were easier to detect by RT-PCR later in infection and under other conditions where more fungal cells were present. Expression of ALS1, ALS2, ALS3 and ALS4 was observed in rats infected for 3 days with ALS5 and ALS9 transcripts detected after 5 days of infection. Expression of ALS6 was observed in a single specimen from a 5-day infection while ALS7 transcript was never found. Expression of all ALS genes was observed in oral clinical material collected from HIV-positive patients although ALS6 and ALS7 transcripts required an extra PCR amplification step to be detected. Overall, the patterns of ALS gene expression were similar between the rat model and human clinical specimens, suggesting that the model would be useful for studying the phenotype of al delta/al delta mutant strains.
Medical Mycology 04/2006; 44(2):103-11. · 2.46 Impact Factor
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ABSTRACT: Candida albicans is the most common etiological agent of vaginal candidiasis. Elevated host estrogen levels and the incidence of vaginal candidiasis are positively associated. Elevated estrogen levels may affect host and/or fungal cells. This study investigates the effect of 17-beta-estradiol, 17-alpha-estradiol, ethynyl estradiol, and estriol on several C. albicans strains at concentrations ranging from 10(-5) to 10(-10) M. The addition of 17-beta-estradiol or ethynyl estradiol to C. albicans cells caused an increase in the number of cells forming germ tubes and an increase in germ tube length in a dose- and strain-dependent manner. The addition of 17-alpha-estradiol or estriol did not have a significant effect on germ tube formation by the cultured cells. Exposure to exogenous estrogens did not significantly change the biomass of any C. albicans culture tested. The transcriptional profile of estrogen-treated C. albicans cells showed increased expression of CDR1 and CDR2 across several strain-estrogen concentration-time point combinations, suggesting that these genes are the most responsive to estrogen exposure. Analysis of strain DSY654, which lacks the CDR1 and CDR2 coding sequences, showed a significantly decreased number of germ tube-forming cells in the presence of 17-beta-estradiol. PDR16 was the most highly up-regulated gene in strain DSY654 under these growth conditions. The cell biology and gene expression data from this study led to a model that proposes how components of the phospholipid and sterol metabolic pathways may interact to affect C. albicans germ tube formation and length.
Eukaryotic Cell 02/2006; 5(1):180-91. · 3.60 Impact Factor
