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Background: Invasive candidiasis is an important cause of fungal infections in immunocompromised patients, including premature infants. The S-type lectin, galectin-3 (gal3), is increasingly recognized for its role in antifungal host defense. This study tested the hypothesis that tissue gal3 expression is affected by disseminated infection with Candida albicans and that supplementation with gal3 will provide a benefit in this setting., Methods: To determine the expression of gal3 at the tissue level in response to disseminated infection with C. albicans, adult and neonatal mice were infected using previously established models. End points were chosen that reflected substantive tissue fungal burden but before mortality., Results: No differences in gal3 were detected in tissues of adult animals relative to uninfected controls. In neonatal animals, gal3 concentration was lower in the spleen of infected animals compared to uninfected. Pretreatment of neonatal mice with recombinant gal3 was associated with reduced mortality and reduced fungal burden in the kidney, spleen, and lung at 24 h following infection., Conclusion: These findings suggest that gal3 has an active role in host defense against candidiasis and that neonatal animals can benefit from supplementation with this lectin in the setting of disseminated candidiasis.

Release of neutrophil extracellular traps (NETs) is a significant antimicrobial host defense mechanism in adults. In neonates, fungal sepsis is a frequent cause of morbidity and mortality and may be a consequence of inadequate neutrophil defense functions. Like neutrophils from adult donors, we found that neutrophils from neonates formed robust cellular aggregates and released NETs in response to fungal β-glucan and Candida albicans hyphae when presented with extracellular matrix. Therefore, in response to fungal stimulation, neonatal neutrophils are capable of NETosis. Neonate susceptibility to fungal infections may not be due to an inability of their neutrophils to produce NETs., (Published by Oxford University Press for the Infectious Diseases Society of America 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

A BLAST search of the Candida Genome Database with the Saccharomyces cerevisiae LYS4 sequence known to encode homoaconitase (HA) revealed ORFs 19.3846 and 19.11327. Both alleles of the LYS4 gene were sequentially disrupted in Candida albicans BWP17 cells using PCR-based methodology. The null lys4Δ mutant exhibited lysine auxotrophy in minimal medium but was able to grow in the presence of l-Lys and α-aminoadipate, an intermediate of the α-aminoadipate pathway, at millimolar concentrations. The presence of d-Lys and pipecolic acid did not trigger lys4Δ growth. The C. albicans lys4Δ mutant cells demonstrated diminished germination ability. However, their virulence in vivo in a murine model of disseminated neonatal candidiasis appeared identical to that of the wild-type strain. Moreover, there was no statistically significant difference in fungal burden of infected tissues between the strains., (Copyright © 2014 John Wiley & Sons, Ltd.)

Objective: To determine whether premature infants with invasive Candida infection caused by strains with increased virulence properties have worse clinical outcomes than those infected with less virulent strains., Study Design: Clinical isolates were studied from 2 populations of premature infants, those colonized with Candida spp (commensal; n = 27) and those with invasive candidiasis (n = 81). Individual isolates of C albicans and C parapsilosis were tested for virulence in 3 assays: phenotypic switching, adhesion, and cytotoxicity. Invasive isolates were considered to have enhanced virulence if detected at a level >1 SD above the mean for the commensal isolates in at least one assay. Outcomes of patients with invasive isolates with enhanced virulence were compared with those with invasive isolates lacking enhanced virulence characteristics., Results: Enhanced virulence was detected in 61% of invasive isolates of C albicans and 42% of invasive isolates of C parapsilosis. All C albicans cerebrospinal fluid isolates (n = 6) and 90% of urine isolates (n = 10) had enhanced virulence, compared with 48% of blood isolates (n = 40). Infants with more virulent isolates were younger at the time of positive culture and had higher serum creatinine levels., Conclusion: Individual isolates of Candida species vary in their virulence properties. Strains with higher virulence are associated with certain clinical outcomes., (Copyright © 2012 Mosby, Inc. All rights reserved.)

As a means to study surface proteins involved in the yeast to hypha transition, human monoclonal antibody fragments (single-chain variable fragments, scFv) have been generated that bind to antigens expressed on the surface of Candida albicans yeast and/or hyphae. A cDNA expression library was constructed from hyphae, and screened for immunoreactivity with scFv5 as a means to identify its cognate antigen. A reactive clone contained the 3' end of the C. albicans gene, orf 19.7136, designated SPT6 based on homology to Saccharomyces cerevisiae, where its product functions as a transcription elongation factor. A mutant containing a homozygous deletion of SPT6 was isolated, demonstrating that unlike S. cerevisiae, deletion of this gene in C. albicans is not lethal. Growth of this strain was severely impaired, however, as was its capacity to undergo filamentous growth. Reactivity with scFv5 was not detected in the mutant strain, although its impaired growth complicates the interpretation of this finding. To assess C. albicansSPT6 function, expression of the C. albicans gene was induced in a defined S. cerevisiaespt6 mutant. Partial complementation was seen, confirming that the C. albicans and S. cerevisiae genes are functionally related in these species.

Background: Candida albicans and Candida parapsilosis are important causes of sepsis among premature neonates. The neutrophil is a key element in the control of Candida infections, yet specific neutrophil mechanisms that may contribute to the susceptibility of the premature neonate to candidiasis are not well understood., Aims: The hypothesis for this study is that neonatal neutrophils have a developmental deficiency in their capacity to generate an oxidative burst in response to Candida species., Study Design: Neutrophils were isolated from cord blood of term and preterm infants and from peripheral blood of adult volunteers. Neutrophils were exposed to Candida species, and assays of oxidative burst and phagocytosis were conducted., Results: Oxidative burst of neutrophils from term and preterm (22-29 weeks) neonates exposed to C. albicans hyphae was similar to adult neutrophils. No detectable burst was induced in either group by exposure to C. parapsilosis yeast, and was attenuated by exposure to C. albicans yeast. Because no deficiency in oxidative burst was seen, phagocytosis was also studied. Phagocytosis of unopsonized C. albicans yeast was low in both adult and neonatal neutrophils (10-12%), but was more efficient with C. parapsilosis as target (76-88%). Neutrophils from both term and preterm infants were capable of phagocytosis equivalent to adults., Conclusion: A deficiency in generation of an oxidative burst or phagocytosis may not contribute to the increased susceptibility of preterm neonates to infections with Candida.

The Candida albicans adhesin, Als3p, was identified as a potential cognate antigen for previously described human antibody fragments [single-chain variable fragment (scFv)] based on similarity of the binding pattern of the scFv to the distribution of this protein on the hyphal surface. Although all scFv bound avidly to wild type, scFv3 showed no detectable binding via immunofluorescence assay to strain 1843, containing a homozygous deletion of ALS3. Binding to the ALS3 reintegrant strain, 2322, was preserved, and scFv3 also bound to Saccharomyces cerevisiae expressing ALS3. Other scFv retained binding to 1843, but with a markedly altered pattern. To determine if scFv3 could interfere with Als3p function, adhesion assays were conducted using human epithelial or endothelial cells as target. Treatment of wild-type C. albicans with scFv3 reduced adhesion of the fungus to both cell types to levels comparable to the als3Delta/als3Delta mutant. These experiments confirm that phage display is a viable method to isolate human scFv specific to an antigen implicated in C. albicans virulence, and that the scFv interfere with adhesion to human cells. The altered pattern of immunostaining with other scFv that retain binding to the als3Delta/als3Delta mutant suggest that Als3p may also have a role in structural organization of the C. albicans cell surface.

Background: Very low birth weight infants (VLBW, < or = 1500 g) are at increased risk for invasive disease caused by fungi, and colonization is an important risk factor. This study was designed to examine the effect of maternal flora on Candida colonization of VLBW infants., Methods: Body site samples were collected within 24 hours of delivery from mothers who gave birth to VLBW infants, from their infants at birth, and then weekly for 12 weeks or until death or discharge. Yeast isolates were identified as Candida albicans by standard methods and typed by DNA fingerprinting using a C. albicans strain-specific DNA probe (CARE-2)., Results: Sixty-six percent (50/76) of mothers were colonized with yeast and 51% (39/76) of their infants had a Candida species isolated at least once. Of 46 infants born to C. albicans-colonized mothers, 18 (39%) became colonized with C. albicans. Twenty-two percent (17/76) of the infants in the study were colonized with C. albicans by 1 week of age; 76% of these infants (13/17) were born to C. albicans-colonized mothers suggesting vertical transmission. DNA fingerprinting was performed on these 13 mother-infant pairs and 11 pairs demonstrated identical band patterns, confirming vertical transmission. However, of all infants colonized with C. albicans by the first week of age, just 65% (11/17) had a maternal source, and among all infants colonized at any time point, only 41% (11/27) became colonized by vertical transmission., Conclusions: Both vertical and horizontal transmission contribute to Candida colonization of VLBW infants in the neonatal intensive care unit.

This study evaluates the conditions in which peripheral blood mononuclear cells mediate toxicity to Candida albicans opsonized with heat-inactivated human serum. Serum concentrations as low as 1% resulted in 50% inhibition of C. albicans metabolic activity after incubation with peripheral blood mononuclear cells at an effector to target ratio of 8. Measurable inhibition was also achieved at lower effector to target ratios and lower serum concentrations, and at least a portion of the metabolic inhibition reflected fungal cell death. Depletion of C. albicans-specific antibody decreased the toxic effect while opsonization with purified human IgG restored toxicity, and cell-cell contact between peripheral blood mononuclear cells and fungus was required. Depletion of or enrichment for monocytes from the peripheral blood mononuclear cells preparation diminished the toxic effect and the monocytic cell line, THP-1, was likewise incapable of toxicity. These studies provide evidence that antibody augments antifungal host defense and underscore the complex interrelationship between humoral and cellular immunity in these infections.

To identify antigens specific for the filamentous form of Candida albicans, a combinatorial phage display library expressing human immunoglobulin heavy and light chain variable regions was used to select phage clones capable of binding to the surfaces of viable C. albicans filaments. Eight distinct phage clones that bound specifically to filament surface antigens not expressed on blastoconidia were identified. Single-chain antibody variable fragments (scFv) derived from two of these phage clones (scFv5 and scFv12) were characterized in detail. Filament-specific antigen expression was detected by an indirect immunofluorescence assay. ScFv5 reacted with C. dubliniensis filaments, while scFv12 did not. Neither scFv reacted with C. glabrata, C. parapsilosis, C. rugosa, C. tropicalis, or Saccharomyces cerevisiae grown under conditions that stimulated filament formation in C. albicans and C. dubliniensis. Epitope detection by the two scFv was sensitive to proteinase K treatment but not to periodate treatment, indicating that the cognate epitopes were composed of protein. The antigens reactive with scFv5 and scFv12 were extractable from the cell surface with Zymolyase, but not with sodium dodecyl sulfate (SDS) and 2-mercaptoethanol, and migrated as polydisperse, high-molecular-weight bands on SDS-polyacrylamide gel electrophoresis gels. The epitopes were detected on clinical specimens obtained from infants with thrush and urinary candidiasis without passage of the organisms on laboratory media, confirming epitope expression in human infection. The availability of a monoclonal immunologic reagent that recognizes filaments from both C. albicans and C. dubliniensis and another specific only to C. albicans adds to the repertoire of potential diagnostic reagents for differentiation between these closely related species.

Efforts to provide active research context to introductory courses in basic sciences are likely to better engage learners and provide a framework for relevant concepts. A simple teaching and learning experiment was conducted to use concepts in organic chemistry to solve problems in the life sciences. Bryant University is a liberal arts university with new programs in biological and environmental sciences. This laboratory exercise was developed for introductory organic chemistry and designed to highlight its applicability to the biological sciences. Students participated in an ongoing project to identify antigens on the surface of Candida albicans hyphae by testing a variety of lipid extraction procedures and characterizing the fatty acid and carbohydrate composition of their extractions by thin-layer chromatography and gas chromatography-mass spectrometry. Student extracts were also tested in an immunoblot assay with a specific antibody fragment (scFv) that recognizes an unknown component of the cell surface of C. albicans hyphae. In order to build communication skills, students were required to prepare and present posters detailing the project and their findings. [ABSTRACT FROM AUTHOR]

Recent in vitro studies have implicated galectin-3 as an important receptor in host recognition and response to specific Candida species; however, its role in protection against disseminated candidiasis in vivo has not been evaluated. This study investigated the importance of galectin-3 in host defense against systemic infection with the highly virulent species Candida albicans, and the less virulent species, C. parapsilosis. Mice deficient in galectin-3 ( gal3−/−) were more susceptible to infection than wild-type (WT) mice. When infected with C. albicans, gal3−/− mice died significantly faster and exhibited a trend towards increased fungal burden and increased abscess formation in infected brains compared to WT mice. When infected with C. parapsilosis, gal3−/− mice had significantly higher renal fungal burdens and abscess formation compared to WT mice. To evaluate whether galectin-3 may contribute to susceptibility to candidiasis in human infants, galectin-3 levels in sera of newborn infants, a patient population uniquely susceptible to infections with both C. albicans and C. parapsilosis, were compared to serum galectin-3 levels of adults. Galectin-3 levels were significantly lower in newborn infant sera compared to adult sera. These data indicate that galectin-3 plays an important role in a murine model of disseminated candidiasis and suggest a potential mechanism of neonatal susceptibility to these infections. [ABSTRACT FROM AUTHOR]

Candida albicans causes the majority of invasive candidiasis in immunocompromised adults while Candida parapsilosis is a leading cause of neonatal candidiasis. While much work has focused on how the immune system recognizes and responds to C. albicans, less is known about host interaction with C. parapsilosis. This study investigates the human neutrophil phagocytic response to these species. Neutrophils underwent phagocytosis of C. parapsilosis yeast and C. albicans hyphae much more efficiently than C. albicans yeast. Treatment of neutrophils with a galectin-3 (gal3) blocking antibody inhibited phagocytosis of C. parapsilosis yeast and C. albicans hyphae, but not C. albicans yeast. The majority of neutrophil gal3 was expressed intracellularly and was secreted from neutrophils after treatment with C. parapsilosis mannan. When neutrophils were treated with exogenous gal3, phagocytosis of both C. albicans and C. parapsilosis yeast increased. Exposure of neutrophils to C. parapsilosis yeast increased phagocytosis of C. albicans yeast and was inhibited by gal3 blocking antibody. Taken together, these data indicate that gal3 secreted from neutrophils may act as a pro-inflammatory autocrine/paracrine signal in neutrophil phagocytosis and suggest that gal3 has a unique role in neutrophil response to C. parapsilosis yeast and C. albicans hyphae distinct from C. albicans yeast. [ABSTRACT FROM AUTHOR]

The article discusses a study by Z. Grozer and colleagues which compared Candida parapsilosis to Candida albicans in regard to its ability to produce prostaglandins from arachidonic acid. Topics discussed include the healthcare-associated infections with Candida species, the high prevalence of C. parapsilosis in neonates compared to other at risk populations, and the response of host innate immune cells.