Heparin-binding motifs and biofilm formation by Candida albicans.

Candida albicans is a leading pathogen in infections of central venous catheters, which are frequently infused with heparin. Binding of C. albicans to medically relevant concentrations of soluble and plate-bound heparin was demonstrable by confocal microscopy and enzyme-linked immunosorbent assay (ELISA). A sequence-based search identified 34 C. albicans surface proteins containing ≥1 match to linear heparin-binding motifs. The virulence factor Int1 contained the most putative heparin-binding motifs (n = 5); peptides encompassing 2 of 5 motifs bound to heparin-Sepharose. Alanine substitution of lysine residues K805/K806 in 804QKKHQIHK811 (motif 1 of Int1) markedly attenuated biofilm formation in central venous catheters in rats, whereas alanine substitution of K1595/R1596 in 1593FKKRFFKL1600 (motif 4 of Int1) did not impair biofilm formation. Affinity-purified immunoglobulin G (IgG) recognizing motif 1 abolished biofilm formation in central venous catheters; preimmune IgG had no effect. After heparin treatment of C. albicans, soluble peptides from multiple C. albicans surface proteins were detected, such as Eno1, Pgk1, Tdh3, and Ssa1/2 but not Int1, suggesting that heparin changes candidal surface structures and may modify some antigens critical for immune recognition. These studies define a new mechanism of biofilm formation for C. albicans and a novel strategy for inhibiting catheter-associated biofilms.

Complete Blood Count Values Over Time in Young Children During the Dengue Virus Epidemic in the Dominican Republic From 2018 to 2020.

Background: Dengue fever (DF) is a mosquito-borne illness with substantial economic and societal impact. Understanding laboratory trends of hospitalized Dominican Republic (DR) pediatric patients could help develop screening procedures in low-resourced settings. We sought to describe laboratory findings over time in DR children with DF and DF severity from 2018 to 2020. Methods: Clinical information was obtained prospectively from recruited children with DF. Complete blood count (CBC) laboratory measures were assessed across Days 1-10 of fever. Participants were classified as DF-negative and DF-positive and grouped by severity. We assessed associations of DF severity with demographics, clinical characteristics, and peripheral blood studies. Using linear mixed-models, we assessed if hematologic values/trajectories differed by DF status/severity. Results: A total of 597 of 1101 with a DF clinical diagnosis were serologically evaluated, and 574 (471 DF-positive) met inclusion criteria. In DF, platelet count and hemoglobin were higher on earlier days of fever (p < = 0.0017). Eighty had severe DF. Severe DF risk was associated with thrombocytopenia, intraillness anemia, and leukocytosis, differing by fever day (p < = 0.001). Conclusions: In a pediatric hospitalized DR cohort, we found marked anemia in late stages of severe DF, unlike the typically seen hemoconcentration. These findings, paired with clinical symptom changes over time, may help guide risk-stratified screenings for resource-limited settings.

The 2019-2020 Dengue Fever Epidemic: Genomic Markers Indicating Severity in Dominican Republic Children.

We performed an observational cohort study to assess associations between genetic factors of dengue fever (DF) severity in children in the Dominican Republic. A total of 488 participants had serologically confirmed DF. We replicated the association between the IFIH1 gene (rs1990760) and severe DF (n = 80/488, p = 0.006) and identified novel associations needing further investigation.

Simvastatin inhibits Candida albicans biofilm in vitro.

By inhibiting the conversion of 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) to mevalonate, statins impair cholesterol metabolism in humans. We reasoned that statins might similarly interfere with the biosynthesis of ergosterol, the major sterol of the yeast cell membrane. As assessed by spectrophotometric and microscopic analysis, significant inhibition of biofilm production was noted after 16-h incubation with 1, 2.5, and 5 muM simvastatin, concentrations that did not affect growth, adhesion, or hyphal formation by C. albicans in vitro. Higher concentrations (10, 20, and 25 muM simvastatin) inhibited biofilm by >90% but also impaired growth. Addition of exogenous ergosterol (90 muM) overcame the effects of 1 and 2.5 muM simvastatin, suggesting that at least one mechanism of inhibition is interference with ergosterol biosynthesis. Clinical isolates from blood, skin, and mucosal surfaces produced biofilms; biofilms from bloodstream isolates were similarly inhibited by simvastatin. In the absence of fungicidal activity, simvastatin's interruption of a critical step in an essential metabolic pathway, highly conserved from yeast to man, has unexpected effects on biofilm production by a eukaryotic pathogen.

The predictive accuracy of pre-adoption video review in adoptees from Russian and Eastern European orphanages.

Many internationally adopted children have a pre-adoption video for prospective adoptive parents to review before their commitment to adopt. No published report to date has examined the value of the pre-adoption video evaluation (PreAVE) as a predictor of post-adoption developmental status. The present study was designed to determine whether PreAVE can predict the post-adoption developmental status of internationally adopted children. In this retrospective chart review, children who presented to the Yale International Adoption Clinic between December 1998 and September 2000, and had both a PreAVE and a post-adoption developmental evaluation (PosADE) were selected (N = 20) PreAVE was done using the Denver II and PosADE was done using the Bayley Scales of Infant Development, 2nd edition. The Pearson r coefficient between the two ratings was determined and sensitivity and specificity were calculated. There was a significant correlation between the PreAVE and the PosADEs (r = 0.53, p = 0.01).The sensitivity of PreAVE to detect moderate to severe developmental delay was 43% and the specificity was 85%. Although ratings of development on PreAVE are similar to PosADE, the ability to detect moderate to severe developmental delay by video review is limited.

The struggle to find reliable results in exome sequencing data: filtering out Mendelian errors.

Next Generation Sequencing studies generate a large quantity of genetic data in a relatively cost and time efficient manner and provide an unprecedented opportunity to identify candidate causative variants that lead to disease phenotypes. A challenge to these studies is the generation of sequencing artifacts by current technologies. To identify and characterize the properties that distinguish false positive variants from true variants, we sequenced a child and both parents (one trio) using DNA isolated from three sources (blood, buccal cells, and saliva). The trio strategy allowed us to identify variants in the proband that could not have been inherited from the parents (Mendelian errors) and would most likely indicate sequencing artifacts. Quality control measurements were examined and three measurements were found to identify the greatest number of Mendelian errors. These included read depth, genotype quality score, and alternate allele ratio. Filtering the variants on these measurements removed ~95% of the Mendelian errors while retaining 80% of the called variants. These filters were applied independently. After filtering, the concordance between identical samples isolated from different sources was 99.99% as compared to 87% before filtering. This high concordance suggests that different sources of DNA can be used in trio studies without affecting the ability to identify causative polymorphisms. To facilitate analysis of next generation sequencing data, we developed the Cincinnati Analytical Suite for Sequencing Informatics (CASSI) to store sequencing files, metadata (eg. relatedness information), file versioning, data filtering, variant annotation, and identify candidate causative polymorphisms that follow either de novo, rare recessive homozygous or compound heterozygous inheritance models. We conclude the data cleaning process improves the signal to noise ratio in terms of variants and facilitates the identification of candidate disease causative polymorphisms.

The iC3b receptor of Candida albicans and its roles in pathogenesis.

On the basis of biochemical and immunologic studies, a receptor for iC3b with some activities reminiscent of the integrins CD11b and CD11c was defined on the cell wall of clinical and laboratory isolates of Candida albicans. The INT1 gene encodes a protein of 1659 amino acids; the Int1 protein participates in adhesion to epithelial cells in vitro and in vivo. Int1 is essential for hyphal morphogenesis and virulence in a murine model. Recent evidence points to the amino terminus of Int1 as the source of a peptide, Pep263, with superantigen-like activities.

Superantigen-like effects of a Candida albicans polypeptide.

The amino terminal sequence of the Candida albicans cell wall protein Int1 exhibited partial identity with the major histocompatibility complex (MHC) class II binding site of the Mycoplasma arthritidis superantigen MAM. Int1-positive C. albicans blastospores activated human T lymphocytes and expanded Vbeta subsets 2, 3, and/or 14; Int1-negative strains were inactive. Release of interferon-gamma (IFN-gamma) but not of tumor necrosis factor-alpha or interleukin-6 was Int1 dependent; interleukin-4 and interleukin-10 were not detected. T lymphocyte activation, Vbeta expansion, and IFN-gamma release were associated with a soluble polypeptide that encompassed the first 263 amino acids of Int1 (Pep(263)). Monoclonal antibody 163.5, which recognizes an Int1 epitope that overlaps the region of identity with MAM, significantly inhibited these activities when triggered by Int1-positive blastospores or Pep(263) but not by staphylococcal enterotoxin B. Histidine(263) was required. Pep(263) bound to T lymphocytes and MHC class II and was detected in the urine of a patient with C. albicans fungemia. These studies identify a candidal protein that displays superantigen-like activities.

Cleavage of E-cadherin: a mechanism for disruption of the intestinal epithelial barrier by Candida albicans.

To investigate how intestinal epithelial cells respond to contact with Candida albicans, an organism able to invade the bloodstream via the gastrointestinal tract, we focused on the junction proteins occludin, E-cadherin, and desmoglein-2. The levels of these 3 junction proteins were reduced in lysates of human intestinal epithelial monolayers (Caco-2) after a 24-h inoculation with C. albicans, compared with lysates from Saccharomyces cerevisiae-inoculated monolayers. Treatment with pepstatin A did not change the effect of C. albicans on full-length occludin, desmoglein-2, and E-cadherin; however, pepstatin A enhanced the accumulation of a 35-kDa fragment derived from the intracellular portion of E-cadherin. This 35-kDa fragment also accumulated in the presence of gamma-secretase inhibitors. These observations suggest that enhancement of E-cadherin cleavage by C. albicans generates an intracellular E-cadherin fragment that can serve as a substrate for gamma-secretase. An 89-kDa extracellular fragment of E-cadherin was detected in supernatants of C. albicans-inoculated monolayers; this cleavage event was insensitive to both pepstatin A and gamma-secretase inhibitors. Transepithelial electrical resistance, a measure of monolayer integrity, decreased significantly and synchronously with increased generation of the 89-kDa extracellular E-cadherin fragment. Cleavage of E-cadherin may destabilize the homotypic interactions between adjacent epithelial cells and could contribute to loss of monolayer integrity. These experiments identify 2 E-cadherin cleavage events that are enhanced by contact with C. albicans: an intracellular cleavage event that generates a substrate for gamma-secretase and an extracellular cleavage event that is temporally associated with an increase in monolayer permeability.

Involvement of Candida albicans pyruvate dehydrogenase complex protein X (Pdx1) in filamentation.

For 50 years, physiologic studies in Candida albicans have associated fermentation with filamentation and respiration with yeast morphology. Analysis of the mitochondrial proteome of a C. albicans NDH51 mutant, known to be defective in filamentation, identified increased expression of several proteins in the respiratory pathway. Most notable was a 15-fold increase in pyruvate dehydrogenase complex protein X (Pdx1), an essential component of the pyruvate dehydrogenase complex. In basal salts medium with < or = 100 mM glucose as carbon source, two independent pdx1 mutants displayed a filamentation defect identical to ndh51; reintegration of one PDX1 allele restored filamentation. Concentrations of glucose < or = 100 mM did not correct the filamentation defect. Expanding on previous work, these studies suggest that increased expression of proteins extraneous to the electron transport chain compensates for defects in the respiratory pathway to maintain yeast morphology. Mitochondrial proteomics can aid in the identification of C. albicans genes not previously implicated in filamentation.