Cell surface expression of adhesins for fibronectin correlates with virulence in Sporothrix schenckii.

The virulence of four Sporothrix schenckii isolates was compared in a murine model of sporotrichosis, together with the protein pattern of the yeast cell surface and the capacity to bind the extracellular matrix protein fibronectin. Virulence was determined by the mortality rate, fungal burden and histopathology. Two clinical isolates were more virulent for C57BL/6 mice, but no direct correlation was seen between virulence and the clinical or environmental origin of the isolates.

Melanin is an essential component for the integrity of the cell wall of Aspergillus fumigatus conidia.

Background: Aspergillus fumigatus is the most common agent of invasive aspergillosis, a feared complication in severely immunocompromised patients. Despite the recent commercialisation of new antifungal drugs, the prognosis for this infection remains uncertain. Thus, there is a real need to discover new targets for therapy.

Hypersusceptibility to azole antifungals in a clinical isolate of Candida glabrata with reduced aerobic growth.

Petite mutations have been described in Saccharomyces cerevisiae and pathogenic yeasts. However, previous studies of the phenotypic traits of these petite mutants reported that they express azole resistance. We describe a clinical isolate of Candida glabrata with a striking association between increased susceptibility to azoles and respiratory deficiency.

Ultrastructural and Immunochemical Changes During the In Vitro Development of Plasmopara halstedii.

ABSTRACT The asexual phase of the life cycle of Plasmopara halstedii, the causal agent of downy mildew of sunflower, plays a key role in the propagation of the disease. We investigated the morphological and ultrastructural changes that occur during the asexual development of the pathogen. Direct examination of infected cotyledons confirmed the presence of sporangiophores.

A nonsense mutation in the ERG6 gene leads to reduced susceptibility to polyenes in a clinical isolate of Candida glabrata.

Unlike the molecular mechanisms that lead to azole drug resistance, the molecular mechanisms that lead to polyene resistance are poorly documented, especially in pathogenic yeasts. We investigated the molecular mechanisms responsible for the reduced susceptibility to polyenes of a clinical isolate of Candida glabrata. Sterol content was analyzed by gas-phase chromatography, and we determined the sequences and levels of expression of several genes involved in ergosterol biosynthesis.

Adherence mechanisms in human pathogenic fungi.

Interactions of human pathogenic fungi with the host tissues are key factors in the pathogenesis of mycoses. Based on the concept that adherence of microorganisms is a prerequisite for initiation of the disease, numerous studies have been conducted to identify the fungal adhesins and their respective receptors. Several adhesins recognizing different host ligands, sometimes with multifunctional properties, have been described.

Reduced susceptibility to polyenes associated with a missense mutation in the ERG6 gene in a clinical isolate of Candida glabrata with pseudohyphal growth.

Little information is available about the molecular mechanisms responsible for polyene resistance in pathogenic yeasts. A clinical isolate of Candida glabrata with a poor susceptibility to polyenes, as determined by disk diffusion method and confirmed by determination of MIC, was recovered from a patient treated with amphotericin B. Quantitative analysis of sterols revealed a lack of ergosterol and an accumulation of late sterol intermediates, suggesting a defect in the final steps of the ergosterol pathway.

Investigation of the antifungal activity of caledonixanthone E and other xanthones against Aspergillus fumigatus.

Among the different xanthones previously isolated from the stem bark of Calophyllum caledonicum, caledonixanthone E presented the strongest activity (MIC (80) = 8 microg/mL) in acidic conditions (pH 3) against the human pathogenic fungus Aspergillus fumigatus. Phase-contrast microscopy studies suggested the assembly or synthesis of cell wall components as the target of the drug. Moreover, the use of fluorescent lectins further supported an impact of caledonixanthone E on the synthesis of chitin, the major structural polysaccharide of the fungal wall.

Purification and partial characterization of a 32-kilodalton sialic acid-specific lectin from Aspergillus fumigatus.

Adherence of the opportunistic fungus Aspergillus fumigatus to the extracellular matrix components is considered a crucial step in the establishment of the infection. Given the high carbohydrate content of these glycoproteins and the role of carbohydrate-protein interactions in numerous adherence processes, the presence of a lectin in A. fumigatus was investigated.