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PubMed1982

Isolation and partial characterization of a growth inhibitor of Paracoccidioides brasiliensis.

A lethal diffusible metabolite excreted by the yeastlike form of Paracoccidioides brasiliensis was isolated, purified, and partially characterized. The chemical structure of this metabolite suggested a relation to the phenol or benzoic acid families. The lethal effect on P. brasiliensis could not be attributed specifically to interference with synthesis of macromolecules, but probably through protein denaturation. This lack of specificity discounts its possible use as an antibiotic.

Chemical Phenomena↗
PubMed1984

Skin and pulmonary models using coated bentonite particles for the study of the inflammation evoked by Paracoccidioides brasiliensis antigens in previously immunized mice.

Bentonite particles coated with polysaccharide antigen or crude soluble antigen of Paracoccidioides brasiliensis were injected intradermally or intravenously in mice. In control animals that were not pre-immunized with P. brasiliensis antigens, coated and uncoated bentonite caused minimal and nonspecific inflammation around the cutaneous injection site or around the bentonite thrombi in small lung vessels after intravenous injection. However, in mice previously immunized with P. brasiliensis antigens, the coated bentonite particles boosted the humoral and cellular immune responses to P. brasiliensis and evoked intense inflammatory reactions. Twelve days after intradermal injection, the inflammatory reaction around the bentonite was rich in neutrophils, macrophages, lymphocytes and plasma cells associated with young granulation tissue. In intravenously injected mice, the pulmonary inflammation was maximal at day 2, and was characterized by a florid neutrophilic and macrophagic cellular infiltration around bentonite thrombi; in some foci, there was incipient organization to mature granuloma. However, in both models, there was no formation of epithelioid granulomata, demonstrating that in paracoccidioidomycosis cellular immunity alone, without the presence of intact micro-organisms, may not be enough for the development of this type of granuloma.

Animals↗
PubMed1984

Effect of temperature on the mycelium to yeast transformation of Paracoccidioides brasiliensis.

The influence of temperature on Paracoccidioides brasiliensis mycelium to yeast transformation was studied by sequential microscopic observations of slide cultures. When incubated at temperatures above 28 degrees C, the mycelial elements gradually produced round to oval chlamydospores and later on, exhibited multiple budding. A sizeable proportion of mycelial elements transformed at 34 degrees C; however, multiple budding was important only at 37 degrees C.

Fungi↗
PubMed1985

Morphogenesis of the mycelium-to-yeast transformation in Paracoccidioides brasiliensis.

The sequential changes observed during the mycelium to yeast transformation in Paracoccidioides brasiliensis were studied microscopically. The mycelial elements produced terminal and intercalary swellings which, later on, became chlamydospore-like structures. These increased in size, acquired a double contour and, finally, gave rise to multiple budding cells. Transformation was asynchronous. During the observation period, multiple budding cells and chlamydospores remained attached to the parent mycelium.

Fungi↗
PubMed1985

Nutritional studies on Paracoccidioides brasiliensis: the role of organic sulfur in dimorphism.

The nutritional requirements of the mycelial and yeast-like phases of the dimorphic fungus Paracoccidioides brasiliensis, a human pathogen, were investigated. For all nine isolates tested, mycelial cells were prototrophic, whereas yeast-like cells required a sulfur-containing amino acid for growth. Moreover, changing the source of nitrogen greatly affected the morphology of the yeast-like cells.

Amino Acids, Sulfur↗
PubMed1985

Characteristics of the conidia produced by the mycelial form of Paracoccidioides brasiliensis.

The sporulation capacities of the mycelial form of Paracoccidioides brasiliensis were determined. Five different culture media were used and four human isolates studied. Conidia were produced in three agar media, namely water-agar, glucose-salts and yeast-extract. Corn meal and Sabouraud dextrose agars failed to induce sporulation. Various types of spores were characterized with peculiar bulging arthroconidia and single-celled, pear-shaped conidia predominating. The size of these conidia varied from 3.6 to 4.6 micron in length. It is concluded that the mycelial form of P. brasiliensis produces characteristic spores if the proper culture media are employed.

Mitosporic Fungi↗
PubMed1986

An evaluation of the enzyme-linked immunoabsorbent assay (ELISA) for quantitation of antibodies to Paracoccidioides brasiliensis.

The ELISA procedure was adapted for quantitation of antibodies against Paracoccidioides brasiliensis. Using a yeast cytoplasmic antigen and sera from patients with proven paracoccidioidomycosis, we found that 66% of sera reacted at titers greater than or equal to 1:128. Titers of this magnitude were obtained only for 4-5% of sera from healthy blood donors, tuberculosis patients and patients with other systemic mycoses. The exception was sera from patients with histoplasmosis (36% had titers greater than or equal to 1:128). Follow-up of 10 paracoccidioidomycosis patients during the course of therapy indicated a gradual decrease in antibody titers. Because of the technical advantages of the ELISA procedure in comparison with the standard complement fixation test, the ELISA test has potential utility for the quantitative determination of antibodies in patients with paracoccidioidomycosis.

Antibodies, Fungal↗
PubMed1988

Morphological study of a variant of Paracoccidioides brasiliensis that exists in the yeast form at room temperature.

Incubation of Paracoccidioides brasiliensis conidia at 20-25 degrees C (RT) results in two types of colonies, mycelial (M) and yeast (YRT). A study of the latter colonies was undertaken. Conidia were plated in complex (BHI) and chemically-defined media (CDCM), with and without fetal calf serum (FCS). Incubation was carried out at 21 degrees C for 4 weeks. The mean number of YRT colonies was approximately 18.5% on BHI agar. Selected YRT colonies were transferred to liquid CDCM, incubated 7 days at 21 degrees C and transferred to solid media; YRT appearance was preserved in 95% of the colonies if media were FCS-supplemented; otherwise, most colonies reverted to the M form. When FCS was replaced by bovine albumin or by alpha-globulin, 63% and 68% respectively of the colonies obtained after plating YRT cells, became mycelial. Comparative morphologic studies of both YRT and yeasts grown at 37 degrees C suggested that there were no major differences between these two types of yeast cells when size and budding were taken into consideration. The results indicate that in this particular variant, dimorphism is not exclusively temperature-dependent.

Culture Media↗
PubMed1988

Secretion of the 43 kDa glycoprotein antigen by Paracoccidioides brasiliensis.

Yeast forms of the pathogenic fungus Paracoccidioides brasiliensis secrete into the culture supernatant a 43,000 daltons glycoprotein (Gp43) which can be immunoprecipitated specifically by sera from patients with paracoccidioidomycosis. We show here that following labelling of P. brasiliensis with (35S)methionine, Gp43 was detected as the major component in the culture supernatant fluid as early as 1 hour after addition of the radiolabel. The amount of Gp43, as determined by a competitive radioimmunoassay, or by staining total protein after sodium dodecylsulfate-polyacrylamide gel electrophoresis, progressively increased in the culture supernatant until the culture reached the late exponential phase. It then decreased and continued to do so in the stationary phase. These results indicate that Gp43 is continuously produced and secreted in the medium by actively growing yeasts and that cultures in the exponential phase of growth should be used for a maximal yield of this exocellular antigen.

Antigens, Fungal↗
PubMed1990

Isolation and characterization of a Paracoccidioides brasiliensis strain from a dogfood probably contaminated with soil in Uberlândia, Brazil.

We report the isolation of a strain of Paracoccidioides brasiliensis from a dogfood, probably contaminated with soil, in a Brazilian city. The fungus was isolated on appropriate culture media, and when inoculated into a guinea-pig testis produced orchitis with abundant fungal elements. Histopathology of sections of the testicle showed an inflammatory reaction with P. brasiliensis inside monocytes. Immunological identification confirmed the identity of the isolate.

Animal Feed↗
PubMed1991

Antigens of diagnostic value in three isolates of Paracoccidioides brasiliensis.

Yeast cellular extracts of three isolates of Paracoccidioides brasiliensis were tested by the Western-blot technique against 53 sera from patients with paracoccidioidomycosis (PCM). Numerous antigens were recognized by the sera but only five were specific for (58, 57, 48, 44 and 23 kDa). These specific antigens had the same relative molecular mass in the different isolates but their reactivity with sera from PCM patients was variable. An antigen in isolate 688, which was specific for PCM, had an apparent molecular mass of 48 kDa. Although a 48 kDa antigen was also present in isolates B339 and 1789.88 it was not specific for PCM, demonstrating antigenic variability among isolates. The 44 kDa antigen in isolate B339 and the 44 and 48 kDa antigens in isolate 688 reacted with a rabbit antiserum raised against a 43 kDa glycoprotein, a specific antigen used in the diagnosis of PCM. There was no correlation between the specific antigen(s) detected and the clinical form of the disease.

Antibodies, Fungal↗
PubMed1991

The use of a mixture of somatic and culture filtrate antigens in the evaluation of the immune response to Paracoccidioides brasiliensis.

Three Paracoccidioides brasiliensis antigens, namely a culture filtrate preparation, a somatic antigen and a mixture of equal parts of the two, were tested by two serological techniques against sera from patients with paracoccidioidomycosis, and in an in vivo delayed hypersensitivity model in mice. The antigen mixture was more sensitive than the two individual antigens for the evaluation of the humoral and cellular immune response to P. brasiliensis, both in man and in experimental animals.

Animals↗
PubMed1993

Effect of ajoene on dimorphism of Paracoccidioides brasiliensis.

Ajoene, a compound derived from ethanolic garlic extracts, inhibits the growth of the dimorphic pathogenic fungus Paracoccidioides brasiliensis, yeast cells being more sensitive to its action than mycelial cultures. Sulphydryl protector groups were able to cancel the inhibitory effect on the yeast cells but not on the mycelial cultures. The dimorphic process was also blocked when mycelia were placed to transform to yeast. Synthesis in vitro of cell wall glucan was not affected by ajoene. We discuss the possible involvement of ajoene on sulphydryl metabolism of P. brasiliensis.

Antifungal Agents↗
PubMed1993

An improved culture medium for detecting live yeast phase cells of Paracoccidioides brasiliensis.

The plating efficiency of standard mycological media such as brain heart infusion (BHI) agar is poor for Paracoccidioides brasiliensis. We prepared a water-extract of yeast phase cells of P. brasiliensis and examined it for growth-enhancing activity for the fungus. The water-extract, when added to BHI agar to a concentration of 5%, improved the plating efficiency of the medium for the fungus to some extent, but the degree of improvement was considerably varied among P. brasiliensis isolates. By contrast, when the water-extract was added in combination with horse serum (4%), the plating efficiency was highly improved (to 94-99%) for all the P. brasiliensis isolates employed. The growth-enhancing factor(s) in the water-extract was heat-stable and heating at 120 degrees C for 15 min had little, if any, effect on growth-enhancing activity.

Culture Media↗
PubMed1994

Gelatinase activity of exoantigens from virulent and non-virulent isolates of Paracoccidioides brasiliensis.

Differences in the occurrence of components with gelatinase activity were detected among four isolates of Paracoccidioides brasiliensis: Pb339 and Pb18 (highly virulent), and Pb265 and Pb18AV (very low virulence). Culture filtrates from these isolates were electrophoresed in substrate gels and tested for gelatinase activity. Pb339 showed three enzyme bands of apparent molecular masses: 43, 53 and 78 kDa; Pb18 had two bands, one at 59 kDa and another with molecular mass higher than 78 kDa. Isolate Pb18AV showed only one band at 78 kDa and Pb265 exhibited a component of molecular mass which failed to enter the separating gel.

Antigens, Fungal↗
PubMed1994

Infection and apparent invasion of Vero cells by Paracoccidioides brasiliensis.

Paracoccidioides brasiliensis probably uses many different mechanisms to establish itself in the host and cause disease. In this work, we assess an in vitro model system which uses cultured mammalian cells to investigate the virulence factors of P. brasiliensis. We were able to demonstrate an invasion process of the yeast form of this fungus in Vero cell cultures. We deduced that the overall invasive process involved three steps: adhesion, followed by invasion of individual epithelial cells and spread to adjacent cells.

Animals↗