Virulence profiles of ten Paracoccidioides brasiliensis isolates obtained from armadillos (Dasypus novemcinctus)

Paracoccidioides brasiliensis is the etiologic agent of paracoccidioidomycosis ( PCM), the most important systemic mycosis in Latin America. The armadillo, Dasypus novemcinctus, has been confirmed as the primary natural reservoir of this fungus. Its geographic distribution is similar to that of human PCM. In this study, virulence profiles of 10 P. brasiliensis isolates from different armadillos and of two clinical isolates were tested in an experimental hamster model. Pathogenicity was evaluated by counting cfu and performing histopathological analysis in the testis, liver, spleen and lung. Circulating specific antibodies were measured using enzyme- linked immunosorbent assay ( ELISA). All isolates from armadillos were virulent in the model, with dissemination to many organs. The clinical isolates, which had long been stored in cultured collections, were less virulent. The isolates were classified into four virulence categories according to number of cfu per gram of tissue: very high, high, intermediate and low. This study confirms that armadillos harbor pathogenic genotypes of P. brasiliensis, probably the same ones that infect humans.

Isolation of coccidioides brasiliensis from armadillos (Dasypus noveminctus) captured in an endemic area of paracoccidioidomycosis

Paracoccidioides brasiliensis, the causative agent of paracoccidioidomycosis (PCM), was first isolated from armadillos from the Amazonian region where the mycosis is uncommon. In the present study, we report on the high incidence of PCM infection in armadillos from a hyperendemic region of the disease. Four nine-banded armadillos (Dasypus novemcinctus) were captured in the endemic area of Botucatu, São Paulo, Brazil, killed by manual cervical dislocation and autopsied under sterile conditions. Fragments of lung, spleen, liver, and mesenteric lymph nodes were processed for histology, cultured on Mycosel agar at 37 degrees C, and homogenized for inoculation into the testis and peritoneum of hamsters. The animals were killed from week 6 to week 20 postinoculation and fragments of liver, lung, spleen, testis, and lymph nodes were cultured on brain heart infusion agar at 37 degrees C. Paracoccidioides brasiliensis was isolated from three armadillos both by direct organ culture and from the liver, spleen, lung, and mesenteric lymph nodes of hamsters. In addition, one positive armadillo presented histologically proven PCM disease in a mesenteric lymph node. The three armadillos isolates (Pb-AL, Pb-A2, and Pb-A4) presented thermodependent dimorphism, urease activity, and casein assimilation, showed amplification of the gp43 gene, and were highly virulent in intratesticularly inoculated hamsters. The isolates expressed the gp43 glycoprotein, the immunodominant antigen of the fungus, and reacted with a pool of sera from PCM patients. Taken together, the present data confirm that armadillos an a natural reservoir of P. brasiliensis and demonstrate that the animal is a sylvan host to the fungus.

High frequency of Paracoccidioides brasiliensis infection in armadillos (Dasypus novemcinctus): an ecological study

The fungus Paracoccidioides brasiliensis has been isolated from nine-banded armadillos (Dasypus novemcinctus) in different regions where paracoccidiodomycosis (PCM) is endemic. The link between PCM and these animals has provided the first valuable clue in the effort to elucidate the ecological niche of P. brasiliensis. The present study was aimed at correlating P. brasiliensis infection in armadillos with local ecological features and, if possible, the presence of the fungus in the soil in the Botucatu hyperendemic area of PCM. In this region the mean temperature ranges from 14.8 to 25.8degreesC and the annual average precipitation is 1520 mm. The sites where 10 infected animals (positive group) were collected were studied and compared with the sites where five uninfected animals were found. The occurrence of the fungus in soil samples collected from the positive armadillos' burrows and foraging sites was investigated by the indirect method of animal inoculation. Environmental data from the sites of animal capture, such as temperature, rainfall, altitude, vegetation, soil composition, presence of water and proximity of urban areas, were recorded. All 37 soil samples collected from the sites had negative fungal cultures. Positive animals were found much more frequently in sites with disturbed vegetation, such as riparian forests and artificial Eucalyptus Or Pinus forests, in altitudes below 800 m, near water sources. The soil type of the sites of positive animals was mainly sandy, with medium to low concentrations of organic matter. The pH was mainly acidic at all the sites, although the concentrations of aluminum cations (H+Al) were lower at the sites where positive animals were found. Positive armadillos were also captured in sites very close to urban areas. Our data and previous studies indicate that P. brasiliensis occurs preferentially in humid and shady disturbed forests in a strong association with armadillos.

Serological follow-up of patients with paracoccidioidomycosis treated with itraconazole using Dot-blot, ELISA and Western-blot

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dimorphism, thermal tolerance, virulence and Heat shock protein 70 transcription in different isolates of Paracoccidioides brasiliensis

The mycelia-to-yeast (M-Y) transition, thermal tolerance and virulence profiles were evaluated for nine isolates of Paracoccidioides brasiliensis, including samples from two of the three recently discovered cryptic species, as well as their relation to the partial sequence and transcription of the hsp70 gene. The isolates Bt84 and T10 (from PS2 species) took more time to convert to yeast form and presented elongated yeast cells at 36 degrees C. Arthroconidia production was also observed during the M-Y transition for some isolates. Our data confirm that the hsp70 transcription may be associated with thermal tolerance, but this does not seem to be directly related to high virulence profiles. The partial sequencing of this gene allowed the separation of our isolates into two clusters that correspond to the two sympatric cryptic species occurring in an area hyperendemic for PCM (Botucatu, SP, Brazil).

Production of pro- and anti-inflammatory cytokines by monocytes from patients with paracoccidioidomycosis

Monocytes and macrophages can produce a large repertoire of cytokines and participate in the pathogenesis of granulomatous diseases. We investigated the production of pro- and anti-inflammatory cytokines by monocytes from patients with active paracoccidioidomycosis. Peripheral blood monocytes from 37 patients and 29 healthy controls were cultivated with or without 10 mug/ml of lipopolysaccharide (LPS) for 18 h at 37 degreesC, and the cytokine levels were determined in the culture supernatants by enzyme immunoassay. The results showed that the endogenous levels of tumor necrosis factor alpha (TNF-alpha), interleukin-1 beta (IL-1beta), IL-6, IL-8, IL-10 and transforming growth factor beta detected in the supernatant of patient monocytes cultivated without stimulus were significantly higher than those produced by healthy controls. These data demonstrated that monocytes from patients with active paracoccidioidomycosis produce high levels of cytokines with both inflammatory and anti-inflammatory activities. However, patient monocytes produced significantly lower TNF-alpha and IL-6 levels in response to LPS when compared to normal subjects, suggesting an impairment in their capacity to produce these cytokines after LPS stimulation. Concentrations of IL-1beta, IL-8 and IL-10 in cultures stimulated with LPS were higher in patients than in controls. These results suggest that an imbalance in the production of pro- and anti-inflammatory cytokines might be associated with the pathogenesis of paracoccidioidomycosis. (C) 2003 Editions scientifiques et medicales Elsevier SAS. All rights reserved.

Molecular detection of Paracoccidioides brasiliensis in road-killed wild animals

Paracoccidioides brasiliensis infections have been little studied in wild and/or domestic animals, which may represent an important indicator of the presence of the pathogen in nature. Road-killed wild animals have been used for surveillance of vectors of zoonotic pathogens and may offer new opportunities for eco-epidemiological studies of paracoccidiodomycosis (PCM). The presence of P. brasiliensis infection was evaluated by Nested-PCR in tissue samples collected from 19 road-killed animals; 3 Cavia aperea (guinea pig), 5 Cerdocyon thous (crab-eating-fox), 1 Dasypus novemcinctus (nine-banded armadillo), 1 Dasypus septemcinctus (seven-banded armadillo), 2 Didelphis albiventris (white-eared opossum), 1 Eira barbara (tayra), 2 Gallictis vittata (grison), 2 Procyon cancrivorus (raccoon) and 2 Sphiggurus spinosus (porcupine). Specific P. brasiliensis amplicons were detected in (a) several organs of the two armadillos and one guinea pig, (b) the lung and liver of the porcupine, and (c) the lungs of raccoons and grisons. P. brasiliensis infection in wild animals from endemic areas might be more common than initially postulated. Molecular techniques can be used for detecting new hosts and mapping 'hot spot' areas of PCM.

Experimental infections with Paracoccidioides brasiliensis obtained from armadillos: comparison to clinical isolates

Paracoccidioides brasiliensis causes paracoccidioidomycosis (PCM) that is one of the most prevalent systemic human mycoses in Latin America. Armadillos show a high incidence of PCM infection and could, therefore, be a natural reservoir for this fungus. In this study were compared the virulence profiles of isolates obtained from nine-banded armadillos (Dasypus novemcinctus) (PbT1 and PbT4) and isolates from PCM patients (Pb265 and Bt83). Pathogenicity was evaluated by fungal load and analysis of colony morphology. Immunity against the fungus was tested by delayed type hypersensitivity test (DTH) and antibody quantification by ELISA. The higher virulence of PbT1 and PbT4 was suggested by higher fungal load in spleen and lungs. Armadillo isolates and Bt83 presented a cotton-like surface contrasting with the cerebriform appearance of Pb265. All isolates induced cellular and humoral immune responses in infected BALB/c mice. DTH reactions were similarly induced by the four isolates, however, a great variability was observed in specific antibody levels, being the highest ones induced by Bt83 and PbT4. The present work confirms that armadillos harbor P. brasiliensis, whose multiplication and induced immunity in experimentally infected mice are heterogeneous, resembling the behavior of isolates from human PCM. This study reinforces the possibility that armadillos play an important role in the biological cycle of this pathogen.

Phylogenetic analysis reveals a high level of speciation in the Paracoccidioides genus

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A synthetic peptide selectively kills only virulent Paracoccidioides brasiliensis yeasts

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effectiveness-ntu computation with a mathematical model for cross-flow heat exchangers

Due to the wide range of design possibilities, simple manufactured, low maintenance and low cost, cross-flow heat exchangers are extensively used in the petroleum, petrochemical, air conditioning, food storage, and others industries. In this paper a mathematical model for cross-flow heat exchangers with complex flow arrangements for determining epsilon -NTU relations is presented. The model is based on the tube element approach, according to which the heat exchanger outlet temperatures are obtained by discretizing the coil along the tube fluid path. In each cross section of the element, tube-side fluid temperature is assumed to be constant because the heat capacity rate ratio C*=Cmin/Cmax tends toward zero in the element. Thus temperature is controlled by effectiveness of a local element corresponding to an evaporator or a condenser-type element. The model is validated through comparison with theoretical algebraic relations for single-pass cross-flow arrangements with one or more rows. Very small relative errors are obtained showing the accuracy of the present model. epsilon -NTU curves for several complex circuit arrangements are presented. The model developed represents a useful research tool for theoretical and experimental studies on heat exchangers performance.

Natural antibodies in paracoccidioidomycosis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Diagnóstico de criptosporidiose em amostras fecais de bezerros por imunofluorescência direta e microscopia de contraste de fase

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Differences in reactivity of paracoccidioidomycosis sera with gp43 isoforms

The glycoprotein gp43 from Paracoccidioides brasiliensis is the main antigenic component in paracoccidioidomycosis (PCM) because it is recognized by 100% of PCM patients. It has also been shown that different fungal strains produce gp43 with at least four isoform profiles. In this study, different isoform profiles from gp43, with pIs ranging from 5.8 to 8.5, were affinity purified from various P. brasiliensis (B-339, S.S., 1925 and I-9) exoantigens. Because of the isoform heterogeneity, we questioned whether those isoform profiles could be similarly recognized by acute or chronic PCM patients. By using a specific and sensitive method for detection of human IgG anti-gp43 antibodies, the monoclonal antibody capture immunoassay, we report that not all gp43 isoform profiles are equally recognized in PCM sera when anti-gp43 MAb 17c was employed as capturing antibody. Our result showed that recognition of pI 8.5 gp43 isoform was significantly lower for both acute (56%) and chronic patients (71%), compared with gp43 isoforms from the standard strain B-339. on the other hand, when anti-gp43 MAb 8a, which recognizes a different antigenic epitope was used to capture the different gp43 isoform profiles, all patient's sera reacted similarly. The results described suggest that not all the antigenic epitopes expressed by gp43 are equally present in all P. brasiliensis strains.