Paracoccidioides and Paracoccidioidomycosis in the 21st Century

Paracoccidioidomycosis (PCM) defines a broad spectrum of human and animal diseases caused by Paracoccidioides species (Onygenales). In the twenty-first century, Paracoccidioides advanced from a monotypic taxon to a genus that harbors seven species, including P. brasiliensis sensu stricto, P. americana, P. restrepiensis, P. venezuelensis, P. lutzii, P. loboi, and P. cetii. Classic PCM, acquired upon inhalation of propagules from P. brasiliensis sensu stricto, P. americana, P. restrepiensis, P. venezuelensis, and P. lutzii, affects the human lungs and may progress to systemic granulomatous disease with tegumentary and visceral involvement. On the other hand, PCM loboi and PCM ceti caused by the unculturable P. loboi and P. cetii are subcutaneous mycoses, typically observed as keloid lesions in humans and dolphins. Such heterogeneity highlights the importance of recognizing species boundaries in Paracoccidioides to gain insights into the ecology, evolution, clinical features, and mitigation strategies to tackle the advance of PCM.

Molecular epidemiology of Paracoccidiodes spp. recovered from patients with paracoccidioidomycosis in a teaching hospital from Minas Gerais State of Brazil

Introduction

Paracoccidioidomycosis (PCM) is caused by several species of the Paracoccidioides genus which can be differentiated by interspecific genetic variations, morphology and geographic distribution. Intraspecific variability correlation with clinical and epidemiological aspects of these species still remains unclear. This study aimed to sequence the loci GP43, exon 2 and ARF of 23 clinical isolates of Paracoccidioides spp. from patients in the Southeast Region of Brazil.

Methodology and main findings

GenBank was used to compare the present (23) with previous described sequences (151) that included ARF and GP43. It was identified a high polymorphism rate among the 23 isolates in comparison to the other 151. Among the isolates, 22 (95.66%) were S1/P. brasiliensis and 1 (4.34%) was identified as PS2/P. americana. A total of 45 haplotypes were found as follows: 19 from S1/P. brasiliensis (13 from the present study), 15 from P. lutzii, 6 from PS2/P. americana (1 from the present study), 3 from PS3/P. restrepiensis and 2 from PS4/P. venezuelensis. Moreover, exclusive haplotypes according to clinical origin and geographical area were found. S1/P. brasiliensis (HD = 0.655 and K = 4.613) and P. lutzii (HD = 0.649 and K = 2.906) presented the highest rate of polymorphism among all species, from which 12 isolates of the present study were clustered within S1b/P. brasiliensis. The GP43 locus showed a higher variability and was found to be the main reason for the species differentiation.

Conclusions

The results herein decribed show a high intraspecific genetic variability among S1/P. brasiliensis isolates and confirm the predominance of this species in the Southeast region of Brazil. The finding of exclusive haplotypes according to clinical origin and geographical area would suggest correlation between the molecular profile with the clinical form and geographic origin of patients with PCM.

Paracoccidioidomycosis (PCM) is one of the most important systemic mycosis of Latin America. This disease can be caused by Paracoccidioides lutzii and four different phylogenetic species: S1/Paracoccidioides brasiliensis sensu stricto that harboring S1a and S1b, PS2/Paracoccidioides americana, PS3/Paracoccidioides restrepiensis and PS4/Paracoccidioides venezuelensis. Some of these species show differences in their main geographic region of predominance such as PS2/P. americana that can be found in Venezuela and Southern Brazil; PS3/P. restrepiensis and PS4/P. venezuelensis which are distributed in Colombia and Venezuela. However, and due to their wide geographical distribution, the species S1/P. brasiliensis and P. lutzii overlapping ecological niches and can be found in different regions of Brazil and other Latin American countries. Regarding eco-epidemiological aspects, the habitat is believed to be the soil due to the predominance of the disease among rural workers who become infected by inhaling infectious propagules during their farm activities. According to other authors, these species could have relation with the different PCM clinical presentation. This study aimed to describe the molecular epidemiology associated with clinical and epidemiological data of Paracoccidiodes spp. in the Minas Gerais State, located in the Southeast region, Brazil. Among the 23 isolates herein evaluated, 22 were S1/P. brasiliensis and 1 was identified as PS2/P. americana. A total of 45 haplotypes were found when these isolates were compared with other 151 deposited in the Genbank. The preliminar finding of exclusive haplotypes according to clinical origin and geographical area would suggest correlation between the molecular profile with the clinical form and geographic origin of patients with PCM. The GP43 locus showed a higher variability and was found to be the main promotor of species differentiation. The results herein described pointed out a high intraspecific genetic variability among S1/P. brasiliensis isolates and confirm the predominance of this species in the Southeast region of Brazil.

An update on the occurrence of Paracoccidioides species in the Midwest region, Brazil: Molecular epidemiology, clinical aspects and serological profile of patients from Mato Grosso do Sul State

BACKGROUND

Paracoccidioidomycosis (PCM) is a systemic and endemic fungal infection in Latin American, mainly in Brazil. The majority of PCM cases occur in large areas in Brazil, comprising the South, Southeast and Midwest regions, with the latter demonstrating a higher incidence of the species Paracoccidioides lutzii.

METHODOLOGY AND MAIN FINDINGS

This study presents clinical, molecular and serological data of thirteen new PCM cases during 2016 to 2019 from the state of Mato Grosso do Sul, located in the Midwest region, Brazil. From these thirteen cases, sixteen clinical isolates were obtained and their genomic DNAs were subjected to genotyping by tub1 -PCR-RFLP. Results showed Paracoccidioides brasiliensis sensu stricto (S1) (11/16; 68.8%), Paracoccidioides restrepiensis (PS3) (4/16; 25.0%) and P. lutzii (1/16; 6.2%) as Paracoccidiodes species. Therefore, in order to understand whether the type of phylogenetic species that are circulating in the state influence the reactivity profile of serological tests, we performed double agar gel immunodiffusion (DID), using exoantigens from genotyped strains found in this series of PCM cases. Overall, our DID tests have been false negative in about 30% of confirmed PCM cases. All patients were male, most with current or previous rural activity, with ages ranging from 17 to 59 years, with 11 patients (84.6%) over 40 years of age. No clinical or epidemiological differences were found between Paracoccidioides species. However, it is important to note that the only case of P. lutzii died as an outcome.

CONCLUSIONS

This study suggests P. brasiliensis sensu stricto (S1) as the predominant species, showing its wide geographic distribution in Brazil. Furthermore, our findings revealed, for the first time, the occurrence of P. restrepiensis (PS3) in the state of Mato Grosso do Sul, Brazil. Despite our setbacks, it would be interesting to provide the complete sequencing of these clinical isolates to complement the molecular information presented.

Paracoccidioides Genomes Reflect High Levels of Species Divergence and Little Interspecific Gene Flow

The fungus Paracoccidioides is a prevalent human pathogen endemic to South America. The genus is composed of five species. In this report, we use 37 whole-genome sequences to study the allocation of genetic variation in Paracoccidioides We tested three genome-wide predictions of advanced speciation, namely, that all species should be reciprocally monophyletic, that species pairs should be highly differentiated along the whole genome, and that there should be low rates of interspecific gene exchange. We find support for these three hypotheses. Species pairs with older divergences show no evidence of gene exchange, while more recently diverged species pairs show evidence of modest rates of introgression. Our results indicate that as divergence progresses, species boundaries become less porous among Paracoccidioides species. Our results suggest that species in Paracoccidioides are at different stages along the divergence continuum.IMPORTANCEParacoccidioides is the causal agent of a systemic mycosis in Latin America. Most of the inference of the evolutionary history of Paracoccidioides has used only a few molecular markers. In this report, we evaluate the extent of genome divergence among Paracoccidioides species and study the possibility of interspecific gene exchange. We find that all species are highly differentiated. We also find that the amount of gene flow between species is low and in some cases is even completely absent in spite of geographic overlap. Our study constitutes a systematic effort to identify species boundaries in fungal pathogens and to determine the extent of gene exchange among fungal species.

Genomic diversity of the human pathogen Paracoccidioides across the South American continent

Paracoccidioidomycosis (PCM) is a life-threatening systemic mycosis widely reported in the Gran Chaco ecosystem. The disease is caused by different species from the genus Paracoccidioides, which are all endemic to South and Central America. Here, we sequenced and analyzed 31 isolates of Paracoccidioides across South America, with particular focus on isolates from Argentina and Paraguay. The de novo sequenced isolates were compared with publicly available genomes. Phylogenetics and population genomics revealed that PCM in Argentina and Paraguay is caused by three distinct Paracoccidioides genotypes, P. brasiliensis (S1a and S1b) and P. restrepiensis (PS3). P. brasiliensis S1a isolates from Argentina are frequently associated with chronic forms of the disease. Our results suggest the existence of extensive molecular polymorphism among Paracoccidioides species, and provide a framework to begin to dissect the connection between genotypic differences in the pathogen and the clinical outcomes of the disease.

Clinical and epidemiological features of paracoccidioidomycosis due to Paracoccidioides lutzii

BACKGROUND

The fungus Paracoccidioides lutzii was recently included as a new causative species of paracoccidioidomycosis (PCM) and most cases have been reported from Brazil. According to available epidemiological information, P. lutzii is concentrated in the Middle-West region in Brazil, mainly in the state of Mato Grosso. However, clinical and laboratorial data available on patients infected with P. lutzii remain extremely limited.

METHODOLOGY/MAIN FINDINGS

This work describes the clinical manifestations of 34 patients suffering from PCM caused by P. lutzii, treated along 5 years (2011-2017) at a reference service center for systemic mycoses in Mato Grosso, Brazil. Adult rural workers (men), aged between 28 and 67 predominated. All patients had the chronic form of the disease, and the oral mucosa (n = 19; 55.9%), lymph nodes (n = 23; 67.7%), skin (n = 16; 47.1%) and lung (n = 28; 82.4%) were the most affected sites. Alcohol intake (n = 19; 55.9%) and smoking (n = 29; 85.3%) were frequent habits among the patients. No patient suffered from any other life-threatening disease, such as tuberculosis, cancer or other inflammatory or infectious parasitic diseases. The positivity in culture examination (97.1%) was higher than that found for the direct mycological examination (88.2%). Particularly, one patient presented fungemia at diagnosis, which lead to his death. The time elapsed between the initial symptoms and the initiation of treatment of PCM caused by P. lutzii was 19.7 (31.5) months, with most patients diagnosed 7 months after the symptoms' onset.

CONCLUSIONS/SIGNIFICANCE

Compared with the classical clinical-epidemiological profile of PCM caused by P. brasiliensis, the results of this descriptive study did not show significant clinical or epidemiological differences that could be attributed to the species P. lutzii. Future studies may confirm or refute the existence of clinical differences between the two fungal species.

Paracoccidioidomycosis manifested by sarcoidosis-like cutaneous lesions and caused by Paracoccidioides brasiliensis sensu stricto (S1a)

Molecular studies have shown more than one species of the genus Paracoccidioides to be the causal agent of paracoccidioidomycosis. Efforts have been made to correlate the identified species with epidemiological and clinical data of patients, aiming to determine the real meaning and impact of new species. Bearing this objective in mind, the authors report a clinical case of paracoccidioidomycosis, from São Paulo state, Brazil, that manifested as uncommon sarcoid-like cutaneous lesions and was caused by Paracoccidioides brasiliensis sensu stricto (S1a). The patient was treated with itraconazole 200mg/day for 12 months, with complete clinical remission.

Cutaneous Granulomas in Dolphins Caused by Novel Uncultivated Paracoccidioides brasiliensis

Our findings could stimulate study of public health implications of diseases caused by this fungus.

Cutaneous granulomas in dolphins were believed to be caused by Lacazia loboi, which also causes a similar disease in humans. This hypothesis was recently challenged by reports that fungal DNA sequences from dolphins grouped this pathogen with Paracoccidioides brasiliensis. We conducted phylogenetic analysis of fungi from 6 bottlenose dolphins (Tursiops truncatus) with cutaneous granulomas and chains of yeast cells in infected tissues. Kex gene sequences of P. brasiliensis from dolphins showed 100% homology with sequences from cultivated P. brasiliensis, 73% with those of L. loboi, and 93% with those of P. lutzii. Parsimony analysis placed DNA sequences from dolphins within a cluster with human P. brasiliensis strains. This cluster was the sister taxon to P. lutzii and L. loboi. Our molecular data support previous findings and suggest that a novel uncultivated strain of P. brasiliensis restricted to cutaneous lesions in dolphins is probably the cause of lacaziosis/lobomycosis, herein referred to as paracoccidioidomycosis ceti.

[Paracoccidioidomycosis: chronicle of a neglected disease]

Paracoccidioidomycosis (PCM) is among the systemic mycoses which are endemic only in Latin America. In Argentina, the vast majority of the cases are reported at north of latitude 34.5° S. The disease is produced by thermodimorphic fungi of the genus Paracoccidoides: P. brasiliensis (S1), P. americana (PS2), P. restrepiensis (PS3), P. venezuelensis (PS4) y P. lutzii. The natural habitat of members of this genus is the soil, where they produce infectious conidia. Little is known, however, about their specific ecologic niche(s), and this knowledge gap hampers the design of measures to control the infection. Rural male workers are the group most at risk of developing PCM. Infection occurs by inhalation of aerosolized conidia and may either be asymptomatic or cause mild respiratory symptoms. In turn, this primary infection may be self-limited or progress to severe pulmonary or disseminated disease. The disease has two clinical presentations: (i) acute or subacute (juvenile), frequent in children, adolescents and people with immunodeficiencies; and (ii) chronic progressive, in adults. Active lesions often resolve into fibrotic scars which can cause dysphagia, dysphonia, adrenal insufficiency, and intestinal obstruction. Although efficient tools are available for diagnosis and treatment, the nonspecific nature of PCM clinical manifestations frequently delay the diagnosis. In addition, the poor adherence to long antifungal treatments allows the advance of the disease and the development of extensive fibrosis compromising severely and permanently respiratory and adrenal functions, thus altering the patient"s quality of life and even causing his/her death.

Species boundaries in the human pathogen Paracoccidioides

The use of molecular taxonomy for identifying recently diverged species has transformed the study of speciation in fungi. The pathogenic fungus Paracoccidioides spp has been hypothesized to be composed of five phylogenetic species, four of which compose the brasiliensis species complex. Nuclear gene genealogies support this divergence scenario, but mitochondrial loci do not; while all species from the brasiliensis complex are differentiated at nuclear coding loci, they are not at mitochondrial loci. We addressed the source of this incongruity using 11 previously published gene fragments, 10 newly-sequenced nuclear non-coding loci, and 10 microsatellites. We hypothesized and further demonstrated that the mito-nuclear incongruence in the brasiliensis species complex results from interspecific hybridization and mitochondrial introgression, a common phenomenon in eukaryotes. Additional population genetic analyses revealed possible nuclear introgression but much less than that seen in the mitochondrion. Our results are consistent with a divergence scenario of secondary contact and subsequent mitochondrial introgression despite the continued persistence of species boundaries. We also suggest that yeast morphology slightly-but significantly-differs across all five Paracoccidioides species and propose to elevate four of these phylogenetic species to formally described taxonomic species.

Acute juvenile Paracoccidioidomycosis: A 9-year cohort study in the endemic area of Rio de Janeiro, Brazil

BACKGROUND

Paracoccidioidomycosis (PCM) is a systemic mycosis caused by pathogenic dimorphic fungi of the genus Paracoccidioides. It is the most important systemic mycosis in Latin America and the leading cause of hospitalizations and death among them in Brazil. Acute PCM is less frequent but relevant because vulnerable young patients are affected and the severity is usually higher than that of the chronic type.

METHODS

The authors performed a retrospective cohort study from 2001 to 2009 including acute juvenile PCM patients from a reference center in Rio de Janeiro, Brazil. Clinical, epidemiological, diagnostic, therapeutic, and prognostic data were reported.

RESULTS

Twenty-nine patients were included. The average age was 23 years old and the male to female ratio was 1:1.07. All cases were referred from 3 of 9 existing health areas in the state of Rio de Janeiro, predominantly from urban areas (96.5%). Lymph nodes were the most affected organs (100%), followed by the skin and the spleen (31% each). Twenty-eight patients completed treatment (median 25 months) and progressed to clinical and serological cure; 1 death occurred. Twenty-four patients completed 48-month median follow-up. Four patients abandoned follow-up after the end of treatment. The most frequent sequela was low adrenal reserve. Paracoccidioides brasiliensis S1 was identified by partial sequencing of the arf and gp43 genes from 4 patients who presented a viable fungal culture.

CONCLUSION

Acute juvenile PCM is a severe disease with a high rate of complications. There are few cohort clinical studies of acute PCM in the literature. More studies should be developed to promote improvement in patients' healthcare.

Paracoccidioides brasiliensis AND Paracoccidioides lutzii, A SECRET LOVE AFFAIR

To commemorate Prof. Carlos da Silva Lacaz's centennial anniversary, the authors have written a brief account of a few, out of hundreds, biological, ecological, molecular and phylogenetic studies that led to the arrival of Paracoccidioides lutzii, hidden for more than a century within Paracoccidioides brasiliensis. Lacaz's permanent interest in this fungus, and particularly his conviction on the benefits that research on paracoccidioidomycosis would bring to patients, were pivotal in the development of the field.

Cryptic species of Paracoccidioides brasiliensis: impact on paracoccidioidomycosis immunodiagnosis

We aimed to evaluate whether the occurrence of cryptic species of Paracoccidioides brasiliensis, S1, PS2, PS3 and Paracoccidioides lutzii, has implications in the immunodiagnosis of paracoccidioidomycosis (PCM). Small quantities of the antigen gp43 were found in culture filtrates of P. lutzii strains and this molecule appeared to be more variable within P. lutzii because the synonymous-nonsynonymous mutation rate was lower, indicating an evolutionary process different from that of the remaining genotypes. The production of gp43 also varied between isolates belonging to the same species, indicating that speciation events are important, but not sufficient to fully explain the diversity in the production of this antigen. The culture filtrate antigen AgEpm83, which was obtained from a PS3 isolate, showed large quantities of gp43 and reactivity by immunodiffusion assays, similar to the standard antigen (AgB-339) from an S1 isolate. Furthermore, AgEpm83 was capable of serologically differentiating five serum samples from patients from the Botucatu and Jundiaí regions. These patients had confirmed PCM but, were non-reactive to the standard antigen, thus demonstrating an alternative for serological diagnosis in regions in which S1 and PS2 occur. We also emphasise that it is not advisable to use a single antigen preparation to diagnose PCM, a disease that is caused by highly diverse pathogens.

Genus paracoccidioides: Species recognition and biogeographic aspects

BACKGROUND

Paracoccidioidomycosis is a systemic mycosis caused by Paracoccidioides brasiliensis (species S1, PS2, PS3), and Paracoccidioides lutzii. This work aimed to differentiate species within the genus Paracoccidioides, without applying multilocus sequencing, as well as to obtain knowledge of the possible speciation processes.

METHODOLOGY/PRINCIPAL FINDINGS

Single nucleotide polymorphism analysis on GP43, ARF and PRP8 intein genes successfully distinguished isolates into four different species. Morphological evaluation indicated that elongated conidia were observed exclusively in P. lutzii isolates, while all other species (S1, PS2 and PS3) were indistinguishable. To evaluate the biogeographic events that led to the current geographic distribution of Paracoccidioides species and their sister species, Nested Clade and Likelihood Analysis of Geographic Range Evolution (LAGRANGE) analyses were applied. The radiation of Paracoccidioides started in northwest South America, around 11-32 million years ago, as calculated on the basis of ARF substitution rate, in the BEAST program. Vicariance was responsible for the divergence among S1, PS2 and P. lutzii and a recent dispersal generated the PS3 species, restricted to Colombia. Taking into account the ancestral areas revealed by the LAGRANGE analysis and the major geographic distribution of L. loboi in the Amazon basin, a region strongly affected by the Andes uplift and marine incursions in the Cenozoic era, we also speculate about the effect of these geological events on the vicariance between Paracoccidioides and L. loboi.

CONCLUSIONS/SIGNIFICANCE

The use of at least 3 SNPs, but not morphological criteria, as markers allows us to distinguish among the four cryptic species of the genus Paracoccidioides. The work also presents a biogeographic study speculating on how these species might have diverged in South America, thus contributing to elucidating evolutionary aspects of the genus Paracoccidioides.

Identification of a gene encoding adaptin-like protein in the Paracoccidioides brasiliensis genome by random amplified polymorphic DNA analysis

Paracoccidioides brasiliensis isolates are not homogeneous in their patterns of pathogenicity in animals and adhesion to epithelial cells. During this investigation, genotypic differences were observed between two samples of P. brasiliensis strain 18 yeast phase (Pb18) previously cultured many times, one taken before (Pb18a) and the other after (Pb18b) animal inoculation. Random amplified polymorphic DNA analysis using the primer OPJ4 distinguished Pb18b from Pb18a by one 308 bp DNA fragment, which after cloning and sequencing was shown to encode a polypeptide sequence homologous to the protein beta-adaptin. It is suggested, by comparison to other micro-organisms, that this protein might play an important role in the virulence of P. brasiliensis. This result demonstrates the influence of in vitro subculturing on the genotype of this organism.

Background selection at the chitin synthase II (chs2) locus in Paracoccidioides brasiliensis species complex

In fungi, chitin synthases have been classified into five classes according to differences in regions of high sequence conservation. The current investigation was initiated to examine the causes for the polymorphism patterns found in a class II chitin synthase gene (chs2) of Paracoccidioides brasiliensis, in an attempt to determine the evolutionary forces affecting the chitin synthesis metabolic pathway. Neutrality tests were applied to the chs2 sequences exhibited by P. brasiliensis species complex. According to these tests and based on non-synonymous differences, P. brasiliensis data rejected the null hypothesis for a pure drift mutational process owing to a large excess of unique polymorphisms. In contrast, the synonymous and intron site differences did not reject the null hypothesis. This pattern appears consistent with weak selection against most amino acid changes, in which the effect of background selection was not detectable at synonymous nor at intron sites.

Genome size and ploidy of Paracoccidioides brasiliensis reveals a haploid DNA content: Flow cytometry and GP43 sequence analysis

The aim of this study was to evaluate genome size and ploidy of the dimorphic pathogenic fungus Paracoccidioides brasiliensis. The cell cycle analysis of 10 P. brasiliensis isolates by flow cytometry (FCM) revealed a genome size ranging from 26.3+/-0.1Mb (26.9+/-0.1fg) to 35.5+/-0.2Mb (36.3+/-0.2fg) per uninucleated yeast cell. The DNA content of conidia from P. brasiliensis ATCC 60855-30.2+/-0.8Mb (30.9+/-0.8fg) -showed no significant differences with the yeast form, possibly excluding the occurrence of ploidy shift during morphogenesis. The ploidy of several P. brasiliensis isolates was assessed by comparing genome sizing by FCM with the previously described average haploid size obtained from electrophoretic karyotyping. The analysis of intra-individual variability of a highly polymorphic P. brasiliensis gene, GP43, indicated that only one allele seems to be present. Overall, the results showed that all analysed isolates presented a haploid, or at least aneuploid, DNA content and no association was detected between genome size/ploidy and the clinical-epidemiological features of the studied isolates. This work provides new knowledge on P. brasiliensis genetics/genomics, important for future research in basic cellular/molecular mechanisms and for the development/design of molecular techniques in this fungus.

Microsatellite analysis of three phylogenetic species of Paracoccidioides brasiliensis

Paracoccidioides brasiliensis is the etiological agent of paracoccidioidomycosis, an important human systemic mycosis in Latin America. Recently, the existence of three different phylogenetic species (S1, PS2, and PS3) of P. brasiliensis was demonstrated. Despite being genetically isolated, all three species were capable of inducing disease in both humans and animals, although lower virulence has been found with the PS2 species. The available molecular methods developed to characterize and type strains have not been useful for assigning isolates to the described species, creating the need for molecular markers capable of distinguishing genetically isolated groups. Here, we describe a PCR and sequencing-based microsatellite marker system that is stable, easy to assay, adaptable to large series of isolates, and discriminatory enough to be used as a typing system in identifying the three proposed species of P. brasiliensis. In addition, this system provides an unambiguous tool for strain discrimination between two (S1 and PS2) of the three phylogenetic species.

Morphological, Biochemical and Molecular Approaches for Comparing Typical and Atypical Paracoccidioides brasiliensis Strains

We evaluated the morphology of typical and atypical Paracoccidioides brasiliensis strains and the expression of its 43 kDa glycoprotein (GP43). Strains of P. brasiliensis preserved under mineral oil for long periods of time presented different morphological patterns on peptone, yeast-extract and glucose (PYG) agar. The intravenous inoculation in BALB/c mice confirmed that a strain bearing morphological alterations was non-virulent. In contrast, another strain also maintained under mineral oil but which did not exhibit such morphological dysfunction was as virulent as the well characterized Pb 339 and Pb 18 strains. The expression of the main antigen expressed by P. brasiliensis, GP43, was assessed in culture filtrates by western immunoblots. Typical and atypical strains were capable of secreting the glycoprotein, except strain Pb IOC 1059. The identity of the atypical strains was confirmed by PCR using specific primers for gp43, though the single PCR-fragment varied in size for the atypical strains. The PCR fragments from an atypical strain, Pb IOC 1210, and the typical Pb 339 and Pb IOC 3698 strains were sequenced and blasted to the gp43 gene from the Pb 18 strain (GenBank AY005429). These results ensured the identity of the atypical strains as P. brasiliensis, and suggested a relationship between the alteration of morphological differentiation and the virulence factor following storage under mineral oil.

Molecular model for studying the uncultivated fungal pathogen Lacazia loboi

Lacazia loboi is an uncultivated fungal pathogen of humans and dolphins that causes cutaneous and subcutaneous infections only in the tropical areas of the Americas. It was recently found by phylogenetic analysis that this unusual pathogen is closely related to Paracoccidioides brasiliensis and to the other fungal dimorphic members of the order Onygenales. That original phylogenetic study used universal primers to amplify well-known genes. However, this approach cannot be applied to the study of other proteins. We have developed a strategy for studying the gene encoding the gp43 homologous protein of P. brasiliensis in L. loboi. The gp43 protein was selected because it has been found that this P. brasiliensis antigen strongly reacts when it is used to test sera from patients with lacaziosis. The principle behind this idea was to obtain the gp43 amino acid sequence of P. brasiliensis and other homologous fungal sequences from GenBank and design primers from their aligned conserved regions. These sets of primers were used to amplify the selected regions with genomic DNA extracted from the yeast-like cells of L. loboi from experimentally infected mice. Using this approach, we amplified 483 bp of the L. loboi gp43-like gene. These sequences had 85% identity at the nucleotide level and 75% identity with the deduced amino acid sequences of the P. brasiliensis gp43 protein. The identity of the 483-bp DNA fragment was confirmed by phylogenetic analysis. This analysis revealed that the L. loboi gp43-like deduced amino acid sequence formed a strongly supported (100%) sister group with several P. brasiliensis gp43 sequences and that this taxon in turn was linked to the other fungal sequences used in this analysis. This study shows that the use of a molecular model for investigation of the genes encoding important proteins in L. loboi is feasible.

Analysis of the genetic polymorphism of Paracoccidioides brasiliensis and Paracoccidioides cerebriformis "Moore" by random amplified polymorphic DNA (RAPD) and 28S ribosomal DNA sequencing--Paracoccidioides cerebriformis revisited

Our purpose was to compare the genetic polymorphism of six samples of P. brasiliensis (113, 339, BAT, T1F1, T3B6, T5LN1), with four samples of P. cerebriformis (735, 741, 750, 361) from the Mycological Laboratory of the Instituto de Medicina Tropical de São Paulo, using Random Amplified Polymorphic DNA Analysis (RAPD). RAPD profiles clearly segregated P. brasiliensis and P. cerebriformis isolates. However, the variation on band patterns among P. cerebriformis isolates was high. Sequencing of the 28S rDNA gene showed nucleotide conservancy among P. cerebriformis isolates, providing basis for taxonomical grouping, and disclosing high divergence to P. brasiliensis supporting that they are in fact two distinct species. Moreover, DNA sequence suggests that P. cerebriformis belongs in fact to the Aspergillus genus.

Detection and selection of microsatellites in the genome of Paracoccidioides brasiliensis as molecular markers for clinical and epidemiological studies

Paracoccidioides brasiliensis, a thermodimorphic fungus, is the causative agent of the prevalent systemic mycosis in Latin America, paracoccidioidomycosis (PCM). Here, we describe the microsatellite patterns observed in a collection of P. brasiliensis random sequence tags. We identified 1,117 microsatellite patterns in about 3.8 Mb of unique sequences (0.47% of the total DNA used in the analysis). The majority of these microsatellites (87.5%) are found in noncoding sequences. We used two polymorphic microsatellites located on noncoding and coding sequences, as well as two microsatellites located on introns, as molecular markers to discriminate P. brasiliensis isolates, to look for relationships between the genetic background of the strains and the types of human disease they cause. We did not observe any correlation between the clinical form of human PCM and four simple sequence repeat patterns analyzed.

Isolation of the CHS4 gene of Paracoccidioides brasiliensis and its accommodation in a new class of chitin synthases

The nucleotide sequence of a chitin synthase gene (PbrCHS4) of the dimorphic fungal human pathogen Paracoccidioides brasiliensis has been determined. A homology search with the deduced amino acid sequence of PbrChs4 (1744 aa) reveals the presence of two distinct domains, an N-terminal domain showing up to 30% homology to myosin motor-like domains and a C-terminal domain with up to 68% homology to chitin synthases, as has been reported for some class V chitin synthases. However, unlike class V chitin synthases with myosin motor-like domains, PbrChs4 does not present characteristic signatures of myosin motor-like domains. Also, although the Chs domain presents the closest homology to other fungal class V enzymes, it is low enough to consider PbrChs4 as belonging to a new class, which we propose as class VII.

Canine paracoccidioidomycosis

Paracoccidioidomycosis (PCM) is a severe disease caused by the dimorphic fungus Paracoccidioides brasiliensis, which is characterized by granulomatous pulmonary and systemic lesions, affecting mainly men between 20 and 60 years of age. Reports of PCM disease in animals are rare, but the disease has been described in armadillos. On the other hand, PCM infection of domestic and wild animals detected by serological or cutaneous tests in the absence of apparent disease has been frequently reported. We present here the case of a female adult Doberman that developed cervical lymphadenomegaly. Histopathological examination of a cervical biopsy specimen revealed active PCM, with an epithelioid, granulomatous inflammation containing numerous yeast-like, multiple budding fungal forms. The diagnosis of PCM was confirmed by immunohistochemistry using a specific antibody anti-gp43 and by nested PCR using primers for the amplification of the gp43 gene region. This is the first report of PCM disease occurring in a dog, an animal that has been shown to play an important role in the natural history of North American blastomycosis.

Comparison of the sequences of the internal transcribed spacer regions and PbGP43 genes of Paracoccidioides brasiliensis from patients and armadillos (Dasypus novemcinctus)

Paracoccidioides brasiliensis isolates from 10 nine-banded armadillos (Dasypus novemcinctus) were comparable with 19 clinical isolates by sequence analysis of the PbGP43 gene and ribosomal internal transcribed spacer 1 (ITS1) and ITS2 and by random amplified polymorphic DNA. In this original ITS study, eight isolates differed by one or three sites among five total substitution sites.

Randomly amplified polymorphic DNA as a valuable tool for epidemiological studies of Paracoccidioides brasiliensis

Randomly amplified polymorphic DNA (RAPD) has been successfully used to detect genetic variations among isolates of Paracoccidioides brasiliensis. However, the usefulness of this technique for assessing important parasitic properties is still unconfirmed. In the present work we further investigated the applicability of RAPD in revealing important intrinsic and extrinsic features of this fungus associated with geographical origin, time of isolation, source of clinical specimen, clinical forms of human disease and also in vitro and in vivo susceptibility to antimicrobial and antifungal drugs. The RAPD patterns allowed us to distinguish all of the analyzed strains, which included 26 clinical isolates, 2 animal isolates, and 1 environmental isolate of P. brasiliensis obtained from different geographic regions, confirming the strong discriminating power of this technique. A phenetic tree, build from the RAPD data, showed that although the two nonclinical Brazilian strains were set together the majority of the clinical Brazilian strains were randomly distributed through different sub-branches of a major cluster without any correlation to any of the parameters analyzed. A second major cluster, however, has grouped isolates from Mato Grosso and Roraima (Brazil) that not only were susceptible in vitro to trimethoprim-sulfamethoxazole but also produced a good in vivo response. These results open new vistas for epidemiological and clinical studies of P. brasiliensis.

Paracoccidioides brasiliensis and paracoccidioidomycosis: molecular approaches to morphogenesis, diagnosis, epidemiology, taxonomy and genetics

Paracoccidioides brasiliensis is an amenable model to study the molecular and biochemical events that lead to morphological transition in fungi, because temperature seems to be the only factor regulating this process. It is the causative agent of paracoccidioidomycosis, a systemic mycosis that affects humans and that is geographically confined to Latin America, where it constitutes one of the most prevalent deep mycoses. With the help of molecular tools, events leading to the morphological transition have been traced to genes that control cell wall glucan and chitin syntheses, and other metabolic processes such as production of heat shock proteins and ornithine decarboxylase activity. Molecular diagnosis and epidemiology of paracoccidioidomycosis are also the focus of intensive research, with several primers being proposed as specific probes for clinical and field uses. Although P. brasiliensis is refractory to cytogenetic analysis, electrophoretic methods have allowed an approximation of its genomic organization and ploidy. Finally, the recognition of P. brasiliensis as an anamorph in the phylum Ascomycota, order Onygenales, family Onygenaceae, has been accomplished by means of molecular tools. This phylogenetic placement has revised the taxonomic position of this fungus, which was traditionally included within now-abandoned higher anamorph taxa, the phylum Deuteromycota and the class Hyphomycetes.

Exfoliative cytology: a helpful tool for the diagnosis of paracoccidioidomycosis

OBJECTIVE

To describe the main cytological findings associated with smears collected from oral lesions of paracoccidioidomycosis and to appraise the use of cytology as a diagnostic tool for the disease.

STUDY DESIGN

Cytological smears and biopsies were collected from 40 lesions with a clinical suspicion of paracoccidioidomycosis. Evaluation of the sensitivity, specificity, positive and negative predictive values, accuracy and the positive likeness ratio of the oral smear when compared with the histological diagnosis, was performed. The latter is considered the 'gold standard' for comparison.

RESULTS

The main morphological findings were the rounded-shaped, birefringent and multiple-budded fungi, Langhans' giant cells and epithelioid cells. The following associative measures were found: sensitivity, 67.9%; specificity, 91.7%; positive predictive value, 95.0%; negative predictive value, 55.0%; accuracy, 75.0%; and positive likeness ratio, 8.14.

CONCLUSION

The cytological findings of paracoccidioidomycosis are characteristic and cytology is accurate in the diagnosis of the disease. Positive patients should be treated. Negative patients should be submitted to biopsy to confirm or to dismiss the diagnosis of this mycosis.

RFLP analysis reveals marked geographical isolation between strains of Paracoccidioides brasiliensis

Restriction fragment length polymorphism (RFLP) was performed on 32 isolates of the pathogenic fungus Paracoccidioides brasiliensis from geographically separated regions of South America. The use of HinfI and HincII gave clear RFLP patterns, for which high discriminatory indices could be calculated. Computational analysis of the RFLP patterns for the 32 isolates suggested that at least five groups of strains existed, each of which was geographically distinct and corresponded closely with present country borders. These results underline the belief that P. brasiliensis infections are acquired from exogenous sources and that this fungus occupies specialist endemic niches within the natural environment.

Small subunit ribosomal DNA sequence shows Paracoccidioides brasiliensis closely related to Blastomyces dermatitidis

The similarities of paracoccidioidomycosis and blastomycosis are highly suggestive of a close relation of the two etiological agents. Whereas the agent of the first disease is exclusively endemic in Latin America, the agent of the latter one is endemic in North America and Africa. In symptomatic travelers visiting both areas of endemicity, differentiation of the diseases might be impossible, even though therapy and prognosis for these two diseases differ significantly. In order to identify differences in the 18S rRNA gene (rDNA) for use as molecular diagnostic tools, we sequenced this gene from five isolates of Paracoccidioides brasiliensis and compared them to known sequences of other fungi. Neighbor-joining, maximum parsimony, and maximum likelihood analyses and, finally, the Kishino-Hasegawa test revealed that P. brasiliensis, Blastomyces dermatitidis, and Emmonsia parva are more closely related than Histoplasma capsulatum and B. dermatitidis, whose teleomorphic forms belong to one genus, Ajellomyces. In accordance with the work of other investigators who have used internal transcribed spacer and large subunit rDNA sequences, our small subunit rDNA data show that the dimorphic fungus P. brasiliensis must be grouped within the order Onygenales and is closely related to members of the family Onygenaceae. There are hints in the molecular phylogenetic analysis that the family Onygenaceae might be further divided into two families. The subgroup that includes P. brasiliensis comprises all zoopathogenic species. The differences in the 18S rDNAs appear to be too small to allow species identification of the members of the family Onygenaceae pathogenic for humans by use of target sequences within this gene.

Molecular identification of Paracoccidioides brasiliensis by PCR amplification of ribosomal DNA

We have amplified and sequenced the 5.8S and 28S ribosomal DNA genes and intergenic regions of Paracoccidioides brasiliensis, strain Pb01. Using primers specifically designed for both ribosomal DNA regions, we were able to discriminate between P. brasiliensis and other human pathogenic fungi by PCR. The use of this molecular marker could be important for paracoccidiodomycosis diagnosis and ecological and molecular epidemiological studies of P. brasiliensis in Latin America.

[In vitro infection by different strains of Paracoccidioides brasiliensis]

We analyzed the in vitro infection process by P. brasiliensis and the effect of extracellular factor(s) produced on monolayers of mammalian Vero cell lines. The yeast phase of four strains was studied: B339 (avirulent or slightly virulent), U, (intermediate virulence), 93745 and 63265 (both highly virulent). Strains of intermediate and high virulence had higher adherence at first contact (about 16%). Strain B339 had a slower adherence at first contact (8%) than the others during the same period. The production of extracellular proteases, soluble extracellular factor(s) and extracellular antigen gP43 showed no correlation with the in vitro physiopathogenicity of the analyzed strains. We demonstrate that the Vero model presented in this paper is a suitable system to study infection and virulence in vitro. We are currently assessing its usefulness as a tool for the analysis of the interaction between pathogen, host and antifungal agents.

Paracoccidioidomycosis

Paracoccidioidomycosis is a systemic infection caused by the dimorphic fungus Paracoccidioides brasiliensis. It is commonly an endemic disease in Latin America, but several cases have been reported outside this area, particularly now in this time of world globalization. Primary pulmonary infection occurs commonly in the first and second decades of life and usually has a benign, self-limited respiratory infection course. The adult chronic manifestation of the disease is usually the result of reactivation of quiescent lesions with diffuse lung infiltrates, predominately of the interstitial pattern, with or without involvement of various other organs. The finding of this disease in a patient is an important step for the large differential diagnosis of the interstitial lung diseases group.

Virulence of Paracoccidioides brasiliensis isolates can be correlated to groups defined by random amplified polymorphic DNA analysis

Fifteen Paracoccidioides brasiliensis isolates were discriminated by the RAPD analysis into two groups with only 17% of genomic identity. The ability of P. brasiliensis isolates to invade tissues was studied in an experimental model using susceptible B10.A mice. The analysis was performed according to the severity of the lesions including the number and size of the granuloma, the number and dissemination of fungi to different organs. The isolates from two RAPD groups demonstrated a marked difference in their virulence patterns for B10.A mice. The isolates Pb S, 662, Bt and 166 (group I) elicited localized infection restricted to the liver showing compact epithelioid granuloma with few fungi in the early post-infection period (slightly virulent). On the other hand the isolates Pb 01 and 7455 (group II) elicited a disseminated infection with a mixed suppurative and looser granulomatous inflammation, showing extensive areas of necrosis and large numbers of viable fungal cells (highly virulent). These results are strong evidence for correlation between RAPD patterns and the virulence degree of P. brasiliensis.

Random amplified polymorphic DNA (RAPD) analysis of Paracoccidioides brasiliensis isolates

Five Paracoccidioides brasiliensis isolates of humans origin were analyzed using three arbitrary primers (3301, 3304 and 3307 of 10, 9 and 10 oligonucleotídes respectively) in random amplified polymorphic DNA (RAPD) analysis. The analysis of the complex RAPD profiles obtained were carried out using the Dice similarity coefficient that distinguished the isolated Pb 02 from the others (Pb 18, Pb 192, Pb 265 and Pb SN). The results revealed limited intraspecific genomic variations in these P. brasiliensis isolates and indicate that RAPD can be useful for analysis of P. brasiliensis genome for characterization or differentiation within this genus.

Comparison between human and armadillo Paracoccidioides brasiliensis isolates by random amplified polymorphic DNA analysis

Sixty-three Paracoccidioides brasiliensis isolates obtained from three nine-banded armadillos (Dasypus novemcinctus), one Amazonian armadillo's and 19 clinical isolates were compared by random amplified polymorphic DNA analysis with the primer OPG-19. The isolates were divided into three major clusters, I, II and III. Coincidences between human and armadillo isolates were observed in clusters I and II. Cluster III consisted only of armadillos' isolates. The results suggested that (I) humans may acquire P. brasiliensis infection by contact with armadillo's environment, (II) there may be P. brasiliensis genotypes peculiar to the animal, and (III) individual armadillos may be infected with P. brasiliensis cells with different genotypes.

Lacazia loboi gen. nov., comb. nov., the etiologic agent of lobomycosis

The new genus Lacazia P. Taborda, V. Taborda, et McGinnis is proposed to accommodate Lacazia loboi (O. M. Fonseca et Lacaz) P. Taborda, V. Taborda, et McGinnis, the obligate pathogen that causes lobomycosis in mammals. The continued placement of that fungus in the genus Paracoccidioides Almeida as Paracoccidioides loboi is taxonomically inappropriate. Loboa loboi Ciferri et al. is a synonym of Paracoccidioides brasiliensis.

Electrophoretic karyotype of environmental isolates of Paracoccidioides brasiliensis

Five of the 12 environmental isolates of the dimorphic fungus Paracoccidioides brasiliensis known to date, were analysed by contour-clamped homogeneous electric field gel electrophoresis (CHEF). The electrophoretic pattern was shown to consist of five bands, with molecular size ranging from 3.2 to 10 Mb, a model quite similar to the one found in the clinical isolates previously tested and used here as controls. However, one of the bands in the environmental isolates had a lesser weight (7.2 Mb), than the one corresponding to the clinical counterparts (8.8 Mb). This resulted in a smaller genome, approximately 29.7 Mb. The small differences that were found indicate the presence of chromosome polymorphism in this fungus.

Paracoccidioides brasiliensis. A mycologic and immunochemical study of two strains

The authors conducted a mycologic, immunochemical and molecular biology study on two strains of Paracoccidioides brasiliensis, one of them, called IBIA, isolated from soil in the municipality of IBIA (Minas Gerais) by Silva-Vergara et al. (1996, 1998), and the other, BAT, cultivated from a human case of paracoccidioidomycosis in Ribeirão Preto (São Paulo/Brazil) by Freitas Da Silva (1996). Both strains showed cotton-like (M) and yeast-like (Y) forms and were pathogenic for testicularly inoculated guinea pigs, producing granulomatous and/or suppurative orchitis. Immunochemically was demonstrated the presence of gp43 by double immunodiffusion, immunoelectrophoresis and immunoblotting.

Interactions of F1 fractions from different strains of Paracoccidioides brasiliensis with human complement and with human neutrophils

The aim of our study was to investigate differences that might exist in the activation of the human complement system by F1 fractions from four different isolates of P. brasiliensis. Isolates HC and 18 (virulent), 265 (low virulence), and 9 (intermediate virulence, attenuated) were used; before the experiments, the virulence of isolates HC and 18 was recovered by in vivo passage in guinea pigs. The four isolates of the fungus were processed for purification of F1 fractions and the activation of the human complement system was studied by a kinetic method of hemolytic activity measurement. The incubation of F1 fractions in normal human serum resulted in different degrees of inhibition of the classical and alternative pathways. The F1 fraction from the low virulence isolate was more efficient than the F1 fraction from the virulent isolates (HC and 18). Previous absorption of sera with F1 fractions completely abolished classical pathway activation. Using zymosan, instead of F1, in the absorption process caused the same phenomenon, suggesting that natural or nonspecific antibodies are responsible for the classical pathway activation. The alternative pathway activation did not depend on these antibodies, but was enhanced by their presence. On the other hand, F1 fractions from virulent isolates were more active in the stimulation of neutrophil chemiluminescence compared with the F1 fraction from the low virulence isolate. Whole P. brasiliensis yeast cells (WYC) from two distinct strains, 18 and 265, showed the same patterns of response of those observed with the F1 fractions in the functions tested. These differences in the behavior of the F1 fractions as well as WYC in relation to human complement activation and consequently to neutrophil stimulation may correlate with the virulence of individual isolates and may contribute to the understanding of the inflammatory response generation and maintenance processes in paracoccidioidomycosis.

Geographic discrimination of Paracoccidioides brasiliensis strains by randomly amplified polymorphic DNA analysis

Randomly amplified polymorphic DNA (RAPD) analysis of 33 Paracoccidioides brasiliensis strains from Argentina, Brazil, Colombia, Peru, and Venezuela produced reproducible amplification products which were sufficiently polymorphic to allow differentiation of the strains. Types generated with five primers (OPG 03, OPG 05, OPG 14, OPG 16, and OPG 18) resulted in a high discriminatory index (0.956). The discriminatory index was slightly reduced (0.940) when only two primers (OPG 3 and OPG 14) were used. A dendrogram based on these results showed a high degree of similarity among the strains, and genetic differences were expressed in clusters related to geographical regions but not to pathological features of the disease. With a few exceptions, strains were sorted into five groups by geographical origin as follows: group I, Venezuelan strains; group II, Brazilian strains; group III, Peruvian strains; group IV, Colombian strains; and group V, Argentinian strains. The group containing the most disparate strains was group V (discriminatory index, 0.633); the discriminatory index for the other four groups was 0.824. The use of primer OPG 18 by itself was sufficient to discriminate species specificity, and the use of primer OPG 14 by itself was sufficient to discriminate among the geographical locations of the strains in the sample. This method may be helpful for epidemiological studies of P. brasiliensis.

Isolation of a Paracoccidioides brasiliensis strain from the soil of a coffee plantation in Ibiá, State of Minas Gerais, Brazil

Paracoccidioides brasiliensis has rarely been isolated from its habitat in rural areas. In order to investigate the hypothesis that human infection with this fungus is linked to coffee plantations (Coffea arabica), material was collected monthly over a period of 1 year from farms in the town of Ibiá, State of Minas Gerais, Brazil. A total of 760 samples of soil, coffee leaves and fruits was cultured and inoculated into mice. A fungus isolated from the liver of a mouse inoculated with soil showed temperature-dependent dimorphism and in vitro mycelium and yeast phases characteristic of P. brasiliensis. Yeast cells of this fungus caused disseminated infection after intraperitoneal inoculation in Wistar rats from which the fungus was re-isolated. An antigen reacting with sera from patients with paracoccidioidomycosis was obtained from this P. brasiliensis strain; antigenic identity with strain 339 and with four other P. brasiliensis strains was detected by gel immunodiffusion. However, when the exo-antigen was submitted to SDS-PAGE, we observed low gp43 expression in this new strain, which we called Ibiá. The isolation of P. brasiliensis from the soil at a coffee plantation suggests that this is one of its habitats and supports the hypothesis of acquisition of paracoccidioidomycosis during agricultural activity in these areas.

Antigenic similarities to Paracoccidioides brasiliensis in thermo-dependent dimorphic fungi isolated from soil in Botucatu, SP, Brazil

We compared the antigenic characteristics of two thermo-dependent dimorphic fungi isolated from soil in Botucatu, an endemic area of paracoccidioidomycosis (PCM) and Paracoccidioides brasiliensis. The soil isolates grew as cerebriform colonies at 37 degrees C (yeast form) and as cottonous colonies at 25 degrees C (mycelial form). No pathogenicity for ddY mice or hamsters were observed. In immunodiffusion test, there were precipitation bands between the 2 soil isolates and pooled PCM patient sera. There were also common precipitation bands at 21, 50 and 58 kDa between the soil isolates antigens and PCM patient sera by Western-blotting, but no gp43 kDa band. No gene for gp 43 kDa protein was detected in the soil isolates by PCR. The fact that these isolates were obtained from an endemic area of PCM and there were some antigenic similarities between the soil isolates and P. brasiliensis in immunodiffusion test and Western-blotting may have some importance in epidemiological surveys done with paracoccidioidin as well interfering with the immune response of the exposed population.

Molecular detection and identification of Paracoccidioides brasiliensis

Nearly 800 nucleotides from the 5' terminus of the 28S ribosomal gene of Paracoccidioides brasiliensis were sequenced, and a 14-base DNA probe specific for this species was identified. Hybridization results showed that the probe identified P. brasiliensis ribosomal DNA in a panel of ribosomal DNAs representing a total of 48 species of fungi.

Paracoccidioides cerebriformis Moore, 1935. Mycologic and immunochemical study

The present study concern on mycologic and immunochemical data obtained from two samples of a fungus considered as belonging to the species Paracoccidioides cerebriformis described by Moore in 1935, and maintained since then on Sabouraud's agar in the mycology collection of the Instituto de Medicina Tropical de São Paulo. After 60 years, the samples exhibited the same characteristics described by MOORE (1935). However, experimental lesions did not resulted in guinea-pigs inoculated intratesticularly. The dominant antigen in Paracoccidioides brasiliensis, 43 kDa glicoprotein (gp43), could not be demonstrated by SDS PAGE and Western blotting. Immunoelectrophoresis did not demonstrated the E arch of cathodic migration using a policlonal anti gp43 serum. According to these findings, it is concluded that the fungus described by MOORE (1935) as P. cerebriformis does not belong to the genus Paracoccidioides. Paracoccidioidomycosis should therefore be considered as resulting from infection by a single species, Paracoccidioides brasiliensis (Splendore, 1912) as asserted by ALMEIDA (1930). Further studies, through molecular biology methods, could identify the mentioned fungus.

An atypical isolate of Paracoccidioides brasiliensis

An atypical strain of Paracoccidioides brasiliensis was obtained from a patient with disseminated paracoccidioidomycosis. This isolate, which has been maintained in the laboratory for 4 years by successive subcultures (30-40 days) in Fava Netto medium, produces cerebriform colonies characteristic of the yeast phase of the fungus when left at room temperature. Microscopy shows a predominance of yeasts with multiple buds, side by side with some branching filamentous structures presenting intercalary chlamydospores. The strain does not develop well at 37 degrees C, suggesting heat sensitivity. Storage at 4 degrees C does not change its macro- or microscopic characteristics. These findings support the hypothesis raised by others that the dimorphism of P. brasiliensis may not be exclusively heat dependent. Studies are currently being developed in our laboratory to better characterize this isolate in terms of biochemical peculiarities, degree of virulence and susceptibility/resistance to antifungal drugs.

Expression and isoforms of gp43 in different strains of Paracoccidioides brasiliensis

Individual exoantigens from 13 Paracoccidioides brasiliensis isolates were obtained and tested against a panel of 50 sera from patients with paracoccidioidomycosis by immunodiffusion test. The index of positivity varied from 20 to 100% according to the isolate. When these exoantigens were analysed by SDS-PAGE, eight presented high amounts of the glycoprotein gp43, two presented small amounts and in three there was no detectable gp43. The eight isolates presenting high amounts of gp43 were submitted to isoelectric focusing, blotted to nitrocellulose membranes, and revealed by monoclonal and polyclonal anti-gp43 antibodies. Four gp43 isoform profiles were obtained: profile A presenting pIs of 6.0, 6.2, 6.6 and 7.0, profile B presenting pIs of 6.4, 6.8 and 7.2, profile C presenting pI > 8.5 and profile D, presenting pIs of 5.8, 6.2 and 6.6. In each pattern observed, a major band with a distinct pI was detected. Despite this variation, our results strongly suggest an epitopic conservation among all isoforms analysed, since all of them were recognized by anti-gp43 monoclonal antibodies.

Cloning and nucleotide sequence of a specific DNA fragment from Paracoccidioides brasiliensis

We cloned and sequenced a species-specific 110-bp DNA fragment from Paracoccidioides brasiliensis. The DNA fragment was generated by PCR with primers complementary to the rat beta-actin gene under a low annealing temperature. Comparison of the nucleotide sequence, after excluding the primers, with those in the GenBank database identified approximately 60% homology with an exon of a major surface glycoprotein gene from Pneumocystis carinii and a fragment of unknown function in Saccharomyces cerevisiae chromosome VIII. By Southern hybridization analysis, the 32P-labelled fragment detected 1.0- and 1.9-kb restriction fragments within whole-cell genomic DNA of P. brasiliensis digested with HindIII and PstI, respectively, but failed to hybridize to genomic DNAs from Candida albicans, Blastomyces dermatitidis, Cryptococcus neoformans, Aspergillus fumigatus, Saccharomyces cerevisiae, Pneumocystis carinii, rat tissue, or humans under low-stringency hybridization conditions. Additionally, the specific DNA fragment from three different P. brasiliensis isolates (Pb18, RP18, RP17) was amplified by PCR with primers mostly complementary to nonactin sequences of the 110-bp DNA fragment. In contrast, there were no amplified products from other fungus genomic DNAs previously tested, including Histoplasma capsulatum. To date, this is the first species-specific DNA fragment cloned from P. brasiliensis which might be useful as a diagnostic marker for the identification and classification of different P. brasiliensis isolates.

Characterization of Paracoccidioides brasiliensis isolates by random amplified polymorphic DNA analysis

We initially used 25 different random primers in order to test their ability to generate random amplified polymorphic DNA fragments from the dimorphic human pathogenic fungus Paracoccidioides brasiliensis. From the tested primers we chose five to distinguish between seven isolates of this microorganism. The DNA amplification patterns allowed clear differentiation of the seven isolates into two distinct groups with only 35% genomic identity. One of these groups contained two subgroups with 81% genetic similarity. The random amplified polymorphic DNA analysis method proved to be a good tool for analyzing and comparing different genomes of P. brasiliensis isolates.