Espécies crípticas em Paracoccidioides brasiliensis: diferenciação antigênica e de resposta a fatores estressantes
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2011-04-29
Autores
Machado, Gabriel Capella [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O fungo termodimórfico Paraccocidiodes brasiliensis, em sua fase leveduriforme, é o agente etiológico de uma das mais importantes micoses sistêmicas da América Latina, a paracoccidioidomicose. A doença pode ser fatal em sua forma aguda, além de gerar, na forma crônica, lesões principalmente de ordem dermatológica e pulmonar. O fato de P. brasiliensis ser considerado uma única entidade biológica vem sendo questionado pelos recentes achados de filogenia molecular. Atualmente acredita-se que P. brasiliensis seja um complexo de quatro espécies crípticas, S1, PS2, PS3 e P. lutzii, sendo esta última a mais distante filogeneticamente. É possível que o fato esteja interferindo em aspectos relacionados à doença, como, por exemplo, a positividade do diagnóstico sorológico. Além disso, tal especiação pode significar diferenças na biologia do fungo, em aspectos como sua morfologia, fisiologia e ocupação de nichos ecológicos.A primeira frente deste trabalho visou produzir e caracterizar antígenos a partir de cepas pertencentes às diferentes espécies de P. brasiliensis, e avaliar o desempenho das mesmas em testes de imunodifusão (ID) contra pacientes das diferentes regiões do Brasil. Melhores resultados foram obtidos com o antígeno produzido por filtrado de cultura de um isolado pertencente ao grupo PS3, o qual apresentou altas taxas do antígeno imunodominante, a glicoproteína gp43, detectável por SDS-PAGE, e apresentou boa positividade nas IDs quando cruzados com soros de pacientes da região de Botucatu, reagindo inclusive com alguns soros falso-negativos para o antígeno considerado padrão, produzido pela cepa B-339. Entretanto, este antígeno, bem como outros aqui avaliados, não foi capaz de apresentar desempenho satisfatório frente a soros de pacientes da Região Centro-Oeste, justamente os que apresentam maiores taxas de negatividade, provavelmente por serem...
The thermo-dimorphic fungus Paraccocidiodes brasiliensis is the causative agent of paracoccidioidomycosis, one of the most important systemic mycosis in Latin America. The disease can be fatal in its acute form, besides causing important lesions especially in lungs and skin when occurs in its chronic form. The fact that P. brasiliensis is considered a single biological entity has been challenged by the recent findings in molecular phylogenetics. Currently, it has been observed that P. brasiliensis is a complex of four cryptic species, S1, PS2, PS3 and Pb01-like, which is the most distantly related, being proposed as new formal species, P. lutzii. It is possible that these facts are interfering with the host/pathogen interactions, as well as with the results of serological diagnosis. Furthermore, this speciation could reflect differences in the biology of the fungus, especially on their morphology, physiology and occupation of ecological niches.The first approach of this work was to produce and characterize antigens from strains belonging to different species of P. brasiliensis, and evaluate their performance in immunodiffusion tests (ID) against sera of pacients from different regions of Brazil. The better results were obtained with the antigen produced by culture filtrate of an isolate belonging to the PS3, AgEpm83, which showed high positivity rates in IDs, against sera of patients from Botucatu. This antigen, in addition, presented high levels of the glycoprotein gp43, the immunodominant component, detectable by SDS-PAGE. However, this antigen, as well as other here evaluated, was unable to provide satisfactory performance against the sera of patients from the Brazilian Midwest Region, probably because they are infected with P. lutzii isolates. The in silico analysis of exon2 of the gene that encodes gp43 indicated that this gene is under purifying selection both... (Complete abstract click electronic access below)
The thermo-dimorphic fungus Paraccocidiodes brasiliensis is the causative agent of paracoccidioidomycosis, one of the most important systemic mycosis in Latin America. The disease can be fatal in its acute form, besides causing important lesions especially in lungs and skin when occurs in its chronic form. The fact that P. brasiliensis is considered a single biological entity has been challenged by the recent findings in molecular phylogenetics. Currently, it has been observed that P. brasiliensis is a complex of four cryptic species, S1, PS2, PS3 and Pb01-like, which is the most distantly related, being proposed as new formal species, P. lutzii. It is possible that these facts are interfering with the host/pathogen interactions, as well as with the results of serological diagnosis. Furthermore, this speciation could reflect differences in the biology of the fungus, especially on their morphology, physiology and occupation of ecological niches.The first approach of this work was to produce and characterize antigens from strains belonging to different species of P. brasiliensis, and evaluate their performance in immunodiffusion tests (ID) against sera of pacients from different regions of Brazil. The better results were obtained with the antigen produced by culture filtrate of an isolate belonging to the PS3, AgEpm83, which showed high positivity rates in IDs, against sera of patients from Botucatu. This antigen, in addition, presented high levels of the glycoprotein gp43, the immunodominant component, detectable by SDS-PAGE. However, this antigen, as well as other here evaluated, was unable to provide satisfactory performance against the sera of patients from the Brazilian Midwest Region, probably because they are infected with P. lutzii isolates. The in silico analysis of exon2 of the gene that encodes gp43 indicated that this gene is under purifying selection both... (Complete abstract click electronic access below)
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Genética, Paracoccidioides brasiliensis, Sorologia, Genetics, Serology
Como citar
MACHADO, Gabriel Capella. Espécies crípticas em Paracoccidioides brasiliensis: diferenciação antigênica e de resposta a fatores estressantes. 2011. 70 f. Dissertacao (mestrado) - Universidade Estadual Paulista, Instituto de Biociências de Botucatu, 2011.