Review

Virulence insights from the Paracoccidioides brasiliensis transcriptome

Published: June 30, 2005
Genet. Mol. Res. 4 (2) : 372-389
Cite this Article:
A.Henrique Tavares, S.Souza Silva, V.Vilmar Bernardes, A.Queiróz Maranhão, A.Queiróz Maranhão, C.Maria Kyaw Kyaw, M. Poças-Fonseca, I. Silva-Pereira (2005). Virulence insights from the Paracoccidioides brasiliensis transcriptome. Genet. Mol. Res. 4(2): 372-389.
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Abstract

Paracoccidioides brasiliensis, the etiologic agent of paracoccidioidomycosis, is a dimorphic fungus, which is found as mycelia at 22-26ºC and as yeasts at 37ºC. A remarkable feature common to several pathogenic fungi is their ability to differentiate from mycelium to yeast morphologies, or vice-versa. Although P. brasiliensis is a recognized pathogen for humans, little is known about its virulence genes. In this sense, we performed a search for putative virulence genes in the P. brasiliensis transcriptome. BLAST comparative analyses were done among P. brasilienses assembled expressed sequence tags (PbAESTs) and the sequences deposited in GenBank. As a result, the putative virulence PbAESTs were grouped into five classes, metabolism-, cell wall-, detoxification-related, secreted factors, and other determinants. Among these, we have identified orthologs of the glyoxylate cycle enzymes, a metabolic pathway involved in the virulence of bacteria and fungi. Besides the previously described α- and β-glucan synthases, orthologs to chitin synthase and mannosyl transferases, also important in cell wall synthesis and stabilization, were identified. With respect to the enzymes involved in the intracellular survival of P. brasiliensis, orthologs to superoxide dismutase, thiol peroxidase and an alternative oxidase were also found. Among the secreted factors, we were able to find phospholipase and urease orthologs in P. brasiliensis transcriptome. Collectively, our results suggest that this organism may possess a vast arsenal of putative virulence genes, allowing the survival in the different host environments.

Paracoccidioides brasiliensis, the etiologic agent of paracoccidioidomycosis, is a dimorphic fungus, which is found as mycelia at 22-26ºC and as yeasts at 37ºC. A remarkable feature common to several pathogenic fungi is their ability to differentiate from mycelium to yeast morphologies, or vice-versa. Although P. brasiliensis is a recognized pathogen for humans, little is known about its virulence genes. In this sense, we performed a search for putative virulence genes in the P. brasiliensis transcriptome. BLAST comparative analyses were done among P. brasilienses assembled expressed sequence tags (PbAESTs) and the sequences deposited in GenBank. As a result, the putative virulence PbAESTs were grouped into five classes, metabolism-, cell wall-, detoxification-related, secreted factors, and other determinants. Among these, we have identified orthologs of the glyoxylate cycle enzymes, a metabolic pathway involved in the virulence of bacteria and fungi. Besides the previously described α- and β-glucan synthases, orthologs to chitin synthase and mannosyl transferases, also important in cell wall synthesis and stabilization, were identified. With respect to the enzymes involved in the intracellular survival of P. brasiliensis, orthologs to superoxide dismutase, thiol peroxidase and an alternative oxidase were also found. Among the secreted factors, we were able to find phospholipase and urease orthologs in P. brasiliensis transcriptome. Collectively, our results suggest that this organism may possess a vast arsenal of putative virulence genes, allowing the survival in the different host environments.

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