Regulatory approaches for genome edited agricultural plants in select countries and jurisdictions around the world.

Genome editing in agriculture and food is leading to new, improved crops and other products. Depending on the regulatory approach taken in each country or region, commercialization of these crops and products may or may not require approval from the respective regulatory authorities. This paper describes the regulatory landscape governing genome edited agriculture and food products in a selection of countries and regions.

Erg6 affects membrane composition and virulence of the human fungal pathogen Cryptococcus neoformans.

Ergosterol is the most important membrane sterol in fungal cells and a component not found in the membranes of human cells. We identified the ERG6 gene in the AIDS-associated fungal pathogen, Cryptococcus neoformans, encoding the sterol C-24 methyltransferase of fungal ergosterol biosynthesis. In this work, we have explored its relationship with high-temperature growth and virulence of C. neoformans by the construction of a loss-of-function mutant. In contrast to other genes involved in ergosterol biosynthesis, C. neoformans ERG6 is not essential for growth under permissive conditions in vitro. However, the erg6 mutant displayed impaired thermotolerance and increased susceptibility to osmotic and oxidative stress, as well as to different antifungal drugs. Total lipid analysis demonstrated a decrease in the erg6Δ strain membrane ergosterol content. In addition, this mutant strain was avirulent in an invertebrate model of C. neoformans infection. C. neoformans Erg6 was cyto-localized in the endoplasmic reticulum and Golgi complex. Our results demonstrate that Erg6 is crucial for growth at high temperature and virulence, likely due to its effects on C. neoformans membrane integrity and dynamics. These pathogen-focused investigations into ergosterol biosynthetic pathway components reinforce the multiple roles of ergosterol in the response of diverse fungal species to alterations in the environment, especially that of the infected host. These studies open perspectives to understand the participation of ergosterol in mechanism of resistance to azole and polyene drugs. Observed synergistic growth defects with co-inhibition of Erg6 and other components of the ergosterol biosynthesis pathway suggests novel approaches to treatment in human fungal infections.

An Immunomodulatory Peptide Confers Protection in an Experimental Candidemia Murine Model.

Fungal Candida species are commensals present in the mammalian skin and mucous membranes. Candida spp. are capable of breaching the epithelial barrier of immunocompromised patients with neutrophil and cell-mediated immune dysfunctions and can also disseminate to multiple organs through the bloodstream. Here we examined the action of innate defense regulator 1018 (IDR-1018), a 12-amino-acid-residue peptide derived from bovine bactenecin (Bac2A): IDR-1018 showed weak antifungal and antibiofilm activity against a Candida albicans laboratory strain (ATCC 10231) and a clinical isolate (CI) (MICs of 32 and 64 µg · ml-1, respectively), while 8-fold lower concentrations led to dissolution of the fungal cells from preformed biofilms. IDR-1018 at 128 µg · ml-1 was not hemolytic when tested against murine red blood cells and also has not shown a cytotoxic effect on murine monocyte RAW 264.7 and primary murine macrophage cells at the tested concentrations. IDR-1018 modulated the cytokine profile during challenge of murine bone marrow-derived macrophages with heat-killed C. albicans (HKCA) antigens by increasing monocyte chemoattractant protein 1 (MCP-1) and interleukin-10 (IL-10) levels, while suppressing tumor necrosis factor alpha (TNF-α), IL-1ß, IL-6, and IL-12 levels. Mice treated with IDR-1018 at 10 mg · kg-1 of body weight had an increased survival rate in the candidemia model compared with phosphate-buffered saline (PBS)-treated mice, together with a diminished kidney fungal burden. Thus, IDR-1018 was able to protect against murine experimental candidemia and has the potential as an adjunctive therapy.

Clinical and Eco-Epidemiological Aspects of a Novel Hyperendemic Area of Paracoccidioidomycosis in the Tocantins-Araguaia Basin (Northern Brazil), Caused by Paracoccidioides sp.

Paracoccidioidomycosis (PCM) is the most prevalent systemic mycosis in Brazil. The disease is caused by dimorphic fungi nested within the Paracoccidioides genus. We described 106 PCM cases (47.1 cases/year) at the Tropical Diseases Public Hospital of Tocantins State. PCM was prevalent in males and rural workers over 50 years; the chronic pulmonary form predominated in 67% of cases. The male-to-female ratio was 2.65:1, with more women affected than other endemic regions of Brazil. Urban or indoor activities were reported in women and are ascribed to disease urbanization. qPCR-based assays confirmed the identification of Paracoccidioides DNA in 37 biological specimens. Paracoccidioides sp. DNA was found in 53% of the environmental samples, suggesting autochthonous infections. Therefore, the Tocantins-Araguaia basin must be considered a novel hyperendemic area of PCM in Brazil, reinforcing the importance of including PCM as a notifiable disease, requiring specific diagnosis and health measures.

Engineered Fluorescent Strains of Cryptococcus neoformans: a Versatile Toolbox for Studies of Host-Pathogen Interactions and Fungal Biology, Including the Viable but Nonculturable State.

Cryptococcus neoformans is an opportunistic fungal pathogen known for its remarkable ability to infect and subvert phagocytes. This ability provides survival and persistence within the host and relies on phenotypic plasticity. The viable but nonculturable (VBNC) phenotype was recently described in C. neoformans, whose study is promising in understanding the pathophysiology of cryptococcosis. The use of fluorescent strains is improving host interaction research, but it is still underexploited. Here, we fused histone H3 or the poly(A) binding protein (Pab) to enhanced green fluorescent protein (eGFP) or mCherry, obtaining a set of C. neoformans transformants with different colors, patterns of fluorescence, and selective markers (hygromycin B resistance [Hygr] or neomycin resistance [Neor]). We validated their similarity to the parental strain in the stress response, the expression of virulence-related phenotypes, mating, virulence in Galleria mellonella, and survival within murine macrophages. PAB-GFP, the brightest transformant, was successfully applied for the analysis of phagocytosis by flow cytometry and fluorescence microscopy. Moreover, we demonstrated that an engineered fluorescent strain of C. neoformans was able to generate VBNC cells. GFP-tagged Pab1, a key regulator of the stress response, evidenced nuclear retention of Pab1 and the assembly of cytoplasmic stress granules, unveiling posttranscriptional mechanisms associated with dormant C. neoformans cells. Our results support that the PAB-GFP strain is a useful tool for research on C. neoformans. IMPORTANCE Cryptococcus neoformans is a human-pathogenic yeast that can undergo a dormant state and is responsible for over 180,000 deaths annually worldwide. We engineered a set of fluorescent transformants to aid in research on C. neoformans. A mutant with GFP-tagged Pab1 improved fluorescence-based techniques used in host interaction studies. Moreover, this mutant induced a viable but nonculturable phenotype and uncovered posttranscriptional mechanisms associated with dormant C. neoformans. The experimental use of fluorescent mutants may shed light on C. neoformans-host interactions and fungal biology, including dormant phenotypes.

Comparative genomics allowed the identification of drug targets against human fungal pathogens.

BACKGROUND: The prevalence of invasive fungal infections (IFIs) has increased steadily worldwide in the last few decades. Particularly, there has been a global rise in the number of infections among immunosuppressed people. These patients present severe clinical forms of the infections, which are commonly fatal, and they are more susceptible to opportunistic fungal infections than non-immunocompromised people. IFIs have historically been associated with high morbidity and mortality, partly because of the limitations of available antifungal therapies, including side effects, toxicities, drug interactions and antifungal resistance. Thus, the search for alternative therapies and/or the development of more specific drugs is a challenge that needs to be met. Genomics has created new ways of examining genes, which open new strategies for drug development and control of human diseases. RESULTS: In silico analyses and manual mining selected initially 57 potential drug targets, based on 55 genes experimentally confirmed as essential for Candida albicans or Aspergillus fumigatus and other 2 genes (kre2 and erg6) relevant for fungal survival within the host. Orthologs for those 57 potential targets were also identified in eight human fungal pathogens (C. albicans, A. fumigatus, Blastomyces dermatitidis, Paracoccidioides brasiliensis, Paracoccidioides lutzii, Coccidioides immitis, Cryptococcus neoformans and Histoplasma capsulatum). Of those, 10 genes were present in all pathogenic fungi analyzed and absent in the human genome. We focused on four candidates: trr1 that encodes for thioredoxin reductase, rim8 that encodes for a protein involved in the proteolytic activation of a transcriptional factor in response to alkaline pH, kre2 that encodes for α-1,2-mannosyltransferase and erg6 that encodes for Δ(24)-sterol C-methyltransferase. CONCLUSIONS: Our data show that the comparative genomics analysis of eight fungal pathogens enabled the identification of four new potential drug targets. The preferred profile for fungal targets includes proteins conserved among fungi, but absent in the human genome. These characteristics potentially minimize toxic side effects exerted by pharmacological inhibition of the cellular targets. From this first step of post-genomic analysis, we obtained information relevant to future new drug development.

In vitro antifungal activity and toxicity of itraconazole in DMSA-PLGA nanoparticles.

Itraconazole (ITZ) is a drug used to treat various fungal infections and may cause side effects. The aim of this study was to develop and evaluate the in vitro activity of DMSA-PLGA nanoparticles loaded with ITZ against Paracoccidioides brasiliensis, as well as their cytotoxicity. Nanoparticles were prepared using the emulsification-evaporation technique and characterized by their encapsulation efficiency, morphology (TEM), size (Nanosight) and charge (zeta potential). Antifungal efficacy in P. brasiliensis was determined by minimal inhibition concentration (MIC), and cytotoxicity using MTT assay. ITZ was effectively incorporated in the PLGA-DMSA nanoparticles with a loading efficiency of 72.8 +/- 3.50%. The shape was round with a solid polymeric structure, and a size distribution of 174 +/- 86 nm (Average +/- SD). The particles were negatively charged. ITZ-NANO presented antifungal inhibition (MIC = 6.25 ug/mL) against P. brasiliensis and showed lower in vitro cytotoxicity than free drug (ITZ).

Polymorphism analysis of the CTLA-4 gene in paracoccidioidomycosis patients.

The CTLA-4 protein is expressed in activated T cells and plays an essential role in the immune response through its regulatory effect on T cell activation. Polymorphisms of the CTLA-4 gene have been correlated with autoimmune, neoplastic and infectious illnesses. This work aimed to verify possible associations between single nucleotide polymorphisms (SNPs) in CTLA-4, -318C/T in the promoter and +49A/G in exon 1 and paracoccidioidomycosis (PCM) caused by Paracoccidioides brasiliensis. For this purpose, 66 chronic form PCM patients and 76 healthy controls had their allele, genotype and haplotype frequencies determined. The genetic admixture structure of the patients and controls was evaluated to eliminate ancestral bias. The comparison of frequencies indicated no significant differences between patients and controls that could link the SNPs to PCM. Groups were admixture matched with no difference observed in population ancestry inference, indicating that the absence of association between CTLA-4 polymorphisms and PCM could not be attributed to ancestral bias. This study showed that there was no association between the CTLA-4 SNPs -318 and +49 and the resistance or susceptibility to PCM.

Amphotericin B in poly(lactic-co-glycolic acid) (PLGA) and dimercaptosuccinic acid (DMSA) nanoparticles against paracoccidioidomycosis.

OBJECTIVES: The present study reports on the preparation and testing of a desoxycholate amphotericin B (D-AMB) sustained delivery system based on poly(lactic-co-glycolic acid) (PLGA) and dimercaptosuccinic acid (DMSA) polymeric blends (Nano-D-AMB) aimed at reducing the number of AMB administrations required to treat mycosis. METHODS: BALB/c mice were infected with the yeast Paracoccidioides brasiliensis intravenously to mimic the chronic form of paracoccidioidomycosis. At 30 days post-infection, the animals were treated with Nano-D-AMB [6 mg/kg of encapsulated D-AMB, intraperitoneally (ip), interval of 72 h] or D-AMB (2 mg/kg, ip, interval of 24 h). Drug efficacy was investigated by the fungal burden recovery from tissues. Toxicity was assessed by renal and hepatic biochemical parameters, physical appearance of the animals and haematological investigation. The control groups used were non-infected and the infected mice mock treated with PBS. RESULTS: Nano-D-AMB presented results comparable to free D-AMB, with a marked antifungal efficacy. The Nano-D-AMB-treated group presented lower loss of body weight and absence of stress sign (piloerection and hypotrichosis) observed after D-AMB treatment. No renal [blood urea nitrogen (BUN), creatinine] or hepatic (pyruvic and oxalacetic glutamic transaminases) biochemical abnormalities were found. The micronucleus assay showed no significant differences in both the micronucleus frequency and percentage of polychromatic erythrocytes for Nano-D-AMB, indicating the absence of genotoxicity and cytotoxic effects. CONCLUSIONS: The D-AMB-coated PLGA-DMSA nanoparticle showed antifungal efficacy, fewer undesirable effects and a favourable extended dosing interval. Nano-D-AMB comprises an AMB formulation able to lessen the number of drug administrations. Further studies would elucidate whether Nano-D-AMB would be useful to treat systemic fungal infections such as paracoccidioidomycosis, candidiasis, aspergillosis and cryptococcosis.

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

Paracoccidioidomycosis (PCM) is a systemic disease endemic to most of Latin America, with greatest impact in rural areas. The taxonomic status of one of the best studied Paracoccidioides isolates (Pb01) as P. brasiliensis remains unresolved due to its genomic differences from the other three previously described phylogenetic species (S1, PS2 and PS3; Carrero et al., 2008. Fungal Genet. Biol. 45, 605). Using the genealogic concordance method of phylogenetic species recognition (GCPSR) via maximum parsimony and Bayesian analysis, we identified a clade of 17 genotypically similar isolates, including Pb01, which are distinct from the S1/PS2/P3 clade. Consistent with GCPSR, this "Pb01-like" group can be considered a new phylogenetic species, since it is strongly supported by all independent and concatenated genealogies. "Pb01-like" species exhibit great sequence and morphological divergence from the S1/PS2/PS3 species clade, and we estimate that these groups last shared a common ancestor approximately 32 million years ago. In addition, recombination analysis revealed independent events inside both main groups suggesting reproductive isolation. Consequently, we recommend the formal description of the "Pb01-like" cluster as the new species Paracoccidioides lutzii, a tribute to Adolpho Lutz, discoverer of P. brasiliensis in 1908.

Ploidy Determination in the Pathogenic Fungus Sporothrix spp.

The pathogenic clade of the Sporothrix genus comprises the etiological agents of sporotrichosis, a worldwide emergent disease. Despite the growing understanding of their successful pathogen traits, there is little information on genome sizes and ploidy within the genus. Therefore, in this work, we evaluated the ploidy of four species of the Sporothrix genus, specifically Sporothrix brasiliensis, Sporothrix schenckii, Sporothrix globosa, and Sporothrix pallida. Through cell cycle analysis of the yeast-phase cells, we showed that the DNA content of G0/G1 cells was similar to the genome size determined by whole genome sequencing. Moreover, ploidy of S. schenckii, S. brasiliensis, and S. pallida that was determined by allele composition using next-generation sequencing (NGS) data is consistent with monomorphic positions at each allele. These data show that the analyzed strains of Sporothrix are haploid, or at least aneuploid, thereby laying the foundation for the development of a molecular toolbox for Sporothrix spp.

The stress responsive and morphologically regulated hsp90 gene from Paracoccidioides brasiliensis is essential to cell viability.

BACKGROUND: Paracoccidioides brasiliensis is a dimorphic fungus that causes the most prevalent systemic mycosis in Latin America. The response to heat shock is involved in pathogenesis, as this pathogen switches from mycelium to yeast forms in a temperature dependent fashion that is essential to establish infection. HSP90 is a molecular chaperone that helps in the folding and stabilization of selected polypeptides. HSP90 family members have been shown to present important roles in fungi, especially in the pathogenic species, as an immunodominant antigen and also as a potential antifungal therapeutic target. RESULTS: In this work, we decided to further study the Pbhsp90 gene, its expression and role in cell viability because it plays important roles in fungal physiology and pathogenesis. Thus, we have sequenced a Pbhsp90 cDNA and shown that this gene is present on the genome as a single copy. We have also confirmed its preferential expression in the yeast phase and its overexpression during dimorphic transition and oxidative stress. Treatment of the yeast with the specific HSP90 inhibitors geldanamycin and radicicol inhibited growth at 2 and 10 microM, respectively. CONCLUSION: The data confirm that the Pbhsp90 gene encodes a morphologically regulated and stress-responsive protein whose function is essential to cell viability of this pathogen. This work also enforces the potential of HSP90 as a target for antifungal therapies, since the use of HSP90 inhibitors is lethal to the P. brasiliensis yeast cells in a dose-responsive manner.

Genetic manipulation of Fonsecaea pedrosoi using particles bombardment and Agrobacterium mediated transformation.

Fonsecaea pedrosoi, a melanized fungal pathogen that causes Chromoblastomycosis, a human disease with a worldwide distribution. Biolistic is a widely used technique for direct delivery of genetic material into intact cells by particles bombardment. Another well-established transformation method is Agrobacterium-mediated transformation (ATMT), which involves the transfer of a T-DNA from the bacterium to the target cells. In F. pedrosoi there are no reports of established protocols for genetic transformation, which require optimization of physical and biological parameters. In this work, intact conidia of F. pedrosoi were particle bombarded and subjected to ATMT. In addition, we proposed hygromycin B, nourseothricin and neomycin as dominant selective markers for F. pedrosoi and vectors were constructed. We tested two parameters for biolistic: the distance of the particles to the target cells and time of cells recovery in nonselective medium. The biolistic efficiency was 37 transformants/µg of pFpHYG, and 45 transformants/µg of pAN7.1. Transformants expressing GFP were successfully obtained by biolistic. A co-culture ratio of 10: 1 (bacterium: conidia) and co-incubation time of 72 h yielded the largest number of transformants after ATMT. Southern blot analysis showed the number of foreign DNA insertion into the genome is dependent upon the plasmid used to generate the mutants. This work describes for the first time two efficient methods for genetic modification of Fonsecaea and these results open new avenues to better understand the biology and pathogenicity of the main causal agent of this neglected disease.

Early transcriptional response of Paracoccidioides brasiliensis upon internalization by murine macrophages.

Paracoccidioides brasiliensis, a thermal dimorphic fungus, is the etiologic agent of the most common systemic mycosis in Latin America, paracoccidioidomycosis. The yeast form of P. brasiliensis acts as a facultative intracellular pathogen being able to survive and replicate within the phagosome of nonactivated murine and human macrophages. This ability has been proposed to be crucial to the development of disease. Thus, P. brasiliensis may have evolved mechanisms that counteract the constraints imposed by phagocytic cells. By using cDNA microarray technology we evaluated the early transcriptional response of this fungus to the environment of peritoneal murine macrophages in order to shed light on the mechanisms used by P. brasiliensis to survive within phagocytic cells. Of the 1152 genes analyzed, we identified 152 genes that were differentially transcribed. Intracellularly expressed genes were primarily associated with glucose and amino acid limitation, cell wall construction, and oxidative stress. For the first time, a comprehensive gene expression tool is used for the expression analysis of P. brasiliensis genes when interacting with macrophages. Overall, our data show a transcriptional plasticity of P. brasiliensis in response to the harsh environment of macrophages which may lead to adaptation and consequent survival of this pathogen.

DNAhsp65 Vaccine as Therapy against Paracoccidioidomycosis.

The conventional treatment for fungal diseases usually shows long periods of therapy and the high frequency of relapses and sequels. New strategies of the treatment are necessary. We have shown that the Mycobacterium leprae HSP65 gene can be successfully used as therapy against murine Paracoccidioidomycosis (PCM). Here, we described the methodology of DNAhsp65 immunotherapy in mice infected with the dimorphic fungus Paracoccidioides brasiliensis, one of PCM agent, evaluating cytokines levels, fungal burden, and lung injury. Our results provide a new prospective on the immunotherapy of mycosis.

Cell organisation, sulphur metabolism and ion transport-related genes are differentially expressed in Paracoccidioides brasiliensis mycelium and yeast cells.

BACKGROUND: Mycelium-to-yeast transition in the human host is essential for pathogenicity by the fungus Paracoccidioides brasiliensis and both cell types are therefore critical to the establishment of paracoccidioidomycosis (PCM), a systemic mycosis endemic to Latin America. The infected population is of about 10 million individuals, 2% of whom will eventually develop the disease. Previously, transcriptome analysis of mycelium and yeast cells resulted in the assembly of 6,022 sequence groups. Gene expression analysis, using both in silico EST subtraction and cDNA microarray, revealed genes that were differential to yeast or mycelium, and we discussed those involved in sugar metabolism. To advance our understanding of molecular mechanisms of dimorphic transition, we performed an extended analysis of gene expression profiles using the methods mentioned above. RESULTS: In this work, continuous data mining revealed 66 new differentially expressed sequences that were MIPS(Munich Information Center for Protein Sequences)-categorised according to the cellular process in which they are presumably involved. Two well represented classes were chosen for further analysis: (i) control of cell organisation - cell wall, membrane and cytoskeleton, whose representatives were hex (encoding for a hexagonal peroxisome protein), bgl (encoding for a 1,3-beta-glucosidase) in mycelium cells; and ags (an alpha-1,3-glucan synthase), cda (a chitin deacetylase) and vrp (a verprolin) in yeast cells; (ii) ion metabolism and transport - two genes putatively implicated in ion transport were confirmed to be highly expressed in mycelium cells - isc and ktp, respectively an iron-sulphur cluster-like protein and a cation transporter; and a putative P-type cation pump (pct) in yeast. Also, several enzymes from the cysteine de novo biosynthesis pathway were shown to be up regulated in the yeast form, including ATP sulphurylase, APS kinase and also PAPS reductase. CONCLUSION: Taken together, these data show that several genes involved in cell organisation and ion metabolism/transport are expressed differentially along dimorphic transition. Hyper expression in yeast of the enzymes of sulphur metabolism reinforced that this metabolic pathway could be important for this process. Understanding these changes by functional analysis of such genes may lead to a better understanding of the infective process, thus providing new targets and strategies to control PCM.

Functional genome of the human pathogenic fungus Paracoccidioides brasiliensis.

Paracoccidioides brasiliensis is a dimorphic and thermo-regulated fungus which is the causative agent of paracoccidioidomycosis, an endemic disease widespread in Latin America. Pathogenicity is assumed to be a consequence of the cellular differentiation process that this fungus undergoes from mycelium to yeast cells during human infection. In an effort to elucidate the molecular mechanisms involved in this process a network of Brazilian laboratories carried out a transcriptome project for both cell types. This review focuses on the data analysis yielding a comprehensive view of the fungal metabolism and the molecular adaptations during dimorphism in P. brasiliensis from analysis of 6022 groups, related to expressed genes, which were generated from both mycelium and yeast phases.

Overview and perspectives the transcriptome of Paracoccidioides brasiliensis.

Paracoccidioides brasiliensis is a dimorphic and thermo-regulated fungus which is the causative agent of paracoccidioidomycosis, an endemic disease widespread in Latin America that affects 10 million individuals. Pathogenicity is assumed to be a consequence of the dimorphic transition from mycelium to yeast cells during human infection. This review shows the results of the P. brasiliensis transcriptome project which generated 6,022 assembled groups from mycelium and yeast phases. Computer analysis using the tools of bioinformatics revealed several aspects from the transcriptome of this pathogen such as: general and differential metabolism in mycelium and yeast cells; cell cycle, DNA replication, repair and recombination; RNA biogenesis apparatus; translation and protein fate machineries; cell wall; hydrolytic enzymes; proteases; GPI-anchored proteins; molecular chaperones; insights into drug resistance and transporters; oxidative stress response and virulence. The present analysis has provided a more comprehensive view of some specific features considered relevant for the understanding of basic and applied knowledge of P. brasiliensis.

Crinipellis brasiliensis, a new species based on morphological and molecular data.

Crinipellis perniciosa infects a diversity of hosts causing severe damage to T. cacao production in many Brazilian growing regions. We compared isolates of Crinipellis from different geographic origins and hosts in Brazil by structural analysis using light (LM) and scanning electronic microscopy (SEM), as well as RFLP and sequence data based on the nuclear rDNA ITS region. Statistical analyses of morphometric data of basidia and basidiospores revealed a distinct group of isolates of Crinipellis obtained from Heteropterys acutifolia when compared to representatives from Theobroma cacao, Solanum lycocarpum and Heteropterys nervosa. A similar distinction also was observed based on sequence data of the ITS region such that combined results allowed for the segregation of a new species within the genus Crinipellis.

Oxidative stress response in Paracoccidioides brasiliensis.

Survival of pathogenic fungi inside human hosts depends on evasion from the host immune system and adaptation to the host environment. Among different insults that Paracoccidioides brasiliensis has to handle are reactive oxygen and nitrogen species produced by the human host cells, and by its own metabolism. Knowing how the parasite deals with reactive species is important to understand how it establishes infection and survives within humans. The initiative to describe the P. brasiliensis transcriptome fostered new approaches to study oxidative stress response in this organism. By examining genes related to oxidative stress response, one can evaluate the parasite's ability to face this condition and infer about possible ways to overcome this ability. We report the results of a search of the P. brasiliensis assembled expressed sequence tag database for homologous sequences involved in oxidative stress response. We described several genes coding proteins involved in antioxidant defense, for example, catalase and superoxide dismutase isoenzymes, peroxiredoxin, cytochrome c peroxidase, glutathione synthesis enzymes, thioredoxin, and the transcription factors Yap1 and Skn7. The transcriptome analysis of P. brasiliensis reveals a pathogen that has many resources to combat reactive species. Besides characterizing the antioxidant defense system in P. brasiliensis, we also compared the ways in which different fungi respond to oxidative damage, and we identified the basic features of this response.