Expressão gênica das adesinas e fatores de virulência da fase miceliar e leveduriforme do complexo paracoccidioides e de sua interação com células epiteliais e fagócitos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Impacto do aumento da concentração de CO2 atmosférico sobre o período latente e o controle biológico da ferrugem do cafeeiro

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação quantitativa de riscos microbiológicos (AQRM) associados à E. coli em águas cinza

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Carvão (Sporisorium scitamineum) e podridão-abacaxi (Ceratocystis paradoxa) em cana-de-açúcar (Saccharum spp.): uma revisão

Sugarcane (Saccharum sp.) is an important grass cultivated in tropical and subtropical regions of the world, such as in Br, Ind, and Ch, and has its biomass being raw material for production of sugar, fuel ethanol, and some other derivatives. Fungal diseases infect sugarcane fields worldwide, damaging crops and thus, causing great economic losses. Fungal specialized structures act during all Pathogen-Host Relationship Cycle (PHRC) (survival, dissemination, infection, colonization, and reproduction of pathogen), maintaining fungal populations in cultivation soil, infecting plants in following crops and vegetative propagation of sugarcane by infected seeds may allow fungal transportation into regions where diseases haven’t occured before. Biotechnological methods and approaches have significantly contributed to understanding of the relationship among parasite and host, as to diseases management (control, detection, and prevention). Some techniques have daily applications in Agriculture, while others are only used in research and to breeding of host resistant varieties. Among notable diseases, smut (Sporisorium scitamineum) and pineapple disease (Ceratocystis paradoxa) are important because they cause damage and losses in sugarcane regions, although there are different periods for each one to occur. This work aims to review the PHRC for each patosystem, the biotechnological methods and approaches and its perspectives in the study and management of these diseases. As environment is an important factor to the effectiveness of PHRC, one chapter is dedicated to Global Climate Change (GCC) and its possible influences over these diseases in a longterm period

Alterations of protein expression in conditions of copper-deprivation for Paracoccidioides lutzii in the presence of extracellular matrix components

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

Pathogenesis II: Fungal responses to host responses: interaction of host cells with fungi

Most of our knowledge concerning the virulence determinants of pathogenic fungi comes from the infected host, mainly from animal models and more recently from in vitro studies with cell cultures. The fungi usually present intra- and/or extracellular host-parasite interfaces, with the parasitism phenomenon dependent on complementary surface molecules. Among living organisms, this has been characterized as a cohabitation event, where the fungus is able to recognize specific host tissues acting as an attractant, creating stable conditions for its survival. Several fungi pathogenic for humans and animals have evolved special strategies to deliver elements to their cellular targets that may be relevant to their pathogenicity. Most of these pathogens express surface factors that mediate binding to host cells either directly or indirectly, in the latter case binding to host adhesion components such as extracellular matrix (ECM) proteins, which act as 'interlinking' molecules. The entry of the pathogen into the host cell is initiated by fungal adherence to the cell surface, which generates an uptake signal that may induce its cytoplasmic internalization. Once this is accomplished, some fungi are able to alter the host cytoskeletal architecture, as manifested by a rearrangement of microtubule and microfilament proteins, and this can also induce epithelial host cells to become apoptotic. It is possible that fungal pathogens induce modulation of different host cell pathways in order to evade host defences and to foster their own proliferation. For a number of pathogens, the ability to bind ECM glycoproteins, the capability of internalization and the induction of apoptosis are considered important factors in virulence. Furthermore, specific recognition between fungal parasites and their host cell targets may be mediated by the interaction of carbohydrate-binding proteins, e.g., lectins on the surface of one type of cell, probably a parasite, that combine with complementary sugars on the surface of host-cell. These interactions supply precise models to study putative adhesins and receptor-containing molecules in the context of the fungus-host interface. The recognition of the host molecules by fungi such as Aspergillus fumigatus, Paracoccidioides brasiliensis and Histoplasma capsulatum, and their molecular mechanisms of adhesion and invasion, are reviewed in this paper.

Interaction of pathogenic fungi with host cells: Molecular and cellular approaches

This review provides an overview of several molecular and cellular approaches that are likely to supply insights into the host-fungus interaction. Fungi present intra- and/or extracellular host-parasite interfaces, the parasitism phenomenon being dependent on complementary surface molecules. The entry of the pathogen into the host cell is initiated by the fungus adhering to the cell surface, which generates an uptake signal that may induce its cytoplasmatic internalization. Furthermore, microbial pathogens use a variety of their surface molecules to bind to host extracellular matrix (ECM) components to establish an effective infection. on the other hand, integrins mediate the tight adhesion of cells to the ECM at sites referred to as focal adhesions and also play a role in cell signaling. The phosphorylation process is an important mechanism of cell signaling and regulation; it has been implicated recently in defense strategies against a variety of pathogens that alter host-signaling pathways in order to facilitate their invasion and survival within host cells. The study of signal transduction pathways in virulent fungi is especially important in view of their putative role in the regulation of pathogenicity. This review discusses fungal adherence, changes in cytoskeletal organization and signal transduction in relation to host-fungus interaction. (c) 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.

Interaction between breeding habitat and elevation affects prevalence but not infection intensity of Batrachochytrium dendrobatidis in Brazilian anuran assemblages

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Interactions of Paracoccidioides brasiliensis with host cells: recent advances

Host-fungal interactions are inherently complex and dynamic. In order to identify new microbial targets and develop more effective anti-fungal therapies, it is important to understand the cellular and molecular mechanisms of disease. Paracoccidioidomycosis provokes a variety of clinical symptoms, and Paracoccidioides brasiliensis can reach many tissues, but primarily attacks the lungs. The ability of the pathogen to interact with the host surface structures is essential to further colonization, invasion, and growth. Epithelial cells may represent the first host barrier or the preferential site of entry of the fungus. For this reason, interactions between P. brasiliensis and Vero/A549 epithelial cells were evaluated, with an emphasis on the adherence, induction of cytoskeletal alterations, and differential signaling activity of the various surface molecules. The adhesion to and invasion of epithelial cells by P. brasiliensis may represent strategies employed to thwart the initial host immune response, and may help in the subsequent dissemination of the pathogen throughout the body.

Surface-expressed enolase contributes to the adhesion of Paracoccidioides brasiliensis to host cells

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Toxoplasma gondii: host-parasite interaction and behavior manipulation

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

Nicotiana tabacum as an experimental host for the study of plant-Xylella fastidiosa interactions

Xylella fastidiosa causes citrus variegated chlorosis (CVC). Information generated from the X. fastidiosa genome project is being used to study the underlying mechanisms responsible for pathogenicity. However, the lack of an experimental host other than citrus to study plant-X. fastidiosa interaction has been an obstacle to accelerated progress in this area. We present here results of three experiments that demonstrated that tobacco could be an important experimental host for X. fastidiosa. All tobacco plants inoculated with a citrus strain of X. fastidiosa expressed unequivocal symptoms, consisting of orange leaf lesions, approximately 2 months after injection of the pathogen. CVC symptoms were observed in citrus 3 to 6 months after inoculation. The pathogen was readily detected in symptomatic tobacco plants by polymerase chain reaction (PCR) and phase contrast microscopy. In addition, X. fastidiosa was reisolated on agar plates in 4 of 10 plants. Scanning electron microscopy analysis of cross sections of stems and petioles revealed the presence of rod shaped bacteria restricted to the xylem of inoculated plants. The cell size was within the limit typical of X. fastidiosa.

On Hepatitis C Virus Evolution: The Interaction between Virus and Host towards Treatment Outcome

Background:Hepatitis C is a disease spread throughout the world. Hepatitis C virus (HCV), the etiological agent of this disease, is a single-stranded positive RNA virus. Its genome encodes a single precursor protein that yields ten proteins after processing. NS5A, one of the non-structural viral proteins, is most associated with interferon-based therapy response, the approved treatment for hepatitis C in Brazil. HCV has a high mutation rate and therefore high variability, which may be important for evading the immune system and response to therapy. The aim of this study was to analyze the evolution of NS5A quasispecies before, during, and after treatment in patients infected with HCV genotype 3a who presented different therapy responses.Methods:Viral RNA was extracted, cDNA was synthesized, the NS5A region was amplified and cloned, and 15 clones from each time-point were sequenced. The sequences were analyzed for evolutionary history, genetic diversity and selection.Results:This analysis shows that the viral population that persists after treatment for most non-responder patients is present in before-treatment samples, suggesting it is adapted to evade treatment. In contrast, the population found in before treatment samples from most end-of-treatment responder patients either are selected out or appears in low frequency after relapse, therefore changing the population structure. The exceptions illustrate the uniqueness of the evolutionary process, and therefore the treatment resistance process, in each patient.Conclusion:Although evolutionary behavior throughout treatment showed that each patient presented different population dynamics unrelated to therapy outcome, it seems that the viral population from non-responders that resists the treatment already had strains that could evade therapy before it started. © 2013 Bittar et al.

Partitioning the net effect of host diversity on an emerging amphibian pathogen

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Role of cyclooxygenase-2 in Trypanosoma cruzi survival in the early stages of parasite host-cell interaction

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)