A series of presumed or confirmed Cryptococcus gattii cases diagnosed between 1999 and 2003 was compiled through review of records from veterinary laboratories and human diagnostic services. There was a continual increase in the annual number of animal, but not human, cases diagnosed; no seasonality was observed. Animal cases exceeded human cases by almost 75% even though it was hypothesized that animal cases are more likely to go undiagnosed or unreported when compared to humans. Animal cryptococcosis cases were identified on Vancouver Island prior to 1999 suggesting the organism may have emerged in the region prior to its identification as a causative agent for human disease; therefore animals may serve as a good sentinel for human cryptococcosis infection. <p> There were 50% more feline than canine cases and disease appeared more commonly in middle aged cats and younger dogs. There was no sex predilection for either species. The primary system involved was most commonly respiratory, followed by central nervous system (CNS) in both cats and dogs. There was a higher proportion of CNS disease in dogs relative to cats, and cats were much more likely to have subcutaneous or dermal masses relative to dogs. Multivariate survival analysis identified only the presence of neurological symptoms as a statistically significant predictor of mortality; those animals exhibiting CNS symptoms were over four times more likely to die than those never showing neural signs. A case-control study identified host and environmental risk factors for clinical C. gattii infection in dogs and cats suggesting that where an infectious agent is not uniformly distributed, individual risk increases when the organism is re-distributed through large scale environmental disturbance, or when the animal has increased opportunities for exposure through travel or activity level. <p> Serum samples and material for fungal culture were collected from dogs, cats, horses and terrestrial mammal species residing within the region where clinical cases had been diagnosed. Nasal colonization was identified in squirrels (<i> Sciurus carolinensis</i>), horses, dogs and cats. Most of the animals sampled had no signs of systemic infection however asymptomatic infection, defined as the presence of cryptococcal antigen in the bloodstream in the absence of clinical symptoms, was identified in a small number of dogs and cats. Fourteen months of follow-up testing of asymptomatic animals revealed that animals can progress to clinical disease, remain sub-clinically infected, or clear the organism.

A series of presumed or confirmed Cryptococcus gattii cases diagnosed between 1999 and 2003 was compiled through review of records from veterinary laboratories and human diagnostic services. There was a continual increase in the annual number of animal, but not human, cases diagnosed; no seasonality was observed. Animal cases exceeded human cases by almost 75% even though it was hypothesized that animal cases are more likely to go undiagnosed or unreported when compared to humans. Animal cryptococcosis cases were identified on Vancouver Island prior to 1999 suggesting the organism may have emerged in the region prior to its identification as a causative agent for human disease; therefore animals may serve as a good sentinel for human cryptococcosis infection. <p> There were 50% more feline than canine cases and disease appeared more commonly in middle aged cats and younger dogs. There was no sex predilection for either species. The primary system involved was most commonly respiratory, followed by central nervous system (CNS) in both cats and dogs. There was a higher proportion of CNS disease in dogs relative to cats, and cats were much more likely to have subcutaneous or dermal masses relative to dogs. Multivariate survival analysis identified only the presence of neurological symptoms as a statistically significant predictor of mortality; those animals exhibiting CNS symptoms were over four times more likely to die than those never showing neural signs. A case-control study identified host and environmental risk factors for clinical C. gattii infection in dogs and cats suggesting that where an infectious agent is not uniformly distributed, individual risk increases when the organism is re-distributed through large scale environmental disturbance, or when the animal has increased opportunities for exposure through travel or activity level. <p> Serum samples and material for fungal culture were collected from dogs, cats, horses and terrestrial mammal species residing within the region where clinical cases had been diagnosed. Nasal colonization was identified in squirrels (<i> Sciurus carolinensis</i>), horses, dogs and cats. Most of the animals sampled had no signs of systemic infection however asymptomatic infection, defined as the presence of cryptococcal antigen in the bloodstream in the absence of clinical symptoms, was identified in a small number of dogs and cats. Fourteen months of follow-up testing of asymptomatic animals revealed that animals can progress to clinical disease, remain sub-clinically infected, or clear the organism.

Three yeast antagonists (two strains of Cryptococcus laurentii and one of Candida sake) from orange trees reduced incidence of green mold by 80 to 95% when tested in wounded orange fruits inoculated with Penicillium digitatum and incubated at 7ºC for 30 days. The yeasts inhibited conidial germination of the pathogen, but did not kill the spores. Effectiveness of the three yeasts as antagonists was associated in part with their ability to rapidly colonize wound sites, despite low nutrient availability. Observations suggested that production of extracellular matrix by the yeasts may have facilitated rapid wound colonization. Germination of P. digitatum conidia was significantly inhibited when the pathogen and antagonists were in direct physical contact in a culture suspension. The results supported the view that competition for nutrients is also a mode of action of yeasts against P. digitatum.

No description available.

Inteins are autocatalytic protein domains that splice out of the nascent polypeptide shortly after translation, requiring no co-factors to facilitate splicing. There is an intein coding sequence within the Prp8 gene of Cryptococcus neoformans, a human pathogen that causes cryptococcosis in immunocompromised people. The intein, Cne PRP8, is a drug target as Prp8 is a central component of the spliceosome and thus believed to be essential to the fungus. Improved knowledge of the intein and its requirements for splicing can contribute to design of a screening system and the search for an inhibitor of intein splicing. Purification of Cne PRP8 for crystallisation was performed using either an N- or a C-terminal His�Tag�, where the N-terminal His�Tag� was removed by 3C protease prior to crystallisation trials. C-terminally His�Tagged� Cne PRP8 formed the largest crystals. The crystals were triangular plates with stepped faces. A 2.8 Å data set was collected with an R[merge] of 0.151 and a mosaicity of 2.1�. A smaller crystal gave a 3.6 Å data set with an R[merge] of 0.085 and a mosaicity of 1.5�. Molecular replacement was not sufficient to solve the structure, likely because the data were weak and the molecules in the asymmetric unit too numerous. Purified Cne PRP8 was additionally shown by circular dichroism to lack regular secondary structure, suggesting that regions of Cne PRP8 could be natively unstructured. Cne PRP8 was expressed as a fusion protein between Haemophilus influenzae trigger factor (HiTF) and a chitin binding domain (CBD). Antibodies to the different parts of the fusion protein facilitated the observation of splicing ability by western blotting. From this it was determined that Cne PRP8 is capable of splicing in a foreign protein context. Context is important, with maximum splicing occurring when Cne PRP8 has two native N-terminal extein residues and one native C-terminal extein residue. The first residue and the last two residues of Cne PRP8 are essential for splicing; additionally the conserved threonine (T62) and histidine (H65) were shown to be catalytically important. Also required for splicing are arginine 154, tyrosine 162, and aspartate 166. Leucine 161 undergoes ~50% splicing when mutated to alanine, and tryptophan 151 undergoes limited C-terminal cleavage, but no splicing, when mutated to alanine. Tryptophan 151 was identified as a potentially crucial residue, which may function to prevent C-terminal cleavage before the N-terminal rearrangements have taken place. Overall it appears that Cne PRP8 residues that are more diverged from the general intein consensus are less essential for splicing. Wild type Cne PRP8 is insensitive to zinc inhibition in vivo. It is also unresponsive to cadmium, calcium, cobalt, lithium, magnesium, manganese and nickel. However, a partially splicing-deficient mutant exhibited further inhibition in response to zinc and cadmium. This mutant also showed a limited increase in splicing efficiency in response to temperatures lower than 37�C. This study has identified critical residues, in addition to those at the splice junctions necessary for catalysis, which participate in splicing intermediates.

A criptococose acomete pacientes imunocomprometidos, principalmente pacientes com a resposta imune mediada por células T debilitada, sendo portanto, suscetíveis a patógenos oportunistas. C. neoformans possui um repertório de fatores de virulência que permitem o estabelecimento da infecção e sua disseminação para o sistema nervoso central, causando meningoencefalite. O tratamento da criptococose é baseado apenas na utilização prolongada de antifúngicos e provoca muitos efeitos colaterais nos pacientes. Por estes motivos, novas terapias estão sendo abordadas, com o intuito de promover a ativação do sistema imune do hospedeiro para debelar a infecção. Para que tais terapias possam ser desenvolvidas se faz necessário identificar moléculas que estimulem a resposta imune celular. Proteínas de choque térmico de patógenos têm sido utilizadas como alvo no tratamento de muitas doenças infecciosas em seres humanos. Estas proteínas estimulam a resposta imune mediada por células T e apresentam resultados promissores em tratamentos contra infecções fúngicas. Da mesma forma, proteínas que fazem parte do sistema de defesa antioxidante, como as catalases, por exemplo, desempenham um papel importante no combate a radicais livres produzidos pelo hospedeiro e parecem ter outras funções no processo da infecção. O entendimento da biologia destas proteínas bem como a sua participação na interação com células do sistema imune do hospedeiro é fundamental para a validação da sua aplicabilidade no tratamento da criptococose. Nesse contexto, apresentamos aqui um estudo das funções biológicas de uma das proteínas de choque térmico (Hsp70) e de uma das enzimas envolvidas na detoxificação de espécies reativas de oxigênio (catalase 2) do fungo C. neoformans. Também foram avaliados os efeitos terapêuticos destas proteínas no tratamento da criptococose. Demonstramos que a proteína Hsp70 de C. neoformans está localizada na cápsula polissacarídica, sendo importante no processo de adesão da levedura a células epiteliais A549. Demonstramos também que Cn_rHsp70 co-localiza com o principal componente da cápsula polissacarídica a glucuronoxilomanana (GXM) na superfície de macrófagos. A Cn_rHsp70 quando em contato com células do fungo, diminui sua viabilidade celular e não altera o tamanho da cápsula, mas interfere na secreção de GXM. Em relação à catalase 2, foi demonstrado que a proteína é localizada na parede celular do fungo e possui atividade de degradação de peróxido de hidrogênio quando associada à superfície celular. Em ensaios de infecção experimental em animais imunizados com construções de DNA contendo as sequências de Hsp70 e catalase 2, nenhuma das proteínas conferiu proteção, mas ocorreu estímulo da resposta mediada por células Th1 e Th2. O mecanismo pelo qual estas proteínas estimulam o sistema imune ainda precisa ser elucidado. / Cryptococcus neoformans affects immunocompromised patients, especially patients with impaired T cell-mediated immune response, and therefore are susceptible to opportunistic pathogens. C. neoformans has a repertoire of virulence factors that allows the establishment and dissemination of the infection in the central nervous system, causing meningoencephalitis. The virulence factors of Cryptococcus has been subject of many studies that have showed the involvement of gene products in the infection process. However, the treatment of cryptococcal meningoencephalitis consists of antifungal therapy and displays many side effects. For these reasons, new therapies are being addressed, in order to promote the activation of the host immune system to overcome the infection. To develop these therapies, it is necessary to identify molecules that stimulate cell-mediated immune response. Heat shock proteins from many pathogens have been used as a target for the treatment of many humans infectious diseases. These proteins stimulate the T cell-mediated immune response and show promising results in treatment against fungal infections. Similarly, proteins from antioxidant system such as catalase for example, play an important role against free radicals produced by the host and appear to have other functions in the infection process. The understanding of these proteins biology and their involvement with host immune system cells is essential for the validation of its applicability in the treatment of cryptococcosis. In this context, we present here a study of the biological function of a heat shock protein (Hsp70) and one of the enzymes involved in detoxification of reactive oxygen species (catalase 2) of the fungus C. neoformans. We evaluated the therapeutic effects of these proteins in the treatment of cryptococcosis. We have demonstrated that the protein Hsp70 from C. neoformans is located in the polysaccharide capsule, and it is important in the adhesion process of the yeast to epithelial cells A549. Also demonstrated that Cn_rHsp70 co-localizes with the main component of the polysaccharide capsule, glucuronoxilomanana (GXM), on the surface of macrophages. When Cn_rHsp70 are in contact with fungal cells, the cellular viability decreased and does not change the capsule size however, interferes with the GXM secretion. Catalase 2 is deposited on the fungal cell wall and showed activity by hydrogen peroxide degradation. In vivo experiments using animals infected and treated with Hsp70 DNA vaccines and catalase 2, no protection were observed, but there are immune response mediated by Th1 and Th2 cells. The mechanism by which these proteins stimulate the immune system has yet to be elucidated.

Cryptococcus neoformans é uma levedura basidiomicética e patógeno humano oportunista, que causa infecção tanto em indivíduos imunocomprometidos quanto em imunocompetentes. A habilidade de sobrevivência e proliferação na temperatura do corpo humano é um fator de virulência essencial deste microrganismo. Análise da Diferença Representacional (RDA) foi aplicada com o intuito de delinear o perfil de expressão gênica durante desenvolvimento de C. neoformans a 37ºC ou 25ºC. Análises de 300 seqüências de cDNA permitiram a identificação de proteínas que podem ser críticas para processos de interação patógeno-hospedeiro. Produtos gênicos envolvidos em integridade da parede celular, resposta ao estresse, filamentação e metabolismo oxidativo são induzidos a 37ºC. Genes relacionados à silenciamento de cromatina e transporte de fosfolipídios possuem maior expressão em cultivo de C. neoformans a 25ºC. A metodologia de RDA mostrou-se viável no intuito de identificar genes regulados pela temperatura neste organismo, os quais podem representar alvos potenciais para estudos de inibição do desenvolvimento de C. neoformans no hospedeiro.

Orientador: Maria José Soares Mendes Giannini / Banca: Márcia de Souza Carvalho Melhem / Banca: Maysa Furlan / Resumo: Cryptococcus neoformans é o patógeno fúngico mais comumente encontrado em infecções do sistema nervoso central, que desperta interesse devido a sua associação com os pacientes imunocomprometidos, em especial aqueles com AIDS. Embora haja ainda pouco relatados, isolados resistentes têm emergido nos últimos anos, e a disponibilidade de um método de sensibilidade rápido e reprodutível pode contribuir para a escolha do tratamento adequado. Os antifúngicos sintéticos possuem elevada toxicidade e sua disponibilidade na prática médica é relativamente pequena, algumas vezes ineficiente, o que reforça a demanda por novas alternativas terapêuticas. A busca por novos agentes antifúngicos a partir de plantas pode viabilizar o tratamento das principais micoses, diminuindo as reações adversas. Neste âmbito, pretendeuse padronizar a citometria de fluxo para a determinação da sensibilidade de anfotericina B e de substâncias de fontes naturais, comparando-as com o micrométodo. A citometria de fluxo foi utilizada no presente estudo para testar a sensibilidade de C. neoformans baseada na ligação de iodeto de propídeo na célula fúngica. Para tanto, isolados clínicos foram selecionados para análise da sensibilidade em citometria de fluxo depois de realizada a tipagem molecular de 151 isolados de Cryptococcus spp. das regiões de São José do Rio Preto e Rio de Janeiro por RFLP do gene URA5, em que a prevalência segue igual ao quadro mundial, em que o tipo molecular VNI é o mais prevalente, bem como verificou-se que a infecção por uma nova cepa e/ou diferentes espécies pode ocorrer com relativa freqüência. Foram ainda testados 57 extratos brutos, 52 frações e 53 substâncias puras isoladas de plantas do Cerrado e Mata Atlântica contra a cepa ATCC 90012 de C. neoformans... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Cryptococcus neoformans is a fungal pathogen most commonly found in infections of the central nervous system that arouses interest because of its association with immunocompromised patients, especially those with AIDS. Although have not been much reported, resistant isolates have emerged in recent years, and the availability of a method for rapid and reproducible susceptibility may contribute to the choice of treatment. The synthetic antifungal agents have high toxicity and its availability in medical practice is relatively small, sometimes inefficient, which reinforces the demand for new therapies. The search for new antifungal agents from natural products may facilitate the treatment of major fungal infections, reducing adverse reactions. In this context, we intended to standardize the flow cytometry to determine the susceptibility of amphotericin B and natural sources substances against C. neoformans, based on binding of propidium iodide (PI) in the fungal cell. For this, clinical isolates were selected for susceptibility analysis in flow cytometry after molecular typing of 151 Cryptococcus spp isolates from São José do Rio Preto and Rio de Janeiro by RFLP of the URA5 gene. The molecular type VNI is the most prevalent, as well as verified that infection by a new strain and / or different species can occur with relative frequency. We also tested 57 crude extracts, 52 fractions and 53 pure compounds isolated from plants of the Cerrado and the Atlantic forest against the C. neoformans ATCC 90012 strain. The pure substances sorbifolin, nitensoside B and isoquercitrin, from the plant Pterogyne nitens, presented MIC of 7.8μg/ml against C. neoformans, These data were confirmed by flow cytometry, after standardizing the method for amphotericin B, whose endpoint was 50% of the PI intensity, corresponding to the... (Complete abstract click electronic access below) / Mestre

Cryptococcus neoformans é uma levedura basidiomicética e patógeno humano oportunista, que causa infecção tanto em indivíduos imunocomprometidos quanto em imunocompetentes. A habilidade de sobrevivência e proliferação na temperatura do corpo humano é um fator de virulência essencial deste microrganismo. Análise da Diferença Representacional (RDA) foi aplicada com o intuito de delinear o perfil de expressão gênica durante desenvolvimento de C. neoformans a 37ºC ou 25ºC. Análises de 300 seqüências de cDNA permitiram a identificação de proteínas que podem ser críticas para processos de interação patógeno-hospedeiro. Produtos gênicos envolvidos em integridade da parede celular, resposta ao estresse, filamentação e metabolismo oxidativo são induzidos a 37ºC. Genes relacionados à silenciamento de cromatina e transporte de fosfolipídios possuem maior expressão em cultivo de C. neoformans a 25ºC. A metodologia de RDA mostrou-se viável no intuito de identificar genes regulados pela temperatura neste organismo, os quais podem representar alvos potenciais para estudos de inibição do desenvolvimento de C. neoformans no hospedeiro.

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