No description available.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2006. / Includes bibliographical references. Also available on the World Wide Web.

No / Using preparative electrophoresis, a low molecular weight protein has been partially purified from a cell extract of the equine pathogen Streptococcus equi susp. equi. N-terminal sequence analysis and Western blotting revealed the protein to be HPr, a central component of the phosphoenolpyruvate:sugar phosphotransferase system (PTS). Interestingly, the only form of the HPr protein detected in S. equi was one with the amino-terminal methionine removed, a modification that has previously been associated with surface localization of streptococcal HPr proteins.

No / Acid phosphatases hydrolyse phosphomonoesters at acidic pH in a variety of physiological contexts. The recently defined class C family of acid phosphatases includes the 32 kDa LppC lipoprotein of Streptococcus equisimilis. To define further the distribution of acid phosphatases in the genus Streptococcus we have examined the equine pathogens Streptococcus equi subsp. equi and Streptococcus equi subsp. zooepidemicus. Whole cell assays indicated that these organisms possess two acid phosphatases with activity optima at pH 5.0 and pH 6.0-6.5 and that only the former of these was, like LppC, resistant to EDTA. Western blotting with a polyclonal anti-LppC antiserum revealed the presence of a cross-reactive 32 kDa protein in both organisms. The cross-reactive protein in S. equi was shown to be a surface accessible lipoprotein as its processing was inhibited by the antibiotic globomycin and it was released from whole cells by treatment with trypsin. The presence of DNA sequences homologous to the S. equisimilis lppC gene were confirmed by PCR. These data strongly suggest that Streptococcus equi subsp. equi and Streptococcus equi subsp. zooepidemicus produce a lipoprotein acid phosphatase homologous to LppC of S. equisimilis.

No / Streptococcus equi is the aetiological agent of strangles, one of the most prevalent diseases of the horse. The animal suffering and economic burden associated with this disease necessitate effective treatment. Current antibiotic therapy is often ineffective and thus recent attention has focused on vaccine development. A systematic understanding of S. equi virulence, leading to the identification of targets to which protective immunity can be directed, is a prerequisite of the development of such a vaccine. Here, the virulence factors of S. equi are reviewed.

Made available in DSpace on 2014-08-20T13:32:45Z (GMT). No. of bitstreams: 1 dissertacao_liana_flores_maciel.pdf: 841596 bytes, checksum: bb4ee1890724891a9fe7618cd7fa3c77 (MD5) Previous issue date: 2012-02-28 / The business related to equines in Brazil has an important participation in activities as leisure, culture and tourism, being responsible for millions of jobs. The equine distemper caused by Streptococcus equi subsp. equi is a disease of the respiratory tract with economical impact, generating losses with treatment and reduction in the animal performance. To solve this problem, prophylactic measures, such as the vaccination, are important. However, available commercial vaccines do not offer protection to more than 50% of the vaccinated animals. Several studies are being performed aiming the achievement of an efficient vaccine against the Adenitis, where several virulence factors are being evaluated as possible vaccine antigens, specially the M protein (SeM). Thus, the present work aimed the development and evaluation of a recombinant vaccine to the control of the equine distemper composed of the SeM antigen co-administrated with the recombinant Heat-labile enterotoxin B subunit of Escherichia coli (rLTB) and/or aluminium hydroxide (Al(OH)3). A total of 72 female BALB/c mice, divided into eight groups and 18 horses, divided into six groups, were inoculated by intramuscular or intranasal routes. The results obtained in the experiments showed that the rSeM was innocuous and immunogenic in both evaluated species, stimulating the production of specific immunoglobulin anti-rSeM without the addition of immunological adjuvant. Both adjuvant rLTB and Al(OH)3 were not capable to increase the titer of immunoglobulin anti-rSeM in mice, while in horses, the treatment rSeM + rLTB (IM) showed a significant increase in the level of seric immunoglobulin IgG anti-rSeM. Interestingly, the production of anti-rSeM secretory IgA in the upper respiratory tract has a significant increase in horses treated with rSeM + Al(OH)3 (IM). This result is promising to further studies with rSeM as an antigen for vaccines, as well as is the administration of rLTB as an immunological adjuvant. / A equinocultura no Brasil ganha espaço em setores ligados ao lazer, cultura e turismo, sendo responsável por milhões de empregos. A Adenite Equina causada pelo Streptococcus equi subsp. equi é uma doença do aparelho respiratório de elevado impacto econômico, gerando gastos com mão-de-obra e perda de desempenho dos animais. Para amenizar este problema, medidas profiláticas são importantes, como por exemplo, a vacinação. Porém, as vacinas disponíveis no mercado protegem apenas 50% dos animais. Vários estudos vêm sendo realizados para obtenção de uma vacina mais eficiente contra a Adenite, onde vários fatores de virulência do patógeno estão sendo avaliados como possíveis antígenos vacinais, com destaque para a proteína M de S. equi (SeM). Com base nisso este trabalho objetivou o desenvolvimento e avaliação de uma vacina recombinante para controle da Adenite Equina, utilizando como antígeno a rSeM e como adjuvantes a subunidade B da enterotoxina termolábil de Escherichia coli (rLTB) e ou hidróxido de alumínio (Al(OH)3). Para este estudo foram utilizados 72 camundongos Balb/c fêmeas divididos em 8 grupos e 18 cavalos divididos em 6 grupos, inoculados por via IM ou IN. Os resultados mostraram que a rSeM foi inócua e imunogênica para ambas as espécies avaliadas, estimulando níveis significativos de imunoglobulinas (lgs) anti-rSeM sem a necessidade de uso de qualquer adjuvante imunológico. Os adjuvantes rLTB e Al(OH)3 não foram capazes de incrementar significativamente os títulos de lgs antirSeM em camundongos, enquanto que em cavalos o tratamento rSeM + rLTB (IM) promoveu um aumento significativo no título sérico de IgG anti-rSeM. Interessantemente, a produção de IgA secretória anti-rSeM no trato respiratório superior de cavalos teve aumento significativo no tratamento com rSeM + Al(OH)3 (IM). Estes resultados são promissores para a continuidade de estudos visando a utilização da rSeM como antígeno vacinal. Da mesma forma, o uso da rLTB como adjuvante em vacinas para cavalos parece ser promissor.

Made available in DSpace on 2014-08-20T13:32:54Z (GMT). No. of bitstreams: 1 tese_carina_moraes.pdf: 479524 bytes, checksum: 9bdbed7287bcee59185e68ac89b72108 (MD5) Previous issue date: 2008-10-13 / Strangles is a contagious disease of the upper respiratory tract of horses caused by Streptococcus equi subsp. equi. Asymptomatic carriers responsible for maintaining the infection in the herd can only be detected by serological or microbiological methods and vaccines used for the control of the disease induce levels of protection generally not exceeding 50%. Considering that S. equi SeM protein is considered the most promising antigen to protect against the disease, this research aimed to produce and evaluate as antigen for vaccines and for ELISA, a recombinant S. equi SeM protein (rSeM). rSeM was produced by cloning and expression in Escherichia coli and purified by affinity chromatography. To test its immunogenicity isogenic female Balb-c mice 4-6 weeks-old were randomly divided and inoculated with 1 / 20th of the estimated dose of the vaccine for horses by the SC route, on days 0 and 21 of the experiment. One group was vaccinated with 250mL (12 mg mL-1) of rSeM without adjuvant, another with 300mL of vaccine containing 12 mg mL-1 of rSeM plus 20% of aluminiun hydroxide, two other groups were vaccinated with two commercial bacterins against Strangles, other two groups were vaccinated with the same commercial vaccines containing 12 mg mL-1 of rSeM and the remaining group was inoculated with a bacterin produced with a field strain. The control group was inoculated the same dose of sterile saline. Blood samples were collected from the retro-orbital venous plexus on days 0, 21, 42. The antibodies were titrated by ELISA using rSeM as antigen. rSeM was immunogenic for mice with a protection index of 100%. For the standardization of an ELISA, groups of 20 negative, vaccinated and positive animals were used. Using as Cut-off the mean plus two SD of the Optical Densities of the negatives, the test showed 100% sensitivity and specificity. / A Adenite Eqüina é uma enfermidade contagiosa do trato respiratório superior dos eqüídeos causada por Streptococcus equi subesp. equi. Animais portadores assintomáticos responsáveis pela permanência da infecção nos rebanhos só podem ser detectados por métodos microbiológicos ou sorológicos e as vacinas utilizadas no controle da doença induzem níveis de proteção geralmente não superiores a 50 %. Considerando que a proteína SeM de S. equi é o antígeno mais promissor na proteção contra a doença, este trabalho objetivou produzir a proteína SeM recombinante de S. equi, visando sua utilização como antígeno em vacinas e em ELISA. Proteína SeM recombinante (rSeM) foi produzida mediante a clonagem e expressão em Escherichia coli e purificada por cromatografia de afinidade. Para testar sua capacidade imunogênica, vacinas elaboradas com rSeM foram aplicadas a camundongos. Fêmeas Balb/c isogênicas com 4-6 semanas foram divididas aleatoriamente e inoculadas por via SC com 1/20 da dose vacinal estimada para cavalos, nos dias 0 e 21 do experimento. Um grupo foi vacinado com 250 mL (12 mg mL-1) de proteína recombinante sem adjuvante, outro com 300 mL de vacina contendo 12 mg mL-1 rSeM adicionada de 20% de hidróxido de alumínio, outros dois grupos com duas bacterinas comerciais contra Adenite Eqüina; dois grupos com as vacinas comerciais, acrescidas de 12 mg mL-1 de rSeM e o grupo restante com uma bacterina contendo cepas de campo. O grupo controle foi inoculado com o mesmo volume de solução salina estéril. Coletou-se sangue por punção do plexo venoso retro-ocular nos dias 0, 21 e 42. Os anticorpos foram titulados por ELISA utilizando a proteína rSeM como antígeno. A rSeM foi imunogênica em camundongos com índices de proteção de 100%. Para a padronização de um ELISA, utilizaram-se grupos de 20 soros equinos de animais negativos, vacinados e positivos. Utilizando um ponto de corte de média das densidades ópticas dos soros negativos acrescidos de dois desvios padrão, o teste teve 100% de sensibilidade e especificidade.

Strangles is considered the main respiratory disease in horses. The etiologic agent is the bacterium Streptococcus equi subsp. equi (S. equi), responsible for approximately 30% of horse diseases worldwide notifications. The clinical signs of strangles are fever, nasal secretion and lymph node enlargement. The last one occurs due the incomplete phagocytosis of S. equi by defense cells because bacterial hyaluronic acid capsule and M protein (SeM). The epidemiology, the risk factors and the strangles control are poorly understood. The 5' end of the seM gene sequence has been used for isolate differentiation by characterization of the alleles. Therefore, this thesis aimed to study the prevalence of Streptococcus equi subsp. equi (S. equi) in healthy horses, the alleles frequency and the risk factors involved on equine adenitis. One thousand and ten nasal swabs were obtained from healthy horses from 341 farms. Twenty four horses were positive for S. equi, confirmed by PCR and DNA sequencing. The prevalence of S. equi per equine was 2.37%, and 20 farms were positive (5.86%). Risk factor analysis showed by confirming and quantifying statistically that: the number of agglomeration events that horses participate (RR: 1.6), the situation with food container shared (RR: 3.74) and the positive diagnosis for adenitis (RR: 3.20) are significant risk factors for Strangles. These results provide important epidemiological contribution to the equine industry and can give support for the disease control. In addition, the 5 'end of the gene seM was amplified by PCR and sequenced and allele characterized. It was found the same allele (SEM-61) in all the samples. These results support the hypothesis of natural selection of alleles apparently more suited to survive, persist and perpetuate in the population studied. / A adenite equina é uma doença infecto-contagiosa que acomete o trato respiratório superior, sendo uma das principais doenças respiratórias de equinos. O agente etiológico dessa enfermidade é o Streptococcus equi subespécie equi (S. equi), responsável por aproximadamente 30% das notificações em todo o mundo. Os principais sinais clínicos da adenite são febre, secreção nasal e enfartamento de linfonodos, que ocorre pela dificuldade de fagocitose do S. equi por células de defesa devido a presença da cápsula de ácido hialurônico e proteína M. O entendimento sobre a epidemiologia, a análise de fatores de risco para adenite equina e o controle dessa enfermidade ainda são limitados. Estudos moleculares demonstram diferenças na extremidade 5 da sequência do gene (seM) codificador da proteína M de S. equi. Esta região do gene já foi utilizada na diferenciação de isolados por meio da caracterização de diferentes alelos. Por tudo isso, essa tese objetivou obter resultados de prevalência, e também análise de fatores de risco para adenite equina através de um desenho experimental para coleta de suabes nasais. Foram obtidos 1.010 suabes nasais de equinos sadios em 341 fazendas, de onde foram identificados 24 equinos positivos para S. equi em isolamento, que posteriormente foram confirmados por PCR e sequenciamento de DNA. A prevalência estimada por equino foi de 2.37%, e 20 fazendas foram consideradas positivas (5.86%). Na análise de fatores de risco, foi comprovado e quantificado estatisticamente que: número de eventos de aglomeração que os equinos participam (RR:1.06), o ato de compartilhar recipiente de alimento (RR:3.74) e ter tido diagnóstico positivo para adenite (RR:3.20) são fatores de risco relevantes para adenite equina. Estes resultados oferecem contribuições epidemiológicas importantes para a indústria de equinos e pode apoiar o controle da doença. Em paralelo, a região 5 terminal do gene seM das 24 amostras positivas foi amplificada por PCR e sequenciada para caracterização de alelos, sendo identificado o mesmo alelo (seM-61) em todas as amostras. Esses resultados evidenciam a hipótese de seleção natural de alelos aparentemente mais adaptados a sobreviver, persistir e se perpetuar na população estudada.

Cette thèse examine les décisions financières à travers la théorie des options Américaines et Exotiques. Dans un premier temps, nous avons présenté une revue de la littérature sur les options de type Américain. La tarification de l’option Américaine standard d’achat est revisitée en vue de fournir les pré-requis. Dans l’étape suivante, un nouveau type de contrat d’option, appelé Strangle Euro-American ou Strangle Hybride, a été introduit. Des formules analytiques ont été fournies pour leurs prix ainsi que leurs paramètres de gestion. Une nouvelle méthode est proposée pour calculer les intégrales qui définissent les bornes d’exercice anticipé. Il a été démontré que cette méthode est efficiente, précise et rapide pour la tarification de tous les types de Strangle voir au delà. Puis, nous avons examiné les options Step de type Américain. Nous avons démontré que les propriétés des options d’achat "vanille" ne s’appliquent pas aux Step dans certaines situations. Les formules d’évaluation et des paramètres de gestion ont été déterminés. Et enfin, nous avons considéré l’évaluation d’une firme détenant simultanément une option d’abandon et une option d’expansion de ses activités selon des conditions du marché (favorables ou défavorables). Les seuils critiques de décision ont été obtenus. Des formules analytiques pour la valeur de la firme ont été obtenues. Des simulations illustrent le comportement de ces seuils critiques de décisions anticipées. / This thesis investigates the financial decisions through the theory of American and Exotic options. First, the literature on American-style derivatives is surveyed. The pricing of standard American call option in the early exercise premium representation is addressed in order to provide prerequisites for what follows. Second, a new variant of Strangle contracts, called Euro-American or Hybrid Strangles, is introduced and priced. Analytical formulas are provided for the prices of all these option contracts as well as their hedging parameters. A new quadrature is proposed to account for the systems of coupled integral equations that locate the early exercise boundaries. It is shown to be efficient, accurate, and fast for pricing all types of early exercisable strangles and more. Third, we examines the valuation of American Step options contract. The structures of the immediate exercise regions of the various contracts are identified. Typical properties of American vanilla calls are shown to fail in some cases. Formulas for prices and hedging parameters, for the American Step options, are derived. Finally, we consider the valuation of a firm holding simultaneously an option to expand and to abandon productions depending on the state of the market (good or bad) in a real option framework. Optimal decision levels are obtained. Analytical formulas for the firm’s value are provided. Numerical results document the behavior of the firm’s value and optimal exercise boundaries levels.