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Escherichia coli : host interactions in the pathogenesis of canine pyometra

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Resumo:Canine pyometra develops as a result of a complex interaction of etiological and physiopathological factors, such as the virulence and type of the bacteria and the individual host defence mechanisms. Since Escherichia coli is the most common bacterium isolated from uterus of bitches with pyometra, one main objective of this work was to characterize E. coli virulence potential, and to evaluate the role of its virulence factors (VF) and traits in the pathogenesis of canine pyometra (Chapters IV, V and VI). A second main objective was to evaluate the innate immune mechanisms within the uterus and their role in E. coli recognition (Chapters III and VI). Results indicate that: i) although no single VF genes or virulence traits were associated with E. coli pyometra isolates, these isolates were mainly from the highly virulent phylogenetic group B2, which are characterized by a high number of uropathogenic E. coli VF genes and pathogenicity-associated islands markers; ii) Toll-like receptors were involved in the activation of the inflammatory response associated with pyometra; iii) β-hemolytic E. coli infection was associated with the occurrence of metritis and with an higher uterine tissue damage; iv) α-hemolysin (HlyA) contributes to the virulence of β-hemolytic E. coli, by inducing endometrial epithelial and stromal damage and a compromised early uterine immune response. Overall, these findings provide new relevant insights into the role of the pathogen-specific modulation of host immunity, which may influence the severity of disease and its clinical outcomes. Also, HlyA is a promising target for a vaccine, with the objective to induce an immunity that can block the binding and action of this toxin.
Autores principais:Henriques, Sofia Correia Rosa de Barros
Assunto:Escherichia coli virulence traits α-hemolysin innate immunity canine pyometra perfil de virulência α-hemolysina imunidade inata piómetra de cadela
Ano:2016
País:Portugal
Tipo de documento:tese de doutoramento
Tipo de acesso:acesso aberto
Instituição associada:Universidade de Lisboa
Idioma:inglês
Origem:Repositório da Universidade de Lisboa

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