Análise do potencial de virulência de amostras de Escherichia coli do sorotipo O51:H40
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Data
2009
Autores
Moreira, Fabiana Campiteli [UNIFESP]
Orientadores
Gomes, Tania Aparecida Tardelli [UNIFESP]
Tipo
Tese de doutorado
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Escherichia coli enteropatogênica (EPEC) constitui um importante patotipo de E. coli envolvido com doença diarréica. EPEC é dividida em dois sub-grupos, EPEC típica (tEPEC), portadora do plasmídio EAF (EPEC adherence factor), e EPEC atípica (aEPEC), desprovida desse plasmídio. EPEC produz lesão attaching-effacing (A/E) em células intestinais, determinada por genes contidos no locus of enterocyte effacement (LEE). LEE codifica um sistema de secreção tipo 3 (SST3), a adesina de membrana externa Intimina e várias proteínas efetoras que incluem Tir (receptor translocado de intimina). Entre as amostras de aEPEC isoladas em nosso meio, aquelas pertencentes ao sorotipo O51:H40 têm sido as mais frequentes. Em estudo anterior, analisamos 11 amostras de E. coli do sorotipo O51:H40 que apresentavam a região LEE aparentemente completa, 70 por cento das quais foram capazes de produzir a lesão A/E, conforme indicado pela positividade em um teste in vitro, que avalia o acúmulo de actina decorrente da lesão A/E. Para ampliar o conhecimento do potencial enteropatogênico dessas amostras, neste estudo, foram investigadas diversas propriedades genotípicas e fenotípicas, bem como o comportamento in vivo de amostras selecionadas em coelho e em rato. Foram pesquisados genes recém descritos em E. coli (lpfA1, cifA, ldaG, espJ, toxB, espM e espT) e a ocorrência de fosforilação de resíduos de tirosina na molécula Tir, em cultivos de células HeLa e células intestinais diferenciadas T84. Os resultados obtidos confirmam que o sorotipo O51:H40 contém amostras com potencial enteropatogênico, uma vez que 75 por cento das amostras testadas produziram lesão A/E em alça ileal de coelhos in vivo. Além disto, a aEPEC 1711-4, como a tEPEC E2348/69, apresentou capacidade significativa de translocar a mucosa intestinal em ensaios de translocação bacteriana (TB) em ratos, sendo que a aEPEC 1711-4 provocou também danos à perfusão tecidual. A ausência de translocação observada com mutante defectivo na montagem do SST3 (1711-4:escN- ) sugeriu que proteínas efetoras secretadas são importantes para a ocorrência do fenômeno. Em conclusão, o sorotipo O51:H40 de E. coli compreende amostras potencialmente enteropatogênicas, a maioria das quais deve ser classificada como aEPEC; o sobrecrescimento de pelo menos uma amostra de aEPEC, em intestino de rato, pode levar à translocação e a danos à microcirculação sistêmica..
Enteropathogenic Escherichia coli (EPEC) is an important pathotype of E. coli involved in diarrheal disease. EPEC is divided into two groups, typical EPEC (tEPEC), carrier of plasmid EAF (EPEC adherence factor), and atypical EPEC (aEPEC), devoid of the plasmid. EPEC produces injury attachingeffacing (A/E) in intestinal cells, determined by genes in the locus of enterocyte effacement (LEE). LEE encodes a type 3 secretion system (SST3), the outer membrane adhesin of Intimin and several effector proteins including Tir (translocated receptor for intimin). Among aEPEC strains of isolated in our midst, those belonging to serotype O51: H40 have been the most frequent. In a previous study, we analyzed 11 strains of E. coli of serotype O51: H40 that had an apparently LEE region complete, 70% of which were of them was able to produce the lesion A/E, as indicated by a positive in vitro assay, which assesses the accumulation of actin due to the injury A/E. To increase the knowledge of the enteropathogenic potential of these strains in this study, we investigated several genotypic and phenotypic properties and the behavior of strains selected in vivo in rabbit and rat. We studied genes recently described in E. coli (lpfA1, cifA, ldaG, espJ, toxB, espM and espT) and the occurrence of residues of tyrosine phosphorylation in Tir molecule in cultures of HeLa cells and T84 intestinal cells differentiated. The results confirm that serotype O51: H40 includes strains with enteropathogenic potential, since 75% of the strains tested produced lesion A/E in the rabbit ileal loop in vivo. Moreover, the aEPEC 1711-4/89, as tEPEC E2348/69, showed significant ability translocation of the intestinal mucosa in bacterial translocation (BT) assays in rats, and the aEPEC 1711-4/89 also caused damage to tissue perfusion. The lack of translocation observed with mutant defect in the assembly of SST3 (1711-4: escN- ) suggested that secreted effector proteins are important for the occurrence of the phenomenon. In conclusion, serotype O51:H40 of E. coli includes potentially enteropathogenic strain, most of which should be classified as aEPEC; the overgrowth of at least one strain of aEPEC in intestine of rats, can lead to damage to the translocation and systemic microcirculation.
Enteropathogenic Escherichia coli (EPEC) is an important pathotype of E. coli involved in diarrheal disease. EPEC is divided into two groups, typical EPEC (tEPEC), carrier of plasmid EAF (EPEC adherence factor), and atypical EPEC (aEPEC), devoid of the plasmid. EPEC produces injury attachingeffacing (A/E) in intestinal cells, determined by genes in the locus of enterocyte effacement (LEE). LEE encodes a type 3 secretion system (SST3), the outer membrane adhesin of Intimin and several effector proteins including Tir (translocated receptor for intimin). Among aEPEC strains of isolated in our midst, those belonging to serotype O51: H40 have been the most frequent. In a previous study, we analyzed 11 strains of E. coli of serotype O51: H40 that had an apparently LEE region complete, 70% of which were of them was able to produce the lesion A/E, as indicated by a positive in vitro assay, which assesses the accumulation of actin due to the injury A/E. To increase the knowledge of the enteropathogenic potential of these strains in this study, we investigated several genotypic and phenotypic properties and the behavior of strains selected in vivo in rabbit and rat. We studied genes recently described in E. coli (lpfA1, cifA, ldaG, espJ, toxB, espM and espT) and the occurrence of residues of tyrosine phosphorylation in Tir molecule in cultures of HeLa cells and T84 intestinal cells differentiated. The results confirm that serotype O51: H40 includes strains with enteropathogenic potential, since 75% of the strains tested produced lesion A/E in the rabbit ileal loop in vivo. Moreover, the aEPEC 1711-4/89, as tEPEC E2348/69, showed significant ability translocation of the intestinal mucosa in bacterial translocation (BT) assays in rats, and the aEPEC 1711-4/89 also caused damage to tissue perfusion. The lack of translocation observed with mutant defect in the assembly of SST3 (1711-4: escN- ) suggested that secreted effector proteins are important for the occurrence of the phenomenon. In conclusion, serotype O51:H40 of E. coli includes potentially enteropathogenic strain, most of which should be classified as aEPEC; the overgrowth of at least one strain of aEPEC in intestine of rats, can lead to damage to the translocation and systemic microcirculation.
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Citação
MOREIRA, Fabiana Campiteli. Análise do potencial de virulência de amostras de Escherichia coli do sorotipo O51:H40. 2009. 139 f. Tese (Doutorado em Ciências) - Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, 2009.