Estudo da patogênese de cepas de Escherichia coli enteroagregativa em modelo de interação empregando Caenorhabditis elegans

• Ano de defesa: 2013
• Autor(a) principal: França, Fernanda Lembo de Souza
• Orientador(a): Gomes, Maria das Graças de Luna
• Banca de defesa: Gonzalez, Alice Gonçalves Martins , Anjos, Débora Henrique da Silva , Cerqueira, Aloysio de Mello Figueiredo , Queiroz, Mara Lucia Penna
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade do Estado do Rio de Janeiro
• Programa de Pós-Graduação: Programa de Pós-Graduação em Microbiologia
• Departamento: Centro Biomédico::Faculdade de Ciências Médicas
• País: BR
• Palavras-chave em Português: Escherichia coli enteroagregativa; EAEC; Patogênese Bacteriana; Caenorhabtidis elegans; Fatores de virulência; Diarréia infantil
• Palavras-chave em Inglês: Enteroaggregative; Escherichia coli; EAEC; Bacterial Pathogenesis; Caenorhabtidis elegans; Virulence Factors; Infantile Diarrhea
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS::MICROBIOLOGIA::MICROBIOLOGIA APLICADA::MICROBIOLOGIA MEDICA
• Link de acesso: http://www.bdtd.uerj.br/handle/1/14370

Enteroaggregative Escherichia coli (EAEC) is an enteropathogen recognized by the capacity to produce an aggregative adherence (AA) pattern in lineage cells. The genetic heterogeneity of EAEC strains hampers the understanding of the pathogenesis, being able to isolate EAEC strains from patients with clinical symptoms as well as asymptomatic individuals. The nematode Caenorhabtidis elegans has been used as model to study EAEC pathogenesis by mimicking the processes of pathogenesis promoted by microorganisms in mammals. Results have shown that EAEC strains from clinical group and asymptomatic-related strains after nematode infection diminish the survival rate of the animals. The strains from phylogenetic group D are related with clinical group, but in C. elegans model no correlation with pathogenicity in the nematode was demonstrated. Within nematodes gut infected by EAEC were observed bacterial colonization and growth, as well as persistence of high pathogenic strains. Colonization and persistence were also observed in the rabbit gut; however, not all strains tested caused clinical symptoms in the animals. No correlation of the invasive potential of EAEC strains in culture cells and C. elegans virulence model was observed. Mutations in well-known virulence factors affected EAEC virulence in C. elegans model. Virulence attenuation was observed in EAEC 042 strain carrying mutations in virulence genes, such as pet gene, that encodes Pet enterotoxin, the aaiC gene, which encodes a secreted protein by Type VI secretion system (T6SS), and the aggR gene, the transcriptional regulator of EAEC. The results suggested that the same genes involved in EAEC pathogenesis in human may also be involved in the pathogenesis in C. elegans. However, EAEC strains already tested in human challenge studies, which not caused disease in volunteers, caused nematodes death a few days after onset infection in C. elegans. The genotypic heterogeneity of EAEC results in the multiplicity of phenotypes observed when EAEC pathogenesis is analyzed in different models of study.