Enteroinvasive Escherichia coli vs. Shigella flexneri : how different patterns of gene expression affect virulence

Important features of the enteroinvasive Escherichia coli (EIEC) phenotype and gene expression likely to confer EIEC with a lower ability to cause disease than Shigella flexneri were described here for the first time. To confirm the lower pathogenicity of EIEC, we have analyzed the keratoconjunctivitis developed in guinea-pigs with EIEC or S. flexneri. Shigella flexneri induced a more pronounced proinflammatory response, whereas EIEC induced a mild form of the disease. EIEC showed a significantly less efficient cell-to-cell Caco-2 dissemination when compared with S. flexneri. Plaques formed by EIEC during intercellular spreading were four times smaller than those formed by S. flexneri. At the molecular level, the lower expression of virulence genes by EIEC during infection of Caco-2 cells highlighted the importance of effective gene transcription for bacterial pathogenicity.

Research Foundation of the State of Sao Paulo (Fundacao de Amparo Pesquisa do Estado de Sao Paulo - FAPESP)[05/56960-6]

National Council for Scientific and Technological Development (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico - CNPq)

Brazilian Federal Agency for Support and Evaluation of Graduate Education (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - CAPES)