A model of interaction between Entamoeba histolytica and Shigella flexneri.

The establishment of a relationship between Entamoeba histolytica and certain bacteria may contribute to the expression and/or enhancement of the pathogenicity of this parasite. Recent experiments have shown that bacteria expressing mannose-binding lectins on their surface could attach to mannose-containing molecules on the surface of amoebae. In this study, we established a model of interaction between. E. histolytica and Shigella flexneri. Using well-characterized mutants of S. flexneri, we studied the role of type I pili expression and the invasive phenotype of S. flexneri in the interaction between amoebae and the bacteria. Type I pili expression allowed attachment and subsequent internalization of S. flexneri by amoebae, these events were not observed in isogenic strains that did not express type I pili. Invasive as well as non-invasive variants of S. flexneri expressing type I pili were slowly digested by amoebae following internalization. Morphological studies showed that the specific features of the interaction depend on the dynamics of the distribution of mannose residues on the amoebic membrane during the interaction.