Comparison of the proteome profiles of Entamoeba histolytica and its close but non-pathogenic relative Entamoeba dispar.

The microaerophilic protist Entamoeba histolytica is a source of considerable morbidity and mortality in many countries of the world by acting as a causative agent of amoebic dysentery and liver abscess. Its close relative, Entamoeba dispar, also colonises the human colon but is non-pathogenic. In the present study, we wanted to assess if the close relatedness of these two organisms could be used to identify virulence factors in E. histolytica through a comparison of the protein expression profiles of the pathogenic and the non-pathogenic species. We applied two-dimensional polyacrylamide gel electrophoresis in order to identify proteins which are specifically expressed in E. histolytica and which therefore could constitute candidate proteins potentially involved in E. histolytica pathogenicity. The evaluation of overall protein expression profiles derived from whole cell extracts, however, revealed that, in spite of the close relatedness at the genetic level, the disparity of the proteomic profiles of these two Entamoeba species is far too great in order to pinpoint proteins whose expression might render E. histolytica pathogenic. Taken together, our study performed at the proteomic level clearly supports the notion of E. histolytica and E. dispar as two distinct species.