Amebiasis and the Role of Virulance Factors in Entamoeba

Amebiasis is a parasitic disease of worldwide which has public health importance, particularly in developing countries having poor sanitary conditions. Clinical amebiasis results from the spread of trophozoites into the colon wall and beyond, and also the parasite may invade other organs such as liver, brain and causes abscess. Current development on E. histolytica pathogenesis is based on the publication of E.histolytica genome and using molecular techniques such as antisense inhibition of target gene expression and irreversible gene silencing. After characterization of E. dispar as a distinct species that is morphologically identical but apathogen in 1993, difference between two microorganisms in genomic level has revealed much information about virulence factors. In the light of recent studies, four virulence factors are defined; adhesion molecules, amoebapores, cysteine proteinases and complex lipophosphopeptidoglycans. The roles of these factors during invasion are the main concept of this review. Furthermore, interactions between parasite and host cell are summarized; this is the key point of understanding the role of inflammation and programmed cell death in the pathogenesis of amebiasis. Although we have learned much about pathogenesis in recent years, there are still many unanswered questions. Most important ones of those questions are about encystation of parasite, inflammation process, apoptosis and necrotic cell death of host cells. In addition, how the parasite causes different clinical signs in different organs is another unexplained part in pathogenesis. Consequently, new studies and realistic animal models are needed to clarify the pathogenesis of E. histolytica.