Silencing of Entamoeba histolytica glucosamine 6-phosphate isomerase by RNA interference inhibits the formation of cyst-like structures.

Encystment is an essential process in the biological cycle of the human parasite Entamoeba histolytica. In the present study, we evaluated the participation of E. histolytica Gln6Pi in the formation of amoeba cyst-like structures by RNA interference assay. Amoeba trophozoites transfected with two Gln6Pi siRNAs reduced the expression of the enzyme in 85%, which was confirmed by western blot using an anti-Gln6Pi antibody. The E. histolytica Gln6Pi knockdown with the mix of both siRNAs resulted in the loss of its capacity to form cyst-like structures (CLSs) and develop a chitin wall under hydrogen peroxide treatment, as evidenced by absence of both resistance to detergent treatment and calcofluor staining. Thus, only 5% of treated trophozoites were converted to CLS, from which only 15% were calcofluor stained. These results represent an advance in the understanding of chitin biosynthesis in E. histolytica and provide insight into the encystment process in this parasite, which could allow for the developing of new control strategies for this parasite.