ANTISENSE INHIBITION OF EXPRESSION OF CYSTEINE PROTEINASES DOES NOT AFFECT ENTAMOEBA-HISTOLYTICA CYTOPATHIC OR HEMOLYTIC-ACTIVITY BUT INHIBITS PHAGOCYTOSIS

Inhibition of most of the expression of the cysteine proteinases of En tamoeba histolytica strain HM-1:IMSS was successfully performed by tra nscription of ehcp5 antisense RNA using the promoter of ehg34, which e ncodes a L21 ribosomal protein of E. histolytica. We have generated a stable transfectant in which the overall level of cysteine proteinase activity is strongly reduced (approximate to 90%). This transfectant h as a normal growth rate in Diamond's TYI-S-33 medium, a cytopathic and haemolytic activity similar to the control HM-1:IMSS pEhAct-Neo trans fectant but with a significantly lower phagocytic activity.