CK18 RNAi treatment inhibit amastigotes multiplication in HeLa cells. HeLa cells were left untreated or treated with CK18 RNAi or control RNAi. After 24 h, cells were infected with culture trypomastigotes of the Y strain of T. cruzi. Forty-eight hours post infection, we estimated: (A) The frequency of infected HeLa; (B) The number of parasites per 100 cells; (C) The frequency of infected cells with 1–5 or > 5 parasites. Bars represent the average of triplicate cultures ± SD. Asterisks denote significantly lower numbers when compared to non-transfected or control RNAi (P < 0.01).