OBJECTIVETo investigate the inhibitive effects of small interfering RNA (siRNA) on hepatitis C virus (HCV) replication in cells infected by HCV in vitro.

METHODSThe HCV RNA transcripts prepared by pFL-JC1 were transfected into Huh-7.5.1 cells. Na ve Huh-7.5.1 cells were incubated with the supernatants of transfected cells and the expression of HCV core protein in infected cells was detected by indirect immunofluorescence. The infected cells were transfected with 4, 40 and 200 nmol/L of NS5B siRNA for 24 h, 48 h and 72 h, respectively. The normal Huh-7.5.1 cells were transfected with 4, 40 and 200 nmol/L of NS5B siRNA. Group of blank, lipofectamine 2000, unrelated siRNA and IFNα-2b (1000 IU/ml) served as controls. The HCV RNA and PKR mRNA levels were examined by quantitative RT-PCR.

RESULTSThe HCV core protein in HCV infected cells was detected. Compared with control groups, the HCV RNA levels in infected cells significantly decreased when transfected with 40 and 200 nmol/L of siRNA for 24 h; 4, 40 and 200 nmol/L of siRNA for 48 h and 72 h (P<0.05). The HCV RNA levels in infected cells treated with IFNα-2b (1000 IU/ml) for 24 h, 48 h and 72 h were significantly lower than those in control groups (P<0.05 or P<0.01). The PKR mRNA levels in Huh-7.5.1 cells transfected with siRNA of three concentrations did not have significant difference, as compared with control groups (P>0.05).

CONCLUSIONsiRNA against HCV NS5B region can effectively inhibit HCV replication in HCV infected cells, but can not activate the dsRNA-dependent protein kinase (PKR).