Effect of small interfering RNAs on the expression of green fluorescent protein from IRES clones of six different HCV genotypes. Huh-7 cells were co-transfected with HCVIRES-GFP plasmid with siRNA plasmid (pSuper-retro) by using the FuGENE 6 transfection reagent. After 48 hours transfected cells were observed under a fluorescence microscope. The experiments were repeated for each genotype IRES clones using different siRNA constructs. SiRNA-74 was the most effective and inhibited the expression of green fluorescence in all genotypes of HCV compared to other siRNA. Control siRNA targeted to EBNA1 had no effect on GFP expression from HCV IRES clones.