Huh7 cells were maintained in Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10% fetal bovine serum (FBS). Huh7.5 cells were maintained in DMEM supplemented with 10% FBS and 1% nonessential amino acids. The stable HCV subgenomic RNA replicon cells had been described before. The HCV JFH1 (HCV genotype 2a) strain variant, which produced a high level of infectious virus particles , was propagated in Huh7.5 cells and used in our infection studies.