Immunocytochemical staining showing the silencing of core protein from full-length clones of HCV by siRNA-74. Huh-7 cells were co-transfected with (10 μg) pSuper-retro-siRNA74 and (10 μg) full-length clones of HCV. After 48 hours, transfected cells were harvested by the treatment with trypsin-EDTA. Cells were washed with PBS and immobilized onto a glass slide by cytospin method. Then slides were blocked and stained with core antibody against HCV using a mouse monoclonal antibody. Immunostaining for HCV core protein was performed using a standard protocol. The expression of core protein of full-length HCV 1a (pCVH77C), Ib (pCVJ4L6S), and 1b (pMO9.6--T7) is observed in the presence of siRNA74 and siRNAEBNA1 (unrelated siRNA).