Control Huh7 cells and genome-length replicon, subgenomic replicon, Core-on, and Core-off cells were fixed with 2.5% glutaraldehyde in 0.1 M Na Cacodylate, pH 7.4 for 2 hrs, postfixed with 2% aqueous osmium tetroxide for 2.5 hrs, and subsequently stained en bloc in 2.5% uranyl acetate (in water) overnight before dehydration and embedding in Eponate 12 resin (Ted Pella, Inc., Redding, CA, USA). Thick (1 mm) sections of the embedded cells were examined at the light microscopic level. The cell blocks were further trimmed to obtain thin sections (80 nm), stained with saturated solution of uranyl acetate (15 min) followed by Reynolds' lead citrate (8 min) , and examined with a JEOL JEM 100CX II transmission electron microscope (JEOL Ltd., Tokyo, Japan).