Time course of HCV RNA replication and core protein expression in transfected cells. (a) Levels of HCV RNA in transfected cells (right) and corresponding culture supernatants (left). Huh7 cells were transfected with given HCV RNAs and passaged up to 30 d. Viral RNA was determined 2, 5, 8, 12, 15, 18, 21, 24, 27 and 30 d after transfection. (b) Immunofluorescence assay of HCV core protein in passaged cells transfected with JFH1 and JFH1/ΔE1-E2 RNA. Transfected cells were harvested 1 d after the fourth passage (day 13 after transfection). Magnification, ×100.