IL-6 suppresses HBV replication in a time-dependent manner. Confluent cells (day0) were treated with or without 20 ng/ml of IL-6 for 2 days (day2), 4 days (day4) or 6 days (day6). For the analysis of HBV replicative intermediates, equal amounts of total DNA were subjected to HindIII digestion and separated by electrophoresis. The integrated viral genome and viral replicative intermediates were then examined by Southern blot analysis using an HBV-specific probe. Bands corresponding to the integrated genome, the relaxed circular double-stranded DNA (RC) and single-stranded DNA (SS) are indicated individually. The intensity of the integrated HBV genome in each lane reflected the amounts of total DNA and was served as the internal control for sample loading. The signals were quantified by densitometry analysis and expressed as percentage of the respective control cells to indicate the inhibitory effect of IL-6.