Experimental studies have demonstrated that the triple combination of amantadine (A)/ ursodeoxycholic acid (UDCA, U)/ biphenyl dimethyl dicarboxylate (DDB, D) might have a preferential antiviral effect compared with that observed in interferon-induced antiviral signal pathways, such as those of $STAT1alpha$ and the 6-16 genes. To confirm the results, this study examined whether th signal transduction for the antiviral activity in HepG2 2.2.15 was induced dependently or independently of interferon. To accomplish this, the correlation between the $STAT1alpha$ and 6-16 genes, and nitric oxide, for the mediation of the antiviral activity was assessed. The increase in nitric oxide in the UDCA groups suggests that the inhibition of viral gene replication was enhanced by the amantadine combinations (AU and AUD), and might be more effective if incubated for longer periods. It was found that $STAT1alpha$ was activated by the amantadine combination, although to a lesser extent than that of $interferon-alpha$, and the primary endpoints examined for the inhibition of gene expression (HBsAg and HBcAg) were remarkably well regulated. This suggests that the amantadine triple, or at least the double, combination had better clinical benefits than those of $IFN-alpha$ and the nucleoside analogue single treatment. This demonstrates that the amantadine combination might be a substitute for the existing HBV therapy if the results of in vivo and in vitro studies concur.