IR415 is a potent anti-HBV agent and inhibits HBV replication by blocking the HBx activity. IR415 selectively interacts with HBx (Kd=2 nM) and blocks HBV-mediated RNAi suppression, reverses the inhibitory effect of HBx protein on the activity of the dicer endoribonuclease. HBx: hepatitis B virus X protein.