Advances in antiviral agents for hepatitis B virus. 
Hepatitis B virus (HBV) is the third most common disease after venereal diseases and chickenpox.  HBV currently infects 2 billion people in the world, of which 350 million are chronic carriers.  At least 1 million chronically infected individuals die each year due to HBV-related diseases, especially cirrhosis and liver cancer.  The greatest concern about the diffusion of this virus is in endemic regions in central and southern Africa, South-East Asia and South America, where neonatal exposure results in high mortality rates.  Anti-HBV therapy has made important progresses in the last decade, with two approved drugs and a number of other potent agents in the pharmaceutical industry pipeline.  Nevertheless, resistance and viral rebound are still major issues in devising a winning strategy, and there is a continuous need of developing new active compounds, as well as therapeutic protocols based on combination therapy and a prophylactic approach.  This review will summarize the latest advances in anti-HBV therapy, with particular regard to the latest clinical data on the most significant anti-HBV agents.  Issues such as viral resistance and combination therapy will be highlighted.