Future prospects in antiviral therapy.

Two important stumbling blocks to the development of effective and nontoxic antiviral drugs are the intracellular localization of the virus and the fact that a virus uses host cell functions to multiply. Therefore, new antiviral drugs must act on a virus-specific function. Most currently available useful antiviral drugs are the result of compound screening of large numbers of possible agents. Advances in our understanding of the molecular biology and biochemistry of the viral multiplication cycle and new laboratory techniques for determining the molecular sites of action have now made it possible to develop and screen new antiviral drugs in a more purposeful manner. Another possible option in antiviral therapy is combination therapy using drugs that enhance the therapeutic effect or diminish side-effects. The most promising new antiviral drugs are discussed according to the different steps they affect in the viral multiplication process. Combination therapy is also reviewed.