Screening for new agents.

Screening for new antiviral drugs is concentrated on a search for inhibitors of the human immunodeficiency virus, herpesviruses, influenza virus, hepatitis B virus and rhinovirus. The first step in the process is usually the screening of virus-infected cell cultures followed by secondary screening in infected animals. The relevance of the different screening methods for predicting clinical efficacy is at present uncertain due to the low number of compounds evaluated in double-blind placebo-controlled clinical trials. As a consequence of the con-siderable activity in ongoing research on antiviral drugs the predictive value of the screening systems is expected to improve.