Viral infectious disease and natural products with antiviral activity.

Viral diseases, such as acquired immunodeficiency syndrome (AIDS), respiratory diseases, and hepatitis, are the leading causes of death in humans worldwide, despite the tremendous progress in human medicine. The lack of effective therapies and/or vaccines for several viral infections, and the rapid emergence of new drug-resistant viruses have urged a growing need for developing new and effective chemotherapeutic agents to treat viral diseases. Recent advances in the understanding of both the cellular and molecular mechanisms of virus replication have provided the basis for novel therapeutic strategies. Several hundred natural products have been isolated for screening and identifying antiviral activity, and some have been shown to have great medicinal value in preventing and/or ameliorating viral diseases in preclinical and clinical trials. There are innumerable potentially useful medicinal plants and herbs waiting to be evaluated and exploited for therapeutic applications against genetically and functionally diverse virus families. This review focuses on several selected pathogenic viruses, including the human immunodeficiency virus (HIV), influenza virus, hepatitis B and C viruses and herpes viruses, and antiviral natural compounds from medicinal plants (herbs), while paying particular attention to promising compounds in preclinical and clinical trials. We also focused our attention on the need to develop effective screening systems for antiviral activity.