ANTIVIRAL AGENTS

Viruses are obligate intracellular parasites; their replication depends primarily on synthetic processes of the host cell. Viral replication consists of several steps: (1) adsorption to and penetration into susceptible host cells; (2) uncoating of viral nucleic acid; (3) synthesis of early, regulatory proteins, eg, nucleic acid polymerases; (4) synthesis of RNA/ DNA; (5) synthesis of late, structural proteins; (6) assembly (maturation) of viral particles; and (7) release from the cell.

Antiviral agents can potentially target any of these steps. Most of the antiviral agents currently available act on synthesis of purines and pyrimidines (step 4); reverse transcriptase inhibitors block transcription of the HIV RNA genome into DNA, thereby preventing synthesis of viral mRNA and protein. The protease inhibitors act on synthesis of late proteins and packaging (steps 5 and 6). In this section drugs used in the treatment of herps, human immunodeficiency virus and other antiviral agents will be discussed.