Nitric oxide has been shown to have important physiological regulatoryroles, i. e, vasodilation, neurotransmitter release, etc. Now, we review its role as an antibacterialand antiviral agent. Nitric oxide has also been identified as an important factor in the developmentof non-specific immunity. And accordingly, nitric oxide synthase (NOS), the catalytic enzyme producingnitric oxide, is a key element in the protective activities of nitric oxide. The expression of inducible(i) NOS is regulated by cytokines. iNOS-derived nitric oxide was found to contribute to both early andlate phases of antibacterial activity. Enzymes, such as proteases (reverse transciptases, and ribonucleotidereductase, etc.) containing cysteine residues, appear to be targets for nitric oxide nitrosylation, aswell as viral-encoded transcription factors that are involved in viral replication. It would appear thatthis multifunctional signaling molecule is not only involved with signaling between cells, it also appearsto maintain the immediate environment free of microbial agents.

Keywords: Anti-Infective Agents, Antiviral Agents, HIV, Nitric Oxide, Research Support, Non-U.S. Gov, Research Support, U.S. Gov