Virokines: mediators of virus-host interaction and future immunomodulators in medicine

A decade ago, after the discovery of the major secretory protein of vaccinia virus with structural similarity to complement control, the term virokine was coined. The term virokine, simply refers to a virally encoded secretory protein. During the past decade several virokines were discovered and most of them have been found to have immunomodulatory effects. A subset of virokines which resemble cytokine/chemokine receptors have been termed viroceptors. Examples of viroceptors include the TNF receptor homolog and the IL-1 beta receptor homolog. During the past several years animal models have been developed to try to understand the in vivo role of the virokines. It has become evident from at least two studies that quite a few of the virokines down-regulate the inflammatory response elicited during infection. This down-regulation at least in one model system seems to indicate that it ensures the preservation of the viral habitat (site of infection). One obvious spinoff of the research on virokines is a new class of immunomodulators has become available as therapeutics in alleviating the symptoms of inflammatory disease conditions.