Applications of plant antiviral proteins.

Abstract

Ribosome-inactivating proteins (RIPs) from plant extracts have been known for centuries for their numerous and seemingly unrelated properties including antitumor activity, abortifacient activity and anti-arthritic activity (reviewed in 1)-2). The first study documented in Western literature of the antiviral property of a RIP was the description of an extract from pokeweed and its inhibition of viral replication when applied to heterologous plants (3). Several years hence, the enzymatic activity of RIPs was elucidated when Endo and colleagues described the removal of a particular adenine corresponding to A4324, from a highly-conserved stem-loop structure within the 28S rRNA of rat (4)-5). This depurination was found to block the binding of elongation factor (EF)-1 and inhibit EF-2 dependent GTPase activity, thereby causing an overall reduction in cellular translation (6-7). Because of the targeted activity and resulting cytotoxicity of RIPs, they are valued as selective cell-killing agents. Several have been used as the toxic moiety of immunotoxins directed against cancerous and virus-infected cells (8-11). The search for more and different RIPs has led to the realization that they are almostKeywordsAntiviral ActivityTobacco Mosaic VirusPotato VirusAntiviral AgentSalicylic Acid LevelThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.