Gene products encoded by cymbidium mosaic virus RNA: proteins translated in vitro

Abstract

The potexvirus, cymbidium mosaic virus (CyMV), a major pathogen of cultivated orchids, has a single-stranded RNA genome that serves, all or in part, as messenger for translation of viral proteins during infection. As a first step in investigating the mechanisms of gene expression in CyMV infection, we have focused on the question of the protein-encoding potential of the viral RNA. CyMV particles have been highly purified from infected Datura stramonium leaves using Percoll gradient sedimentation and intact RNA has been extracted from the virus and used as messenger in an in vitro translation system from wheat germ. Translated polypeptides were analyzed by SDS-polyacrylamide gel electrophoresis. CyMV genomic RNA encoded at least eight major polypeptide species in the in vitro translation system. Our results suggest that some protein processing by specific cleavage might occur as part of the process of gene expression.