Positive strand RNA viruses

Abstract

Brome mosaic virus (BMV) is an isometric. positive strand RNA virls of cereal plants, related by substantial nonstructural protein homologies and features of RNA replication to a variety of other plant virus groups and t o t h e animal alphaviruses. In vitro transcripts of complete cDNA clones of t h e three BMV genomic RNAs can be used t o infect either whole plants (1) or protoplasts (2). 50% or more of inoculated protoplasts can be routinely infected with appropriately tailored BMV transcripts, allowing direct examination of virus replication in primarily infected cells. Such expressible BMV cDNA clones have been used to alter t h e virus for a variety of studies on gene expression and replication.