Packaging of tobacco mosaic virus subgenomic RNAs by brome mosaic virus coat protein exhibits RNA controlled polymorphism

The coat protein (CP) of icosahedral Brome mosaic virus (BMV) was expressed from a genetically engineered rod-shape Tobacco mosaic virus, Molecular ch aracterization of the progeny recovered from symptomatic plants revealed th at BMV CP selectively packaged the three subgenomic RNAs of the hybrid viru s into two differently sized icosahedral virus-like particles (VLPs). The s maller VLPs packaged only the two smaller subgenomic RNAs. Additional in vi tro reassembly assays with BMV CP subunits and transcripts of hybrid subgen omic RNAs further demonstrated that the ability of BMV capsids to display p olymorphism is not dependent on the RNA size alone and appears to be contro lled by some other feature(s) of the genetically engineered RNA. (C) 2000 A cademic Press.