Some Properties of Isometric Virus Particles which Contain the Satellite RNA of Tobacco Mosaic Virus

Abstract

A ssRNA, which has a satellite-like relationship with tobacco mosaic virus (TMV), had an estimated mol. wt. of 0.38 .times. 106 and was found to be encapsidated in isometric particles with a diameter of 17 nm. The capsid protein had a mol. wt. of 18 .times. 103. This satellite virus of TMV (STMV) is highly immunogenic and no serological relatedness was detected between it and either TMV or satellite tobacco necrosis virus (STNV) or satellite panicum mosaic virus (SPMV) in immunodiffusion tests with antibodies specific for STMV, TMV, STNV and SPMV. Randomly primed STMV cDNA hybridized with STMV-specific dsRNA and ssRNA but did not hybridize to ssRNA of TMV, SPMV, panicum mosaic or cucumber mosaic viruses. The dsRNAs of different isolates of STMV differed in their electrophoretic mobilities, but they all shared nucleotide sequence homology. Particles of STMV tended to aggregate and crystallize upon purification. Replication of STMV in tobacco plants was supported by TMV but not by cucumber mosaic virus. This is the first report of a satellite virus of a rod-shaped plant virus.