Satellite tobacco mosaic virus.

Satellite tobacco mosaic virus (STMV) is a small, spherical ssRNA virus common in a natural wild plant, Nicotiana glauca or tree tobacco, in southern California and is one of the best-studied satellite viruses. It is the only satellite virus that has rod-shaped viruses (tobamoviruses) for its helper. In addition to describing the general properties of STMV, this review focuses on (a) the structural properties of the virus particle including the RNA within the particle that is partially double stranded; (b) the genetic diversity within the type strain before and after serial passage and between different field isolates; (c) the effect of experimental mutation on infectivity, replication, and symptomatology; and (d) the genetic changes that occur when the satellite virus adapts to different helper tobamoviruses.