Mixed infection with two tobamoviruses: the formation of particles containing the coat protein messenger RNAs of either virus.

Plants mixedly infected with the U2 strain of tobacco mosaic virus (T2MV) and sunnhemp mosaic virus (SHMV) and grown at 35 degrees, yield particles of the same modal lengths (300 and 40 nm) as those found in plants singly infected with SHMV, but not in plants infected with T2MV, which yield only the long particles. At least some of the particles produced in mixedly infected plants contain coat proteins of both viruses. When RNAs from these particles are translated in vitro the coat proteins of both viruses are produced, although when a mixture of RNAs from particles of SHMV and T2MV, grown separately, are translated in vitro only SHMV protein is produced. These and other results suggest that the short particles produced in mixedly infected plants contain both coat protein messengers.