Structural and autoradiographic observations of the infection of tobacco protoplasts with pea enation mosaic virus.

The structural changes accompanying infection of tobacco protoplasts with pea enation mosaic virus have been examined by electron microscopy. The first visible response to infection is the appearance at about 17 h post inoculation of cytoplasmic membrane bound bodies enclosing a series of fibril-containing vesicles. At later stages of infection a proportion of these bodies appear to fuse with the nuclear membrane. Intact virus is found only within the nucleus. The fibrils within the vesicles are digestible by RNAse but not DNAse and they may be labelled using [(3)H]uridine. These results are discussed in terms of the course of infection of plant cells by viruses.