Abstract
We examined the behavior of movement protein (MP) of tobacco mosaic virus in epidermal cells infected with mutant viruses expressing the MP:GFP fusion protein or free GFP, using time-lapse micrography. These studies revealed that intercellular movement of infection from initially infected cells to adjacent cell occurred 18 to 20 hpi. However, movement from the first to secondarily infected cells occurred in less than 4 hrs, in striking contrast to the first movement. We also observed the behavior of the viral replication complexes that contain MP:GFP at different times post infection using a confocal microscope. At early stages of infection the complexes exhibited rapid intracellular movement, while at mid-stage of infection the complexes were located at or near plasmodesmata, and intracellular movement of complexes were halted. We suggest that these events are preconditions of cell-cell spread of infection, and propose a modified model of virus movement based on these studies.
