Plant virus movement proteins

The ease with which plant viruses move throughout their hosts appears quite remarkable, considering that viral progeny must cross the plant cell wall to move from cell to cell. The cell wall acts as a barrier to the extracellular release and subsequent uptake of virus progeny by either surface fusion or receptor-mediated endocytosis, the two general pathways for entry used by animal viruses. Consequently, plant viruses have evolved a distinct mechanism for cell-to-cell movement. With few exceptions, virus particles are initially introduced into host cells during mechanical damage or biological damage (via vectors) to the integrity of the cell wall and the plasma membrane. If, following entry and replication, progeny viruses are not capable of moving into adjacent healthy cells, a subliminal infection occurs, and the host appears to be resistant to the virus. If, however, virus progeny capable of spreading into adjacent cells, a progressive virus infection results. While the specific virus-host interaction will ultimately define the nature of the infection, virus movement represents an important component in determining pathogenicity and virulence.