Movement protein

Successful infection of a plant by a plant virus depends on its ability to move from the cell initially infected to neighbouring cells in order to spread infection. Unlike animal cells, plant cells have robust cell walls, which viruses cannot easily penetrate. A movement protein is a non-structural protein which is encoded by some plant viruses to enable their movement from one infected cell to neighbouring cells. Many, if not all, plant viruses encode a movement protein, and some express more than one. The movement protein of tobacco mosaic virus (TMV) has been most extensively studied. Plant viruses can also be transported over longer distances through the host plant in the vascular system via the phloem.

Plant virus movement between cells

Most plant viruses move between plant cells via plasmodesmata, pores between plant cell walls that allow the plant cells to communicate with each other. Plasmodesmata usually only allow the passage of small diffusible molecules, such as various metabolites. Neither virus particles nor viral genomic nucleic acid can pass through plasmodesmata unaided.