Plant viruses replicate and then move between cells through plasmodesmata, gatable channels in the walls of adjoining cells. Although the process of virus movement can be complex and requires support by the coordinated activity of several virus-and host-encoded proteins, many viruses achieve their movement with the help of classical, virus-encoded movement proteins that bind nucleic acids and target and dilate plasmodesmata.
Replication and movement are structurally and functionally linked processes and occur in association with the cytoskeleton and motor proteins. Plant viruses may exploit mechanisms of endogenous macromolecular trafficking for movement. Plant viruses depend on interactions with cellular proteins and membranes to support the formation of membrane-associated, multifactorial protein:nucleic acid complexes for replication and movement. To enhance these processes, viruses assemble and replicate in membrane-associated complexes that may develop into “virus factories” or “viroplasms” in which viral components and host factors required for replication are concentrated.
Plant virus replication and movement. (2015) Virology, 479, 657-671. doi: 10.1016/j.virol.2015.01.025
Replication and intercellular spread of viruses depend on host mechanisms supporting the formation, transport and turnover of functional complexes between viral genomes, virus-encoded products and cellular factors. To enhance these processes, viruses assemble and replicate in membrane-associated complexes that may develop into “virus factories” or “viroplasms” in which viral components and host factors required for replication are concentrated. Many plant viruses replicate in association with the cortical ER-actin network that is continuous between cells through plasmodesmata. The replication complexes can be highly organized and supported by network interactions between the viral genome and the virus-encoded proteins. Intracellular PD targeting of replication complexes links the process of movement to replication and provides specificity for transport of the viral genome by the virus-encoded movement proteins. The formation and trafficking of replication complexes and also the development and anchorage of replication factories involves important roles of the cortical cytoskeleton and associated motor proteins.