The role of host and viral proteins in intra- and inter-cellular trafficking of geminiviruses

Geminiviruses are insect-transmitted ssDNA plant viruses that reproduce in intact host nuclei. To be infectious, the viral DNA must be able to overcome numerous transport barriers. Upon entrance into a host cell, the virus enlists host machinery to facilitate both its transport through the complex lattice-like structure of the cytoplasm to the nucleus and its uptake into the nucleus through the nuclear pore complex (NPC). Following replication and transcription of its genome, the infectious form of the virus exploits host transport machinery together with virus-encoded movement proteins (MP) to egress from the nucleus and to be transported through the cytoplasm to, and through, the virus-modified plasmodesmata (Pd). Here we describe viral and plant proteins involved in these processes and present a model summarising our accumulated knowledge. (C) 2002 Elsevier Science Ltd. All rights reserved.