Krichevsky, A., Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, United States
Kozlovsky, S.V., Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, United States
Gafni, Y., Department of Genetics, Agricultural Research Organization, PO Box 6, Bet Dagan 50250, Israel
Citovsky, V., Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, United States

Nuclear import and export are crucial processes for any eukaryotic cell, as they govern substrate exchange between the nucleus and the cytoplasm. Proteins involved in the nuclear transport network are generally conserved among eukaryotes, from yeast and fungi to animals and plants. Various pathogens, including some plant viruses, need to enter the host nucleus to gain access to its replication machinery or to integrate their DNA into the host genome; the newly replicated viral genomes then need to exit the nucleus to spread between host cells. To gain the ability to enter and exit the nucleus, these pathogens encode proteins that recognize cellular nuclear transport receptors and utilize the host's nuclear import and export pathways. Here, we review and discuss our current knowledge about the molecular mechanisms by which plant viruses find their way into and out of the host cell nucleus. © 2006 Blackwell Publishing Ltd.