HOW DO ANIMAL DNA VIRUSES GET TO THE NUCLEUS

Genome and pre-genome replication in all animal DNA viruses except pox viruses occurs in the cell nucleus (Table 1). In order to reproduce, a n infecting virion enters the cell and traverses through the cytoplasm toward the nucleus. Using the cell's own nuclear import machinery, th e viral genome then enters the nucleus through the nuclear pore comple x. Targeting of the infecting virion or viral genome to the multiplica tion site is therefore an essential process in productive viral infect ion as well as in latent infection and transformation. Yet little is k nown about how infecting genomes of animal DNA viruses reach the nucle us in order to reproduce. Moreover, this nuclear locus for viral multi plication is remarkable in that the sizes and composition of the infec tious particles vary enormously. In this article, we discuss virion st ructure, life cycle to reproduce infectious particles, viral protein's nuclear import signal, and viral genome nuclear targeting.