The viral genome consists of a ~145 kilobase-long unique region, encoding all of expressed viral genes, which is flanked by ~20-30 kilobases of terminal repeat sequences. Each terminal repeat unit is 801 bp in length, has 85% G+C content and is oriented in a repetitive head-to-tail fashion. During latency, the virus genome depends on the host replication machinery and replicates as a closed circular episome ("plasmid") using sequences within the terminal repeats as a replication origin. When the virus reactivates into lytic replication, it is believed that the virus genome is replicated as a continuous linear molecule off from an episome (so-called rolling circle model). As each unit genome is replicated, it is cut within the terminal repeat region, and then packaged into a virus particle (virion). The virus then becomes enveloped with a lipid membrane as it transits the nucleus and the cytoplasm to exit the cell. Thus, whereas KSHV genome is circular in the nucleus of latently infected cells, it is packaged into infectious viruses as a linear molecule. Once the virus newly infects a cell, the lipid membrane is shed and the virion travels to the nucleus. The viral genome is released where it recircularizes through a poorly understood process that appears to involve homologous recombination.