Visualization of a functional KSHV episome-maintenance protein LANA in living cells.

The latency-associated nuclear antigen (LANA) of Kaposi's saroma-associated herpesvirus (KSHV) can maintain a plasmid containing the KSHV origin of DNA replication (oriP) as episomes in dividing human cells. Hence, LANA is considered to play crucial roles in persistent KSHV infection in human cells. In this study, we characterized a LANA fusion protein of green fluorescent protein (GFP-LANA). Like the wild-type LANA, GFP-LANA interacted tightly with mitotic chromosomes, and maintained the plasmid selectively with the KSHV oriP for more than three weeks in a human B cell line. Moreover, equivalent amount of GFP-LANA protein was segregated into two daughter cells in living metaphase cells. Our results suggested that the activity of LANA serves the segregation of equivalent amounts of viral genomes tethered with LANA into two daughter progeny cells during cell division. Thus, GFP-LANA is a useful tool for the analyses of the functions and dynamics of LANA in living cells.