Localization of latency-associated nuclear antigen (LANA) on mitotic chromosomes

- This is the first report showing LANA dots on mitotic chromosomes by fluorescent microscopy followed by electron microscopy.
- LANA dots localized randomly on condensed chromosomes other than centromere/pericentromere and telomere/peritelomre.
- Cellular mitotic checkpoint should not be always involved in the segregation of KSHV genomes in the latency.

In latent infection of Kaposi's sarcoma-associated herpesvirus (KSHV), viral gene expression is extremely limited and copy numbers of viral genomes remain constant. Latency-associated nuclear antigen (LANA) is known to have a role in maintaining viral genome copy numbers in growing cells. Several studies have shown that LANA is localized in particular regions on mitotic chromosomes, such as centromeres/pericentromeres. We independently examined the distinct localization of LANA on mitotic chromosomes during mitosis, using super-resolution laser confocal microscopy and correlative fluorescence microscopy-electron microscopy (FM-EM) analyses. We found that the majority of LANA were not localized at particular regions such as telomeres/peritelomeres, centromeres/pericentromeres, and cohesion sites, but at the bodies of condensed chromosomes. Thus, LANA may undergo various interactions with the host factors on the condensed chromosomes in order to tether the viral genome to mitotic chromosomes and realize faithful viral genome segregation during cell division.