During the latent phase, the Kaposi Sarcoma-associated herpesvirus (KSHV) genome remains dormant in cell nuclei, but it can re-enter the lytic cycle if cell conditions become unfavorable (e.g. cell stress).

Thomas Günther and Adam Grundhoff, Heinrich-Pette-Institute for Experimental Virology and Immunology, Hamburg, Germany, performed a spatial and temporal analysis of DNA methylation and histone modifications during latent infection with KSHV.

They found that KSHV genomes are subject to profound methylation at CpG dinucleotides, but these patterns evolve slowly, while histone modification patterns were rapidly established upon a de novo infection. Their analysis demonstrates that such patterns are not solely characterized by the absence of activating histone modifications, but the presence of repressive ones as well, removal of which lead to rapid activation.

• The Epigenetic Landscape of Latent Kaposi Sarcoma-Associated Herpesvirus Genomes,
  T. Günther, A. Grundhoff,
  PLoS Pathog 2010, 6 (6), e1000935
  DOI: 10.1371/journal.ppat.1000935