Changes occurring on the cell surface during KSHV reactivation.

Following an infection, Kaposi's sarcoma-associated herpes virus (KSHV) exists predominantly in its latent state, with only 1-2% of infected cells undergoing lytic reactivation. We have previously demonstrated along with others a relationship between lytic reactivation and cell cycle progression (Bryan et al., 2006. J. Gen. Virol. 87: 519; McAllister et al., 2005. J. Virol. 79: 2626). Infected cells in the S phase are much more likely to undergo lytic reactivation when compared to those in G(0)/G(1) phase. Through the use of scanning electron microscopy (SEM), we analyzed changes occurring on the surface of cells undergoing KSHV reactivation. KSHV reactivation was observed predominantly in cells with smoother surface topology; a hallmark of cells derived from S phase. Interestingly, during the late stages of the reactivation process, we observed KSHV particles to egress cells through budding. Taken together, based on scanning electron microscopy and transmission electron microscopy evidences, we demonstrate for the first time the existence of a direct link between cell surface topology, cell cycle progression and KSHV reactivation.