Cytomegaloviruses (CMV) are large DNA virus of the beta-herpesvirus family. After acute infection CMV genomes remain life-long in host tissue in a state of replicative latency. During their co-evolution virus and host have established a fine balance of immune evasion and immune control to maintain latency. We aim to understand the molecular and immunological basis of CMV control by the immune system and the virus's counteractions that lead to latency.