Human cytomegalovirus latency and reactivation - a delicate balance between the virus and its host's immune system

Human cytomegalovirus (HCMV) is a ubiquitous herpesvirus that still causes severe morbidity and mortality in immunocompromised individuals. During its evolution, the virus has developed sophisticated methods to evade immune recognition and to establish life-long persistence in its host. Today, we know that the virus establishes latency in myeloid lineage cells and that the virus is dependent on immune activation mechanisms to reactivate it from latency to produce a new viral progeny. During this process, a number of viral proteins are produced that interfere with different immune recognition pathways. The current knowledge of the delicate balance between the virus' continuous existence and its host's immune system will be summarized in this chapter.