HCMV microinfections in inflammatory diseases and cancer

Human cytomegalovirus (HCMV) is a wide-spread human virus that was mainly known to cause disease in immunocompromised patients. A new entity of infection can be diagnosed with high sensitive techniques; HCMV microinfections that often exhibit an altered pattern of IE protein expression. We have recently discovered that HCMV microinfections are very common in patients with inflammatory diseases and certain cancers. The discovery of active HCMV infections in tissue specimens from patients with inflammatory diseases raises the question of whether the infection is an epiphenomenon or whether the virus plays a causative role in disease development. After a primary infection, which is generally asymptomatic in immunocompetent individuals, HCMV establishes latency and persists in its host. In infected cells, the virus can produce over 250 proteins, but only about 50–60 are believed to be essential for viral replication. Thus, the vast majority of these viral proteins enable the virus to co-exist with its host. Such proteins act through highly sophisticated mechanisms to control different cellular and immunological functions in order to facilitate viral production and to avoid detection and elimination of the virus by the immune system. These proteins may also contribute to the development of common inflammation-related diseases.