Viruses and apoptosis

Apoptosis, or programmed cell death, is essential in development and homeos tasis in multi-cellular organisms. It is also an important component of the cellular response to injury. Many cells undergo apoptosis in response to v iral infection, with a consequent reduction in the release of progeny virus . Viruses have therefore evolved multiple distinct mechanisms for modulatin g host cell apoptosis. Viruses may interfere with either the highly conserv ed 'effector' mechanisms of programmed cell death or regulatory mechanisms specific to mammalian cells. In addition to conferring a selective advantag e to the virus, the capacity to prevent apoptosis has an essential role in the transformation of the host cell by oncogenic viruses. This article prov ides a focussed review of apoptosis and illustrates how the study of viruse s has informed our understanding of this process. Selected mechanisms by wh ich viral gene products interfere with cell death are discussed in detail a nd used to illustrate the general principles of the interactions between vi ruses and apoptosis.