Suicide watch: how cytomegalovirus interferes with the cell-death pathways of infected cells

The cytomegaloviruses (CMVs) are a family of species-specific viruses that have evolved sophisticated methods to interfere with the host's ability to generate innate and adaptive immune responses. In addition, CMVs must guard against another host defence mechanism, namely the induction of apoptosis that results in the elimination of infected cells. The importance of inhibiting cell death to the evolutionary survival of CMVs is underlined by the fact that these viruses encode an array of molecules devoted to interfering with host apoptotic pathways. CMVs have also been recognised for their ability to inhibit non-apoptotic forms of cells death. Recent publications have provided important insights into how some of these CMV-encoded molecules mediate their pro-survival effects, and this review will compare the mechanisms used by various members of the CMV family to prevent the premature death of the host cell. The capacity for some of the virally encoded cell-death inhibitors to mediate effects unrelated to the suppression of cell death will also be discussed.