Control of Apoptosis by Poxviruses

Abstract

Poxviruses express a variety of proteins which can function to inhibit apoptosis in infected cells, allowing virus replication to continue and conferring a broad host range. Some poxvirus antiapoptosis proteins act by sequestering or inactivating inducers of apoptosis such as dsRNA and superoxide anions. Others interfere with signaling by receptors including those belonging to the TNF receptor superfamily that would otherwise activate a proteolytic cascade that terminates with the cleavage of death substrates. The cowpox virus crmA protein directly inhibits cysteine proteinases within the cascade and can also block apoptosis triggered by the serine proteinase granzyme B. Finally there are poxvirus antiapoptosis proteins containing ankyrin repeat regions that are thought to interact with cellular proteins.