Vaccinia Virus Protein C6: A Multifunctional Interferon Antagonist.

Vaccinia virus (VACV) is the prototypic member of the Orthopoxvirus genus of the Poxviridae. It is also the live vaccine that was used to eradicate smallpox. Like other poxviruses, VACV replicates in the cytoplasm and has a large double-stranded (ds)DNA genome and a complex virion. Approximately, half of the VACV genes are nonessential for virus replication in cell culture but encode a remarkable array of immunomodulators that antagonise the innate immune response to virus infection. This short review concerns one such protein, C6, that is a multifunctional inhibitor of interferon. C6 can both diminish the production of interferon and inhibit interferon-induced signalling and thereby the expression of interferon-stimulated genes.