Poxvirus interference with the host cytokine response.

Poxviruses have evolved successfully to survive and replicate in a variety of species in the presence of an active host immune and inflammatory response. They manage this, at least in part, by the acquisition and modification of host immune and inflammatory response modulating genes. A proportion of these virulence genes encode homologues of host cytokines and cytokine receptors. These include soluble interferon, IL-1 beta, and TNF-alpha receptor homologues, that block the host cytokines. Other virulence gene products interfere with interferon signalling within cells and prevent the cleavage of biologically active IL-1 beta from its precursor protein. The parapoxvirus orf virus encodes a homologue of ovine IL-10 and a novel GM-CSF-binding protein. By studying poxvirus virulence proteins that interfere with host cytokine effector responses, important and novel aspects of the host immune and inflammatory response to infection have been revealed.