TNF and infection: Parapoxvirus ovis (PPVO, Orf virus) infections or administration of inactivated PPVO (iPPVO) particle preparations have previously been found to stimulate a complex and autoregulating Th1-dominated cytokine response in mice including IFN-α, INF-γ, and tumor necrosis factor-alpha (TNF-α) thereby activating the innate arm of the immune response including APCs (i.e. dendritic cells and NK cells as well as the adaptive arm of the immune response including CD4+ and CD8+ T-cells (reviewed in [13]).