MX1 and infection: To directly assess the role of FPV184 in the absence of other immunomodulatory proteins expressed during infection, we used a construct (pFPV184) to overexpress FPV184 in immortalised DF-1 chicken fibroblast cells and assessed its ability to modulate the induction of the chicken IFN-β promoter by the dsRNA analogue polyI:C (Figure 4a) or the chicken Mx1 promoter by recombinant IFN-α, as detected using a luciferase reporter assay (Figure 4b).