Mouse monoclonal antibody against phosphotyrosine 701-STAT1 were purchased from BD Biosciences. Polyclonal antibodies against STAT1, STAT2, and phosphotyrosine 689-STAT2 were obtained from Upstate. Mouse monoclonal antibody against proliferating cell nuclear antigen (PCNA) was obtained from Santa Cruz Biotechnology. Mouse monoclonal anti-His antibody was purchased from Sigma Aldrich and HRP-tagged anti-HA antibody from Roche. The rabbit anti-N antiserum recognizing the amino terminus of the NSDV and GV N protein were previously made in our laboratory. Mouse monoclonal antibody against the V5 epitope tag was purchased from AbD Serotech. Mouse monoclonal antibody U85 recognising Newcastle disease virus was the kind gift of Ruth Manvell, AHVLA, Weybridge, UK.