De novo synthesis of H1N1 influenza A virus nucleoprotein (NP) is delayed by porcine Mx1 expression. Production of viral NP by induced and non-induced V50 cells was monitored for 9 h after infection by indirect immunofluorescence, after sequential incubation with the anti-NP mAb from Abcam and Alexa 488-conjugated goat anti-mouse IgG. See text for detailed comparative analysis of NP production scenario in induced and non-induced cells.