The N-terminal protease Npro from pestiviruses has been shown to rapidly dismantle the innate immune response by targeting IRF3 for degradation, resulting in inhibition of apoptosis and interferon production. To understand it’s role in these different responses, we have identified multiple cellular factors that interact with this viral protein using mass spectrometry and proteomic analysis. Pull-down experiments were performed with Npro, and the samples were run on an SDS gel. Each lane was cut into 5-6 sclices and the slices were digested with trypsin. Peptides were extracted and analysed by LX-MSMS on an LTQ-Orbitrap (Thermo). Data were processed with MaxQuant (1.3.0.5) and searches performed with Mascot on the Sptrembl database (taxonomy human). All gel slices from one sample were merged in one Mascot search. Mascot results were imported into Scaffold 3.6.5.