Pathogen host interactions: Proteomics of Influenza NEP during infection reveals an antagonistic role in the formation of tight junctions

Host-pathogen interaction networks are key to understanding the molecular mechanisms driving disease and can provide new targets for therapeutic intervention. We discovered new host factors interacting with the influenza nuclear export protein (NEP) using an engineered influenza virus expressing NEP with an N-terminal 3xFLAG tag. We collected immunopurification mass spectrometry data for 3xFLAG-NEP during an active infection and during plasmid expression in HEK293T cells. Network analysis of these complementary datasets revealed an enrichment of tight junction proteins in the NEP interactome. Expression of NEP in MDCK cells results in inhibition of tight junction formation as measured by transepithelial electrical resistance and inulin diffusion across the polarized cell monolayer. These findings reveal a new role for NEP as a tight junction antagonist.