Human interactome of the influenza B virus NS1 protein

This work was partially supported by NIAID grant U19AI106754, and by CRIP (Center for Research in Influenza Pathogenesis), an NIAID funded Center of Excellence for Influenza Research and Surveillance (CEIRS, contract #HHSN272201400008C) to A. G-S. Work at the University of Zurich was supported by the Swiss National Science Foundation (grant 31003A_159993 to BGH). NS1 proteins of influenza A and B viruses share limited sequence homology, yet both are potent manipulators of host cell processes, particularly interferon (IFN) induction. Although many cellular partners are reported for A/NS1, only a few (e.g. PKR and ISG15) have been identified for B/NS1. Here, affinity-purification and mass spectrometry were used to expand the known host interactome of B/NS1. We identified 22 human proteins as new putative targets for B/NS1, validating several, including DHX9, ILF3, YBX1 and HNRNPC. Consistent with two RNA-binding domains in B/NS1, many of the identified factors bind RNA and some interact with B/NS1 in an RNA-dependent manner. Functional characterization of several B/NS1 interactors identified SNRNP200 as a potential positive regulator of host IFN responses, while ILF3 exhibited dual roles in both IFN induction and influenza B virus replication. These data provide a resource for future investigations into the mechanisms underpinning host cell modulation by influenza B virus NS1. Publisher PDF