Project 467124

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the viral agent responsible for the COVID-19 pandemic. A defining feature of SARS-CoV-2 infections are severely impaired antiviral type I interferon (IFN) α and β responses in patients, resulting in exacerbation of symptoms. Its non-structural protein 2 (NSP2) is of interest because NSP2 interacts with the 4E-homlogous protein/Grb10-interacting GYF protein 2 (4EHP-GIGYF2) complex, which translationally impairs IFNβ production. It is hypothesized that NSP2 interacts with the 4EHP-GIGYF2 complex to facilitate translational repression of Ifnb1 and impair the induced antiviral immune response to enhance viral replication. To explore the immunosuppressive role and mechanisms of NSP2, in vitro and in vivo aims will be pursued. Preliminary in vitro data confirm that NSP2 interacts with the 4EHP-GIGYF2 complex and demonstrate robust inhibition of IFNβ protein levels in NSP2-transfected vs. non-transfected cells, while IFNβ mRNA levels are consistent between the two sets of cells. The mechanism of NSP2-mediated translational repression of IFNβ expression will be explored by seeing whether its proposed method of action aligns with the proposed model of 4EHP-mediated repression of IFNβ, that is via recruitment of microRNA-34a to the 3' UTR on its mRNA. Polysome profiling will subsequently be performed to validate that NSP2-mediated IFNβ repression occurs at the translational level.The In vivo experimentswill generate data regarding how viral replication and host IFN responses fluctuate when 4EHP-GIGYF2-mediated NSP2 immunosuppression is functioning vs. deficient. Overall, the data will inform on the mechanism of NSP2-mediated IFN impairment, which can be used for developing SARS-CoV-2 and oncolytic viral therapies.