Lentiviral Knockdown of Transcription Factor STAT1 in Peromyscus leucopus to Assess Its Role in the Restriction of Tick-borne Flaviviruses.

Cellular infection with tick-borne flaviviruses (TBFVs) results in activation of the interferon (IFN) signaling pathway and subsequent upregulation of numerous genes termed IFN stimulated genes (ISGs) ( Schoggins et al., 2011 ). Many ISGs function to prevent virus pathogenesis by acting in a broad or specific manner through protein-protein interactions (Duggal and Emerman, 2012). The potency of the IFN signaling response determines the outcome of TBFV infection (Best, 2017; Carletti et al., 2017 ). Interestingly, data from our lab show that TBFV replication is significantly restricted in cells of the reservoir species Peromyscus leucopus thereby suggesting a potent antiviral response ( Izuogu et al., 2017 ). We assessed the relative contribution of IFN signaling to resistance in P. leucopus by knocking down a major transcription factor in the IFN response pathway. Signal transducer and activator of transcription 1 (STAT1) was specifically targeted in P. leucopus cells by shRNA technology. We further tested the impact of gene knockdown on the ability of cells to respond to IFN and restrict virus replication; the results indicate that when STAT1 expression is altered, P. leucopus cells have a decreased response to IFN stimulation and are significantly more susceptible to TBFV replication.