The ETS transcription factor ELF1 regulates a broadly antiviral program distinct from the type I interferon response
Fig 2
Impact of ELF1 on influenza A virus growth.
a. A549 were transduced to express transgenes and RFP as control. 48 h post transduction, cells were challenged with a low MOI of influenza A virus, and % of virus–infected (NP–positive) cells determined by high content microscopy after one or multiple replication cycles. b. Mean ± SEM of % influenza A/WSN/1933 virus–infected cells by high content microscopy in A549 expressing ELF1, IFITM3 as early (entry) ISG inhibitor control, or empty vector as negative control (n = 4). 12 hpi (one cycle of replication, left y–axis) or 48 hpi (multi–cycle replication, right y–axis). One–way ANOVA and Dunnett’s multiple comparison test versus “empty”. c. A549 were transduced to express transgenes ELF1 or IFITM3, or empty vector control. Endogenous and overexpressed ELF1 or IFITM3 protein and actin control post transduction by western blot. Influenza A/WSN/1933 virus growth kinetics on transduced cells (n = 3). Extracellular virus titers by plaque assay on MDCK cells. Individual t–tests between empty and ELF1, or IFITM3 and ELF1, *p<0.1. d. Influenza A/WSN/1933 virus growth kinetics on primary normal human bronchial epithelial (NHBE) cells expressing ELF1 or empty vector (n = 3). Extracellular virus titers by plaque assay on MDCK cells. Individual t–tests between empty and ELF1, *p<0.1. e. In vivo morpholino oligomers (MO)–mediated ELF1 knockdown in A549. ELF1, ELF1 5’UTR–targeting MO; NTC, 5–base–pair non–targeting mismatch control. Endogenous ELF1 protein and actin control post MO knockdown prior to infection by western blot. % ELF1 protein normalized to actin and mismatch control. Influenza A/WSN/1933 growth kinetics post MO knockdown, n = 3. Mean ± SEM virus titer by plaque assay on MDCK cells. Individual t–tests between PBS control and ELF1 knockdown, or NTC control and ELF1 knockdown, *p<0.1.