Fig 1. L pro reduces IFN- β gene transcription when introduced into a recombinant EMCV containing an inactive stress antagonist. (A) Schematic representation of the recombinant EMCV-L Zn and EMCV-L pro viruses (the latter was described in detail in [45]). In EMCV-L Zn , L contains inactivating mutations in its Zn-finger domain (C19A/C22A) which abolishes its ability to suppress antiviral responses. To generate EMCV-L pro , the Lb pro gene of FMDV O-strain was introduced at the 5’ end of the EMCV-L Zn open reading frame. The L pro cleavage site at its own C-terminus was mutated to AAA. Instead L pro is released from this viral polyprotein via an EMCV 3C cleavage site. (B) Hela R19 cells were infected at MOI 10 with the indicated viruses and cells were lysed at 2,4,6,8 h pi. Total RNA was isolated and used for RT-qPCR analysis for IFN- β and actin mRNA, and EMCV vRNA. The IFN- β levels are depicted as a fold induction compared to levels in mock-infected cells, after correction for actin mRNA levels. The EMCV vRNA is depicted as a copy number per cell, calculated from a plasmid standard. Error bars depict the SD. One-way ANOVA with the Dunnet post hoc test was used to determine statistical significance compared to the results for EMCV-L Zn -infected cells ( � , p < 0.05; ��� , p < 0.001; ���� , p < 0.0001; ns, no significant