IFNB1 and infection: In addition, infection with a recombinant influenza virus expressing the mutant NS1 R38A/K41A protein (rgPR8/NS138/41A) significantly enhanced the detectable levels of cytosolic mtDNA and STING-dependent IFN-β gene expression compared to WT virus-infected cells without affecting the expression levels of the NS1 protein (Fig. 6c, d).