IFNAR1 and infection: Next, to check whether Type I IFN dependency in MAB-R strains induced cell-to-cell spread, we compared the cell-to-cell spreading capacity of EGFP-expressing recombinant strains of MAB-R [rEGFP_MAB-R (Asan 50594)] strain, M. smegmatis (rEGFP_M.smeg), and M. bovis BCG (rEGFP_BCG) after their infection into BMDMs from wild mice or IFNAR1 KO mice.