Quantification of Myddosomes by image segmentation based on particle size and fluorescence intensity displayed a pattern similar to IRF-1 activation: live Mav increased Myddosome formation over the first 24 hours followed by a decrease 2 and 3 days post infection, whereas the number of Myddosomes per cell increased substantially at day 3 in macrophages harboring PFA-killed Mav (Fig 5B). Here, IRF1 is linked to infection.