Oral infection challenge with murinised Lmo-InlA-mur-lux is associated with elevated IFN-β induction. Albino IFN-β-reporter (Ifnb1tm2.2Lien) mice on a C57BL/6J genetic background were infected intragastrically with 5 × 109 CFU Lmo-EGD-lux or Lmo-InlA-mur-lux (n = 5). At the indicated timepoints, mice were first analysed for dissemination of bioluminescent L. monocytogenes as described for Figure 1 (A) and then subsequently i.v. injected with luciferin and monitored for firefly luciferase activity as a reporter of IFN-β induction (B), see Methods. Serial BLI for bacterial and firefly luciferase activity was performed at 1 h post infection and then daily till 8 d.p.i.. The colour bar indicates photon emission with 4 min integration time in photons/s/cm2/sr. Uninfected Ifnb1tm2.2Lien reporter mice are shown as controls at the top in (B). (C) Quantification of firefly luciferase light signals presented in (B) in Lmo-EGDe-lux (grey columns) and Lmo-InlA-mur-lux (black columns) infected IFN-β-reporter mice by measuring luminescence intensity in an identical selected region in each animal as indicated on the left. Data represent means ± SEM. Bacterial luciferase photon emission was subtracted from firefly BLI signals to generate the graph shown in (C). One out of two representative experiments is shown (A-C).