Listeria monocytogenes is an intracellular pathogen, broadly used as a model to investigate host-pathogen interactions. Different groups have shown the production of type I IFN in vitro and in vivo upon infection with Listeria monocytogenes [10, 11] . We followed IFN-b induction in the mouse using non-invasive whole body in vivo imaging. This way we derived a spatiotemporal resolved picture of the early IFN-b response during Listeria infection. We focused on production of IFN-b, because IFN-b appears to be the primary member of type I IFN family that is induced after infection with Listeria [16, 17] and initiates the cascade of type I IFN in most cell types [4, 5] .