Figure 2

Absence of CSK29544_02616 reduces fitness in competition with WT during host infection. (a) Impaired fitness caused by the lack of CSK29544_02616. HeLa and RAW264.7 cells and rat pups (2–3 days old) were administered with a mixture of bacterial suspension containing equivalent CFUs of WT and ΔCSK29544_02616::kan^R strains. Bacterial fitness was assessed using CI. Mean CIs from indicated mammalian cells and five animals are presented above average lines. (b) Fluorescence microscopic analysis of RAW264.7 cells. Mammalian cells were infected with a bacterial mixture containing equivalent CFUs of WT expressing GFP (arrows) and ΔCSK29544_02616 expressing mCherry (arrow heads). At 1.5 h (phagocytosis) and 5 h post-infection, infected macrophage cells were stained with Hoechst 33342 (blue) and CellMask Deep Red (cyan) to detect the nucleus and plasma membrane, respectively. Scale bar: 5 or 10 μm.