SPI1 and infection: In the murine salmonellosis model, SPI1 is needed for invading non-phagocytic cells in the small intestine (Hansen-Wester and Hensel, 2001; Galan, 2001), while SPI2 is crucial for the intracellular phase of infection (Hensel, 2000; Figueira and Holden, 2012).